宽输入电压范围单相光伏并网变换器的控制策略

Control strategy for single phase grid-connected photovoltaic converter with wide input voltage range

双级型光伏并网变换器中,如果光伏阵列电压接近或高于直流母线电压,升压斩波器将不能正常工作.为了扩大变换器对输入电压的适应范围,本文为双级型变换器增加了单级式工作模式:当光伏阵列电压高于逆变所需的直流母线电压时,切除升压斩波器,由并网逆变器实现最大功率点跟踪.在临界电压附近设置滞环,以免升压斩波器频繁投切.通过上述方法,当光伏阵列的电压在150 V到550 V的宽范围内变化时,变换器都能良好工作.实验结果验证了本文方法的可行性.

In dual-stage grid-connected photovoltaic （PV） converters, if the PV array vokage is dose to or higher than the de-link voltage, the boost converter will not work properly, in order to extend the input voltage range of the PV converter, single-stage mode is added. When the PV voltage is higher than the minimum de-link voltage at which the inverter can work, the boost converter is turned off, and the grid-connected inverter is responsible for maximum power-point tracking （MPPT）. Thus, the dual-stage converter operates in single-stage mode. A hysteresis controller is applied near the critical voltage to prevent the boost converter from switching frequently. The PV converter can operate in wide input voltage range from 150V to 550V. Experimental result shows the feasibility of proposed method.