Research On IPT Resonant Converters With High Misalignment Tolerance

Inductive power transfer(IPT)technology,due to its advantages of safety,convenience and adaptability to harsh environment,has shown great application potentials in electric vehicles(EV),desktop peripherals,etc.However,it allows for limited misalignment,which is not suitable for some applications such as EV charging.The thesis gives a comprehensive analysis of the methods to improve the misalignment tolerance with small output fluctuations and high efficiency simultaneously.After reviewing the existing solutions,this thesis proposes three ways to improve the misalignment tolerance: weak-detuning compensation,magnetic-field orientation and output-gain compensation.Firstly,a general design method of weak-detuning compensation is proposed.For primary series compensation,the quantization expression of output fluctuation is derived.On this basis,the compensation parameters design method and detailed design procedure are given with the purpose of minimizing the output fluctuation,and further applied in higher order compensation schemes.A 50 W prototype is constructed for principle verification.Secondly,a magnetic-field orientation method is proposed.A mathematical model is presented to describe the relationship between the spatial magnetic field distribution and the excitation current.The primary excitation parameters,which makes the strongest magnetic field automatically track the secondary coil,are derived.An 80 W prototype is fabricated to verify the effectiveness of the proposed method.12% output voltage fluctuation within the range of +/-9cm misalignment for Q receiver,and 17.6% output fluctuation within the range of +/-6cm misalignment for DD rceiver are achieved.Finally,a gain-compensation method based on primary DDQ structure is proposed.Acording to the changing law of mutual inductances under different misalignments,the design method for some key parameters of DDQ,i.e.,dimensions and turns ratio,is given.Aiming to minimize the copper loss of primary winding,the exciting currents of the DD and the Q windings are given as well as the implementations.A 100 W prototype is built to verify the misalignment performance,achieving a minimum of 90.9% efficiency and maximum 11% output fluctuation within +/-40% misalignment of Q secondary coil;a minimum 90.1% efficiency and maximum 6.3% output fluctuation within the range of +/-60% misalignment of DD secondary coil.