BLDC Motor Speed Control with RPM Display System

BLDC (Brushless DC) motor speed control with  rpm display system is a system, that offers the BLDC motor to run at different speeds and display this speed on LCD display. The importance of BLDC motor is increasing day by day because it has been mostly used in industries for different applications such as spinning, drilling and elevators. Similarly, its speed control is also too much important. Different companies are making their motor drive circuits with different types of controllers such as VFD (very frequency drive) but their cost is so much high and its operating system is quite difficult. Here we are offering a system that is called a BLDC motor speed control with RPM display system with the help of PIC microcontroller 18F452, LCD display, transformer, voltage regulator, optocoupler and IR sensors. In this system, the speed of BLDC motor is controlled by changing the duty ratio of supplying voltages. This system is less costly, quite simple and control the speed of BLDC motor more precisely with displaying of on LCD display.




Block Diagram of the BLDC Motor Speed Control with RPM Display System

Here is the Block diagram of BLDC motor speed control with rpm display system with all essential componentsBLDC Motor Speed Control with RPM Display System

Figure 1 Block Diagram of the BLDC Motor Speed Control with RPM Display System

Components List with Detail of the BLDC Motor Speed Control with RPM Display System

Transformer: In this BLDC motor speed control with rpm display system, transformer is used for directly connected this system to wapda power supply or 220V ac. It steps down the 220V ac into 12V ac on the principle of mutual induction.

Bridge Rectifier: In this BLDC motor speed control with rpm display system, bridge rectifier is used for converting the ac voltages into dc voltages for supplying the power to whole components of this system. It consists of foure diodes

 Blocking Diodes: In this system, the blocking diode is used only for blocking reverse polarity current, in other words it protects the transformer. It is connected at the output of bridge rectifier.




Voltage Regulator: In this BLDC motor speed control with rpm display system, voltage regulator is used for regulating the 12V dc into 5V dc for supplying the voltages to microcontroller and motor drive circuit. It is connected at the output of voltage regulator. Here LM 7805 voltage regulator IC have been used for this purpose.

LCD Display: In this BLDC motor speed control with rpm display system, the LCD display is used for displaying the rpm (revolution per minute) of BLDC motor. It is a 16 pins LCD display and is powered up with 5V dc supply. It is interfaced with microcontroller.

UP and Down Switches: This BLDC motor speed control with rpm display system consists of two switches Up and down. up is used for increasing the speed and down is used for decreasing the speed of BLDC motor. Both are interfaced with microcontroller.

Pic Microcontroller: In this BLDC motor speed control with rpm display system, the pic microcontroller 18F452 is used for the intelligent control of this system. It is 40 pins integrated circuit IC programmed in c language with the help of mikro/c software. It is powered up with 5V dc and is interfaced with LCD display, up and down switches, speed sensors and motor drive circuit.

Motor Drive Circuit: In this BLDC motor speed control with rpm display system, the motor drive circuit is used for driving the BLDC motor. It consists of power MOSFT and optocoupler, MOSFET is used running the motor at different speeds and optocoupler is used for biasing the MOSFET at different duty ratio.

Speed Sensor: In this BLDC motor speed control with rpm display system, two ir sensors are used for measuring the speed of motor. One is transmitter is for sending the infrared light and second one is receiver for receiving the infrared light after the collision from the shaft of BLDC motor.

BLDC Fan Motor: In this BLDC motor speed control with rpm display system, BLDC motor is used for speed controlling purposes. This is brushless dc motor, which is powered up through power inverter or switching dc supply. Here we would be powered up through switching dc supply.

Working Principle of BLDC Motor Speed Control with RPM Display System

This BLDC motor speed control with rpm display system works on the principle of switching dc supply. The switching dc supply is gained by changing the duty ratio of supplying voltages. In this system, motor drive circuit is triggered at different duty ratio and when it is triggered at different duty ratio then motor runs at different speeds. Here for demonstration purposes a fan speed is controlled through microcontroller. When up switch is pressed then microcontroller set the duty ratio from 10% to 80% and then this duty ratio voltages are given to motor drive circuit, which set the speed of motor from 0 to 100%. Similarly, for decreasing the speed of motor down switch is pressed again and again until the desired speed is acquired. For displaying the rpm of this motor at LCD display ir sensors have been used here which are interfaced with microcontroller. Microcontroller counts each revolution of motor after receiving the speed signal from ir sensors then displays this speed at LCD display in form of percentage like 10%,20%80% or 100%. So, we can drive the BLDC motor at out desired speed.

Applications and Advantages of BLDC Motor Speed Control with RPM Display System

  1. This BLDC motor speed control with rpm display system could be used in spinning mills where spinning motors could be derived through this system.
  2. This BLDC motor speed control with rpm display system could be with elevators and drilling machine for controlling their speed.
  3. This system is more compact, more efficient and less costly as compared to other motor drive systems.
  4. This system change the speed of motor more precisely as compared to other systems.
  5. This system is very easy to drive.

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