Study of Understanding Electro-Magnetic Interferences Caused by Power Electronic Equipment and its Mitigation

功率半导体器件的显着进步使得采用IGBT的电压源PWM逆变器的载波频率得以提高。这为可调速电机驱动系统带来了电压、电流和转矩可控性的显著改善。它还有助于减少噪音。然而，具有高dv/dt值的阶跃式共模电压不仅可以感应高频接地泄漏电流，而且还可以感应电机轴电压和随之而来的轴承电流，从而导致轴承故障。许多关于无源和有源EMI滤波器的技术论文都集中在消除逆变器驱动电机的高频泄漏电流。然而，还没有人提出实际的EMI滤波器的成本和性能。当用于电绝缘二极管和IGBT模块的公共散热器接地时，高频漏电流可能流过散热器和存在于二极管和IGBT模块内部的寄生电容器。 ...更多信息 为了更清楚地区分电机漏电流与散热器漏电流，本研究探讨一种无源EMI滤波器，以消除变频器驱动电机的轴承电流、散热器漏电流与电机漏电流。设计并搭建了两套实验系统：一套由两电平电压型PWM逆变器和一台额定电压为200 V、功率为3.7 kW的感应电动机组成，工作频率为15 kHz;另一套由三电平电压型PWM逆变器和一台额定电压为400 V、功率为8 kHz的感应电动机组成。从未配备EMI滤波器的200 V 3.7 kW系统获得的实验波形显示，不可忽略的泄漏电流量（频率约为3 MHz）流经接地散热器，而不是进入系统接地，而是进入电机框架。这些理解导致示出了考虑二极管和IGBT模块内部存在的寄生电容器的等效共模电路。该等效电路表明，作者提出的EMI滤波器是有效的衰减不仅散热器泄漏电流和接地泄漏电流，但也轴承电流内循环的电机。实验结果验证了EMI滤波器的有效性和可行性。少

Remarkable progress of power semiconductor devices has enabled an increase in the carrier frequency of a voltage-source PWM inverter using IGBTs. This has brought significant improvements in controllability of voltage, current, and torque to adjustable-speed motor drive systems. It also contributes to reducing acoustic noise. However, a step-wise common-mode voltage with a high value of dv/dt may induce not only high-frequency ground leakage current but also motor shaft voltage and the ensuing bearing current leading to bearing failure.Many technical papers concerning passive and active EMI filters have focused on eliminating high-frequency leakage current from an inverter-driven motor. However, no one has proposed practical EMI filter in terms of cost and performance. When a common heat sink for electrically-insulated diode and IGBT modules is grounded, a high-frequency leakage current may flow through the heat sink and parasitic capacitors existing inside the diode and IGBT modules. … More The leakage current flowing through the motor frame is referred to as the motor-frame leakage current, while the leakage current flowing through the heat sink is referred to as the heat-sink leakage current, in order to distinguish the two leakage currents clearly.This research discusses a passive EMI filter far the purpose of eliminating bearing current, heat-sink leakage current, and motor-frame leakage current from an inverter-driven motor. Two sets of experimental systems was designed and constructed : One consists of a two-level voltage-source PWM inverter operated at a carrier frequency of 15 kHz, and an induction motor rated at 200 V and 3.7 kW, and the other consists of a three-level voltage-source PWM inverter operated at a carrier frequency of 8 kHz, and an induction motor rated at 400 V and 15 kW. Experimental waveforms obtained from the 200-V 3.7 kW system equipped with no EMI filter reveal that a non-negligible amount of leakage current with a frequency of about 3 MHz flows through the grounded heat sink, not into the system ground, but into the motor frame. These understandings lead to illustrating an equivalent common-mode circuit taking into account the parasitic capacitors existing inside the diode and IGBT modules. This equivalent circuit suggests that the EMI filter proposed by the authors is effective in attenuating not only the heat-sink leakage current and the ground leakage current but also the bearing current circulating inside the motor. Experimental results verify the effectiveness and viability of the EMI filter. Less