研究者詳細 - 平木　英治

論文 - 平木　英治

分割表示 309 件中 21 - 40 件目／全件表示 >>

High-Efficiency Solenoid Coil Structure for Induction Heating of Cylindrical Heating Object

Daiki Miyake, Kazuhiro Umetani, Shota Kawahara, Masataka Ishihara, Eiji Hiraki

IEEE International Symposium on Industrial Electronics 2022-June 307 - 313 2022年

掲載種別：研究論文（国際会議プロシーディングス）

The solenoid coil is a typical heating coil structure for induction heating of cylindrical heating objects. Conventionally, a bare solenoid coil without any soft-magnetic core has been commonly utilized. However, this conventional structure suffers from worse heating efficiency caused by the large coil copper loss and the low magnetic field induction at the heating object. This paper addresses these difficulties by proposing a novel heating coil structure. In addition to the solenoid coil, the proposed heating coils structure further incorporates the soft-magnetic cores that cover the outer coil periphery and the coil opening edges. These additional cores can reduce the local intense magnetic field around the coil, thus mitigating the eddy current induction inside the wire to reduce the copper loss, and also can increase the magnetic field inside the heating object, thus increasing the heat generation. The simulation was carried out to test the effectiveness of the proposed heating coil structure. The results inferred the reduction of the coil copper loss by 25% and the increase in the heat generation in the heating object by 53%, both of which suggest the promising features of the proposed heating coil structure for heating the cylindrical magnetic material. The heating operation of the proposed heating coil structure was tested by the experiment, although the current prototype was found to have larger power loss than expected from the simulation. The reason may lie in unintended eddy current generation of the metal case of the heating coil, which will be addressed in future work.

DOI： 10.1109/ISIE51582.2022.9831459

Secondary-Side Resonating LLC Converter for Reducing Transformer Voltage in High Power Applications

Hayato Nakamura, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki

2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia 547 - 554 2022年

掲載種別：研究論文（国際会議プロシーディングス）

The data centers of the telecommunication infrastructure are recently consuming more electric power than before. This increasing electrical burden is requiring a small but high-power isolated power converter with a high step-down ratio. Conventionally, the LLC converter is regarded to be a promising candidate, although this converter needs vacant space for galvanic isolation due to extremely high voltage caused by the resonance in the primary side, i.e. high voltage side, of the isolation transformer, which hinders the compact implementation inside the server computers in high power design. The purpose of this paper is to propose a novel LLC converter topology to reduce this extremely high voltage by locating the LC resonator on the secondary side. The performance analysis revealed that the proposed converter exhibits a similar frequency-voltage characteristic enabling the boost and buck operation modes as well as the small rectifier conduction loss similar to the full-wave rectifier with a center-tapped transformer. The simulation confirmed the operating principles and reduction of the resonance voltage amplitude of the proposed LLC converter in comparison with the conventional LLC converter. Furthermore, the experiment also supported the operating principles, which suggests the usefulness of the proposed converter for a high voltage dc power supply system.

DOI： 10.23919/IPEC-Himeji2022-ECCE53331.2022.9806826

Phase-Shift Based on Power Factor Control for LLC Converter with High Output Stability Against Load Fluctuation

Kenta Yamada, Kazuhiro Umetani, Eiji Hiraki, Masataka Ishihara

2022 IEEE 7th Southern Power Electronics Conference, SPEC 2022 2022年

掲載種別：研究論文（国際会議プロシーディングス）

The LLC converter is a very effective topology for miniaturization of power supplies. However, its application is currently limited. That is because of the problem of degraded system stability when the load condition changes. This paper proposed a practical control circuit that controls the power factor cos\theta by adjusting the phase difference \theta between the inverter voltage and primary current of the LLC converter to control the output voltage to address this problem. As a result, experimental result confirm that the proposed control method has robust control characteristics against wide load impedance and shows low output impedance regardless of the output voltage.

DOI： 10.1109/SPEC55080.2022.10058371

A Secondary-Side Resonant LLC converter for Reducing Resonance Voltage with Boost Mode Operation Using Resonance Including Current Doubler Rectifier

Hayato Nakamura, Naoyuki Yokoshima, Masataka Ishihara, Kazuhiro Umetani, Eiji Hiraki, Tatsuya Miyazaki, Yuta Okawauchi, Ken Nakahara

2022 IEEE 7th Southern Power Electronics Conference, SPEC 2022 2022年

掲載種別：研究論文（国際会議プロシーディングス）

Isolated DC-DC converter in data centers are now required to have a high step-down ratio and be suitable for high-power applications. As such DC-DC converters, LLC resonant converters have been attracting attention. However, the LLC resonant converter generates a large resonance voltage at the resonator, so the resonance inductor and resonance capacitor must be large in size. Recently, a previous study proposed a secondary-side resonance LLC converter to reduce the resonant voltages of the passive components. Nevertheless, this LLC converter requires a resonant capacitor in parallel with the rectifier to achieve boost mode operation, which complicates the circuit operation and design. Therefore, we have considered the use of the magnetizing inductance of the coupled transformer of the current doubler rectifier as a method to realize the boost mode operation. In this paper, we propose a new method of boost mode operation for LLC resonant converter using secondary-side resonance and the current doubler rectifier.

DOI： 10.1109/SPEC55080.2022.10058227

Sinusoidal-Flux Reluctance Machine Driven with Three-Phase Inverter for Improving Power Density with Reduced Torque and Input Current Ripples

Masaki Iida, Kazuhiro Umetani, Takayuki Kusumi, Masataka Ishihara, Eiji Hiraki

2021 23rd European Conference on Power Electronics and Applications, EPE 2021 ECCE Europe 2021年9月

掲載種別：研究論文（国際会議プロシーディングス）

Reluctance machines such as the switched reluctance machines (SRMs) and the synchronous reluctance machines (SynRMs) are recently investigated for propulsion motors of the electrified vehicles owing to their robust mechanical construction, high thermal tolerance, and cost-competitiveness. However, practical application of the reluctance machines to the vehicle propulsion has been hindered by the fact that the conventional SRMs and SynRMs are difficult to meet all the three preferable features for the vehicular application: 1. High power density, 2. Low torque and input-current ripples, 3. Being drivable by the normal three-phase inverter. This paper addresses this issue by proposing a novel reluctance machine. The prominent features of the proposed reluctance machine are the sinusoidal reluctance profile and the delta-connected phase windings, both of which differ from conventional reluctance machines. Along with the theoretical discussion of the basic operating principles of the proposed reluctance machines, this paper presents a simple performance estimation of the proposed machine, the SRM, and the SynRM, which supported that the proposed machine can meet the three preferable features. Furthermore, the experiment successfully supported the operating principles of the proposed machine, suggesting the feasibility of the proposed machine for vehicle applications.

Autonomous System Concept of Multiple-Receiver Inductive Coupling Wireless Power Transfer for Output Power Stabilization against Cross-Interference among Receivers and Resonance Frequency Tolerance

Masataka Ishihara, Keita Fujiki, Kazuhiro Umetani, Eiiji Hiraki

IEEE Transactions on Industry Applications 57 ( 4 ) 3898 - 3910 2021年7月

掲載種別：研究論文（学術雑誌）

Multiple-receiver resonant inductive coupling wireless power transfer (RIC-WPT) technique is emerging as a promising charging method for multiple household appliances, mobile devices, and wearable devices. However, this technique often suffers from output power fluctuation owing to the cross-interference among receivers as well as the manufacturing and aging tolerance of the resonant frequency (i.e., resonant frequency tolerance). This article proposes an autonomous RIC-WPT system concept to solve this difficulty. The proposed concept addresses the cross-interference and resonant frequency tolerance by incorporating the following two functions. First, the amplitude of the transmitter current is controlled to have a constant amplitude. Second, the phase of each receiver current is controlled to be orthogonal to that of the transmitter current by using an active reactance compensator installed in each receiver. The experiment of a two-receiver RIC-WPT system successfully verified that the two functions of the proposed system concept can stabilize the output voltage against the cross-interference and resonant frequency tolerance.

DOI： 10.1109/TIA.2021.3081071

Analytical Formulation of Copper Loss of Litz Wire With Multiple Levels of Twisting Using Measurable Parameters

Kazuhiro Umetani, Shota Kawahara, Jesus Acero, Hector Sarnago, Oscar Lucia, Eiji Hiraki

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 57 ( 3 ) 2407 - 2420 2021年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Litz wire has been widely utilized in power transformers and inductors as a wire with low copper loss at high-frequency operation. The Litz wire is commonly made of many thin isolated strands twisted in multiple levels. Due to its complicated structure, the copper loss prediction of the Litz wire has been difficult, hindering the design optimization of the Litz wire structure. To overcome this difficulty, preceding studies have investigated the analytical copper loss models of the constituting elements of the Litz wire, i.e., the strands and the bundles of strands. The purpose of this article is to propose an analytical copper loss model of the Litz wire by utilizing these preceding knowledge. The proposed model is formulated only with parameters that can be measured by basic testing instruments. Besides, the proposed model considers the bundle structure of the Litz wire, which affects the local ac current distribution, and the twisting pitch, which causes the inclination of the Litz wire strands. The proposed model was tested by comparing the analytical prediction and experimental measurements of the ac resistance of commercially available Litz wires. As a result, the predicted ac resistance showed good agreement with the measured ac resistance, suggesting the appropriateness of the proposed model.

DOI： 10.1109/TIA.2021.3063993

Industrial Electronics Education: Past, Present, and Future Perspectives

Oscar Lucia, Joao Martins, Yousef Ibrahim, Kazuhiro Umetani, Luis Gomes, Eiji Hiraki, Houcine Zeroug, Milos Manic

IEEE INDUSTRIAL ELECTRONICS MAGAZINE 15 ( 1 ) 140 - 154 2021年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Industrial electronics (IE) covers a wide range of technologies and applications, being a key enabling technology for numerous industrial, domestic, and biomedical uses, among others. In this context, IE education has become a relevant and challenging topic for society and industry. This article covers its evolution and state-of-the-art methodologies and provides an overall view of its status around the world. Finally, future trends and challenges in IE education are discussed.

DOI： 10.1109/MIE.2020.3002488

Feasibility of Sinusoidal Flux Drive Design of Reluctance Motor for Reducing Torque and Input Current Ripples with Three-Leg Inverter

Masaki Iida, Takayuki Kusumi, Kazuhiro Umetani, Eiji Hiraki

2021 IEEE 19TH INTERNATIONAL POWER ELECTRONICS AND MOTION CONTROL CONFERENCE (PEMC) 439 - 446 2021年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

Reluctance motors, represented by the switched reluctance motor (SRM) and the synchronous reluctance motor (SynRM), are attractive for vehicle propulsion owing to their high thermal tolerance and simple mechanical construction. However, the SRM exhibits large torque and large input current ripples, deteriorating driving comfort and battery lifespan. Furthermore, a driving system of the SRM requires the special inverter topology with additional switching or rectifying devices, leading to the cost-up. Meanwhile, the SynRM does not have these drawbacks, although this motor tends to be difficult to cover the wide range of the torque and the rotation speed required for vehicle propulsion because of large phase flux induction. To solve the obstacles of these conventional reluctance motors, this paper proposes a novel reluctance motor. The proposed reluctance motor is based on magnetization by the sinusoidal phase flux waveform, whereby the torque and input current ripples are eliminated using a common three-leg inverter without inducing large phase magnetic flux. This paper presents the operating principles of the proposed reluctance motor as well as analysis and simulation results in comparison with the SRM and the SynRM. As a result, the proposed reluctance motor is elucidated to reduce the torque and input current ripples with the three-leg inverter. Furthermore, the proposed reluctance motor can improve the torque range and rotating speed range compared to the SynRM because of the sinusoidal flux waveform with reduced amplitude. These results imply feasibility of the proposed motor for vehicle propulsion.

DOI： 10.1109/PEMC48073.2021.9432579

Parasitic Inductance Design for Preventing Oscillatory False Triggering of Parallel-Connected GaN-FETs.

Yusuke Hatakenaka, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki, Hiroshi Tadano

IECON 2021 - 47th Annual Conference of the IEEE Industrial Electronics Society(IECON) 1 - 8 2021年

Tiny Approaches to the Interactive Online Lectures Under the COVID-19 Pandemic.

Eiji Hiraki, Masataka Ishihara, Kazuhiro Umetani

IECON 2021 - 47th Annual Conference of the IEEE Industrial Electronics Society(IECON) 1 - 4 2021年

Feasibility of Parasitic Drain Inductance Design for Minimizing Switching Loss in Bridge Circuits Using GaN-FETs.

Koki Abe, Masataka Ishihara, Yusuke Hatakenaka, Kazuhiro Umetani, Eiji Hiraki

30th IEEE International Symposium on Industrial Electronics(ISIE) 1 - 5 2021年

A Control Method Based on Power Factor for Improving Output Voltage Stability and Efficiency of LLC Converter in Wide Range of Output Voltage and Load Impedance

Kazuhiro Umetani, Kota Shimomura, Kenta Yamada, Taichi Kawakami, Masataka Ishihara, Eiji Hiraki

2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 3436 - 3443 2021年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

The LLC converter is attractive for its small volume and comparatively high efficiency. However, the application of this converter is limited to the power supply to a static load with almost constant output voltage and current because the LLC design covering a wide range in the output voltage and the load variation can deteriorate the output voltage stability and efficiency. This paper addresses this issue by proposing a novel control method. Unlike the conventional control, which adjusts the operating frequency to stabilize the output voltage, the proposed control adjusts the power factor of the transformer primary-side to achieve the same excellent dynamic performance as the buck chopper. Simulation supported the effectiveness of the proposed control at a wide load variation range.

DOI： 10.1109/ECCE47101.2021.9595420

Multiple-Transmitter with Phase-Shift and Dynamic ZVS Angle Controls at Fixed Operating Frequency for Cross-Interference Free Wireless Power Transfer Systems

Kodai Matsuura, Masataka Ishihara, Akihiro Konishi, Kazuhiro Umetani, Eiji Hiraki

2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 5767 - 5774 2021年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

Resonant inductive coupling wireless power transfer (RIC-WPT) systems with multiple transmitters and multiple receivers often suffer from cross-interference among transmitters as well as among receivers. The cross-interference causes the fluctuation of the output power of the receiver and hard switching of the inverter on the transmitter. To avoid the cross-interference, controlling the amplitude and the phase of each transmitter current is an effective method. Therefore, this paper proposes a multiple-transmitter that can compensate for the cross-interference influence by implementing two controls. First, adopting the phase-shift control on the full-bridge inverter, the current amplitude is controlled to be constant. Second, applying the reactance control, each phase of the current is controlled to be in phase. In addition to the above operations, especially under a high-frequency operation, zero-voltage switching (ZVS) at a fixed operating frequency is essential for improving the power efficiency while not exceeding an allowable narrow bandwidth. Thus, the reactance control also works to ensure ZVS in all load conditions without adjusting the frequency. The RIC-WPT prototype with two transmitters and a single receiver is built to verify that the proposed multiple-transmitter can compensate for the cross-interference influence while achieving ZVS in different load conditions at a fixed operating frequency.

DOI： 10.1109/ECCE47101.2021.9595950

Autonomous Resonant Frequency Tuning Controller for Repeater Resonator in Resonant Inductive Coupling Wireless Power Transfer System

Akihiro Konishi, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki

PROCEEDINGS OF 2021 IEEE 30TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) 2021年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

The resonant inductive coupling wireless power transfer technique (RIC-WPT) is emerging as a promising wireless power transfer method for small mobile devices with comparatively high-power transfer capability and good efficiency. However, the performance of the RIC-WPT system is severely deteriorated by the resonant frequency detuning of the transmitter, repeater, and receiver resonators, which can be naturally caused by the manufacturing tolerance and the aging effect of these resonators. Particularly, the detuning of the repeater resonator tends to severely affect the performance due to its high-quality factor, which should be solved for practical application of RIC-WPT technology. This paper addresses this difficulty by proposing an autonomous resonant frequency tuning controller circuit for the repeater resonator. The controller tunes the resonant frequency of the repeater resonator to the operating frequency of the inverter, driving the transmitter, without an external power supply and wireless communication with the inverter controller, which restricts the freedom of the installation location and therefore preferably be avoided in the wireless power transfer system. The operating principles of the proposed controller were confirmed by the circuit simulator, supporting the feasibility of the proposed controller.

DOI： 10.1109/ISIE45552.2021.9576268

AC resistance Prediction of Litz Wire Planer Spiral Coil Based on Litz wire Loss Model

S. Kawahara, K. Umetani, E. Hiraki

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 1541 - 1546 2020年11月

掲載種別：研究論文（国際会議プロシーディングス）

The Litz wire is utilized to wireless power transfer system and induction heating according to has small AC resistance in high frequency. Prediction of AC resistance of the Litz wire is important for design optimization of the Litz wire, hence the recent study has proposed analytical AC resistance prediction model of the Litz wire. However, verification in practical coils using the Litz wire is still insufficient. The purpose of this paper is to verify the prediction accuracy of AC resistance using a full analytical model in a practical coil. For practical coil, planer spiral coils are selected, and AC resistance of the planer spiral coil is calculated by combining with the loss model and the FEM analysis. As a result, the Litz wire loss model is found to well predict the measured AC resistance of the Litz wire planer spiral coil, supporting the appropriateness of the Litz wire loss model.

DOI： 10.23919/ICEMS50442.2020.9290802

Phase-current waveform for switched reluctance motors to eliminate input-current ripple and torque ripple in low-power propulsion below magnetic saturation

Takayuki Kusumi, Takuto Hara, Kazuhiro Umetani, Eiji Hiraki

IET POWER ELECTRONICS 13 ( 15 ) 3351 - 3359 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：INST ENGINEERING TECHNOLOGY-IET

In recent decades, switched reluctance motors (SRMs) have been attracting increasing attention as a promising type of traction motors for electric vehicle propulsion, owing to their robust construction, elimination of permanent magnets. However, their phase inductance profile contains significant high-order harmonics, which generates input-current and torque ripples under SRM drive with the conventional square phase-current waveform. This study solves this problem by proposing a novel phase-current waveform in replacement of this square waveform. The proposed waveform is a predetermined waveform that can be stored as a look-up table in the inverter controller and can be magnified or attenuated to adjust the output torque, similarly as the conventional square waveform. Certainly, SRMs generally exhibit magnetic non-linearity due to magnetic saturation, which complicates the analysis. Therefore, the proposed waveform is analytically derived under the assumption that the magnetisation of the motor remains below the saturation level because vehicle propulsion tends to require a torque output far smaller than the maximum rating of the motor in normal vehicle travel. The proposed phase-current waveform is experimentally tested in comparison with the conventional square phase-current waveform. Consequently, the proposed waveform revealed smaller ripples in both the input-current and torque, supporting the effectiveness of the proposed phase-current waveform.

DOI： 10.1049/iet-pel.2019.1207

Simultaneous Tuning of Rotor Shape and Phase Current of Switched Reluctance Motors for Eliminating Input Current and Torque Ripples With Reduced Copper Loss

Takayuki Kusumi, Takuto Hara, Kazuhiro Umetani, Eiji Hiraki

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 56 ( 6 ) 6384 - 6398 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Switched reluctance motor (SRM) is recently emerging as a cost-effective but mechanically and thermally robust motor for vehicle propulsion. However, the conventional driving method of the SRM causes a large input current and torque ripples, both of which are scarcely acceptable for vehicle application. Recently, a promising driving method has been proposed that tunes the phase current to eliminate the input current and torque ripples simultaneously, although this method suffers from large copper loss when applied to the normal SRMs. To solve this problem, this article proposes simultaneous tuning of the rotor shape in combination with the recently proposed driving method, which includes only tuning of the phase current. Tuning of the rotor shape is targeted at minimizing the copper loss. Meanwhile, the stator structure is the same as the normal SRM design. The proposed approach was revealed to reduce the effective value of the phase current by 18% in simulation and by 23% in experiment compared with the recently proposed driving method, without increasing the input current and torque ripples. This result suggests the effectiveness of tuning both the rotor shape and the phase current for applying SRMs to vehicle propulsion.

DOI： 10.1109/TIA.2020.3015446

Strategy of Topology Selection Based on Quasi-Duality Between Series-Series and Series-Parallel Topologies of Resonant Inductive Coupling Wireless Power Transfer Systems

Masataka Ishihara, Kazuhiro Umetani, Eiji Hiraki

IEEE TRANSACTIONS ON POWER ELECTRONICS 35 ( 7 ) 6785 - 6798 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Series-series (SS) and series-parallel (SP) topologies are widely used in resonant inductive coupling wireless power transfer systems for various applications. However, the selection of an appropriate topology to achieve higher output power or higher efficiency is typically difficult because design optimization of the circuit parameters (e.g., characteristic impedance, load resistance, and mutual inductance) for each topology is generally separately discussed using different equivalent circuits with multiple resonance modes. Therefore, the purpose of this study involves proposing a simple strategy to select an appropriate topology. The proposed strategy is based on quasi-duality between the SS and SP topologies that are elucidated from the novel equivalent circuits derived using Lagrangian dynamics. Based on the quasi-duality, the output power and efficiency of the SP topology are calculated via the equivalent circuit of SS topology. Thus, the quasi-duality offers a simple comparison between the SS and SP topologies. The proposed strategy selects an appropriate topology by comparing only the equivalent ac load resistance, which is the ac resistance including the rectifying circuit and the load resistance, the characteristic impedance, and the ac load resistance that achieves the maximum efficiency ormaximum output power of the SS topology. Experiments verify the appropriateness and effectiveness of the proposed strategy.

DOI： 10.1109/TPEL.2019.2956732

Effects of Secondary Leakage Inductance on the LLC Resonant Converter

Mostafa Noah, Tomohide Shirakawa, Kazuhiro Umetani, Jun Imaoka, Masayoshi Yamamoto, Eiji Hiraki

IEEE TRANSACTIONS ON POWER ELECTRONICS 35 ( 1 ) 835 - 852 2020年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

It is quite often to utilize the transformer leakage inductance in the resonant tank of the LLC resonant converter to allow for a drastic reduction in the converter cost, weight, size, and volume. The effects of the secondary leakage inductance on the operation of the LLC resonant converter are not well discussed in the relevant literature, and it is the purpose of this paper to give an insight into these effects. The contribution of this paper lies in the following: first, highlighting that it is not always an accurate assumption to consider that the values of the primary and secondary leakage inductance are identical, specifically in asymmetric magnetic core structures. Second, it has been disclosed that the well-known coupling factor (k(12)) cannot properly express the unequalized leakage inductance distribution in the proposed asymmetric transformer. Therefore, the authors bring the primary coupling factor (k(1)) and secondary coupling factor (k(2)) into practice to appropriately express the unequalized leakage distribution on the primary and secondary windings, which can be controlled by the allocation of the relevant winding with respect to the air gap, utilizing the noise absorber, and changing the distance between the winding. Several transformer prototypes had been built and experimentally tested to validate these hypotheses. Third, it has been observed that the transformer voltage gain and efficiency can be improved when the transformer leakage inductance is concentrated on the secondary side to avoid the voltage drop inflicted by the relatively large value of the magnetizing current (i(m)), especially at the light load condition. Fourth, it has been reported that in a transformer structure with a concentrated value of leakage on the secondary side would decrease the resonant tank input impedance, vertically widen the voltage-gain curve of the converter, and eventually increase the frequency control bandwidth with respect to the load variation. Transformer prototypes had been constructed and tested in a 390 V/12 V-220 W LLC resonant converter to evaluate the proposed analysis.

DOI： 10.1109/TPEL.2019.2911093

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16