单相全桥逆变器共模等效电路研究

Common-Mode Equivalent Circuit of Single-Phase Full-Bridge Inverters

提出了一种新型单相全桥逆变器共摸等效电路。与现有电路相比,该电路适用叠加原理,而且它更好地反映了共模电流的传播机理。考虑叠加原理的需要,分别针对以下三种情况进行了仿真和实验:①两桥臂中的某一个从装置中完全拆离;②被拆离的桥臂恢复原位但不进行开关动作;③两桥臂按单极倍频PWM调制方式同时进行开关动作。根据所提出的等效电路和从实验装置上测量得的电路参数,用Matlab软件进行了仿真,仿真结果与实测的共模电流时域波形和频谱吻合得较好。

A modified equivalent circuit for common-mode current of single-phase full-bridge inverters is proposed. The circuit allows application of superposition theorem, and it provides more insights into the propagation mechanism of the CM noise. Taking the needs of applying the theorem of superposition into account, simulations and experiments are conducted on an inverter test-setup to validate the proposed equivalent circuit. Three operation conditions are studied, which is with one of the two legs detached from the DC bus, with that leg installed back in place but not switching and with normal unipolar PWM switching of both the two legs. Based on the proposed equivalent circuit and measured parameters from the test-setup, simulations with Matlab software predicted the CM current both in time and frequency domains with reasonable precision.