Qingbin Chen

Common mode chokes (CMCs) are key components in electromagnetic interference (EMI) filters, and accurate modeling of these components is critical for filter design and EMI noise simulation. This paper proposes a behavioral model and parameter extraction technique for characterizing three-phase four-wire common mode chokes (4W-CMCs). The proposed model considers the inductance nonlinearity caused by the nonlinear permeability of manganese-zinc ferrite and nanocrystalline magnetic materials, as well as the asymmetry and local symmetry in the winding distribution of 4W-CMCs. The parameters for the common mode (CM) and differential mode (DM) models are extracted using a parameter extraction program and a simple equation-based method, respectively. For the DM model parameter extraction, this paper proposes a measurement method that utilizes the local symmetry of 4W-CMCs. The equivalent circuit of this measurement method decouples the inter-winding capacitance (CW) from the differential mode inductance parallel capacitance (CD) by transforming two-port network parameters, greatly simplifying the parameter extraction process. The accuracy of the model and the effectiveness of the method are validated through experiments using several 4W-CMCs with manganese-zinc ferrite and nanocrystalline magnetic cores.

The complex permeability of magnetic materials at radio frequencies significantly impacts the electromagnetic compatibility characteristics of magnetic components. The precision of its measurement is crucial for the design, selection, and study of electromagnetic compatibility properties of magnetic components. This paper discusses the key material parameters affecting the radio frequency characteristics of magnetic materials and provides a detailed analysis of how these parameters influence the complex permeability of magnetic materials. It reveals why traditional methods for measuring the complex permeability of magnetic materials are not applicable at high frequencies. The paper identifies the parasitic inductance and capacitance in the measurement winding as the primary factors affecting measurement accuracy. Consequently, it proposes a new method for testing the complex permeability of magnetic materials in the radio frequency range, considering the effects of parasitic parameters in the measurement winding. This method effectively combines small-signal measurements with finite element simulation to calibrate parasitic parameters, significantly extending the frequency range of the measurement results. Experimental findings demonstrate that the proposed method accurately extracts the characteristic parameters of magnetic materials in the frequency range of 30 MHz to 1 GHz.

The ignition module is the start-up of the pulsed plasma thrusters (PPT), in which the high-voltage pulse transformer is the most important component, as its output characteristics can affect the reliability of PPT ignition. This article discusses the influence of the parasitic parameters of the high-voltage pulse transformer on the output pulse waveform. It reveals that the leakage inductance of the high-voltage pulse transformer is the root factor affecting the output voltage’s rise time, while parasitic capacitance and excitation inductance have little influence and can be ignored in most real applications. The smaller the leakage inductance of the high-voltage pulse transformer, the better the overall performance of the output pulse voltage waveform. The toroidal high-voltage pulse transformer’s leakage inductance mechanism is analyzed based on the electromagnetic field principle, and the theoretical calculation model of leakage inductance is established. Furthermore, the high-voltage pulse transformer optimization guideline is proposed. The optimized high-voltage pulse transformer can reduce leakage inductance by 71.8%. Finally, the experimental results verify the theoretical analysis to be correct and useful.

Capacitive power transfer (CPT) technique uses coupled metal plates for energy transmission, which has the advantages of negligible eddy-current loss and low weight. To achieve efficient power transfer, CPT system often adopts circuit resonance and impedance compensation, which are generally realized by integer-order components, such as inductors and capacitors. However, it remains a fundamental challenge to create a CPT system whose transfer efficiency and output power are robust against the variation of resonant frequency and the coupled plates’ relative position. Therefore, this paper proposes a robust fractional-order autonomous CPT system containing a fractional-order inductor. Theoretical analysis shows that the transfer efficiency and output power of the proposed fractional-order CPT system are inherently robust not only to the variation of the coupled plates’ relative position but also to the resonant frequency. In contrast, the transfer efficiency and output power of traditional integer-order CPT systems are sensitive to the resonant frequency. The available experimental results verify the effectiveness of the proposed system.

High-power inductors are fundamental components in high-power DC–DC converters, with their performance being a crucial metric of converter efficiency. This paper presents an in-depth analysis of a novel calculation method for the air gap length in such inductors. Taking into account the effects of air gap diffusion and the winding magnetic field, an expression for the air gap diffusion radius is derived, focusing on a distributed air gap structure. Furthermore, models for calculating the air gap and winding reluctance are developed, grounded in electromagnetic field theory. An equivalent magnetic circuit model, formulated based on Kirchhoff's second law, facilitates the proposed method for air gap length calculation. This study also involves the development of 3D models for both discrete and decoupled integrated inductors. The comparison between simulation outcomes and calculated air gap lengths indicates a maximum error of less than 8%, with the minimum error being as low as − 0.79%. Compared with traditional methods, the calculation method proposed in this paper has significant advantages. Additionally, the discrepancy between calculated values and experimental measurements is found to be 1.11%. These results validate the accuracy and applicability of the theoretical analysis and calculation method, underscoring their significance in the design and optimization of high-power DC–DC converters.

Wireless power transfer (WPT) technology has been widely investigated and applied in recent times. Increasing operation frequency proves to be effective in enhancing power transfer distance and reducing the volume of the magnetic coupling system (MCS) in the WPT system. However, once the frequency reaches MHz, the capacitive parasitic parameters of the coil in MCS can not be ignored, as it adversely affects the output characteristics in a series/series (S/S) compensation wireless power transfer system. This paper presents a method for parasitic capacitance modelling method and introduces a technique for its reduction in MCS. The parasitic capacitance is not only determined by the coil structure, including capacitance between adjacent and nonadjacent turns, but also by the electrical potential distribution of the winding turns. Based on the mathematical model of parasitic capacitances in MCS, a distributed capacitance compensation structure is adopted, and the capacitance parameters determination method is proposed. With the method, the coil parasitic capacitance can be reduced by changing the voltage potential distribution of the coil in MCS to minimize the impact of parasitic capacitances. Experimental results verify the accuracy and effectiveness of the theoretical analysis.

High-power inductors are fundamental components in high-power DC-DC converters, with their performance being a crucial metric of converter efficiency. This paper presents an in-depth analysis of a novel calculation method for the air gap length in such inductors. Taking into account the effects of air gap diffusion and the winding magnetic field, an expression for the air gap diffusion radius is derived, focusing on a distributed air gap structure. Furthermore, models for calculating the air gap and winding reluctance are developed, grounded in electromagnetic field theory. An equivalent magnetic circuit model, formulated based on Kirchhoff's second law, facilitates the proposed method for air gap length calculation. This study also involves the development of 3D models for both discrete and decoupled integrated inductors. The comparison between simulation outcomes and calculated air gap lengths indicates a maximum error of less than 5%, with the minimum error being as low as 0.54%. Additionally, the discrepancy between calculated values and experimental measurements is found to be 1.11%. These results validate the accuracy and applicability of the theoretical analysis and calculation method, underscoring their significance in the design and optimization of high-power DC-DC converters.

With high power density and high-frequency power electronics technologies, parasitic capacitances of inductors and transformers have been widely discussed, in which parasitic capacitance may lead to electromagnetic interference (EMI) and efficiency performance degradation. Therefore, it is significant to analyze and model the parasitic capacitance of the inductors and transformers. This paper proposes a new parasitic capacitance calculated model of multilayer windings inductors and transformers. Based on the electromagnetic field theory, it can fully consider the edge effect of multilayer inductor windings, including the edge effect between adjacent and non-adjacent layers. Finally, the accuracy of the model is validated by simulation and experiment. Compared with the traditional parasitic capacitance calculated method, the proposed model can calculate the parasitic capacitance more accurately, and the maximum error between calculations and simulations is less than 8%.