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A compact spatial free-positioning wireless charging system with a novel three-dimensional (3D) transmitting (Tx) coil is proposed to charge consumer electronics in the working area. Because of the strengthened electromagnetic field generated by the proposed 3D Tx coil in the space, this system can charge consumer electronics wirelessly with great tolerance to positional and angular misalignments between the transmitter and receiver. Benefiting from the compact design of the 3D Tx coil, the system can be easily embedded in some corners of office furniture/cubic panels, which will not cause any extra working space consumption when charging devices. The inductor-capacitor-capacitor (LCC) compensation circuit on the Tx side can achieve constant current output, which is independent of load condition and can protect the transmitter. With the LCC compensation circuit, the MOSFETs of the H-bridge high-frequency inverter realized zero voltage switching (ZVS). The small-sized planar receiving (Rx) coil and series (S) compensation circuit is applied to achieve compact receiver design. The theoretical and experimental results show that the spatial free-positioning wireless charging prototype can transfer 5 W to the small-sized receiver in around 350 mm × 225 mm × 200 mm 3D charging area and achieve the highest efficiency of 77.9%.

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Considering the fact that electric vehicle battery charging based on the current charging station is time-consuming, the charging technology needs to improve in order to increase charging speed, which could reduce range anxiety and benefit the user experience of electric vehicle (EV). For this reason, a 1 MW battery charging station is presented in this paper to eliminate the drawbacks of utilizing the normal 480 VAC as the system input to supply the 1 MW power, such as the low power density caused by the large volume of the 60 Hz transformer and the low efficiency caused by the high current. The proposed system utilizes the grid input of single-phase 8 kVAC and is capable of charging two electric vehicles with 500 kW each, at the same time. Therefore, this paper details how high-voltage SiC power modules are the key enabler technology, as well as the selection of a resonant-type input-series, output-parallel circuitry candidate to secure high power density and efficiency, while intelligently dealing with the transient processes, e.g., pre-charging process and power balancing among modules, and considering the impact on the grid, are both of importance.

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