单相光伏并网系统中级联多电平逆变器的研究

摘要

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.%针对光伏并网系统的改善输出电压和输出电流波形、降低谐波含量以及提高直流电压的利用率等问题,将级联多电平逆变器应用在光伏并网系统中.在分析级联式多电平逆变器工作原理和其载波移相控制方法的基础上,建立了多DC-DC变换器和多电平逆变器相结合的光伏并网模型,并用Matlab对模型进行了仿真.同时提出了TMS320C2812数字信号处理器(DSP)实现逆变系统的数字化控制方案,实现了多路SPWM脉冲对功率单元级联式逆变器的控制.研究结果表明,该模型具有优良的输出特性和有效的电压利用率.