A zero voltage switching (ZVS) detection method, which relies on the half-bridge output voltage slopes during the MOSFET turn-on and turn-off transient processes, is proposed for the wireless power transfer (WPT) systems in this Letter. A voltage slope detection circuit and its active control method are also proposed to convert the nanosecond transient signal to a steady voltage level, which can be handled by the microcontroller easily. By having the information of the turn-on and turn-off voltage slopes, the state of ZVS can be evaluated to optimise the switching losses. A 500 kHz, three-coil resonant WPT system is built in order to evaluate the performance of the proposed detection method. Experimental results show that the ZVS state can be detected effectively. Also, the turn-off current can be controlled to a constant value to optimise the switching losses under the load and parameter variations.

This paper presents a new zero voltage switching (ZVS) tuning method for the double-sided inductor/capacitor/capacitor (LCC) compensated wireless power transfer (WPT) system. An additional capacitor is added in the secondary side of the double-sided LCC compensation network in order to tune the network to realize ZVS operation for the primary-side switches. With the proposed tuning method, the turn off current of the primary-side switches at the low input voltage range can be reduced compared with the previous ZVS tuning method. Consequently, the efficiency of the WPT at the low input voltage range is improved. Moreover, the relationship between the input voltage and the output power is more linear than that of the previous ZVS tuning method. In addition, the proposed method has a lower start-up voltage. The analysis and validity of the proposed tuning method are verified by simulation and experimental results. A WPT system with up to 3.5 kW output power is built, and 95.9% overall peak efficiency is achieved.

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In this paper a novel wireless power charging system is proposed. A bridgeless SEPIC circuit working at the discontinuous mode is adopted as the front AC-DC power factor correction (PFC) stage. A LCC-S compensation network is used to compensate the leakage inductance of the sending and receiving coils. The SEPIC PFC circuit has a constant ac power characteristic at a fixed duty ratio. And the LCC-S compensation network makes the intermedia dc bus voltage and output battery voltage a fixed relation. By combining the SEPIC and LCC-S, the proposed wireless charging system can eliminate the use of electrolytic capacitor. Also, the charging power can be controlled just by adjusting the duty ratio of SEPIC converter. These make the proposed system especially suitable in several hundred watts applications, like the electric bike wireless charging. The analysis of the proposed system, system design and implement, and preliminary experimental results are given in the paper.

In order to reasonably design the six degrees of freedom turntable (hereinafter referred to as the transfer table), based on the structure size and motion index parameters of the turntable, The motion mechanics calculation model was established to simulate and analyze the mechanical variation curve of singing platform under different motion modes. The analysis shows that when the upper platform load and the component mass are 3000 kg, the maximum action force of the rotating platform support moving cylinder is 1376.4 kg.