两级式单相逆变器输入谐波特性分析及抑制

Analysis and Suppression of Input Harmonic Current in the Two-stage Single-phase Inverter

两级式单相逆变器的输出瞬时功率存在系统输出频率两倍的功率脉动信号,从而导致前级DC/DC变换器的输入电流存在同样脉动频率的谐波,严重影响了输入电源的使用寿命。分析了两级式单相逆变器输入电流二次谐波的来源,指出了从抑制电感电流脉动角度来达到抑制输入电流脉动方法的局限性。提出了在电路现有的采样点上,利用乘法器与带通滤波器提取输入电流脉动,并同时通过反馈电感电流实现对输入二次谐波电流的抑制策略。1 kVA原理样机实验结果显示所提出的控制策略对二次谐波电流脉动的抑制直接、有效,且有利于系统动态的提高。

There is power pulsation signal twice the system output frequency contained in the output instantaneous power of two-stage single-phase inverter,generating second harmonic current in the front-end DC/DC converter.Though reducing the second harmonic current of the output filter inductor of the DC/DC converter can reduce the second harmonic current of the input port effectively,it depends on the DC bus capacitance totally.To reduce the second harmonic current of the input port,a control strategy is proposed which extracts the second harmonic current of the input port into the inductor current feedback path by a multiplier and a band-pass filter.The proposed control scheme can not only reduce the second harmonic current significantly,but also is beneficial to improve the dynamic performance of the front-end DC/DC converter.Finally,the effectiveness of proposed control strategy is verified by 1 kVA prototype.