The main objective of this project is to force the BLDC motor in electric vehicles to run exactly at stored speed in EEPROM (non volatile memory). The BLDC motor has various application used in industries like in drilling, lathes, spinning, electric vehicles, elevators and etc. The speed control of BLDC motors is very essential. The present system speed control is not very effective. This proposed system provides a very precise and effective control system. The user can enter the desired speed (predefined speed) which is stored in an EEPROM and the motor will run at that speed. If the power supply is off, the EEPROM retains the last speed entered. When the supply is resumed, the motor will run at the last entered speed.
Based on the principle of PWM speed can be controlled. This is achieved by keeping BLDC motor on closed loop feedback and giving RPM reference of the motor by a shaft mounted IR sensing arrangement which is fed to the microcontroller in the circuit. A display unit displays the full speed and one can enter the desired percentage with help of switches to vary the speed. The pulse width would be automatically adjusted to maintain the DC power to the motor such that the entered speed percentage matches the present RPM. The above operation is carried out by using one opto-isolator and a MOSFET for driving the BLDC motor and IR sensing is used for getting the speed reference to the microcontroller.
An EEPROM is interfaced to the microcontroller. EEPROM being a non volatile memory stores the speed reference to feed to the control circuit that forces the motor to always run at the same speed. Two switches are used as input to the MC for increasing or decreasing the speed of the BLDC motor.
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