The Research Of Photovoltaic Water Pump System Driving By Sensorless BLDC

A kind of intelligent and high efficiency photovoltaic water pump is introduced in this dissertation. Permanent magnet brushless DC motor is selected for pump driving, a neutral simulator of back-EMF is set up for rotor position sensing solution instead of sensor ,which proved to be right in theory . At the same time, the principle which taking searching motor maximum-speed point as control object for MPPT (Maximum Power Point Tracking) is put forward and the static error of tracking is analyzed in detail.Chip JL3, a kind of micro-controllers of 68HC08 series, is used as control unit of the system, with which we complete the designs of the periphery hardware circuit and the control software. In the system, control unit accomplishes back-EMF zero-crossing information reading and closed loop commutation .the system eliminates the PWM interferences and the commutating interferences by filtering with software algorithm. In order to make the BLDC commutate exactly, the method of three-point estimation is used for phase locking in the system. The system also accomplishes several important objects, such as TMPPT of photovoltaic arrays, unmanned supervision of the system, fault detection etc.The results of the experiment show that the device, which is made on the base of the principle above, can control the motor to complete the exact commutation. The system runs smoothly and presents good static and dynamic performance . Also, we get a good tracking result of MPPT. In the end, we analyze the drawback of this system in detail and give some advice for improvement.