Showing papers by "Tomokazu Mishima published in 2022"

MHz-Driving Current-Fed Snubberless Soft Switching DC-DC Converter

Abstract: This paper presents a novel current-fed step-up DC-DC converter that is suitable for the front-end high-frequency link DC-DC converter (DC-X) in a grid-tied inverter of a fuel cell interface. The proposed DC-DC converter features the snubberless zero current soft-switching (ZCS) commutation with high-frequency switching by adopting quasi-resonance and parallel load resonance; the multi resonance while minimizing the number of additional circuit components. The switch-mode transitions of the proposed DC-DC converter are explained in detail for revealing the principle of snubberless ZCS due the multi resonance. In order to analysis the proposed DC-DC converter more precisely, a time-domain analysis is employed to examine the high-order harmonics in the three-level stepwise voltage of the quasi-resonant high frequency inverter, which is superior to a conventional sinusoidal AC analysis. The effectiveness of the proposed converter and the analytical strategy is demonstrated by comparing the theoretical and simulation results, after which the feasibility is verified by experiment of a 1 MHz-55 W class prototype with Gallium Nitride (GaN) high-electron-mobility-transistor (HEMT).

An Interleaved Charge-Pump Bidirectional DC/DC Converter With Duty Limit Control Strategy

Abstract: Two-phase interleaved charge-pump bidirectional DC/DC converter (ICPBDC) topology exhibits very good performance in terms of improved voltage conversion ratio, low conduction loss, low switch stress, fast transient response, and high power density. However, the applicability of the ICPBDC topology is limited because of its operating duty. A duty limit control (DLC) strategy is proposed in this study to achieve wide-range DC-bus voltage operation. Both bidirectional power flow and current-balancing characteristics can be achieved within the full range in duty without any additional cost with this novel design. Two modes of the proposed ICPBDC with DLC strategy, namely, charge and discharge, are realized for electric vehicle (EV)-connected DC-micro grid (EV-DCMG) with wide-range DC-bus voltage. The circuit topology acts as a voltage-doubler boost converter in the discharge mode to achieve a wide voltage range from 60 V to 200–380 V. Meanwhile, the circuit topology acts as a voltage-divider buck converter in the charge mode to achieve a wide voltage range from 200–380 V to 60 V. Circuit configuration and operating principle of the proposed converter are presented in this study. The simulation and experimental results based on a 500 W laboratory prototype validate the effectiveness of the proposed strategy.

A Dual-Active Single-Ended Wireless V2H System with Mutually Synchronized Phase-Difference Control Method

Abstract: The bidirectional Wireless Power Transfer(WPT) apparatus for the vehicle to home(V2H) is discussed in this study. It utilizes a straightforward, small single-ended converter and a cooperatively synchronized phase-difference control mechanism. This paper illustrates the configuration of the wireless V2H system as well as the operation of the bidirectional wireless power transmission. Practical solutions to issues with operational frequency stability are explored. It is shown that the phase difference between the power supplying and the power receiving circuits determines how much power is transferred.A dual-active phase-shift power-variable constant-frequency single-ended bidirectional converter control approach with mutually synchronized phase-difference is proposed. It is simple to validate that the designated frequency band complies with international requirements because the wireless V2H system can be operated under a consistent operating frequency [1]. Despite the low coupling coefficient between the transfer coils, the high-power wireless transmission is accomplished via the optimal phase difference. In addition, compared to the prior frequency-controlled system, the suggested system ensures the stability of the power transfer operation against parameter change. The newly created single-ended, low-cost wireless V2H system is thus ready for mass manufacturing.

A New Prototype of Dynamic WPT Charging EDLC Scooter System with 5×2 Multi-Transfer Coils and SiC-VMOSFET Single-Ended inverters

Abstract: An electric scooter is a promising solution to the global warming problem due to its high driving efficiency and carbon-free drive by electric power from renewable energy. It is a problem that their widespread use is limited by the time and effort required to recharge them. This paper proposes a new Dynamic Wireless Power Transfer EDLC scooter system with 5×2 multi-coils feeding and Si C-VM OSFET single-ended inverters. An EDLC energy storage unit allows many charges of the stepping-stone type Dynamic-Wireless Power Transfer. Transfer power can be small despite the large amount of energy by the 5×2 multi-transfer coil power feeding system. The developed single-ended inverter with a new V-trench SiC-MOSFET is small-size, light-weight, and low-cost. It can operate stably against extreme fluctuations of load by running through power-feeding stations.

A Dual-Active Single-Ended Wireless V2H System with Self-Synchronized Phase-Difference Control Method

Abstract: This paper discusses the bidirectional Wireless Power Transfer (WPT) device for vehicle-to-house (V2H). It uses a simple, compact single-ended converter and self-synchronized phase-difference control mechanism. This paper proposes a way whereby phase difference control could be self-contained on the slave side without mutual communication. This method allows for high-power wireless transmission despite the low coupling coefficient between the transfer coils. The phase difference and transmission power can be altered by changing the MOSFET conduction time on one side without synchronizing the phases on both sides.

MHz-Driving Snubberless Zero-Current Soft-Switching High Step-Up DC-DC Converter with Multi-Resonant Circuitry

Abstract: A new high step-up dc-dc converter suitable for fuel cell power interface is presented in this paper. The proposed converter features multi-resonant tank for achieving high-step up ratio under zero current soft switching without any snubber circuits. The simple and minimized-component topology contributes for Mega-hertz driving of Gallium Nitride (GaN) under the condition of reduced switching loss, electromagnetic emission interference (EMI) noise, and ripple-free dc input current. Mode-transitional power stages are described by in-depth manner, after which the high step-up principle is revealed in a frequency-domain analysis. The essential performances of the proposed topology are demonstrated by simulation and experiment of 1.8 MHz-120 W prototype, whereby the effectiveness of snubberless and multi-resonant topology are verified from the practical point of view..