This paper presents a high efficiency control method of the proposed Wireless Power Transfer (WPT) system based on minimizing conduction loss of the transmission coils. The proposed control strategy achieves high efficiency by controlling the high-frequency voltages to minimize conduction loss. The proposed control method is also applicable to changes in output power and output DC voltage. The authors propose a WPT system that uses a matrix converter on the primary side and a full-bridge converter on the secondary side. The matrix converter is suitable for WPT systems because it can convert commercial AC to the high-frequency AC in a single stage. This paper also presents Pulse Width Modulation (PWM) control methods of the power converters. The usefulness of these proposed control methods is verified by experiments using a prototype system.

This paper describes a stable start-up control for Single-Active-Bridge (SR-SAB) DC-DC converters. The proposed control method can control the output capacitor voltage by charging the output capacitor of the proposed circuit without overcurrent. Therefore, stable start-up of the SR-SAB DC-DC converter can be achieved. The effectiveness of the proposed method was verified by experiments using a laboratory prototype.

Wireless power transfer technology is essential for the widespread use of electric vehicles. Conventional curcuit of wireless power transfer system needs two times power convertion, therefore it increases power loss. Also, wireless power transfer system which communicates controller and vehicles will be unstable when communication delay occurs because of high frequency power transfer. This paper proposes curcuit that realizes downsise and high efficiency using matrix converter as power converter for ground side. Furthrermore, it proposes a fast and safe power control method of no communication delay by detecting power of ground side. The effectiveness of the proposed control method is confirmed by experiments.

This paper presents output power characteristics of a three-phase isolated Secondary-Resonant Single-Active-Bridge (SR-SAB) DC-DC converter with a delta-star connected transformer. The SR-SAB converter is a high power converter for quick battery chargers. The primary side of the SR-SAB converter is a three-phase inverter and the secondary side is a diode rectifier circuit with six resonant capacitors. It is necessary for power converters for EVs, which require a various output powers, to be able to easily control output power. The output power of the SR-SAB converter is varied significantly by controlling the transformer frequency. The effectiveness of the characteristics is verified by experiments.

These days, the world is right in the middle of EV shift. Introducing regenerative technology in EV charging facilities becomes possible to exchange power between EVs and power systems (V2G/G2V). This paper focuses on regeneration mode, from EV's DC battery to three-phase AC power supply, in wireless power transfer system using a matrix converter. Wireless charging for EVs uses high frequency, resulting in high switching losses. Therefore, in the proposed system in regeneration mode, the soft-switching strategy by controlling transfer frequency and the duty cycles of the matrix converter are proposed in this paper. The effectiveness of the theory is verified by an experiment.

This paper presents a simple PWM strategy of high-frequency link AC/DC converter which controls the output voltage and the input current, simultaneously. In the PWM strategy, calculating the duty cycles are obtained by simple calculation, and the switching loss can be reduced because of the commutations of the low line voltages. In order to obtain high efficiency, the SiC devices are used for the primary converter and the secondary diode rectifier circuit to reduce the conduction and switching losses. The effectiveness of the proposed PWM strategy and the circuit using SiC devices in the high-frequency link AC/DC converter have been verified by experiments.

This paper presents independent control of input current and output voltage for Modular Matrix Converter (MMxC). The MMxC is a multi-level converter without a transformer that converts from the high voltage AC to high voltage AC with arbitrary amplitude and frequency. The control method is difficult due to the simultaneous control of the input current and output voltage. The authors propose a novel control method that is divided into two parts of the positive-sequence circuit for the input current control, and the zero-sequence circuit for the output voltage control. The effectiveness of the proposed control method has been verified by simulations and experiments.