Researches on new coils with large displacement for wireless electric vehicles and explicit circuit models for magnetic resonant systems

Abstract

Several researches on new coils with large displacement for wireless electric vehicles and equivalent explicit circuit models for magnetic resonant systems were presented in this paper. In chapter 1, a new inductive power transfer system with a narrow rail width, a small pick-up size, and a large air-gap for On-Line Electric Vehicles is proposed in this paper. By introducing a new core structure, the orientation of the magnetic flux alternates along with the road; hence, an inductive power transfer system with a narrow rail width of 10 cm, a large air-gap of 20 cm, and a large lateral displacement about 24 cm was implemented. The resonant circuit of the inductive power transfer system, driven by a current source, was fully characterized. The experimental results showed that the maximum output power was 35 kW and that the maximum efficiency was 74 % at 27 kW. The proposed system was found to be adequate for electric vehicles, allowing them to drive freely on specially implemented roads by obtaining power from the buried power supply rail. In chapter 2, new coil set with large lateral displacement for a wireless stationary EV charger that can automatically charge a battery on an EV by inductive coupling is proposed in this paper. To facilitate realization of a practical wireless stationary EV charger, the developed coil set has large lateral displacement, longitudinal displacement, robustness to air-gap variation, and low EMF characteristics. An inductive power transfer system including the proposed coils was designed and verified by simulations and experiments, where variation of the resonant frequency due to local saturation of the ferrite core and core loss was considered. An output power of 15 kW at a maximum efficiency of 75 %, a large lateral displacement of 40 cm, a large air-gap of 15 cm, and a low EMF of 4.1 μT at 20 kHz were achieved. In chapter 3, an explicit frequency-domain circuit model for the conventional coupled magnetic resonance system (CMRS)...