Study on Electro Magnetic Interference in Power Electronics

本论文主要研究了影响电磁干扰的电路元器件（如高频漏电流和辐射噪声）的预测、电磁干扰故障的机理分析以及电磁干扰的抑制技术，主要研究结果如下：1.电路元器件的预测。(1)功率晶体管模块中存在的寄生电容：证明了功率晶体管模块中存在的寄生电容是导致高频漏电流的原因。通过对寄生电容与漏电流关系的研究，提出了抑制漏电流的有效方法。通过实验装置和仿真实验，证明了该方法的有效性。(2)蓄电池中存在的寄生电容：对蓄电池连接到变换器直流母线的情况进行了研究，发现存在大量的高频漏电流流过寄生电容， ...更多信息 ng在电池中。针对漏电流进行了等效电路分析，并提出了采用共模电压抑制电路的抑制方案。(3)其他组件：针对直流母线中存在的滤波电抗器和寄生电感等电路元件，指出了影响EMI故障的重要工作特性。2.高频泄漏电流抑制技术：（1）共模电压抑制法：在传统的降低高频泄漏电流的方案中，共模电抗器串联在三相交流线路上。然而，在这种方法中，很难将其应用于大电流系统。在这项研究中，提出了一种新的共模电流减少技术，通过连接一个共模电压抑制电路的逆变器/转换器电路串联。给出了抑制电路的最佳电路条件，并通过实验和仿真验证了其有效性。(2)软开关和直流共模电抗器法：研究了在主开关管上引入直流共模电抗器以抑制高频漏电流的同时，使主开关管上的开关瞬态波变软的方法。3.高频辐射噪声的抑制技术：（1）由于开关器件的高速开关，会产生高频辐射噪声。由于这项研究，它是澄清的辐射噪声的来源是高频谐振电流流过直流母线电容器和开关器件。在此基础上，提出了抑制辐射噪声的有效方法，并通过实验和仿真验证了该方法的有效性。少

In this research, prediction of the circuit components which affect EMI such as high frequency leakage current and radiation noise, analysis of the mechanism of EMI troubles, and suppression technique of EMI are studied.The results are as follows,1.Prediction of the circuit components.(1) Parasitic capacitance existing in the power transistor modules : It is proofed that the parasitic capacitance existing in the power transistor modules cause the high frequency leakage currents. Through the investigation of the relation between the parasitic capacitance and the leakage currents, effective technique for suppressing the leakage current is proposed. From experiment by using a experimental set-up and simulation, the effectiveness is proofed.(2) Parasitic capacitance existing in the batteries : In case that the batteries are connected to the DC-bus in the converter is investigated, and found out that a lot of high frequency leakage current was flowing trough the parasitic capacitance existi … More ng in the battery. The equivalent circuit focused on the leakage current is carried out, and the suppression scheme by using the common mode voltage suppression circuit, described in 2 chapter on this abstract, is proposed.(3) The other components : With regard to the circuit components such as filter reactor and parasitic inductance existing in the DC-bus line, very important operating characteristics affecting EMI trouble are pointed out.2.Suppression technique for high frequency leakage current :(1) Common mode voltage suppression method : In the conventional scheme for reducing high frequency leakage currents, common mode reactors are connected to three phase AC lines in series. However, in this method, it is difficult to apply it to large current systems. In this study, a novel common mode current reduction technique by connecting a common mode voltage suppression circuit to the inverter/converter circuit in series is proposed. The optimum circuit condition of the suppression circuit is carried out and the effectiveness is proofed from the experimental and simulation results.(2) Soft switching and DC common mode reactor method : In this method, making the switching transient waves on the main switch soft in addition to inserting a DC common mode reactor for suppressing the high frequency leakage current is studied. The consideration of the optimum circuit parameter and the suppression effect is done.3.Suppression technique for high frequency radiation noise :(1) As a result of high speed switching of the switching devices, high frequency radiation noise is caused. Owing to this study, it is clarified that the origin of the radiation noise is the high frequency resonant current flowing through the DC-bus capacitor and the switching devices. The equivalent circuit for the radiation noise is estimated and proofed it. Furthermore, the effective technique for suppressing the radiation noise is proposed and proofed its effectiveness from the experimental and simulation results. Less