Validation of Wireless Power Transfer by using 3D Representation of Magnetically Coupled Resonators Considering Peak Efficiency

Nur Bekiroglu,Ali Agcal,Selin Ozcira 한국자기학회 2018 Journal of Magnetics Vol.23 No.1

This paper focuses on wireless power transfer system based on magnetic resonance coupling which involves creating a resonance and transferring the power without radiating electromagnetic wave outwith the critical distance. Modelling with Ansys<SUP>®</SUP> Maxwell 3D software provides the means to observe the main field quantities with its post-processing capability. Therefore mathematical expressions of optimal coupling coefficients are analyzed by considering mutual coupling model which is presented along with a derivation of key system identifiers such as transmission distance, characteristic impedance and resonance frequency. The effectiveness of the system is analyzed by exciting the resonators with sinusoidal voltage source. Ansys<SUP>®</SUP> Maxwell 3D software is utilized to solve equivalent circuit and also to calculate mutual inductance and characteristic impedance according to air gap variations. Resonance frequency is a key parameter in system design whose value can be changed according to distance between resonators. The peak efficiency is analyzed depending on different air gap values for various characteristic impedances at optimum resonance frequency. In this study, modelling resonators in 3D has been constituted correspondingly. The approach demonstrated in this paper allows fixed load receiver to be moved to different orientation within the range of critical coupling distance and approximately efficiency of 70 %.

Birdcage Coil with Inductively Coupled RF Coil Array for Improving |B₁|-Field Sensitivity In 7-T MRI

Jong-Deok Byun,Jeung-Hoon Seo,Taewon Kang,Yeunchul Ryu,Kyoung-Nam Kim 한국자기학회 2017 Journal of Magnetics Vol.22 No.3

A birdcage coil integrated with a 16-channel, inductively coupled, radio-frequency (RF) array was designed to improve the magnetic-flux distribution for human brain magnetic resonance imaging at 7-T. A numerical calculation was performed using the finite-difference time-domain method for the birdcage coil with an inductively coupled array. The electromagnetic calculation results for the birdcage coil with the inductively coupled array were compared to those for the birdcage coil without an inductively coupled array in terms of their magnetic- flux, electric-field, and specific-absorption-rate distributions in a cylindrical phantom and human model. The proposed birdcage coil with an inductively coupled array offers a superior magnetic-flux sensitivity without sacrificing the RF power deposition at 7-T. The modifications of the coil geometry accompanying the inductively coupled RF array could be applied to the generally used transmit/receive volume coils and extended to parallel RF transmission array in ultra-high-field magnetic resonance imaging.

Magnetic-Field-Model and Circuit-Model Based Analysis of Three-Phase Magnetically Coupled Resonant Wireless Power Transfer Systems with Cylinder-Shaped Coils

Xuling Chen,Xiewei Fu,Chong Jiang,Cunhui Pei,Fuxin Liu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

In single-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the transfer characteristics, including the output power and transfer efficiency, are significantly influenced by the spatial scales of its coils. As a potential alternative, a three-phase MCR WPT system with cylinder-shaped coils that are excited in a voltage-fed manner has been proposed to satisfy the requirements of compact space. This system adopts a phase-shifted angle control scheme to generate a rotating magnetic field and to realize omnidirectional WPT that is immune to spatial scales. The magnetic field model and equivalent circuit models are built to holistically analyze the system characteristics under different angular misalignments. Research results show that the transfer characteristics can be improved by modulating the phase-shifted angle in each phase. Experiments have also been carried out to evaluate the accuracy of the theoretical analysis and to confirm the validity of the system modeling method.

A Coupled-Inductor-Based Input-Parallel Output-Parallel Quasi-Resonant Single-Stage DC-DC Converter to Mitigate Current Discrepancy

Fei Li,Laili Wang 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

The input-parallel output-parallel (IPOP) DCDC converter is suitable for low-voltage and high-current applications, such as voltage regulator module. However, the parameter mismatch in the IPOP converter causes uneven current sharing between the constituent modules, which makes the IPOP converter unreliable for practical use. In this paper, a coupled-inductor-based IPOP quasi-resonant (QR) single-stage DC-DC converter is proposed to mitigate current difference. The coupled inductor integrates the discrete external inductors of parallel modules to automatically balance the primary currents between modules and act as resonant inductors, which can reduce the number of magnetic components and simplify the control strategy. A 48V/1.8V 144W two-module QR single-stage converter prototype is made and tested to verify the analysis.

Frequency-Domain Circuit Model and Analysis of Coupled Magnetic Resonance Systems

Huh, Jin,Lee, Wooyoung,Choi, Suyong,Cho, Gyuhyeong,Rim, Chuntaek The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.2

An explicit frequency-domain circuit model for the conventional coupled magnetic resonance system (CMRS) is newly proposed in this paper. Detail circuit parameters such as the leakage inductances, magnetizing inductances, turn-ratios, internal coil resistances, and source/load resistances are explicitly included in the model. Accurate overall system efficiency, DC gain, and key design parameters are deduced from the model in closed form equations, which were not available in previous works. It has been found that the CMRS can be simply described by an equivalent voltage source, resistances, and ideal transformers when it is resonated to a specified frequency in the steady state. It has been identified that the voltage gain of the CMRS was saturated to a specific value although the source side or the load side coils were strongly coupled. The phase differences between adjacent coils were ${\pi}/2$, which should be considered for the EMF cancellations. The analysis results were verified by simulations and experiments. A detailed circuit-parameter-based model was verified by experiments for 500 kHz by using a new experimental kit with a class-E inverter. The experiments showed a transfer of 1.38 W and a 40 % coil to coil efficiency.

Frequency-Domain Circuit Model and Analysis of Coupled Magnetic Resonance Systems

Jin Huh,Wooyoung Lee,Suyong Choi,Gyuhyeong Cho,Chuntaek Rim 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.2

An explicit frequency-domain circuit model for the conventional coupled magnetic resonance system (CMRS) is newly proposed in this paper. Detail circuit parameters such as the leakage inductances, magnetizing inductances, turn-ratios, internal coil resistances, and source/load resistances are explicitly included in the model. Accurate overall system efficiency, DC gain, and key design parameters are deduced from the model in closed form equations, which were not available in previous works. It has been found that the CMRS can be simply described by an equivalent voltage source, resistances, and ideal transformers when it is resonated to a specified frequency in the steady state. It has been identified that the voltage gain of the CMRS was saturated to a specific value although the source side or the load side coils were strongly coupled. The phase differences between adjacent coils were π/2, which should be considered for the EMF cancellations. The analysis results were verified by simulations and experiments. A detailed circuit-parameter-based model was verified by experiments for 500 kHz by using a new experimental kit with a class-E inverter. The experiments showed a transfer of 1.38 W and a 40 % coil to coil efficiency.

Magnetic-Field-Model and Circuit-Model Based Analysis of Three-Phase Magnetically Coupled Resonant Wireless Power Transfer Systems with Cylinder-Shaped Coils

Chen, Xuling,Fu, Xiewei,Jiang, Chong,Pei, Cunhui,Liu, Fuxin The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

In single-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the transfer characteristics, including the output power and transfer efficiency, are significantly influenced by the spatial scales of its coils. As a potential alternative, a three-phase MCR WPT system with cylinder-shaped coils that are excited in a voltage-fed manner has been proposed to satisfy the requirements of compact space. This system adopts a phase-shifted angle control scheme to generate a rotating magnetic field and to realize omnidirectional WPT that is immune to spatial scales. The magnetic field model and equivalent circuit models are built to holistically analyze the system characteristics under different angular misalignments. Research results show that the transfer characteristics can be improved by modulating the phase-shifted angle in each phase. Experiments have also been carried out to evaluate the accuracy of the theoretical analysis and to confirm the validity of the system modeling method.

Frequency-Domain Circuit Model and Analysis of Coupled Magnetic Resonance Systems

허진,이우영,최수용,조규형,임춘택 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.2

An explicit frequency-domain circuit model for the conventional coupled magnetic resonance system (CMRS) is newly proposed in this paper. Detail circuit parameters such as the leakage inductances, magnetizing inductances, turn-ratios, internal coil resistances,and source/load resistances are explicitly included in the model. Accurate overall system efficiency, DC gain, and key design parameters are deduced from the model in closed form equations, which were not available in previous works. It has been found that the CMRS can be simply described by an equivalent voltage source, resistances, and ideal transformers when it is resonated to a specified frequency in the steady state. It has been identified that the voltage gain of the CMRS was saturated to a specific value although the source side or the load side coils were strongly coupled. The phase differences between adjacent coils were π/2, which should be considered for the EMF cancellations. The analysis results were verified by simulations and experiments. A detailed circuit-parameter-based model was verified by experiments for 500 kHz by using a new experimental kit with a class-E inverter. The experiments showed a transfer of 1.38 W and a 40 % coil to coil efficiency.

Surface Coil with an Inductively Coupled Wireless Surface and Volume Coil for Improving the Magnetic Field Sensitivity at 400-MHz MRI

Jeung-Hoon Seo,Jae Jun Lee,Kyoung-Nam Kim 한국자기학회 2018 Journal of Magnetics Vol.23 No.2

This work presents the use of combinations between a wireless radio-frequency surface coil and a wireless 16-leg birdcage coil that are inductively coupled to improve the magnetic field sensitivity and uniformity. A single surface loop coil operating as transmission/reception (Tx/Rx) coil was designed for mouse head imaging at a magnetic field strength of 9.4-T. Numerical analyses using finite-difference time-domain were performed to compute the sensitivity and homogeneity of magnetic and electric flux density fields for each of the coil combinations. Maximum field values and standard deviation were used as statistical parameters to compare the sensitivity and homogeneity of the fields produced by the Tx/Rx surface coil for each case, when the wireless inductively coupled coils were used. The electromagnetic analyses were applied to a cylindrical oil-based phantom and a mouse model. The proposed combinations of the surface coil with the inductively coupled wireless surface and wireless volume coils offer an enhanced magnetic-flux sensitivity and RF excitation field distribution at 9.4-T. The modifications to the surface coil geometry by adding the inductively coupled radio-frequency coil combinations could be applied to the generally used transmit/receive surface coils and extended to parallel radio-frequency transmission array at ultra-high-field magnetic resonance imaging.

전자기-구조 상호 작용을 고려한 IPM 모터의 전자기 가진원 해석

남자현(Jahyun Nam),강치호(Chiho Kang),정근수(Geunsu Jeong),장건희(Gungee Jang) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

We investigated the magnetic excitation of an IPM motor considering magnetic and structural interaction through finite element method. The finite element model was developed and the magnetic-structural coupled analysis was performed by using COMSOL, a commercial multiphysics finite element analysis software package. In the coupled analysis, the magnetic force calculated by using the Maxwell stress tensor was applied to the structure, and the magnetic finite element model was rearranged by using the moving mesh method. We showed that coupled analysis predicted the excitation frequency of 667 Hz (the first natural frequency of the rotor) of magnetic force undergoing rotor eccentricity. This paper will contribute the accurate prediction of magnetic excitation in electromechanical machines.