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    Special Issue on Electromagnetic Interference and Electromagnetic Compatibility in Power Electronics System-Part 2

    Guest Editors：Shuo Wang  (University of Florida, USA)    

    Stephan Frei  (TU Dortmund University, Germany)

    Hong Li (Beijing Jiaotong University, China)


    With the development of high and new technologies such as 5G, big data, high-speed railway, renewable energy generation, flexible AC/DC transmission and electric vehicles, the power conversion system as the key support function is also developing rapidly in the direction of high frequency, high efficiency, high power and high-power density. The electromagnetic environment of the power and energy conversion system becomes more and more complex, which puts forward more stringent requirements for the electromagnetic compatibility design of the system, especially with the technological breakthrough and commercial use of wide band gap semiconductor power devices represented by SiC and GaN. Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) have become the important challenges to ensure the functionality, safety, reliability and performance of the system. Therefore, it is of great significance to study the EMI and EMC theory and key technologies of power electronics system.
    At present, EMI prediction and EMC technology of power electronics system have been widely studied. However, different industries have different technical characteristics and needs. Further, there are new challenges for satisfying EMC standard of power electronics system under the new situations such as the use of wide-band gap power switches, higher switching frequency, higher integration, higher voltage and higher power. Thus, it is necessary to carry out in-depth scientific research on the basic theory and key technologies of EMI and EMC of power electronics system.


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    Prediction and Measurement Techniques for Radiated EMI of Power Converters with Cables
    Zhedong Ma, Shuo Wang
    Chinese Journal of Electrical Engineering    2022, 8 (4): 1-10.   DOI: 10.23919/CJEE.2022.000033
    Abstract （297）      PDF      
    Recently, radiated electromagnetic interference (EMI) has become a research hotspot in power electronics systems, as the switching frequencies of power electronics systems have increased significantly with the adoption of wide-bandgap devices. In this article, a generalized radiated EMI model for power electronics converters with power cables is first reviewed. The radiated EMI model is then developed for a flyback power converter with critical ground impedance included. Based on the developed model, accurate high-frequency parameter extraction techniques and a radiated EMI prediction technique are developed and experimentally validated. Finally, essential measurement techniques are identified and developed to accurately extract parameters for accurate EMI prediction. The effects of the resolution bandwidth of the spectrum analyzer and critical PCB ground impedance on the radiated EMI are experimentally validated. PCB's impact on the common-mode (CM) choke's impedance and the radiated EMI is further validated. Techniques for minimizing the undesired near-field couplings in parameter extraction are discussed. The predicted EMI properly agreed with the measured EMI in the range of 30-230 MHz based on the EN55032 3 m class B standard.
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    Frequency-selective Optimization of Periodic Gate Control Signals in DC/DC Converters for EMI-reduction
    Caroline Krause, Stephan Frei
    Chinese Journal of Electrical Engineering    2022, 8 (4): 11-18.   DOI: 10.23919/CJEE.2022.000034
    Abstract （248）      PDF      
    High-frequency switching of power transistors in power electronic systems can cause electromagnetic emissions. Simple approaches for reducing high-frequency disturbances, such as inserting an additional gate resistor, lead to increased power losses. This makes achieving both electromagnetic compatibility and power efficiency difficult. Active gate drivers help to find a trade-off between these two. Typically, only narrow-band disturbances must be reduced. Accordingly, a target signal with a spectrum notched at some frequencies can be defined. The target signal can be reached by a target-signal-oriented control of the transistor's gate. This leads to steeper switching slopes, such that the power losses are less increased. Generating arbitrary target signals is impossible. The transistor signal exhibits some physical limitations. A constraint satisfaction problem must be solved, and the gate drive signal must be optimized by applying a residual and Newton's method. The proposed optimization process in the frequency domain is based on the circuit simulation method named “harmonic balance”. Measurements on a DC/DC converter exhibit the benefits of this method.
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    Dual-current-injection CSCC Active Common-mode EMI Filters with High Insertion Loss for DC-DC Converters*
    Hong Li, Siyi Wang, Chongmo Zhang, Bo Zhang
    Chinese Journal of Electrical Engineering    2022, 8 (4): 19-29.   DOI: 10.23919/CJEE.2022.000035
    Abstract （239）      PDF      
    With the increase in the switching frequency and power density, DC-DC converters encounter more severe electromagnetic interference (EMI) problems. To suppress the common-mode EMI generated by converters, as well as maintain the high-power-density of converters, the active EMI filter (AEF) has attracted increasing interest owing to its small volume. The EMI suppression effect of the common single-stage single-sense single-injection AEF is confined because of the limited insertion loss, and the volume of the multi-stage AEF will be bulky. To solve this problem, this paper proposes a compact dual-current-injection current-sense current-compensation (DCJ-CSCC) AEF to increase the insertion loss in the entire conducted EMI frequency band, as well as considering the volume of the AEF. The structure and operating principle of the proposed AEF are introduced. Finally, taking a boost converter as an example, the effectiveness and advantages of the proposed DCJ-CSCC AEF were verified through a simulation and experiment, the results show that the proposed AEF has a better EMI suppression effect on the entire conducted EMI frequency band with a similar volume compared with existing single-injection feedforward current-sense current-compensation (FF-CSCC) and feedback current-sense current-compensation (FB-CSCC) AEFs. This paper provides a new selection for EMI suppression in DC-DC converters.
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    Physics Informed Neural Network-based High-frequency Modeling of Induction Motors
    Zhenyu Zhao, Fei Fan, Quqin Sun, Huamin Jie, Zhou Shu, Wensong Wang, Kye Yak See
    Chinese Journal of Electrical Engineering    2022, 8 (4): 30-38.   DOI: 10.23919/CJEE.2022.000036
    Abstract （394）      PDF      
    The high-frequency (HF) modeling of induction motors plays a key role in predicting the motor terminal overvoltage and conducted emissions in a motor drive system. In this study, a physics informed neural network-based HF modeling method, which has the merits of high accuracy, good versatility, and simple parameterization, is proposed. The proposed model of the induction motor consists of a three-phase equivalent circuit with eighteen circuit elements per phase to ensure model accuracy. The per phase circuit structure is symmetric concerning its phase-start and phase-end points. This symmetry enables the proposed model to be applicable for both star- and delta-connected induction motors without having to recalculate the circuit element values when changing the motor connection from star to delta and vice versa. Motor physics knowledge, namely per-phase impedances, are used in the artificial neural network to obtain the values of the circuit elements. The parameterization can be easily implemented within a few minutes using a common personal computer (PC). Case studies verify the effectiveness of the proposed HF modeling method.
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    Uniform Distribution Spread-spectrum Modulation Strategy for MMC to Reduce Conducted EMI and Switching Loss*
    Hui Liu, Jianan Chen, Dong Jiang, Hong Li, Xuejun Pei, Wei Sun
    Chinese Journal of Electrical Engineering    2022, 8 (4): 39-51.   DOI: 10.23919/CJEE.2022.000037
    Abstract （271）      PDF      
    Modular multilevel converters (MMCs) have been widely used owing to their superior performance. However, the rapid switching of power electronics devices causes serious electromagnetic interference (EMI). There are a large number of obvious EMI peaks in the frequency spectrum of the carrier phase-shifted constant-switching-frequency pulse-width modulation (CSFPWM). Spreading the EMI across a wider frequency range can help to reduce the EMI peaks. In this study, we designed a uniform distribution (UD) spread-spectrum modulation technology using the principle of uniform switching frequency distribution and minimum switching loss for MMC. Its feasibility is verified by theoretical derivation and simulation. Then, the effectiveness of UDPWM in reducing the EMI is verified in experiments with a prototype MMC testbed in the lab. Compared with traditional CSFPWM, UDPWM can reduce conducted EMI by 10-20 dB. Also, compared with random PWM (RPWM), UDPWM can improve efficiency and reduce total harmonic distortion (THD) of output voltage and current in MMC.
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    Hybrid Common-mode EMI Filter Design for Electric Vehicle Traction Inverters
    Yongjie Han, Zhihong Wu, Deliang Wu
    Chinese Journal of Electrical Engineering    2022, 8 (4): 52-60.   DOI: 10.23919/CJEE.2022.000038
    Abstract （271）      PDF      
    A feedforward current-sense current-compensation (CSCC) active EMI filter (AEF) for the direct current-side common-mode (CM) electromagnetic interference (EMI) suppression of high-power electric vehicle traction inverters is analyzed and designed. A detailed design of the components with formulas is provided based on an analysis of the CSCC AEF, including the CSCC AEF topology and its implementation. The feedforward active filter stage was implemented using a simple current transformer and a small circuit board. Only a small passive filter with a high resonant frequency is required for high-frequency noise attenuation. The filter's effectiveness was validated using the simulation results and experimental measurements.
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