Hardware Implementation of Sensorless BLDC Motor Control To Expand Speed Range

This paper presents sensorless control method for BLDC motor to expand speed range using input capture facility in dsPIC30F4012. Back-EMF signal can be shifted freely to compensate for the error that has been generated by LPF (Low Pass Filter), so it can produce the proper commutation angle that capable of operating BLDC motors with a wide speed range. Generally, back-EMF errors occur due to phase shifts caused by LPF installation. This shift on the back-EMF can cause an inaccurate commutation angle and narrow the speed range of BLDC motor. The shift produced by the LPF is significant enough that it can adversely affect BLDC motor operation both at low speeds and at high speeds. This shift can be compensated by shifting back-EMF back to its original position using the input capture facility in dsPIC30F4012. This shifting process can be carried out freely so that this method can be applied in a range of low speeds to high speeds. This method can produce the proper commutation angle because the back-EMF displaced can be returned to the correct position. Implementation of hardware with a low to high speed range has been carried out to verify the proposed method.