BLDC Motor Speed Control with RPM

Display

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Introduction

BLDC Motor Speed Control with RPM Display

The main objective of this project is controlling speed of BLDC motors with the help of microcontroller. To make the industry automation the equipment and machineries should be controlled automatically. So control of the machineries which involving this motor can be done accurately. It displays its speed using an IR method of speed sensor mechanism. The DC motor has various application used in industries like in drilling, lathes, spinning, elevators and etc.

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BLDC Motor Speed Control with RPM Display

Why Controlling the Speed of Motor is Essential

The speed control of a DC motor is very essential in industries.

Controlling the speed has many applications such as drilling, spinning, elevators, etc.

To control the speed of the BLDC motor by varying duty cycles of the power fed to it.

This proposed system provides a very precise and effective speed control system.

The user can increase or decrease the speed as per the requirement.

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BLDC Motor Speed Control with RPM Display

Block Diagram

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BLDC Motor Speed Control with RPM Display

Hardware Components• 8051 Microcontroller• Level Shifter IC• GSM modem• LCD• LED• Crystal• Relay driver IC• Resistors• Capacitors• Diodes• Transformer• Voltage Regulator• Opto Isolator• Digital Energy Meter• Lamp

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BLDC Motor Speed Control with RPM Display

Software Requirement

Keil compiler

Language: Embedded C or Assembly

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BLDC Motor Speed Control with RPM Display

Power supply

The system requires a regulated +5v supply for the semiconductors. These can be delivered from the 230V domestic supply. Before applying this to the system we must step down this high voltage to an appropriate value. After that it should be rectified. To achieve +5 V DC we should regulate this.

A step down transformer and a bridge rectifier is used here to convert AC to DC. A regulator IC is also used here to give constant supply.7805 IC is used for power supply.

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BLDC Motor Speed Control with RPM Display

Power supply

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BLDC Motor Speed Control with RPM Display

BLDC Motor

BLDC motors have a rotor and a stator.

BLDC motors are a type of synchronous motor.

The magnetic field generated by the stator and the magnetic field generated by the rotor rotates at the same frequency.

BLDC motors do not experience the“slip” that is normally seen in induction motors.

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BLDC Motor Speed Control with RPM Display

Opto - Isolator

Opto coupler or Opto Isolator is a 6 pin IC. It is a combination of 1 LED and a diac. Pin 5 is not generally used and when light falls on the diac then it switches ON the diac.

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BLDC Motor Speed Control with RPM Display

MOSFET

The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of transistor used for amplifying or switching electronic signals.

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BLDC Motor Speed Control with RPM Display

Voltage Regulator (LM 7805)

A voltage regulator is designed to automatically maintain a fixed voltage level.

7805 is a voltage regulator integrated circuit.

It is a member of 78xx series of fixed linear voltage regulator ICs.

The xx in 78xx indicates the fixed output voltage it is designed to provide.

7805 provides +5V regulated power supply.

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BLDC Motor Speed Control with RPM Display

IR Sensor

The IR Sensor is a general purpose proximity sensor.

Here we use it for collision detection.

The module consists of a IR emitter and IR receiver pair.

The high precision IR receiver always detects a IR signal.

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BLDC Motor Speed Control with RPM Display

Three Stages Of Controlling Speed of BLDC Motors

The Input stage

The Processing Stage

The Output Stage

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BLDC Motor Speed Control with RPM Display

The Input stage

The input stage consists of entering the required speed through switches.

The Processing Stage

The processing stage provides RPM reference of the motor. A shaft mounted IR sensor interfaced to the microcontroller in the circuit.

The output stage

The output stage uses a MOSFET being driven by the microcontroller output.

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BLDC Motor Speed Control with RPM Display

Working Principle

The proposed system uses a microcontroller of the 8051 family and a rectified power supply. A set of IR transmitter and photodiode is connected to the microcontroller for counting the number of rotations per minute of the DC motor as a speed sensor. Opto-coupler is connected to trigger the MOSFET for driving the BLDC motor which is duly interfaced to the microcontroller. Two switches are interfaced to the microcontroller for controlling the speed.

The speed control of the DC motor is achieved by varying the duty cycles (PWM Pulses) from the microcontroller as per the program. The microcontroller receives the percentage of duty cycles from the switches and delivers the desired output to switch the driver IC to control the speed of the DC motor. The speed sensed by the IR sensor is given to the microcontroller to display it on the LCD display.

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BLDC Motor Speed Control with RPM Display

Application

BLDC machines are used in applications of vital importance such as aerospace industry, tool drives, actuators and electric vehicle propulsion system.

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BLDC Motor Speed Control with RPM Display

Conclusion

The circuit was designed and implemented. Desired rpm was entered through matrix keyboard. Speed of motor was displayed on LCD display. IR sensor feedback the actual rpm. Motor rotates with 100% accuracy. Different rpm values were checked and corresponding displays were obtained on the LCD screen. The proposed method is very useful for speed control of BLDC motor.

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