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This article investigates the radiated electromagnetic interference (EMI) due to the voltage between input and output cables in a non-isolated power converter. The radiated EMI model of a non-isolated power converter is first developed and quantified based on the circuit topologies, printed circuit board (PCB) parasitics, switching waveforms, and transfer functions. Second, an antenna model is developed for converter cables based on the antenna impedance and the antenna transfer function. Third, a complete radiated EMI model is developed based on the converter's EMI model and the cable's antenna model. Fourth, the radiated EMI is analyzed based on the developed model. Finally, two radiated EMI noise reduction techniques, optimizing PCB layout and adding a cross capacitor, are proposed. The developed radiated EMI model and the proposed radiated EMI reduction techniques are verified with both simulations and experiments. The techniques are also extended to other two non-isolated power converter topologies when the radiated EMI is caused by the voltage between the input and output cables. [ABSTRACT FROM AUTHOR]

This article develops magnetic dipole moment models based on Maxwell's equations for inductor's near magnetic field evaluation and reduction in power electronics systems. In the developed model, the near magnetic field source of an inductor is composed of the magnetic dipole moments from the winding and the air gaps. The superposition of the magnetic dipole moments determines the near magnetic field. The developed model can be easily applied to inductors with different winding and air gap configurations, such as those with lumped or distributed air gaps, for near magnetic field assessment and reduction. Simulations and experiments are conducted to validate the developed theory. [ABSTRACT FROM AUTHOR]

The drain to gate capacitance (Miller capacitance) of SiC MOSFETs leads to the Miller effect during switching transients. The Miller capacitance in a phase-leg configuration causes the crosstalk, the interaction between the two complementary switches, and the Miller plateau during the switching transient. The Miller effect reduces the switching speed, reduces reliability, and increases electromagnetic interference. In this article, by injecting a mirror cancellation current, the effects of Miller capacitance are canceled. The proposed technique includes a two-stage sensing and injection network to compensate for the nonlinearity of the Miller capacitance. The proposed technique can suppress both positive and negative gate voltage spikes induced by the crosstalk and reduce the switching power loss with the increased switching speed. Because no external control signals are required in the proposed technique, it can work with almost all commercial gate drivers. The detailed design for this proposed technique is presented in this article. The proposed technique was validated with both simulations and experiments. [ABSTRACT FROM AUTHOR]

This article first developed an inductance model that includes the parasitic mutual inductance between parallel current path segments for SiC multichip power modules. Based on the developed model, the SiC multichip module's transient response was analyzed, important parasitic inductances were identified. The layout was improved based on the transient analysis. The improved package layout can reduce the parasitic inductance without increasing the fabrication difficulty. Experiments were conducted to validate the reduction of parasitic inductances. The parasitic ringing and the crosstalk effect were significantly reduced with the proposed technique. The thermal performance was also improved with the proposed layout. [ABSTRACT FROM AUTHOR]

In this article, the effects of the parameters of GaN HEMTs and Si mosfets and the load conditions on the radiated electromagnetic interference (EMI) are analyzed based on the compositions of the equivalent noise voltage sources. These compositions include the rising and falling edges of the switching voltages, the zero-voltage-switching voltage drops and the parasitic ringing. The radiated EMI from two identical dual-active bridge converters with GaN HEMTs and Si mosfets is investigated and compared. Experiments were conducted to validate the analysis. [ABSTRACT FROM AUTHOR]

In consumer electronics, high power density power adapters are designed to minimize the adapter size. As a result, the components are getting very close and the near-field coupling issue tends to be severe. This compromises the performance of electromagnetic interference filters, especially at high frequencies. This article investigates near-field capacitive couplings and the reduction techniques in a high power-density power adapter with a dc-bus filter. The parasitic capacitive coupling theory is developed and parasitic coupling capacitances are experimentally extracted. The common-mode (CM) noise model with parasitic capacitive couplings is developed and the techniques to reduce the CM noise due to parasitic capacitive couplings are explored. Simulation and experiments were conducted to verify the analysis and the proposed techniques. [ABSTRACT FROM AUTHOR]

The near magnetic field emitted from magnetic components may generate electromagnetic interference (EMI) and degrade EMI filter's performance. This article discussed the near magnetic field emission from toroidal inductors. The emission mechanisms are analyzed for different inductor winding structures with either common-mode (CM) or differential-mode (DM) excitation. The winding structures with low near magnetic field emission are identified. A CM inductor structure is proposed to improve inductor's high-frequency CM performance and greatly reduce its near magnetic field emission due to DM currents. The improvements are achieved with a small extra toroid. The proposed structure can also increase CM inductor's DM inductance for DM noise reduction at the expense of a reduced DM saturation current. To avoid saturation, a design procedure is developed for the proposed CM inductor to achieve desired CM inductance, minimized near magnetic field emission, high DM inductance, and optimal magnetic flux density. Three-dimensional (3-D) finite-element analysis models were developed and experiments were conducted to validate the developed theory and techniques. EMI measurement results show that the proposed CM inductor has a better performance for both DM and CM noise reduction than a conventional CM inductor. [ABSTRACT FROM AUTHOR]

EMC spectrum analyzers are popularly used for electromagnetic interference (EMI) measurement in power electronics systems. Depending on the specifications of EMI standards, the EMI measurement could be very time consuming. Conventionally, the fast Fourier transform is used to derive the EMI spectrum from the measured time-domain waveforms. However, these results may not agree with the measurement results from spectrum analyzers, and sometimes the difference could be significant. In this paper, a technique to quickly and accurately predict and analyze the EMI spectrum from time-domain waveforms is proposed. The technique is developed based on the spectrum analyzer's operating principle and the requirements of EMI standards. The EMI spectra of three modulation schemes are also analyzed. Theoretical analysis, simulations, and experiments were all conducted. The predicted peak, quasi-peak, and average EMI matches the measured EMI in whole conductive frequency range. The developed technique can accurately predict EMI using much shorter time than conventional EMC spectrum analyzers and it saves cost of expensive spectrum analyzers. [ABSTRACT FROM AUTHOR]

To analyze the radiated electromagnetic interference generated by isolated power converters, this paper proposes a technique to develop a general radiation model for the converters. The radiated electric field can be predicted from the developed model. The interaction between the impedance of the converter and the undesired antenna in the converter's power delivery paths is explored in detail based on the developed model. Moreover, a dual active bridge converter is taken as an example to demonstrate the developed modeling technique based on the converter's topology. The radiated electric field of the dual active bridge converter is predicted from the developed model. Experiments are conducted to validate the developed model and the predicted interaction between the converter impedance and the undesired antenna impedance in the power delivery paths. [ABSTRACT FROM AUTHOR]

This paper investigates the magnetic field immunity and near magnetic field reduction for different inductor-winding structures. A double-twisted winding structure, which includes two magnetic cores, is proposed for common mode (CM) inductors. The proposed CM inductor can achieve much lower near magnetic field emission, much better magnetic field immunity against the external magnetic field, and much bigger differential mode (DM) impedance than conventional winding structures. The proposed inductor structures are good for high power-density applications. Theoretical analysis, magnetic three-dimensional simulations and experiments were conducted to validate the developed theory and technique. [ABSTRACT FROM AUTHOR]

In this paper, the active differential-mode (DM) electromagnetic interference (EMI) filter topology for ac/dc converters is first briefly investigated. The active DM EMI filter model was developed based on the models of filter components including a current transformer, a high-pass filter, an operational amplifier, and a class AB amplifier. The system model including the active filter, ac/dc converter, and line impedance stabilization networks (LISNs) are explored. With the developed system model, the loop gain and insertion gain of the active filter are derived. Based on the loop gain, the stability of the active filter is investigated and the compensation is applied to achieve stability and good EMI reduction. Both simulations and experiments are conducted to validate the developed technique. [ABSTRACT FROM AUTHOR]

A grid-tied cascaded H-bridge (CHB) converter with low frequency modulation techniques needs to meet power quality standards. At the same time, the effects of grid voltage harmonics on CHB converter's current harmonics must be considered in the modulation techniques. Furthermore, the dc link voltages of grid-tied converters need to be regulated. In this paper, an asymmetric selective harmonic current mitigation-pulse width modulation (PWM) (ASHCM-PWM) technique is used to meet the current harmonic limits of a power quality standard with the effects of grid voltage harmonics considered in the equation set of its optimization process. A voltage balancing technique based on the average power of each cell is derived to regulate the dc link voltages of the CHB converters without using dc voltage sensors. By using the proposed voltage balancing technique, the CHB converters do not need complicated dc link voltage controllers. As a result, the cost and complexity of the grid-tied converters can be significantly reduced. Simulations and experiments were conducted on a 7-level grid-tied CHB converter to validate the proposed voltage balancing technique with ASHCM-PWM modulation technique. [ABSTRACT FROM AUTHOR]

For isolated dc–dc power converters, the interwinding parasitic capacitance of the transformer is usually one of the main paths for common-mode (CM) noise. In order to simplify the CM noise analysis, this paper proposes a two-capacitor transformer winding capacitance model. The model is derived based on general conditions so it can be applied to different isolated converter topologies. A measurement technique is also proposed to obtain the lumped capacitance for the model. The CM noise models of several isolated converter topologies are analyzed with the proposed two-capacitor transformer winding capacitance model to achieve simplicity. Finally, the proposed transformer winding capacitance model and measurement technique are verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

Hybrid electromagnetic interference (EMI) filters (HEFs), which are composed of an active filter and a passive filter, have been proposed to reduce the size and weight of conventional passive EMI filters in literatures. However, accurate models that can be used to predict the stability and performance of HEFs have not been developed. To cope with this, this paper presents a modeling technique for a hybrid common-mode (CM) filter. The technique can be applied to the modeling of other HEFs. Critical component models were first developed for the HEF. HEF's overall model was further developed based on these individual component models. Experimental results validated that the developed model can successfully predict the stability and performance of active/hybrid CM filters. [ABSTRACT FROM AUTHOR]

This paper first analyzes the current paths on a planar busbar based on insulated-gate bipolar transistor bridge switching states and dc-link capacitor configurations. The busbar's circuit models which include both self- and mutual inductances are developed based on the identified current paths. The inductance circuit models are analyzed and reduced for different switching states, transition states, and dc-link capacitor configurations. Inductance and current sharing is analyzed based on circuit theory. Both simulations and measurements are conducted to verify the developed technique. [ABSTRACT FROM AUTHOR]

This paper proposes a stacked common-mode (CM) inductor for electromagnetic interference (EMI) attenuation. The proposed stacked CM inductor consists of two CM inductors with identical cores and the same number of winding turns but with opposite winding directions. The proposed stacked CM inductor has three advantages. First, it is much less susceptible to external magnetic field interference than conventional CM inductors. This suppresses the EMI due to the near-magnetic-field coupling to the CM inductor. Second, the proposed winding structure effectively increases the leakage inductance of the CM inductor, which enhances its ability to suppress differential-mode (DM) noise. Third, the magnetic field generated by the DM current in the stacked CM inductor is partially canceled outside of the inductor. As a result, the stacked CM inductor has lower magnetic field emission than that of a conventional CM inductor. Simulation and experimental results validate the advantages of the proposed CM inductor, which show the proposed technique greatly improves the performance of CM inductors. [ABSTRACT FROM AUTHOR]

The paper first proves the existence of a nonlinear, feedback loop due to the effect of an active power filter (APF) on the grid voltage for a multifunctional electric vehicle charging station. A linear, open-loop model is derived based on direct quadrature (DQ)-theory in discrete time (DT). Based on this model, a linear, closed-loop model is further developed with DQ-theory in DT. A triangle-hold equivalent instead of a zero-order-hold equivalent is employed in the model for better representation. The developed linear, closed-loop model is finally generalized to general power systems. Simulations are carried out to verify the developed models under transient conditions. The short-time (1–2 ms), transient stability of the grid with an APF is determined with the developed model. In contrast to existing stability analyses in the phasor domain, using DQ-theory can linearize the loop and simplify the loop model in DT domain. [ABSTRACT FROM AUTHOR]

In this paper, three-phase noise is first analyzed using symmetrical component theory. Three-phase noise separators are modeled and characterized using symmetrical component theory and S-parameters. The critical formulas used to evaluate a three-phase noise separator are derived. A function scheme and a circuit structure for three-phase noise separators are proposed based on the theory developed. The technique to design a high-performance three-phase noise separator is explored. A three-phase noise separator prototype is finally built, measured, and evaluated using the theory developed in this paper. The prototype is used in a practical three-phase power electronics system for electromagnetic interference measurement. [ABSTRACT FROM AUTHOR]

Interleaved multichannel power factor correction (PFC) converter is very popular today because of its ability to reduce input and output current ripples. In this paper, the common-mode (CM) electromagnetic interference noise emission model of the multichannel PFC converter is studied. A balance technique is introduced to reduce CM noise emission. To improve the high-frequency balance, a novel topology with coupled-inductor structure is proposed. Its CM noise model is derived and balance condition for minimizing CM noise is calculated. Effects of phase shift and channel shedding on this solution are also studied. The proposed topology has effectively reduced CM noise under any phase shift and channel shedding conditions. A two-channel PFC converter is built to verify the proposed balance technique. Experimental results show that CM noise can be reduced up to 20 dB between 150 kH and 7 MHz. [ABSTRACT FROM AUTHOR]

In this paper, at first, three requirements for noise separators are specified and the disadvantages of traditional evaluation methods are pointed out. Noise separators are then characterized using scattering parameters (S-parameters). Existing noise separators are evaluated according to the specified requirements. Finally a noise separator is proposed with parasitic controlled design and the prototype is evaluated using the proposed method. An electromagnetic interference (EMI) measurement shows that the proposed noise separator can effectively separate noise and that it is easy to use. [ABSTRACT FROM AUTHOR]

This article first develops a radiated electromagnetic interference (EMI) model for a gallium nitride (GaN) integrated circuit (IC)-based active clamp flyback converter. Important capacitive couplings, which play a big role in the radiated EMI, are identified, extracted, and validated in the converter. The radiated EMI model is improved to characterize the impact of capacitive couplings. Based on the improved model, techniques to reduce capacitive couplings and the radiated EMI are proposed and experimentally validated. [ABSTRACT FROM AUTHOR]

In this article, the common-mode (CM) noise model is developed for an ac–dc–ac system with paralleled power modules. The CM noise contributions from both rectifiers and motor drives are analyzed. The interaction between the ac/dc rectifiers and dc/ac motor drives is explored. The CM noise reduction techniques which include a decoupling inductor technique and a CM noise balance technique are proposed to reduce the CM noise on the ac input side. Experiments and simulations were conducted to validate the developed CM noise model, rectifier and inverter interaction theory and CM noise reduction techniques. [ABSTRACT FROM AUTHOR]

Applying the selective harmonic elimination (SHE) technique to grid-connected-cascaded modular multilevel inverters has been widely discussed in the literature. However, due to the difficulties of solving high-order nonlinear transcendental equations, the SHE technique cannot be implemented in real time so its applications are limited. This paper presents a technique to convert the nonlinear equations to a specific control system and use a look-up table, integral controllers and a decoupling controller to help the system converge to a zero-error steady state. An inner instantaneous observer is introduced to directly extract the harmonic spectrum of the output voltages without applying FFT algorithm to output step voltage waveforms. It can not only simplify software design but also eliminate the phase delay generated by conventional spectrum extracting algorithm. The proposed technique can achieve an accurate switching angle control and a fast response. Simulation and experimental results verified that the system can achieve zero-error steady state within one line period. [ABSTRACT FROM AUTHOR]

In this article, an efficiency-oriented control strategy is proposed for LCC–LCC-compensated wireless power transfer (WPT) system to achieve zero-voltage-switching (ZVS) operation over a wide current regulation range, in which full-bridge (FB) and half-bridge (HB) modes are combined and switchable based on requirements from load. The harmonic-considered time-domain models for FB and HB modes are first built to calculate current through the switches at the turn-off moment accurately. Then, focused on the constant voltage charge stage with variable output current, the ZVS boundaries are identified in HB and FB modes as the preferable control trajectories, which determines the desired current output with joint considerations of frequency, phase-shift angle, and duty ratio. Next, a least squares optimization method is introduced to fit the theoretical control trajectories into a smooth curve that is practical for implementation on microcontrollers. Finally, a 4.4-kW WPT prototype is built to verify the feasibility and validity of the proposed control strategy. Results show that a high system efficiency can be achieved over a wide output current range, with an efficiency of 94.68% even at 20% rated power. [ABSTRACT FROM AUTHOR]

A high switching frequency isolated voltage-fed dual-transformer-based hybrid semidual active bridge converter is introduced in this article for unidirectional power flow and wide voltage range applications. The converter embraces the full-bridge and half-bridge properties under varying operating conditions to improve efficiency. Five appropriate working patterns are elaborated, including ideal output power derivation, current stress analysis, working voltage matching, output power distribution, and soft switching features. Afterward, a simple segmented control strategy is adopted in accordance with the analysis results. The zero voltage switching of all switches is achieved by introducing the magnetic current and suitable drive logic. Compared with the existing works, the proposed converter has outstanding merits in terms of reduced conduction loss, switching loss, and peak current of ac inductor, resulting in high conversion efficiency. Hence, the converter is more suitable for cases with wide and frequent input voltage variations. Eventually, the effectiveness of the converter and the control strategy is verified by a 1.0-kW prototype. [ABSTRACT FROM AUTHOR]

The transmission-line busbar filter is an innovative high-density electromagnetic interference (EMI) containment solution for power electronics systems. It uses the concept of the transmission-line EMI filter as a part of the power interconnection to eliminate the EMI noises in power converters. This paper presents a systematic study of the transmission-line busbar filter in a motor drive system, which includes its design, modeling, and improvement using a hybrid approach. The paper investigates the relationship between the busbar filter's in-circuit attenuation and its geometry, and then derives a general design guideline for the transmission-line busbar EMI filters. To improve the performance of the transmission-line busbar filter, the paper proposes a hybrid busbar filter combining a transmission-line busbar filter and a one-turn inductor. This improvement provides much higher attenuation than the traditional transmission-line busbar filters. These proposed concepts have been verified experimentally not only with small-signal measurement but also with in-circuit tests in a medium-power motor drive system. [ABSTRACT FROM AUTHOR]

In the past few years, coupled inductors have become more and more popular in microprocessor voltage regulators (VRs) for they can increase the VRs' steady-state and transient performances. In this paper, twisted core coupled inductors are proposed to reduce the winding path of coupled inductors. Next, the reluctance model of the twisted core coupled inductors is proposed. After that, based on the proposed reluctance model, the design procedure of the twisted core coupled inductors is shown. Finally, experimental results verify the proposed twisted core coupled inductors and the reluctance model. [ABSTRACT FROM AUTHOR]