Research On Bifurcation Phenomenon Of Inductively Coupled Power Transfer System

As one of the typical wireless power transfer technologies, inductively coupled power transfer (ICPT) technique which utilizes the electromagnetic coupling of two coils to transfer power from power supply to powered devices has been a global popular research project in recent years. Because of no wires between the primary and secondary side of the loosely coupled transformer, ICPT realizes both electrical and physical isolation. Thus dangers from contact such as mechanical wear and high-voltage electric shock could be avoided. Apart from this, it remains unaffected of surroundings. Therefore, ICPT will be widely used in wireless power transfer for electric vehicles.In this paper, the advantage of wireless power transfer technology, basic principle and key technologies of ICPT system, and research status of bifurcation phenomenon are briefly overviewed.Then, the cause of bifurcation phenomenon of ICPT system is analyzed. The paper focuses on the mutual inductance model and equivalent circuit of loosely coupled transformer which is the key component of ICPT system. To reduce the impact of leakage inductance of the primary and secondary sides of loosely coupled transformer and improve the performance of ICPT system, the primary and secondary compensation circuit is analyzed, further coming to the full-bridge resonant converter with series compensation capacitor on primary side and parallel compensation capacitor on secondary side.But, a problem is coming! ICPT system becomes a high level system with more complex characteristics. Then, in terms of impedance angle, the cause of bifurcation phenomenon is analyzed in detail. Then, the critical condition and affect of bifurcation phenomenon is focused on, including the relationship of quality factor and coupling coefficient, and affect of output voltage gain under the condition of fixed coupling factor, fixed coupling coefficient or fixed frequency.At last, the hardware and software of the system is designed, including of schematic diagram of ICPT system, the choice of the devices, the parameters of loosely coupled transformer. The bifurcation phenomenon of ICPT system is simulated and tested. It provides the experimental data for ICPT technology applications.