Research on cascaded multilevel inverter of singlephrase photovoltaic power system

ZHONG Degang, WANG Pei
(College of Information Engineering, Zhejiang University of Technology, Hangzhou 310023, China)

Abstract: Aiming at the problems of improving waveforms of output voltage and output current, reducing harmonics and increasing the utilization of DC voltage, the cascade multilevel inverters were used in photovoltaic systems. Based on analyzing the principle of cascaded multilevel inverter and the phaseshifted carrier sine pulse width modulation(SPWM) control strategy, a new photovoltaic grid model with several DCDC converters and cascade multilevel inverter was proposed, and the model was simulated by Matlab. And TMS320C2812 digital siginal processor(DSP) was used in this system to achieve digital control programs, and the multipulse SPWM which can control cascade inverter was realized. The experimental result shows that the model has excellent output characteristics and effectiveness of voltage.
Key words: cascaded inverter; photovoltaic; digital signal processor(DSP); sine pulse width modulation(SPWM)