The Research Of A New Inverter With Photovoltaic Pump Control Function

The photovoltaic pump system has become an important part of solar energy application. Futhermore, with its tremendous social and economic advantages, the photovoltaic pump system has been getting more and more attention. Nowdays, converters used in the photovoltaic pump system give priority to special and lower power ones with single function, lower market share and high cost, which may affect the development of the photovoltaic pump system. In this paper, a new function inverter is developed, and it combines the characteristics of the photovoltaic pump system with the technologys of the inverters based on space-vector PWM(SVPWM) and vector-controlled induction motor.SVPWM technique has many good qualities, such as less pulse ating torque, higher use ratio of DC bus voltage, less switching loss, better high-speed regulation performance, so it is applicable for the high-performance motor control system. Starting from optimizing the modulation performance, three kinds of optimal switching pattern of space-vector modulation were established. The vector control strategy of the space-vector PWM voltage source inverter-fed induction motor was studied later. A rotor-oriented control system of induction machine was advanced, whose arithmetic was simple and convenient to operate economically. And then, according to the theory of photovoltaic pump system and the tracking theories, advantages and disadvantages of CVT(Constant Voltage Tacking) and TMPPT(True Maximum Power Point Tracking) used in maximum power point tracking of photovoltaic cells were analyzed. These methods were realized in vector-controlled induction motor. At last, combined with the traits of vector-controlled induction motor and photovoltaic pump system, the control diagram of system was designed.The simulation with both load and unload proved the scheme proposed in this paper could modulate the CVT voltage quickly and make it work stably. It showed the scheme was of the good characters both in load ability and dynamic operation.