A Control Strategy of Depressing the Voltage Spike During Soft-Switch Based on the Method of PI in Photovoltaic Converter System

For the problem of voltage spike which is caused by the MOSFET, and the issue of Variable calculation complex, given in the fly-back photovoltaic converter system (hereinafter abbreviated as PV). A new physical circuit of soft-switch control strategy is proposed which based on PI controller with the algorithm of variable power step to suppress the voltage spike value. According to the theoretical analysis, in this paper, the output voltage of DC part is equal to the input voltage of photovoltaic array and the reflected voltage of secondary side by clamping the voltage of clamped capacitor. The output voltage value from PI controller is used to recovery the leak inductance energy which will help the converter for working on the maximum power point(MPP) steadily. The new design can absorb the leak inductance energy and suppress the voltage spike efficiently. In this paper, for solve the traditional problem, we correct the formula of soft-switch by the method of maximum power point tracking (MPPT) algorithm. The new soft-switch algorithm formula can simplify the demand of physical circuit design through the method of variable power step.