A Method of Reducing Output Waveform Distortion in Photovoltaic Converter System

For the problem of leak inductance energy and voltage spike, given in the fly-back photovoltaic converter system (hereinafter abbreviated as PV), a new physical circuit of RCD (resistor-capacitor-diode) is proposed which based on the Boost circuit topology to recovering leak inductance energy and depressing main switch voltage spike during the commutation of power MOSFET. The circuit can recycle the leak inductance energy effectively [1−2], and suppress output capacitance (hereinafter abbreviated as Coss) electric discharge which caused the voltage spike during MOSFET switch-on. In addition, after detailed analysis, the new physical circuit can solve the problem of the energy loss generate from the Coss electric discharge which is not pay more attention by the other papers. The new design can clamp the drain-source voltage and implement the control policy of soft-switch. In this paper, we give the theoretical derivation of the circuit parameter and the implemented physically experimental curve of the physical circuit by analyzing the causes of voltage spike generated. Compared with the traditional method, improved the converter efficiency from 94.2 % to 96.2 %, and the MPPT efficiency to 99.4 %.