PWM逆变器共模干扰电流的衰减和抑制

PWM逆变器在IGBT高速开关瞬间，会使桥臂中点对参考地形成很大的dv／di，由于寄生电容的作用，PWM逆变器会对参考地产生很大的充放电电流。基于对共模电流的源和传播途径的研究，把共模电流回路等效为LCR串联谐振电路，简化了共模电流的分析。文中同时分析了在共模回路中插入共模电感对共模电流的影响。借鉴在PWM逆变器与电机之间插入共模变压器衰减轴电流的方法，提出在逆变器直流侧插入共模变压器来抑制共模电流的振荡。从时域和频域的角度对比分析了用共模电感和共模变压器衰减共模电流的本质。实验结果验证了理论分析的正确性。

DAMPING AND SUPPRESSION OF COMMON MODE INTERFERENCE CURRENTS IN PWM INVERTER

Pulse width modulation (PWM) inverter can generate very large dv/di in the instant of insulated gate bipolar transistor (IGBT) high speed switching, which could produce charge-discharge current due to the parasitic capacitor. Based on the search of source and propagation path, a LCR serial resonant circuit is proposed for common mode (CM) current, thus the analysis for CM current is simplified. The CM choke is used to reduce CM current. Referencing the method of inserting CM transformer between PWM inverter and motor, CM transformer inserted in dc input port is used to damp the resonant CM current. The mechanism of the two methods is compared in time and frequency domain. Experimental results verify the validity of theory analysis.