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You can learn how to control a motor using simple tools and basic parts. This arduino tutorial guides you through building a motor driver circuit with arduino. Many beginners enjoy hands-on electronics projects like this because they make learning fun and practical. When you build a motor driver, you get to see how motor drivers work and how a motor responds to your code. Projects like this arduino project help you gain real skills and let you explore new ideas.Motor Drivers OverviewWhat Are Motor DriversYou use motor drivers to control the flow of electricity to a motor. These devices act as a bridge between your microcontroller and the motor. Microcontrollers, like Arduino, cannot supply enough current or voltage to run a motor directly. Motor drivers solve this problem by taking low-power signals from your microcontroller and switching higher currents to the motor.Motor drivers come in many forms. The most common type is the h-bridge. An h-bridge lets you control the direction and speed of a DC motor. You can make the motor spin forward, backward, or stop. The h-bridge design uses four switches, which you turn on or off in pairs. This setup gives you full control over the motor’s movement.Did you know? The electric motor market is huge. In 2024, it is worth about $166 billion and keeps growing. This growth comes from industries like manufacturing, electric vehicles, and consumer electronics. Motor drivers play a key role in these areas, making them important in many electronics projects.Here are some technical terms you may see when learning about motor drivers:ParameterDefinitionUnitsTorque constant (kM)Shows how much torque you get for each amp of current.mNm/ASpeed constant (kn)Tells you how fast the motor spins for each volt you apply.rpm/VBack EMF constant (kG)Relates the voltage produced by the spinning motor to its speed.V/rpmTerminal inductance (L)Measures how the motor windings resist changes in current.mHWhy Use a Motor DriverYou need a motor driver when you want to control a DC motor with a microcontroller. Microcontrollers cannot handle the high current needed for dc motor control. Motor drivers, especially h-bridge circuits, allow you to safely and efficiently manage this current.H-bridge motor drivers let you:Change the direction of the motor.Adjust the speed using pulse-width modulation (PWM).Stop the motor quickly or let it coast.H-bridge dc motor control is popular because it works well for many projects, from robots to fans.In real-world projects, h-bridge motor drivers help you build systems that are easy to test and maintain. For example, in cars, h-bridge circuits control seat adjustments. They work with sensors and communication systems to make movements smooth and safe.Using motor drivers in your projects gives you:More control over dc motor control.Protection for your microcontroller.The ability to add features like overcurrent protection and diagnostics.You will find that motor drivers make your electronics projects more reliable and flexible. As you learn to use h-bridge circuits, you open the door to advanced robotics and automation.Components and ToolsImage Source: unsplashParts List for Motor DriverYou need a few basic parts to build your motor driver project. Here is a list of what you should gather before you start:Arduino board (Uno or similar)Breadboard2N2222 transistor1N4001 diode220 ohm resistor0.1uF capacitorDC motor9V batteryTip: You can find these parts in most beginner electronics kits. Using a breadboard helps you test your circuit before making it permanent.Component FunctionsEach part in your motor driver circuit has a special job. Understanding these roles helps you build and troubleshoot your project.ComponentFunctionArduinoSends control signals to turn the motor on or off.BreadboardLets you connect parts without soldering.2N2222 transistorActs as a switch to control the current flowing to the dc motor.1N4001 diodeProtects your circuit from voltage spikes when the motor turns off.220 ohm resistorLimits the current going into the transistor’s base from the Arduino.0.1uF capacitorReduces electrical noise and smooths out voltage changes.DC motorConverts electrical energy into motion.9V batterySupplies power to the motor and the circuit.When you connect the battery, chemical energy changes into electrical energy. The current flows through the complete circuit path, making the dc motor spin. The Arduino sends a signal to the transistor, which then lets current reach the motor. The diode keeps your components safe by blocking sudden voltage spikes. The resistor and capacitor help control and stabilize the flow of electricity.You can use a circuit diagram to see how each part connects. Circuit diagrams use symbols to show the layout. This makes it easier to understand and build your project. If you add or remove parts, you change how much current flows. This can affect how fast or strong your motor runs.Hands-on activities like this help you see how each component works together. You learn how batteries in series add up their voltages, and how each part influences the whole circuit.Building the Motor DriverCircuit DiagramYou need a clear circuit diagram before you start building. The diagram shows how each part connects. It helps you avoid mistakes and makes the assembly process easier. In this project, you use a simple h-bridge design to control the motor. The h-bridge lets you change the direction and speed of the motor using a pwm signal from the Arduino.A typical circuit diagram for this project includes:Arduino connected to the base of a 2N2222 transistor through a 220 ohm resistor.The collector of the transistor connects to one terminal of the DC motor.The other terminal of the motor connects to the positive side of the 9V battery.The emitter of the transistor connects to ground.A 1N4001 diode is placed across the motor terminals, with the cathode to the positive side, to protect against voltage spikes.A 0.1uF capacitor is placed near the motor to reduce electrical noise.Note: Engineers use tools like Altium's PDN Analyzer to simulate current paths in the circuit. This helps check if the copper traces and connectors can handle the expected current. The simulation also shows areas that might overheat and suggests ways to improve the design, such as changing resistor values or adding more copper for better heat dissipation. These steps make sure your circuit works safely and reliably.Wiring StepsFollow these steps to assemble your motor driver on a breadboard:Place the Arduino and breadboard on your workspace.Insert the 2N2222 transistor into the breadboard. Make sure you know which pin is the collector, base, and emitter.Connect the base of the transistor to a digital pin on the Arduino (for example, pin 9) using a 220 ohm resistor.Attach the collector of the transistor to one terminal of the DC motor.Connect the other terminal of the motor to the positive terminal of the 9V battery.Connect the emitter of the transistor to the ground rail on the breadboard.Connect the Arduino ground to the breadboard ground rail.Place the 1N4001 diode across the motor terminals. The cathode (marked end) should go to the battery positive side.Add the 0.1uF capacitor across the motor terminals to help reduce noise.Double-check all connections before powering up.You control the motor speed by sending a pwm signal from the Arduino to the transistor base. The pwm signal turns the transistor on and off very quickly. This controls how much current flows through the motor, which changes the motor speed. If you want to reverse the direction, you can use a full h-bridge circuit. For now, this simple setup lets you practice basic motor speed control.Tip: Use short wires and keep your connections neat. This reduces noise and makes troubleshooting easier.Safety TipsYou must follow safety tips when working with any circuit, especially when controlling motor speed with an h-bridge or pwm signal. Proper safety steps protect you and your components.Always check the polarity of your battery and diode. Reversing them can damage the circuit.Never touch the circuit when it is powered. Disconnect the battery before making changes.Use the correct value for the resistor and capacitor. Wrong values can cause overheating or unstable motor speed.Place the diode in the right direction. The cathode should face the positive voltage. This protects your circuit from voltage spikes when the motor stops.Make sure your wires are secure. Loose connections can cause the pwm signal to fail or the h-bridge to malfunction.Automotive safety standards like ISO 26262 and ASIL show why safety matters. These standards cover risk analysis, design, and testing for motor driver circuits. They help prevent hazards like overheating or loss of control. Engineers use these guidelines to design safe circuits for cars and robots. You can follow similar steps to keep your project safe.Safety Function DescriptionSafety Rating StandardKey Components and NotesEmergency Stop using programmable controllers and safety contactorsCategory 3, PLd to EN ISO 13849-1: 2008Compact GuardLogix Controller, POINT Guard I/O Module, Dual-channel E-Stop ButtonAccess and Door Guarding with GuardLogix controller and safety switchesCategory 4, PLe to EN ISO 13849-1: 2015GuardLogix 5570 Controller, ArmorBlock Guard I/O Module, SensaGuard Switch, ArmorStart ST Motor Controller (Safety Version)Programmable Controller with Cable Pull SwitchesCategory 3, PLd to EN ISO 13849-1: 2015GuardLogix Controller, Lifeline Cable Pull Switch, POINT Guard I/O Safety ModulesSafety Relay for Emergency StopCategory 3, PLd to EN ISO 13849-1: 2008800F E-Stop, Guardmaster Single-input Safety Relay, 100S Safety ContactorsRemember: Careful wiring and correct component placement help you avoid common mistakes. Always test your circuit with low power first. If you notice any heat or strange smells, disconnect power right away.You now have the knowledge to build a safe and reliable motor driver. You can control motor speed with a pwm signal and practice using an h-bridge for more advanced projects. This hands-on experience prepares you for bigger challenges in robotics and automation.Arduino and L298N Motor DriverImage Source: unsplashL298N Motor Driver BasicsYou can use the L298N motor driver to control motors in more advanced Arduino projects. This driver works well for dc motor control and arduino robot car control. The L298N motor driver supports up to 46V and 4A, which means you can drive bigger motors than with basic circuits. It uses a dual H-bridge structure, so you can control two motors at the same time. You can change the speed and direction of each motor by sending signals from your Arduino.SpecificationDetailsOperating Voltage RangeUp to 46VMaximum Continuous CurrentUp to 4AMaximum Output Current3A per outputPower Dissipation25WLogic Input CompatibilityTTL-compatibleOver-temperature ProtectionYesThe L298N motor driver uses enable pins for speed control. You send a PWM signal from your Arduino to these pins. The driver also has built-in protection features, such as overheating shutdown and freewheeling diodes. These features help keep your project safe and reliable.Note: The L298N motor driver can control two DC motors or one stepper motor. This makes it a flexible choice for many Arduino robot car control projects.Connecting Arduino and L298NYou connect your Arduino and L298N motor driver using a few simple steps. The most efficient way is to remove the jumper between the enable pin and 5V on the driver. Then, connect the enable pin to a PWM pin on your Arduino. Connect IN1 and IN2 to two digital pins. This setup lets you control the speed and direction of each motor with fewer PWM pins.ENA/ENB pins: Connect to Arduino PWM pins for speed control.IN1, IN2, IN3, IN4: Connect to Arduino digital pins for direction control.Power supply: Use 12V to 35V for stable operation.This method protects your Arduino and gives you full control over dc motor control and arduino robot car control. The L298N motor driver can output up to 2A per channel, which is enough for small and medium motors. If you notice your motors running at different speeds, check your wiring and power supply. Sometimes, small differences in speed can happen due to the motors or the driver.Tip: Always test your setup with different motors or power supplies if you see problems. This helps you find the cause quickly.Stepper Motor Driver OptionYou can also use the L298N motor driver as a stepper motor driver. Stepper motors are popular in robotics because they offer precise movement and high reliability. Microstepping drivers give you smoother motion, which is important for arduino robot car control and other robotics projects. When you use a stepper motor driver, you can adjust the speed and stepping resolution to match your needs.Stepper motor drivers work well for projects that need accurate control, such as 3D printers or robotic arms. They let you set the distance, speed, and accuracy for each move. Many robotics projects use stepper motor drivers because they balance cost, performance, and control.Code and TestingUploading CodeYou can upload arduino code to your board to control motor speed with pwm signals. Start by opening the Arduino IDE on your computer. Connect your Arduino to the computer using a USB cable. Select the correct board and port in the Tools menu. Copy and paste the code below into the IDE. This code uses pwm to control motor speed and direction. You can change the values to test varying speeds.const int motorPin = 9; // PWM pin connected to transistor basevoid setup() { pinMode(motorPin, OUTPUT);}void loop() { analogWrite(motorPin, 128); // Set motor speed to half (128 out of 255) delay(2000); // Run for 2 seconds analogWrite(motorPin, 255); // Set motor speed to full delay(2000); // Run for 2 seconds analogWrite(motorPin, 0); // Stop motor delay(2000); // Pause for 2 seconds}Efficient coding practices help you get reliable results. Use modular functions for direction and speed control. Debounce button inputs with short delays to avoid signal jitter. The table below shows how you can use digital pins and pwm for h-bridge dc motor control and pwm dc motor control.Motor Control FunctionDirection Pin (Left Motor)Speed Pin (Left Motor, PWM)Direction Pin (Right Motor)Speed Pin (Right Motor, PWM)ForwardLOW (D4)200 (D6)LOW (D2)200 (D5)BackwardHIGH (D4)50 (D6)HIGH (D2)50 (D5)Turn LeftHIGH (D4)200 (D6)LOW (D2)200 (D5)Turn RightLOW (D4)200 (D6)HIGH (D2)200 (D5)StopLOW (D4)0 (D6)LOW (D2)0 (D5)You can see how pwm signal values change for different actions in this chart:Image Source: statics.mylandingpages.coTesting the Motor DriverAfter uploading the arduino code, test your circuit. Watch the motor as it runs at different speeds. The pwm signal controls how fast the motor spins. You should see the motor speed change every two seconds. If you use an h-bridge, you can also test direction changes. Use the serial monitor to check if the Arduino receives the right signals. When you press buttons or send commands, the motor should respond right away.Test codes on Arduino Nano boards show that you can control motor speed and direction. You can rotate servo arms to different angles or make the motor move forward, backward, left, or right. The serial monitor helps you confirm that the pwm signal and arduino code work as expected.TroubleshootingIf your motor does not spin or the speed does not change, follow these steps:Check all wiring and connections for loose or incorrect placement.Make sure the battery has enough voltage for the motor.Use a multimeter to check for voltage at the motor terminals.Inspect the transistor and diode for correct orientation.Look for error messages in the Arduino IDE.Use built-in diagnostic tools to monitor pwm signal and motor speed.Observe the motor for unusual sounds, vibrations, or heat.Review your arduino code for mistakes in pwm or direction control.Document any error codes or strange behavior.Consult the motor driver manual or seek help if needed.Manufacturers often provide fault codes for motor drivers. These codes help you find problems like internal faults, power issues, or motor load errors. You can use software tools to read these codes and compare them with normal operation. This process helps you fix issues quickly and keep your project running smoothly.Tip: Always test your circuit at low speed first. If you notice overheating or odd smells, disconnect power and check your setup.You followed this tutorial to build and test a basic motor driver. You learned how to connect parts, upload code, and check your results. Try using different sensors or adding lights to make your project unique. You can also use other types of motors for new challenges.Share your results or ask questions in the comments. Your feedback helps others learn from this tutorial.FAQHow do you know if your motor driver circuit works?You should see the motor spin when you upload the code. If the speed changes as expected, your circuit works. If nothing happens, check your wiring and power.Can you use a different transistor instead of 2N2222?Yes, you can use other NPN transistors like BC547 or 2N3904. Make sure the transistor can handle the current your motor needs.Why does the diode go across the motor?The diode protects your circuit from voltage spikes. When you turn off the motor, it can send a sudden voltage back. The diode blocks this and keeps your parts safe.What should you do if the motor gets hot?Unplug the power right away. Check if your motor draws too much current. Use a lower voltage or a bigger motor driver if needed.

IntroductionWhat is RS485?MaterialsMAX485 pinoutHalf duplex operationHere is how the program worksFull duplex operationHalf duplex operation codeFull duplex codeIntroductionIn digital computer communication between two computers can be made using either parallel or serial method. In parallel communication separate line is dedicated for a one-bit information to transfer. This communication is fast and easy, but it requires a lot of wires at least as many as the number of bits need to be sent in parallel. For example, to transfer a 64-bit data from one device to another, 64 data lines will be required which is impractical in embedded systems. The alternative method to transfer data is to use serial communication. In serial communication one bit at a time is transferred from one device to another one. While this method solves the wiring problem it has a lot of other problems such as bandwidth, data lagging, complex protocol, and electrical standards. There are lot of different methods to do serial communication while one method is good in one situation another one is better in another situation. In this article we will discuss RS485 communication protocol which is one of the many available serial communication methods.Materials1MAX485 module2STM32 F401CDU6What is RS485?An industry specification called RS-485 outlines the physical layer and electrical interface for point-to-point electrical device communication. RS485 is the industrial standard for communication that defines the electrical interface and physical layer for point-to-point communication. RS485 is a robust communication system it can support multiple devices on a single bus, works in a noisy environment as well and requires a maximum of 4 lines.RS485 was first developed in 1983 and has since been used in many industrial applications because of its robustness and simplicity. It has the ability to transmit data over long distances while at the same time it is cheap, thus engineers are using it in all sorts of applications such as automotive, manufacturing, and theater spaces. Nowadays almost all motor controllers, VFDs and manufacturing machines will have a port available for RS485.RS485 is actually a standard that defines the electrical characteristics of the transmitters and receivers for communication protocols. RS482 uses two lines usually called A and B which must be balanced and differential. It means that the two lines must have same impedance, nearly same length and must be differential. The key features of RS485 communication are given belowMultipoint operation10 Mbps data transfer rate at 40 feet lengthMaximum cable length is 4000 feetRS485 works both in half duplex as well full duplex mode. In half duplex mode one device can either transmit or receive data at a time. While in full duplex mode, a device can transmit and receive data at the same time. Having more than one device on a bus can cause problem when two or more devices transmit data at the same time. Therefore, software control is necessary to ensure only one device transmit data at a time.RS485 is the physical layer of communication in the OSI model. It means this layer can be used as a base for other protocols such as UART which in most application people use because UART is an asynchronous communication protocol that does not require any clock signal which make it very easy to use. In this article we will demonstrate how RS485 can be used between two STM32 microcontrollers to communicate and exchange data. We will be using MAX485 module which is an easily available RS485 module. MAX485 pinoutRO → Receiver outputRE → Receiver enableDE → Data enableDI → Data inputVCC → Input voltageGND → GroundA, B → RS485 differential linesHalf duplex operationIn half duplex operation either data can be received or transmitted at a time. Both operations cannot be done at the same time. MAX485 has data flow control pins called DE and RE which puts the module in receiver mode or in transmit mode. Making them low puts the module in receiving mode while making them high puts the device in transmitter mode.In CubeMX the microcontroller of our choice is selected which in our case is STM32 F401CDU6. In connectivity UART1 should be enabled with 115200 bps baud rate. Other necessary settings are given below.RCC → Crystal/Ceramic ResonatorSYS → Debug → Serial WireClock Configuration → HCLK → 84 MHzClock Configuration → PLL Source Mux → HSEGPIO A7 is set as outputHere is how the program worksThe setup has two microcontrollers. We will call one side as A and the other side as B. When a user presses the user key on A STM32 microcontroller it will send the information to the B microcontroller via RS485. The receiving B microcontroller will switch on the onboard LED and will responds with an OK message. The OK message will blink the led on A microcontroller twice. Similarly, when the user presses key on B microcontroller it will transmit a message to A microcontroller and turns on the onboard LED and will responds with an OK message. The OK message will blink LED on B microcontroller twice. Similarly pressing the button again will do the same except this time it will turn off the LED.Full duplex operationIn full duplex operation data can be received or transmitted at the same time. Both operations can be done at the same time. In this mode two MAX485 modules will be required at each end and overall, 4 MAX485 modules will be used. It means that the two MAX485 modules will be constantly in receiving mode while the other two will constantly in transmission mode. MAX485 has data flow control pins called DE and RE which puts the module in receiver mode or in transmit mode. We will put the data control pins of two module as high while put the data control pins of other two module low. The configuration is shown below.The program works the same way as it was working in the half duplex mode however, this time the transmitted and received by MCUs at the same time.Half duplex operation code#include "main.h" UART_HandleTypeDef huart1; /* USER CODE BEGIN PV */int8_t R_Data[1] = {0};int8_t T_Data[1] = {69};/* USER CODE END PV */ /* Private function prototypes -----------------------------------------------*/void SystemClock_Config(void);static void MX_GPIO_Init(void);static void MX_USART1_UART_Init(void); int main(void){   HAL_Init();   SystemClock_Config();     MX_GPIO_Init();  MX_USART1_UART_Init();  /* USER CODE BEGIN 2 */  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);   //Put RS485 module in receiving mode  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET);   //Turn Off LED pin    while (1)  {      HAL_UART_Receive(&huart1, R_Data, 1, 10);  // If button is pressed on the other MCU  if(R_Data[0] == 83)  {  HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);                //Toggle LED pin  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);    //Put RS485 module in transmission mode  HAL_UART_Transmit(&huart1, T_Data, 1, 10);             //Send acknowledgment  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  //Put RS485 module in transmission mode  R_Data[0] = 0;  }  // If OK message is receive  if(R_Data[0] == 69)  {  if (HAL_GPIO_ReadPin(GPIOC,GPIO_PIN_13))  {  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  }  else  {  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  }  R_Data[0] = 0;  }  // Button is pressed  if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0))  {  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);    //Put RS485 module in transmission mode  T_Data[0] = 83;  HAL_UART_Transmit(&huart1, T_Data, 1, 10);  T_Data[0] = 69;  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);    //Put RS485 module in Receiving mode  }  }  /* USER CODE END 3 */}Full duplex code#include "main.h" UART_HandleTypeDef huart1; /* USER CODE BEGIN PV */int8_t R_Data[1] = {0};int8_t T_Data[1] = {69};/* USER CODE END PV */ /* Private function prototypes -----------------------------------------------*/void SystemClock_Config(void);static void MX_GPIO_Init(void);static void MX_USART1_UART_Init(void); int main(void){   HAL_Init();   SystemClock_Config();     MX_GPIO_Init();  MX_USART1_UART_Init();  /* USER CODE BEGIN 2 */  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET);   //Turn Off LED pin    while (1)  {      HAL_UART_Receive(&huart1, R_Data, 1, 10);  // If button is pressed on the other MCU  if(R_Data[0] == 83)  {  HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);                //Toggle LED pin  HAL_UART_Transmit(&huart1, T_Data, 1, 10);             //Send acknowledgment  R_Data[0] = 0;  }  // If OK message is receive  if(R_Data[0] == 69)  {  if (HAL_GPIO_ReadPin(GPIOC,GPIO_PIN_13))  {  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  }  else  {  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);  HAL_Delay(500);  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  }  R_Data[0] = 0;  }  // Button is pressed  if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0))  {  T_Data[0] = 83;  HAL_UART_Transmit(&huart1, T_Data, 1, 10);  T_Data[0] = 69;  }  }  /* USER CODE END 3 */}  

CatalogIntroductionⅠ Types of Relay    1.1 What is a SPDT Relay    1.2 What is a DPDT Relay    1.3 The Symbol of DPDT RelayⅡ 12V SPDT Type RelayⅢ SPDT type Relay Pins ConfigurationⅣ How does a DPDT Relay Work?Ⅴ How to Connect DPDT Relays in the CircuitⅥ Uses of a DPDT RelayⅦ How to Connect a DPDT Relay in a CircuitSummaryIntroductionA relay is a switch that is controlled by an electrical circuit. It has a sequence of input and control signals because it is a circuit. It operates by receiving an input signal from connected input power sources that function as normal switches. This article will show you how to wire dpdt relays in a circuit. It will also assist you in comprehending how the dpdt relay operates and its applications.Quick DPDT relay component introduction and demonstrationⅠ Types of RelayElectrical Relay Switches of many varieties are available on the market.SPST – Single Pole Single ThrowDPST – Double Pole Single ThrowSPDT – Single Pole Double ThrowDPDT – Double Pole Double ThrowHowever, the most commonly utilized Relays are SPDT Relays and DPDT Relays, both of which function as electromechanical switches.1.1 What is a SPDT RelayA single pole double throw (SPDT) relay has two coil terminals and a common terminal, followed by two switching terminals N/O (Normally Open), N/C (Normally Closed) (Normally Close)If there is insufficient DC supply in the coil terminals, the relay displays the idle situation, which is represented by the common terminal attached to the N/C terminal. When the coil receives the needed DC supply, it becomes magnetically energized, and the magnetic flux force attracts the common terminal lever, which is composed of iron and connects to the N/O terminal, causing the N/C to open.1.2 What is a DPDT RelayA dpdt relay is an electromagnetic device used in electric motors. It is also known as a Double(D) Pole(P) Double(D) Throw(T) relay. There are two inputs to a dpdt. Furthermore, each piece of data has two outputs.This DPDT Relay has two coil terminals, two independent common terminals C1, and C2, and two Normally Open (N/O1, N/O2), and two Normally Close (N/C1, N/C2) terminals. It makes two different connections and controls the coil with a single control signal.If there is no bias at the coil, the relay remains in an idle state, with common terminals connected to N/C terminals. When DC bias arrives at the coil, it magnetically energizes and attracts common terminal levers, forming a connection between common terminals and N/O terminals. The N/C terminals now become open and work with their pairs.1.3 The Symbol of DPDT RelayLet's look at the DPDT Relay connection diagram to better comprehend its operation.The coil of the relay is connected to a battery series with a switch designated S1 in this diagram. Two distinct circuits are linked by two distinct input and output pairs. Battery1, LED1, and LED2 make up Circuit 1. Circuit 2 is made up of batteries 2, LED 3, and LED 4.When switch S1 is turned off, the relay's coil is not energized, so LED2 and LED4 are turned on since they are linked to NC terminals, but LED1 and LED3 are turned off.When the switch S1 is turned on, the coil of the relay is activated, which turns off the LED2, and LED4, and turns on the LED1, and LED3.DPDT relays are found in sophisticated electronic circuits and gadgets.The DPDT relay is highly intriguing and may be utilized in a variety of scenarios, including altering the direction of a motor, as seen in the illustration below. It has two terminals and four connectors, and it is equivalent to two Single Pole Double Throw SPDT relays.Ⅱ 12V SPDT Type RelayThis is a 12V SPDT relay (Single Pole and Double Throw). Normally, I utilize these types of relays to manage alternating current loads. The specifications for the relay are displayed on the top. This relay can be controlled using 12VDC, which is the voltage utilized to energize the relay coil. This voltage is fully isolated from the voltage supplied to the relay's Common and typically closed or normally open contacts.It can handle AC load currents of up to 7Amps at 250VAC, 10A AC loads at 125VAC, and 12A AC loads at 120VAC. This relay can also manage DC loads with a voltage of up to 28VDC and a current of up to 10Amps.Ⅲ SPDT type Relay Pins ConfigurationEven if you use a 5v Relay, the pin configuration of these sorts of relays is the same.This relay has a total of 5 pins or contacts, with 3 on one side and 2 on the other. The center of the three contacts on the left side is the common contact, while the other two are coil contacts. On the right, there are two contacts, NC and NO. The normally closed contact is NC, and the normally open contact is NO. The coil connections are electrically insulated from the Common, Normally Closed, and Normally Open contacts. In other words, no physical connection exists between the coil contacts and the other relay connections.Connect 12V and GND to the coils relay coil connections to test this relay. Because the relay coil has no polarity, it makes no difference whether the side of the coil is connected to the 12VDC and which side is connected to the GND.Ⅳ How does a DPDT Relay Work?When manual switching is unavailable, a relay-insulated coil automatically flips changeover switches. As a result, it functions as a control circuit. When electricity is applied, relays frequently use components that resemble transistors to carry the electrical loads. However, there is a type known as electromechanical relays. These relays are simple to understand.The relays use low voltage to convert the electromagnet into a magnetic field. It also contains a contact switch for controlling the magnetic circuit. When the maintained course is within the magnetic field, the relay mostly operates as if a button is flipped with the contacts in place.Because of the operating principles of a household switch, it will always remain in the state you left it. If you turn it on, it will remain on until you turn it off, and vice versa. A relay coil, on the other hand, operates differently since its basic activities need electromagnetic actions. The electrical switches are relaxed when the magnet present is in a field during deactivation. It says that if the current ratings are off, the external circuit will switch on; else, the device would fail.A dpdt relay is a type of relay with two poles. As a result, this double pole can toggle the circuit on both sides. Furthermore, the dpdt has a double throw. Because of the double-throw, the course may simply switch between wires rather than just control output by turning it on and off using electric power systems.Ⅴ How to Connect DPDT Relays in the CircuitA dpdt is an electromagnetic relay that contains a solenoid wrapped in an insulated wire coil. This device features some connections as well as a reasonably moveable iron armature motion. It also has a magnetic flux of a low reluctance path that is emitted by an iron yoke. Not to mention the standard circuit conditions it possesses. Change the direction of a motor with a dpdt relay. (Circuits that explain the operation of a dpdt relay in a motor.)We're using a 12v battery and various contact sets based on the circuit design's printed circuit board. Similarly, any continuous power battery can be used in the relay coil connection. We also link the contacts in parallel. The power source's positive end will be connected to the T1 terminal, while the negative end will be connected to the T2 terminal. We also have DPDT contacts 1 and 4 connected, as well as DPDT auxiliary contact sets 2 and 3.When no trigger voltage is applied to the single coil, the positive end of the battery is connected to T1. This will then be related to contact 1. Furthermore, the opposing end will connect to T2 and make contact with 2. These contacts that link to T1 are known as positive-guided contacts. It causes that motor to rotate clockwise.When we provide trigger voltage to the single-coil, the automotive relay switches automatically. As a result, the contacts in the circuit track alter, resulting in contact resistance. T1 from the battery's +Ve terminal connects to contact 2, whereas T2 from the negative terminal connects to contact 4. As a result, the motor's rotational orientation is reversed anticlockwise.(battery icon showing the positive and negative ends.)Switch between 2 different loads using dpdt switches.(circuits that explain the switch between two different loads)The coil terminals link to a fan from the first circuit's contactor coil, as well as green and red LED lamps. The lighting loads are the bulbs. The green LED and fan turn on when no direct current is provided to the coil form. When a current is applied to the coil, as in circuit 2, the coil current switches the relays. As a result, the red LED and light bulb are turned on.Ⅵ Uses of a DPDT RelayUsed to separate two electronic circuits in an industrial motor starter. Then, in the presence of a magnetic field, it magnetically joins them.When the electronic switch is relaxed, we utilize them in electronic gadgets as well. This connects electronic circuits that use a low contact currently to others that use a larger contact current.an electric motorⅦ How to Connect a DPDT Relay in a CircuitTerminal PinsA Double Pole Double Throw Relay comes with 8 terminal points.The terminals are COIL, COIL, COM, COM, NO, NO, NC, NC.This correlates to the following in the relay:Terminal DescriptionsCOIL- The COILterminal is located here. These are the terminals to which you apply voltage in order to power the coils (which then will close the switch). Polarity is irrelevant. One side receives positive voltage, while the other receives negative voltage. It makes no difference which order you use. Polarity is only important when using a diode.NO- This is a switch that is normally open. When the relay is energized, meaning when the COIL receives adequate voltage, this is the terminal to which you connect the device that you want the relay to power. When the relay is not powered, the device linked to NO will be turned off, and when the relay is powered, it will turn on.NC- The Normally Closed Switch is what it sounds like. When the relay does not receive power, connect this terminal to the device you want to power. When the relay is not powered, the device linked to NC will be on and will turn off when the relay is powered.COM- This is the relay's common. COM and NO have continuity if the relay is powered and the switch is closed. COM and NC have continuity if the relay is not energized and the switch is open. This is the relay terminal to which you connect the initial part of your circuit.Now that we understand what each terminal pin represents, we can connect it to a circuit and use it to perform a real-world operation. To light up LEDs, we'll connect a Double pole double throw relay to a circuit. When the relay is not turned on, both the red LED and the DC fan illuminate. When the relay is turned on, the red LED and fan switch off, and the green LED and DC motor turn on.This is the circuit below:Because the relay is rated for 12 volts, it must be powered on using 12 volts. It may function with a lower voltage, but 12V is the minimum it should receive. This connects to the COIL terminals on either side. Even if you switched the power supply's positive and negative voltages, it should still work.The relay's COM terminals are connected to the first half of the circuit. This terminal can be left open if there is no first part of the circuit. In this scenario, the 5-volt power supply and the 9-volt power supply are used to power the LEDs, as well as the DC fan and DC motor.Even when the relay is not energized, the NC terminals receive power. This means that as long as the 5-volt power source is turned on, the red LED and DC fan will be activated.Only when the relay is energized do the NO terminals receive power. When the relay receives 12 volts of power, it switches from the NC to the NO position. The red LED and DC fan has now been turned off, and the green LED and DC motor has begun to work.SummaryA dpdt relay is widely used in electronic devices. It regulates the circuit to ensure that no current is wasted.We hope that this article shed some light on the dpdt relay. If you enjoyed it, please read more of our articles. Please contact us if you have any more questions!

CatalogIntroductionⅠ What is the Run Capacitor?1.1 Specifications of Run Capacitor1.2 The Function of the Run CapacitorⅡ Motor Run Capacitors2.1 What Does A Motor Capacitor Do?Ⅲ How Does a Run Capacitor Work?Ⅳ How Long do Run Capacitors Last?Ⅴ How Do You Know if Your Run Capacitor is Failing?Ⅵ How to Test a Run Capacitor with a MultimeterⅦ Start Capacitors vs Run Capacitors7.1 Are start and run capacitors interchangeable?Ⅷ Dual Run vs. Run CapacitorsⅨ FAQIntroductionA run capacitor is used to continuously change current or phase shift to a motor's windings to improve the torque and efficiency performance of the motor. It has a substantially lower failure rate than a start capacitor because it is designed for continuous duty.Ⅰ What is the Run Capacitor?A run capacitor is a compact cylindrical device that supplies and stores energy inside your air conditioner. It is capable of storing energy in the form of an electrical charge.start run capacitor wiring diagramSpecificationsof Run CapacitorMost run capacitor applications employ capacitance ratings of 2.5-100 uf (microfarads) and voltages of 370 or 440 VAC. They are also commonly rated at 50 and 60 Hz. Cases are typically round or oval, with a steel or aluminum shell and cover. Terminations are typically 14-inch push-on terminals with 2-4 terminals per connection post.Voltage: Choose a capacitor with a voltage rating equal to or greater than the original capacitor. If you have a 370-volt capacitor, either a 370 or a 440-volt capacitor will work, albeit the 440 volt one will last longer. A run capacitor will have a designated voltage indicating the permissible peak voltage - not the working voltage.Capacitance: Choose a capacitor with the same capacitance value (measured in MFD, uf, or microfarad) as the original capacitor. Do not stray from the original value, as it determines the motor's working characteristics.Hz: Choose a capacitor with the same Hz rating as the original. Almost all tun capacitors will be marked 50/60.Is your case round or oval? Although round run capacitors are by far the most prevalent, oval versions are still used in many motors. Electrically, there is no distinction. The only question here is fit. The case style is unimportant if space in the mounting box is not constrained.Overall Size: Just like case style, overall size has no electrical significance. Choose a capacitor that will fit in the available space.Terminal Design: Most run capacitor terminal designs contain 1-4 14" push on tabs with 3 or 4 tabs. Just make sure you have enough tabs per connection post to connect everything.The Function of the Run CapacitorOnce the system is up and running, the run capacitor takes over and provides the extra power needed to run the air conditioner for extended periods. When the air conditioner is turned on, both capacitors generate and store energy for the next cycle's push. Many air conditioning and heat pump systems include a dual capacitor arrangement that connects the start and run capacitors to the compressor and fan motors.Ⅱ Motor Run CapacitorsMotor run capacitors keep a charge and remain active while a motor is running. They improve the running performance of a motor by continuously providing additional torque, whereas start capacitors are removed from the circuit after the motor reaches its operational speed. When replacing a run capacitor, it's critical to match the form (round, oval, or rectangle) as well as the original capacitor's microfarad rating, voltage, and dimensions. Run capacitors are most commonly employed in medium-to-high torque applications such as air conditioners, auger drives, compressors, and conveyors.2.1 What Does A Motor Capacitor Do?Capacitors are used in single-phase motors to help them start and to save energy.Motor capacitors are classified into two types:Start CapacitorsRun CapacitorsA start capacitor is used to provide an extra electrical shove to start a motor. A start capacitor is only used in the motor circuit for a few seconds when it first turns on.When the motor reaches full speed, the start capacitor disconnects and is not used again until the motor is restarted. If the start capacitor fails, the motor will not be able to start.A run capacitor is an energy-saving device that is always present in the motor circuit.When a run capacitor fails, the motor can experience several issues, including not starting, overheating, and vibrating.A faulty run capacitor deprives the motor of the full voltage required to operate.A faulty run capacitor deprives the motor of the full voltage required for proper operation.Ⅲ How Does a Run Capacitor Work?The capacitor's job is to produce 240 volts to start the compressor, fan motor, and blower motor when your thermostat signals your air conditioner to chill the house.After the capacitor kickstarts those components, your air conditioner can start cooling outside air and blowing it throughout your home. The capacitor, like a rechargeable battery, gathers and stores energy while your air conditioner is running. When you switch on your air conditioner, the capacitor releases a new burst of energy. Your air conditioner may feature many capacitors, depending on its model.The run capacitor, also known as a "A/C capacitor," uses the energy it has stored to spin or run the fan motor. The fan will not turn on without the run capacitor.The start capacitor supplies the first energy required for the system to boot up. Because starting an AC system requires a lot of torque, a start capacitor will have a higher capacitance than a run capacitor. A dual capacitor supplies electricity to both the fan and the compressor, which is the large pump installed in your outdoor cabinet that circulates refrigerant between the indoor evaporator and the outdoor condensing unit.Ⅳ How Long do Run Capacitors Last?Most run capacitors are intended to last ten years. Having said that, failing capacitors are most likely the most prevalent cause of A/C repair. Allowing the fins of your outdoor coil to become so dusty and congested that air cannot circulate properly, causing the compressor to work harder.Ⅴ How Do You Know if Your Run Capacitor is Failing?If you have noticed that:Your air conditioner no longer blasts cold air; Your air conditioner no longer blasts cold air; your air conditioner makes a low humming sound that was not present previously; your energy expenses have been rising.Your air conditioner occasionally ....your run capacitor may be nearing the end of its useful life.Ⅵ How to Test a Run Capacitor with a Multimeter1. Using The Capacitance Function on a MultimeterTurn on the meterSelect the capacitance function on the dial. (See note below.) In this example, we're using a Klein multimeter, and we need to press the select button till we see capacitance mode.Capacitance Setting on the Multimeter2. Testing the Condenser Fan Section of the CapacitorPut one multimeter probe on C (common)Put the other probe on FAN.Reading the Capacitance for the Fan Motor Section of the Capacitor3. After a few seconds, the capacitance reading should appear on the monitor. Microfarads should be within 10% of the labeled specification in a good reading.4. Testing the Compressor Fan Section of the CapacitorPut one multimeter probe on C (common)Place the second probe on HERM. (HERM is an abbreviation for hermetic, which refers to a hermetically sealed compressor.)Reading the Capacitance for the Compressor Section of the CapacitorWait a few seconds and you should see the capacitance reading on the display. A good reading will have the microfarads within 10% of the labeled specification.5. Using The Resistance Function on a MultimeterA capacitor can also be examined by measuring resistance, which is best done using an analog meter. Digital meters often do not show the ohms jump that signals a good capacitor.Switch on the meter.Set the meter to Ohms. (Resembles the omega sign)6. Get a Quick Ohm Reading Between the TerminalsConnect one probe to C and the other to FAN. The ohm reading on the needle should leap and then return to infinity ohms.Reverse the probes and check the multimeter needle for the same behavior.Do the same with C and HERM.7. Get an Ohm Reading Between the Terminals and the Casing of the run CapacitorPlace one probe on C and the other on the capacitor's outside metal shell. If you receive a reading that indicates continuity, the capacitor is faulty.Rep this procedure for the FAN and HERM terminals.Testing for Shorts from the Terminals to the Casing on a Capacitor8. Test the Run CapacitorDual capacitors contain three terminals: one common (C), one fan (F), and one hermetic (Herm) connector for the hermetically-sealed compressor. The line-voltage wires connect to two more terminals on the capacitor's other end.Put one lead on the Common (C) terminal and the other on one of the other two terminals with a digital multimeter set to "Capacitance." The meter should display a number rather than "OL," which denotes a short.Here's a video that explains how to test and replace a capacitor in further detail.Before disconnecting the wires, take a short digital photo of them so you know where to reinstall them.Ⅶ Start Capacitors vs Run CapacitorsThe starting capacitor's purpose is to lag the current in a gallery winding during the motor's starting operation, and it is detached from the circuit when the router reaches its predetermined speed.The run capacitor can be used as a start capacitor, but the start capacitor cannot be used as a run capacitor. A high capacitance value is necessary to show the run capacitor array (two or more capacitors are connected in cascade) can be connected to start the motor or create strong torque across the motor.Both the start capacitor and the run capacitor are motor capacitors that serve separate functions in motor operation. Because the construction of both capacitors is the same, let's compare Start Capacitor versus Run Capacitor.Start CapacitorRun CapacitorThey are used for starting the motor. They are used for providing continuous power to the motor. Small duty cycle.Long duty cycle.Higher Capacitance rating (70-120 micro Farad)Lower Capacitance rating (7-70 micro Farad)Remain connected to the circuit for short period of time.Remain connected to the circuit for long period of time.The start capacitor is used during the startup phase of the motor and gets disconnected from the circuit when the motor reaches its predetermined speed, which is 75% of the maximum speed of the motor. Run Capacitor stays directly linked with the auxiliary coil even after the starting capacitor is disconnected (or deactivated) from the circuitry. The run capacitor remains constantly charged while providing a controlled contiguous (or continuous) power to the motor. 7.1 Are start and run capacitors interchangeable?A run capacitor could be utilized as a start capacitor in uncommon circumstances, although the values available for them are substantially lower than the values typically available for dedicated start capacitors. The capacitance and voltage ratings would have to match the specifications of the original start capacitor. A start capacitor can never be used as a run capacitor since it cannot handle continuous current (only a couple of seconds).Learn the distinctions between the start and run capacitors by watching the video instruction below.Ⅷ Dual Run vs. Run CapacitorsThe only advantage of the twin-run capacitor design is that it comes in a tiny container with only three connections. Aside from that, there is no distinction between run and dual run capacitors. If there is enough room for mounting, replacing your original dual-run capacitor with two independent run capacitors is okay. They typically have "C" connectors for "common," "H" or "Herm" connections for "Hermetic Compressor," and "F" connections for "Fan." They will also have two distinct capacitor ratings for each part.Ⅸ FAQ1. Wll a capacitor leak?Electrolytic capacitors can rupture and spill fluid if they are damaged or subjected to high loads over extended periods.2. Do capacitors boost voltage?No. While they can be employed in circuits that increase voltage, a capacitor does not increase the voltage on its own.3. Can you replace a dual run capacitor with two single run capacitors?A dual run capacitor is just two single runs housed in one housing to save space. If you have enough space and can't find a twin-run cap replacement, you can use two separate ones.4. Does the style of casing on the outside of an AC capacitor matter?The design does not affect performance as long as the capacitor is of high quality and properly placed. However, round shapes are more frequent than oval styles.5. Do all HVAC systems need a capacitor to work?While all single-phase motors have a start capacitor, certain electric motors are built without one.6. Why do start capacitors have higher ratings than run capacitors if a run capacitor is used continuously?A start capacitor requires a lot of energy to provide adequate torque to start motors in an alternating current system.7. What happens if the wrong size run capacitor is used?It will cause several issues and put unnecessary strain on the motor, such as overheating or a decrease in speed.

Introduction In this lesson, we'll look at what a servo motor is and how it works. First, let's define what a servo motor is and look at some of the unique characteristics of the different types of servo motors and their applications. You will also learn how to control Servo Motors with an Arduino and a Raspberry Pi in this blog. Introduction Ⅰ What is a Servo Motor? Ⅱ Servo Motor Related Video: Ⅲ Types of Servo Motors 3.1 AC or DC 3.2 Brushed or Brushless 3.3 Synchronous or Asynchronous Ⅳ Servo Motor Working Principle Ⅴ Applications of Servo Motors Ⅵ Difference Between Stepper Motor and Servo Motor  Ⅶ Servo Motors Control with an Arduino  7.1 Experiment 1 Ⅷ Control with  Raspberry Pi 8.1 PWM (Pulse Width Modulation) 8.2 Components Required 8.3 Circuit Diagram 8.4 Working and Programming Explanation 8.5 Code Ⅸ FAQ   Ⅰ What is a Servo Motor? A servo motor is a self-contained electrical device that rotates machine parts with high efficiency and precision. This motor's output shaft can be moved to a specific angle, position, and velocity that a standard motor cannot. The Servo Motor  combines a standard motor with a sensor to provide positional feedback. The most important component of the Servo Motor  designed and used specifically for this purpose is the controller  . Figure1:Servo Motor      Ⅱ Servo Motor Related Video:   How servo motor works   Servo Motor Video Description: This movie gives an overview of how RC servo motor works and how it's made.   Ⅲ Types of Servo Motors Servo motors are classified into two types based on their application: AC servo motors  and  DC  servo motors. There are three major factors to consider when evaluating servo motors. The first type of consideration is the current type –  AC  or  DC – and the second type of consideration is the type of commutation used, whether the motor uses brushes. The third type of consideration is the motor's rotating field, the rotor, and whether the rotation is synchronous or asynchronous.   3.1 AC or DC Let's start with the first servo consideration. The most fundamental classification of a motor is based on the type of current it will use. When it comes to performance, the primary distinction between  AC and DC motor  s is their inherent ability to control speed. Figure2:DC or AC Servo Motor  With a constant load, the speed of a DC motor  is directly proportional to the supply voltage. The frequency of the applied voltage and the number of magnetic poles determine the speed of an alternating current motor.   Figure3:DC or AC Servo Motor  While both AC and DC motor  s are used in servo systems, AC motors  can handle more current and are more commonly used in servo applications such as robots, in-line manufacturing, and other industrial applications requiring high repetitions and precision.   3.2 Brushed or Brushless The next step is to decide whether to use a brushed or brushless finish. A DC Servo Motor  can be commutated mechanically with brushes, electronically without brushes, or mechanically with a commutator. Brushed motors are less expensive and easier to operate in general, whereas brushless designs are more reliable, have higher efficiency, and are quieter.   Figure4:brushed or brushless Servo Motor  A commutator is a rotary electrical switch that reverses the current direction between the rotor and the drive circuit on a regular basis. It is made up of a cylinder made up of multiple metal contact segments on the rotor. Two or more electrical contacts known as "brushes" made of a soft conductive material such as carbon press against the commutator, making sliding contact with commutator segments as it rotates. Figure5:brushed or brushless Servo Motor  While the majority of servo motors are AC brushless designs, brushed permanent magnet motors are occasionally used as servo motors due to their simplicity and low cost. The permanent magnet DC motor  is the most common type of brushed DC motor  used in servo applications. Figure6:brushed or brushless Servo Motor  Brushless DC motors replace the physical brushes and commutator with an electronic commutation method, typically using Hall effect sensors or an encoder. Figure7:brushed or brushless Servo Motor  AC motors are generally brushless, though some designs do have brushes and are mechanically commutated, such as the universal motor, which can run on either AC or DC power. Figure8:brushed or brushless Servo Motor      3.3 Synchronous or Asynchronous While DC motor  s are generally classified as brushed or brushless, AC motors  are often distinguished by the rotational speed of their synchronous or asynchronous field. If we recall from the AC-DC discussion, the frequency of the supply voltage and the number of magnetic poles determine the speed of an AC motor. This speed is known as the synchronous speed. As a result, in a synchronous motor, the rotor rotates at the same rate as the rotating magnetic field of the stator. Figure9:synchronous or asynchronous Servo Motor  In an asynchronous motor, also known as an induction motor, the rotor rotates at a slower rate than the stator's rotating magnetic field. However, the speed of an asynchronous motor can be varied using a variety of control methods, including changing the number of poles and changing the frequency, to name a few. Figure10:synchronous or asynchronous Servo Motor      Ⅳ Servo Motor Working Principle A servo is made up of a motor (either DC or AC), a potentiometer, a gear assembly, and a control circuit. First and foremost, we use gear assembly to reduce RPM and increase motor torque. Assume that at the initial position of the servo motor shaft, the position of the potentiometer knob is such that no electrical signal is generated at the potentiometer's output port. An electrical signal is now applied to the error detector amplifier's other input terminal. The difference between these two signals, one from the potentiometer and one from other sources, will now be processed in a feedback mechanism and output will be provided in the form of an error signal. This error signal serves as the motor's input, and the motor begins to rotate. The motor shaft is now connected to the potentiometer, and as the motor rotates, so does the potentiometer, generating a signal. As a result, as the potentiometer's angular position changes, so does its output feedback signal. After a while, the position of the potentiometer reaches a point where the output of the potentiometer is the same as the external signal provided. There will be no output signal from the amplifier to the motor input because there is no difference between the externally applied signal and the signal generated at the potentiometer in this condition, and the motor will stop rotating. Figure11:synchronous or asynchronous Servo Motor    Ⅴ Applications of Servo Motors Servo Motors are used in a variety of applications, some of which are listed below:In robotics, the servo motor is used to activate movements, giving the arm its precise angle.The servo motor is used to start, move, and stop conveyor belts that transport the product through multiple stages. As an example, consider product labeling, bottling, and packaging.The servo motor is built into the camera to correct a lens and improve out-of-focus images.In a robotic vehicle, the servo motor is used to control the robot wheels, producing enough torque to move, start, and stop the vehicle as well as control its speed.In a solar tracking system, the servo motor is used to correct the angle of the panel so that each solar panel faces the sun.The servo motor is used in metal forming and cutting machines to provide milling machines with precise motion control.Textiles use servo motors to control spinning and weaving machines, knitting machines, and looms.The Servo motor is used in automatic door openers in public places such as supermarkets, hospitals, and theaters to control the door.   Ⅵ Difference Between Stepper Motor and Servo Motor  Comparison Chart Basis for ComparisonStepper MotorServo MotorBasicStepper motor operates in steps.It is continuous operating machine.System configurationOpen loopClosed loopPower requirementMoreComparatively lessDesignSimpleComplexAbility to responseHighComparatively lowCostInexpensiveExpensiveReliabilityMoreLessNoise and vibrationHighComparatively lessOperating speedSlowFastFeedback mechanismNot existExistHeat generationMoreComparatively lessNumber of polesGenerally 50 to 150Around 4 to 12Life spanMoreLessDamage due to overloadLess prone to get damaged.Comparatively more prone to get damaged.Torque producedHighLowEfficiencyLessMoreTolerance towards moment of inertiaHighLowApplicationsIn gaming, textile, welding machineries, medical and 3D printing equipments, etc.In robotics, antenna positioning systems, automatic doors, cameras, remote controlled equipments, etc. Ⅶ Servo Motors Control with an Arduino  You can connect small servo motors directly to an Arduino  to control the shaft position very precisely. Most servo motors have the following three connections: Black/Brown ground wire.Red power wire (around 5V).Yellow or White PWM wire. In this experiment, the power and ground pins will be connected directly to the Arduino  5V and GND pins. The PWM input will be connected to a digital output pin on the Arduino,  7.1 Experiment 1 Hardware Required1 x TowerPro SG90 servo motor1 x Arduino  Mega25603 x jumper wires   Wiring Diagram The best thing about servo motors is that they can be directly connected to an  Arduino ,  Connect the motor to the Arduino  in the manner shown in the table below: Servo red wire – 5V pin Arduino          Servo brown wire – Ground pin Arduino          Servo yellow wire – PWM(9) pin Arduino  Caution: Do not try to rotate the servo motor by hand, as you may damage the motor.     Figure12: Wiring Diagram Code When the program starts, the servo motor will slowly rotate from 0 to 180 degrees, one degree at a time. When the motor has rotated 180 degrees, it will start rotating in the opposite direction until it reaches the home position. #include //Servo library Servo servo_test; //initialize a servo object for the connected servo int angle = 0; void setup() { servo_test.attach(9); // attach the signal pin of servo to pin9 of arduino} void loop() { for(angle = 0; angle < 180; angle += 1) // command to move from 0 degrees to 180 degrees { servo_test.write(angle); //command to rotate the servo to the specified angle delay(15); } delay(1000); for(angle = 180; angle>=1; angle-=5) // command to move from 180 degrees to 0 degrees { servo_test.write(angle); //command to rotate the servo to the specified angle delay(5); } delay(1000);} Ⅷ Control with  Raspberry Pi In this tutorial, we will use the Raspberry Pi  to control a servo motor. Before we get to the servo, let's talk about PWM because it's the basis for controlling a servo motor.   8.1 PWM (Pulse Width Modulation) PWM is an abbreviation for 'Pulse Width Modulation.' PWM is a technique for obtaining variable voltage from a steady power supply. Consider the circuit below to better understand PWM.   Figure13:PWM   In the figure above, if the switch is closed continuously for a period of time, the LED will be 'ON' during that time. If the switch is closed for half a second and then opened for the next half a second, the LED will be turned on only for the first half a second. The percentage of time the LED is on over the total time is known as the  Duty Cycle , and it can be calculated as follows:   Duty Cycle =Turn ON time/ (Turn ON time + Turn OFF time) Duty Cycle = (0.5/ (0.5+0.5)) = 50% As a result, the average output voltage will be 50% of the battery voltage. When we increase the ON and OFF speed to a certain level, the LED will dim instead of being ON and OFF. This is because our eyes cannot clearly detect frequencies higher than 25Hz. Consider a 100ms cycle with an LED that is off for 30msec and on for 70msec. We will have 70% stable voltage at the output, so the LED will glow continuously at 70% intensity. The Duty Ratio ranges from 0 to 100. '0' denotes complete inactivity, while '100' denotes complete activation. This Duty Ratio is critical for Servo Motor,  This Duty Ratio determines the position of the Servo Motor,    8.2 Components Required We're running Raspbian Jessie on a Raspberry Pi  2 Model B. All of the basic hardware and software requirements have already been discussed, and you can find them in the Raspberry Pi  Introduction; however, we will need: Connecting pins 1000uF capacitor SG90  Servo Motor  Breadboard   8.3 Circuit Diagram Figure14:Circuit Diagram If A1000F is not connected across the +5V power rail, the  PI  may shut down unexpectedly while controlling the servo.   8.4 Working and Programming Explanation Once everything is connected according to the circuit diagram, we can power on the  PI and begin writing the program in PYHTON. We will go over a few commands that we will use in the PYHTON program. We will import a GPIO file from the library, and the function below will allow us to program the GPIO pins on the PI. We're also renaming "GPIO" to "IO," so in the program, whenever we refer to GPIO pins, we'll say "IO." import RPi.GPIO  as IO When the GPIO pins that we are attempting to use are performing other functions. In that case, we'll get warnings while running the program. The following command instructs the PI to disregard the warnings and continue with the program. IO.setwarnings(False) We can refer to the GPIO pins of the PI by either their pin number on the board or their function number. On the board, for example, 'PIN 29' is 'GPIO5'. So we specify whether we want to represent the pin here by '29' or '5'. IO.setmode (IO.BCM) PIN39 or GPIO19 is selected as the output pin. This pin will provide PWM output. IO.setup(19,IO.OUT) After we have set the output pin, we must configure it as a PWM output pin. p equals IO. Power-Wave Modulation (PWM) (output channel, frequency of PWM signal) The above command is for configuring the channel as well as the frequency of the channel." 'p' is a variable that could be anything. We'll use GPIO19 as the PWM "Output channel," and the "Frequency of PWM signal" will be 50, because the SG90's working frequency is 50Hz. The command below is used to initiate PWM signal generation. 'DUTY CYCLE' is used to specify the 'Turn On' ratio, as previously explained. p.start(DUTYCYCLE) The following command is used to create a forever loop, which means that the statements inside the loop will be executed indefinitely.   8.5 Code import RPi.GPIO  as IO        # calling for header file for GPIO’s of PI import time                           # calling for time to provide delays in program IO.setwarnings(False)          # do not show any warnings IO.setmode (IO.BCM)            # programming the GPIO by BCM pin numbers. (like PIN29 as‘GPIO5’) IO.setup(19,IO.OUT)             # initialize GPIO19 as an output p = IO.PWM  (19,50)              # GPIO19 as PWM output, with 50Hz frequency p.start(7.5)                             # generate PWM signal with 7.5% duty cycle while 1:                                                       # execute loop forever                                             p.ChangeDutyCycle(7.5)                   # change duty cycle for getting the servo position to 90º         time.sleep(1)                                      # sleep for 1 second         p.ChangeDutyCycle(12.5)                  # change duty cycle for getting the servo position to 180º         time.sleep(1)                                     # sleep for 1 second         p.ChangeDutyCycle(2.5)                  # change duty cycle for getting the servo position to 0º         time.sleep(1)                                     # sleep for 1 second   Ⅸ FAQ 1. Are servo motors AC or DC? AC servo motors depend on an AC power source whereas DC Servo motors depend on DC power source (like Batteries). AC servo motors performance is dependent upon voltage as well as frequency whereas DC servo motors performance mainly relies upon voltage alone. 2. Can servo motors rotate 360? The position of the servo motor is set by the length of a pulse. ... The end points of the servo can vary and many servos only turn through about 170 degrees. You can also buy 'continuous' servos that can rotate through the full 360 degrees. 3. Which motor is used in servo motor? While the majority of motors used in servo systems are AC brushless designs, brushed permanent magnet motors are sometimes employed as servo motors for their simplicity and low cost. The most common type of brushed DC motor used in servo applications is the permanent magnet DC motor.

Introduction In the FOC(Field Oriented Control) algorithm, the sampling current is the basis of the algorithm implementation and a very important part. So accurate current sampling can bring better result to the algorithm. In other words, if the current sampling is accurate, it will be very helpful for the subsequent coordinate transformation to obtain required results. From this we can see the role of current sampling in the entire FOC algorithm. Understanding Field-Oriented Control Catalog Introduction Ⅰ Current Sampling Method Ⅱ Three Sampling Methods and Precautions 2.1 Single-resistor Sampling 2.2 Dual-resistor Sampling 2.3 Triple-resistor Sampling Ⅲ The Key to Sampling Ⅳ Delay Source Ⅴ Delay Type and Typical Time Ⅵ Analysis in Details 6.1 PWM Dead Time Insertion 6.2 Optocoupler Delay and Pre-Driver Delay 6.3 Transistor Switching Delay 6.4 Other Delays Ⅶ FAQ Ⅰ Current Sampling Method In motor control, the current sampling method is generally to use PWM to trigger ADC to convert. Taking SoC(System-on-a-Chip) as an example, the ADC module will be configured to automatically sample and trigger conversion. When the trigger point set by the PWM module matches, the signal will be given to the ADC module. At this time, the sampling switch in circuit will be disconnected, and then the ADC module will start to convert, and the voltage of the corresponding sampling current can be obtained after the conversion is completed. The AD value of the signal, you can use this value in the program to write and verify the algorithm. Figure 1. Current Sampling Time Ⅱ Three Sampling Methods and Precautions Current sampling is the basis of FOC, including current sensor sampling and resistor sampling. Resistor sampling is widely used for its simple and low-cost characteristics. The method includes single-resistor sampling, dual-resistor sampling, and triple-resistor sampling. 2.1 Single-resistor Sampling The biggest difference between the single-resistor and the other two methods is that it cannot obtain two current signals at the same time. Even if two current signals are obtained, there is an error in estimating the third current signal. The formula Iu+Iv+Iw=0 is conditional, that is, the three currents must be recorded at the same time. When the inductance of the motor is larger, the two currents obtained are closer to the real situation. When the inductance is small, the deviation may be relatively large. So if the inductance of the current is large, single-resistor sampling can be selected.This method requires two samplings in one PWM cycle. In this case, it is necessary to analyze the switch state in the algorithm to clarify which phase current the reconstructed current corresponds to at the time of sampling. 2.2 Dual-resistor Sampling In the case of dual-resistor sampling, the sampled two-phase current must be used directly. Even if there is a deviation, it needs to be used. This method cannot be used to calculate the third-phase current based on the other two-phase sampling like the triple-resistor sampling. That is to say, this method needs to consider the problem of the sampling window. If the sampling current is to be guaranteed to be accurate, the sampling window must be large enough. To make the sampling window large enough, the PWM waveform needs to be deformed. But this will increase the execution time of the algorithm. The advantage of this approach is to reduce a current-sense resistor and an op amp.As shown in the figure below, the front of the red circle is the oscillating area. If the sampling window is small, only the oscillating area will not be able to obtain an accurate current. To process the sampling window, you can refer to the following figure, so that the obtained current will be more accurate. Figure 2. Current Sampling Zone 2.3 Triple-resistor Sampling This method is the simpler among the three methods. It directly uses three current-sensing resistors to sample the three-phase phase current of the motor, and the result obtained in this way is relatively straightforward. Using the formula Iu+Iv+Iw=0, recalculate the phase current of one phase with a small sampling window. So that the accuracy of the result obtained is the highest, and the implementation of the following related algorithms is easier. It is the advantage of this method. However, three current-sense resistors and three op amps are used, the hardware cost will be higher than the other two.   Ⅲ The Key to Sampling The current sampling includes peak current and average current sampling. Generally, the most common is the average current sampling and its control, so there are actually two ways to sample the average current. One is that the current-sense resistor is placed on the upper bridge of the inverter bridge. The other is that the current-sense resistor of the inverter bridge is connected to the lower end of the lower bridge.The general method is the latter. The current detection circuit corresponding to this method is relatively simple, and the corresponding power consumption will also be reduced. In this case, the freewheeling current is collected at the lower end, and then we can sample at the midpoint of the lower bridge opening. At this time, the corresponding current reflects the average current, so the corresponding current control is the average.Then, if we use the three-resistor sampling method, the selected ADC module must have at least the function of simultaneous sampling of three channels. So as to ensure that the three-phase currents obtained by sampling are the currents at the same time, and at this time, to meet the condition, Iu+ Iv+Iw=0.In the case of dual-resistor sampling, there are only two sampling resistors, and the obtained current cannot use the formula Iu+Iv+Iw=0. Therefore, even if the sampling window is small, if the algorithm is not processed, the double-resistor scheme has limitations. In order to get a better adaptation to the scene, algorithm compensation must be performed on the dual-resistor method, which is also the key point of it.Similarly, for the single-resistor sampling way, the corresponding current needs to be obtained according to different switch combinations, and it needs to be sampled twice in a PWM cycle. This method cannot satisfy Iu+Iv+Iw=0, and can only be determined by an algorithm. Compensation and correction are performed, so the single-resistor method is more difficult to take. However, if the difficulty can be solved, this method is the best and cheapest one.   Ⅳ Delay Source During the development of the motor-driven FOC control, have you encountered the situation that the motor is too noisy, inefficient or even unable to operate? All of this may be due to sampling anomalies of the phase currents, resulting in the inability to reconstruct the correct three-phase currents in the FOC algorithm. Here is an analysis of a factor that affects current sampling: the delay source.In the motor drive FOC control of double-resistor sampling, the sampling point is set as the middle moment when the lower tube of the drive bridge is turned on. Note that this is the middle moment when the lower tube of the drive bridge is turned on, not the middle moment of the PWM cycle output by the MCU. There are as many as seven delay sources in this typical drive topology because the PWM is calculated from the MCU to the ADC module where the current signal is sent to the MCU. Figure 3. MCU Output Ⅴ Delay Type and Typical Time The table below details the seven sources of delay that exist in motor drive system topologies and their typical timings. These delays will be superimposed together, and the effect is that the actual output PWM waveform lags behind the PWM waveform that the MCU calculates the expected output. According to this calculation, the phase current sampling point needs to lag the middle moment of the MCU calculating the expected output PWM waveform. Delay Type Typical Time PWM Dead Time Insertion 100ns-2μs Optocoupler Isolation to Pre-driver 40ns-300ns Pre-driver Switch Delay About 50ns MOSFET Switching Time 100ns-1μs Amplifier Delay <1μs Low-pass Filter Delay 1-2μs ADC Delay 50ns-200ns   Ⅵ Analysis in Details 6.1 PWM Dead Time Insertion In the three-phase brushless motor drive system, three bridge arms are required to control the current flow of the phase line, and there are two power devices on each bridge arm, such as MOSFET and IGBT. The pair of power devices cannot be turned on at the same time, otherwise a short circuit will occur. Here MOSFET is used as a power device to illustrate. In the control, dead time must be inserted to ensure that the upper and lower MOSFETs are not turned on at the same time. Typical values of dead time may be between 100ns and 2μs, depending on various factors in the system, such as MOSFET drive voltage and type.After the required PWM waveform is inserted into the dead time, what you get is that both the PWM midpoint and the rising edge are shifted to the right. When using the FOC control algorithm calculates the proper PWM, we start seeing the first delay, recording the dead time. Figure 4. Dead Time Insertion 6.2 Optocoupler Delay and Pre-Driver Delay The signal response of the various optocouplers and pre-drivers causes additional delays between the moment the MCU controls the FTM module to output the PWM waveform and the moment the MOSFET gate is controlled. The output of the pre-driver is delayed by a period of time (Delay1) compared to the waveform output from the MCU pins. Figure 5. Delay 1 6.3 Transistor Switching Delay Through the pre-driver, the PWM waveform reaches the MOSFET transistors, but due to their inherent characteristics, all transistors take a certain amount of time to turn on and off. This delay time varies depending on the transistor type and the voltage level required to switch between on/off. Delay 2 is the total delay between the theoretical switching point (CMP2) of the phase line voltage and the instant of the actual switching point. Figure 6. Delay 2 Finally, the gate voltage reaches the level that can make the transistor turn on, the current passes through the phase line and the sampling resistor, and a voltage difference is generated across the sampling resistor. The red waveform is the phase current waveform in an ideal state. At this time, there is a total delay time between the midpoint of the PWM cycle calculated and generated by the MCU, and the "phase current midpoint shift" is shown in the figure. Figure 7. Phase Current Midpoint Shift 6.4 Other Delays As shown in the figure below, the final delay chain that affects the current sampling is formed by the amplifier slew rate, the low-pass filter on the MCU pins, and the ADC slew rate. The time marked by the red circle in the figure is the correct current sampling time. It can be seen that the phase current sampling point is greatly delayed compared with the PWM midpoint output by the FTM. Figure 8. Other Delay In all and electrical and electronic circuits, there will be signal delay problems. And it is impossible to completely eliminate them, but the impact can be reduced by selecting low-delay devices. In the motor drive, in addition to selecting the appropriate device, it is also necessary to perform software compensation for the signal delay. The precise delay time of these delay sources mentioned in the article can be obtained by oscilloscope and calculation, and the correct current sampling time can be obtained by compensating for these delays in software. In this way, the data collected at the correct moment can be used as the data source for reconstructing the three-phase current of the motor in the FOC control.   Ⅶ FAQ 1. What is FOC algorithm?Field-oriented control (FOC), or vector control, is a technique for variable frequency control of the stator in a three phase AC induction motor. 2. What is FOC drive?Vector control, also called field-oriented control (FOC), is a variable-frequency drive (VFD) control method in which the stator currents of a three-phase AC or brushless DC electric motor are identified as two orthogonal components that can be visualized with a vector. 3. What is FOC brushless motor?FOC implementation allows the BLDC motor to run more efficiently (high power factor and better light load efficiency), more smoothly (lower torque ripples) with quick dynamic response (better dynamic performance to load and speed changes). 4. What is FOC in BLDC motor?Field oriented control (FOC) is an important control approach for Brushless DC motors. It resembles sinusoidal commutation but adds a major mathematical twist. Figure 3a shows control schemes for both sinusoidal commutation and field oriented control. 5. How is Bldc phase current measured?With a BLDC motor use an ac voltmeter to measure the voltage between any 2 wires of the 3 motor wires and then convert the line-to-line voltage to the phase voltage value by dividing the line-to-line voltage by 3 =1.73. 6. Do BLDC motors have inrush current?Handle Peak Inrush Current of a BLDC Motor to protect the Power Supply. Summary: BLDC motors have a Peak current on startup which is 3x or more the rated current. The motor has a rated current of 7.3A. 7. What causes motor inrush current?When an electrical device, such as an AC induction motor, is switched on, it experiences a very high, momentary surge of current, referred to as inrush current. ...The interaction of these two magnetic fields produces torque and causes the motor to turn.