Common Mode Choke Research Articles

Winding Optimization for Reducing Parasitic Capacitances of Common-Mode Chokes

Winding Optimization for Reducing Parasitic Capacitances of Common-Mode Chokes

Simulation and optimization of EMI filter of conducted emission for high voltage gain DC-DC converter

In the continuity of the work on design of high voltage gain DC-DC converter, used for feeding the CubeSat electrospray thrusters with a variable output voltage according to the maneuver size, this paper introduces a simulation of the converter model with MATLAB/Simulink to determine its conducted emission level. By referring to the MIL-STD-461 standard, a required passive electromagnetic interference (EMI) filter parameters are calculated to reduce, under thresholds, the converter noise. With consideration of the available volume and power constraints in this kind of satellite, the design of common-mode (CM) choke is optimized with proposed procedure optimization, so as to reduce its volume and electrical losses. Also, this optimization procedure can be generalized and applied for any passive EMI filter design.

Analyzing and Characterizing Common Mode Chokes for Three Phase Systems

Analyzing and Characterizing Common Mode Chokes for Three Phase Systems

COMMON-MODE AND DIFFERENTIAL CHOKES

The types of interference in power supplies and DC/DC converters are described. The principle of operation, parameters and design designs of common-mode and differential chokes are given. The features of filters used in power supply circuits and in signal interfaces are established. These data can be used to design commonmode chokes and electrical devices containing them.

Surrogate Model-Based Parameter Identification for 3-D Modeling of Common Mode Chokes

Surrogate Model-Based Parameter Identification for 3-D Modeling of Common Mode Chokes

A Novel Common-Mode Voltage Suppression Strategy for Current Source Converter

The problem of common-mode voltage (CMV) in current source converter (CSC) has been concerned with the development and application of CSC, such as in the transformerless motor drive system. Using a common-mode choke is a popular solution to suppressing CMV. The high-frequency harmonics of the CMV can be eliminated by the common-mode filter. However, the low-order harmonics cannot be eliminated effectively, especially at low modulation index, which may cause common-mode resonance and increase the size of the choke. In this paper, a novel virtual space vector modulation (VSVM) method is proposed, which constructs virtual space vectors by the original vectors. The average value of the CMV produced by each virtual vector is zero. The proposed method can reduce the amplitude and third-order harmonic component of the CMV. In addition, the number of switching transitions in a switching sequence of the proposed method is the same as the conventional 5-segment SVM. The suppression effects of different methods on the low-order harmonics of CMV are compared through simulation and experiments, and the effectiveness of the proposed methods is verified.

Modal Theory and Approach for Accurate Characterization of Common-Mode Chokes

This work presents a method for characterization of common mode chokes, aimed at constructing accurate virtual prototypes of electromagnetic interference filters. This method is based on a general modal analysis that identifies the natural modes of a symmetric four-ports network in a power line. Natural modes excited in the setups defined in the CISPR-17 norm to characterize filtering devices are determined. From this analysis, two simple measurement setups particularly suitable for characterizing common mode chokes are identified, and a decision-making algorithm is presented to determine the parameters of a configurable circuit model of the common mode choke. This circuit model is especially devised so that each one of its different circuit blocks can be associated with a single modal response of the common mode choke. This, along with the use of physical criteria to define the basic schematic of each circuit block, ensures the simplicity, accuracy, and generality of the final circuit model. Characterization of many commercial common mode chokes with different core materials and winding configurations has been carried out to demonstrate that this circuit model is able to accurately account for the actual response of different types of common mode chokes in a wide frequency range.

Sigma-Delta Modulation on a Three-Phase Four-Leg VSI to Eliminate the Common Mode Voltage and Comply With the Military Standards

This paper demonstrates sigma-delta pulse density modulation (PDM) without common mode voltage on a four-leg voltage source inverter designed as a grid-forming inverter. Using PDM ensures that switching updates occur simultaneously for all phases and sigma-delta modulation is the most advantageous PDM for this application. The converter does not produce common mode voltage in the switching frequency range, thus meeting the conducted electromagnetic interference limits in MIL-STD-461G without the need for a large common mode choke. Further, the proposed common mode elimination method does not degrade the output voltage power quality, which meets the requirements in MIL-STD-1399 section 300 part I for type 1 voltage. The practical implementation of the control system on a Field Programmable Gate Array (FPGA) is presented and compliance with the two military standards is demonstrated on a laboratory prototype built with SiC MOSFETs.

Analysis of Common-Mode Noise and Design of a Reduced-Volume Concentric Choke for Dual Active Bridge dc–dc Converter With Integrated Magnetics

Dual active bridge (DAB) dc-dc converter with integrated transformer is explored in recent years due to its advantages of the low component count, high power density and high efficiency. Although the operational performance of the DAB converter is well reported, the common-mode (CM) noise with the integrated transformer is yet to be thoroughly analyzed. Hence, this paper presents a detailed analysis of the CM noise performance of the DAB converter employing integrated transformer. Moreover, the conventional CM chokes incorporated to mitigate the CM noise cause a deleterious impact on volume and power density of the converter. This paper proposes a concentric CM choke that occupies less volume compared to its equivalent conventional CM choke of the same CM impedance. The analysis and design guidelines for the proposed concentric CM choke are presented. The above-mentioned analyses of the integrated transformer and the concentric CM choke are experimentally validated on a DAB converter prototype.

VNA-Based Fixture Adapters for Wideband Accurate Impedance Extraction of Single-Phase EMI Filtering Chokes

Differential-mode and common-mode chokes (DMC and CMC) are key components of electromagnetic interference (EMI) filters. Accurate impedance knowledge of these chokes allows optimal EMI filter design to meet the conducted emission requirements. An impedance analyzer (IA) or vector network analyzer (VNA) with a fixture adapter is commonly adopted for impedance measurement of a passive component. Usually, the non-standard terminals of both DMC and CMC make them incompatible for direct mounting on commercially available fixture adapters. Relying on additional interconnects to the fixture adapters introduce inherent parasitic effects that limit measurement accuracy up to several megahertz. This paper proposes a design method of customized fixture adapters which are specifically tailored for impedance measurement of single-phase DMC and CMC. Through a systematic parasitic de-embedding process, the choke impedance can be extracted with excellent accuracy up to 120 MHz.

Suggesting a Non-Unity Turn Ratio Two-Winding Coupled Inductor for Filtering CM EMI Noise in an SRC

Switched-mode power supplies (SMPS) are the source of both conducted and radiated electromagnetic interference (EMI) noise. Resonant converters are popular due to the possibility of switching loss reduction using zero voltage switching (ZVS) or zero current switching (ZCS) and also attenuating conducted EMI noise. Conventionally, a common-mode (CM) choke with a single core and two identical windings is used to suppress the CM noise in an EMI filter. This paper introduces an effective and cost-efficient method for mitigating the CM EMI noise in SRCs. The proposed method benefits a two-winding coupled inductor instead of the simple resonant inductor in the SRC. While a unity turn ratio does not meet the desired resonance inductance, the suggested two windings coupled inductor with an unequal number of turns deals with the EMI noise as well as the normal operation of an inductor in the resonant tank. Applying the proposed method significantly achieves up to 20 dB attenuation in the noise amplitude both at the input and output terminals of the converter. Simulations are used for investigating the analysis of the method. Moreover, a series resonant converter is designed and implemented to verify both analysis and simulations.

Study of High Frequency Characteristics Modeling and EMI Suppression of Common Mode Chokes

This paper proposes a method for building a high-frequency model of common-mode chokes in the frequency range of 9kHz to 200MHz. The method only needs to measure the common mode and differential mode impedance data of the common mode choke, and then use the differential evolution algorithm to process the impedance data to complete its high-frequency modeling. Comparison with the high-frequency model obtained by using a genetic algorithm shows that the method has high accuracy. After the high frequency modeling of the common mode chokes, the high frequency modeling of the X and Y capacitors is performed using the differential evolution algorithm, and the high frequency model of the EMI filter is obtained by combining it with the established high frequency model of common mode chokes. By comparing the measured and simulated conducted interference noise suppression effect of the EMI filter, the high frequency model of the common mode chokes is verified to suppress the conducted interference, and the effectiveness of the common mode choke high frequency modeling method is determined.

Circulating current suppression for ground tied variable frequency to constant frequency converter system in aircraft

This paper presents a solution to the circulating current fault of aircraft power supply. The DC-link type Variable Frequency to Constant Frequency (VFCF) converter system is the preferred scheme to feed the constant 400 Hz load in an aircraft with a variable frequency power supply. Due to the requirement of aircraft standards, both grounds of the rectification and inversion stage are tied to the metal frame of the aircraft. With such a tied ground, the DC bus voltage rises greatly, and a large circulating current appears in the casing as the ground, which leads to equipment failure and potential safety hazards. According to the existing methods of circulating current fault suppression, this paper analyzes the causes of the above faults and the harmonic components of circulating current and points out the limitations of the existing methods. Therefore, a Common-Mode (CM) choke-based method is proposed to provide a high impedance in the path of the CM circulating current. By doing so, the circulating current can be suppressed without the additional burden of the hardware and control algorithm, which is quite friendly for quality control of mass-production aircraft. Moreover, a simplified mathematic model of the VFCF converter system is derived to calculate the minimum inductance value reference of the CM choke, which saves the weight of passive devices to the greatest extent. Finally, simulation and experimental results are studied to verify the effectiveness of the proposed method.

Full Electromagnetic Integration of Impedance-Balanced EMI Filters for Single-Phase Power Converters

Utilizing passive electromagnetic interference (EMI) filters is the most widely used approach to restrain the conducted emissions from power converters. However, the introduction of these filters will significantly raise the weight and size of the systems. Using the emerging flexible multi-layer foil (FMLF) technique, this paper investigates a complete electromagnetically integrated design concept of single-phase EMI filters based on EE-type cores, which can be applicable to engineering application scenarios with different EMI noise attenuation requirements. Two types of integrated structures are constructed with different well-designed FMLF-windings and terminal configurations. One is a common-mode (CM) choke with controllable leakage inductances, which is able to realize the integration design of CM inductor, CM capacitors and differential-mode (DM) inductors. The other is an EMI choke with integrating the CM and DM inductances & capacitances, which achieves electromagnetic integration of all the CM and DM filtering components. Compared to the existing UU-type core based integration methods, the proposed methods can ameliorate the noise suppression performance while reducing filter's weight and volume. Theoretical analyses for modeling and design of the EMI chokes is presented. Then prototypes of different FMLFs based EMI filters have been built for a 500W 100kHz SiC-MOSFET inverter, experiments demonstrate the feasibility and validity of the proposed structures.

Comparison of ESD Damage Test for Common-Mode Chokes With ESD Gun and TLP-HMM

The method of electrostatic discharge (ESD) damage test for common-mode chokes has been standardized in IEC 62228–5 Annex E. However, there is a concern about the reproducibility of the ESD damage test using the ESD gun described therein. Against this background, the possibility of replacing the ESD gun with a transmission line pulse–human metal model (TLP-HMM) was investigated. The results of the ESD damage test using the ESD gun and TLP-HMM are found to be similar but not exactly the same, especially at low frequencies. Moreover, due to the different waveform generation principles and circuit configurations of the ESD gun and TLP-HMM, even if a load of the same structure is used to calibrate the ESD gun and TLP-HMM, when they are applied to other loads, it is still difficult to guarantee that the discharge currents are the same. The findings raise an issue on how to define a standard TLP-HMM so that it could provide the worst test result compared to the ESD gun.

Construction and testing of a common mode choke for cryogenic detector pre-amplifiers

Common-mode choke inductors are useful tools for resolving grounding issues in large detector systems. Using inductive components on cryogenic pre-amplifier boards has so far been prevented by the poor low-temperature performance of common ferrite materialssuch as NiZn and MnZn. Recentlydeveloped nanocrystallineand amorphous ferrite materials promise improved performance up to the point where using magnetics at liquid mitrogen temperatures becomes feasible. This research applies the work of Yin et al. on characterizing ferrite materials by constructing and testing a common mode choke inductor for use on detector pre-amplifiers for the ELT first generation instruments.

Novel Common Mode Voltage Elimination Methods in Three-Phase Four-Wire Grid-Connected Inverters

This paper presents two current control methods to attenuate the common mode (CM) conducted emissions in three-phase four-wire four-pole inverters connected to an AC distribution bus and operating in grid-following mode. Delta modulation and model predictive control both achieve elimination of the common mode voltage at the output of the three-phase four-pole inverter and meet the requirements of the military standard 461G without a full-size CM choke. The differential mode performance is comparable to that achieved with the benchmark three-dimensional space vector modulation, which does not cancel the CM voltage. A physics-based model of the system was developed to simulate the conducted emissions and DM performance of the two proposed methods. As the CM voltage cancellation methods result in increased switching frequency, wide bandgap devices were used to build a laboratory prototype, on which the simulated results were successfully validated.

Prediction and Measurement Techniques for Radiated EMI of Power Converters with Cables

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.

Magnetic Saturation Suppression of Common-Mode Choke Coil by Selecting Suitable Inverter Carrier Frequency

Common-mode choke (CMC) plays an important role in suppressing the leakage current produced during the operation of pulse width modulation (PWM) inverters. However, when the common-mode path exhibits a large series stray capacitance, particularly the capacitance produced by long shielded cables, the CMC core reaches magnetic saturation. This paper presents a technique of selecting a suitable carrier frequency for the inverter to suppress the magnetic saturation of the CMC. First, the analytical approach leads to a non-saturation condition, and clarifies the maximum and minimum carrier frequency design conditions. Subsequently, the effect of the design is demonstrated by a non-linear circuit simulation and experimental tests using an actual inverter system demonstrate the effectiveness of the design technique.

Planar Common-Mode EMI Filter Design and Optimization for High-Altitude 100-kW SiC Inverter/Rectifier System

Silicon-carbide (SiC) devices are receiving popularity for high-power converter systems in aircraft due to many advantages over silicon counterparts. However, the electromagnetic interference (EMI) problems are more serious with the SiC devices operating at higher switching speeds and higher switching frequencies. The common-mode (CM) EMI filter design of the high-power SiC converter is especially challenging for high-altitude applications due to the harsher requirements of insulation and heat dissipation. The optimization of the parameters and physical design of a CM EMI filter in a 100-kW SiC inverter/rectifier system operating at 50 000 ft is conducted in this article to obtain the highest power density. The effect of the switching frequency on the EMI filter volume and the total power density of the converter system is analyzed. The lower breakdown voltage of air and the higher thermal resistance of natural convection make the conventional design of the CM choke infeasible at high altitudes. A printed circuit board (PCB)-based planar CM choke is designed with the consideration of partial discharge (PD) and heat dissipation at the altitude of 50 000 ft. The structure of the CM choke is optimized with embedded electric-field shielding plates, which controls the electric-field intensity in the air below 300 V/mm. The PCB windings improve the efficiency of heat dissipation at high altitudes and reduce the profile of the CM choke. A Pareto optimization is conducted to minimize the size of the choke and the volume of the final design is only 155 cm3. The experimental results show that the CM noise is reduced effectively with the CM EMI filter. PD is not observed even at the altitude of 50 000 ft and the thermal performance is excellent with a current of 190 A. With the optimization and the dedicated design of the CM EMI filter, the power density of the converter system is up to 33.3 kW/L.