The Study Of The Control Technology On The Green And High Efficiency Photovoltaic Water Pumping Systems

The water pumping system uses Photovoltaic (PV) panels which produce electricity directly from sunlight using silicon cells and drive the pump through series of new technologies of electronics, motors, control units and different modern devices to bring water up from river, lake or deep well. Photovoltaic, mechanical and electronic theories etc. multi-across subject are involved in the system. The photovoltaic water pumping system droved by sensorless BLDC is a novel system developed recently. This paper studied the control technology of sensorless BLDC deeply. The chip JK3CE that is one of micro-controllers in Motorola 68HC08 family is used as control unit in this system. The zero crossing point of the back EMF can be obtained by comparing the terminal voltage with the virtual neutral point, then using the software of the system can figure out the commutation period. The electronic commutation replaces the mechanical commutation in this way. It helps to enhance the reliability of the system and reduce the maintenance cost. The timer interface module generates interrupt request every 25us, which is fine enough comparing with 1 OOus and used as one-step in adjusting commutation periods. The digital-adjust module that changes the steps automatically due to the difference between two commutation periods is beneficial to the quick adjustment of the commutation period. The full time self-synchronization technology that developed from step-start technology can reduce the current and starting-time. It solves one of the key problems in controlling many water pumps to work together and develops the control technology greatly.