Rectifier load modeling and zero voltage switching design of inductive power transfer system with S-type topology on the secondary side

Rectifier load in inductive power transfer system has nonlinear characteristics. However, the traditional analysis method equates it to a pure resistor, which leads to a certain deviation between the theoretical analysis and the actual circuit. This will reduce the accuracy of the inductive power transfer (IPT) system model and affect the soft switching operation of the inverter. In this paper, the IPT system with S-type topology on the secondary side is studied. Firstly, the resistance-inductance characteristics of the rectifier load are analyzed by simulation, and then a second-order circuit response model is established to solve the time-domain expression of voltage and current. Then, the fundamental component of voltage and current is extracted by Fourier transform to calculate the impedance value of the rectifier load, and the mathematical calculation model of the rectifier load is established. On this basis, the influence of the inductive component of the rectifier load on the input impedance of the IPT system is analyzed. Then, a parameter design method for zero voltage switching is proposed for S-S and LCC-S topologies. Finally, an experimental platform of S-S and LCC-S IPT system is built. The correctness and effectiveness of the theoretical analysis and the proposed parameter design method are verified by experiments. The rectifier filter circuit and the DC side load of the inductive power transfer system are equivalent to the rectifier load. The circuit response equation is established to obtain the accurate calculation model of the rectifier load through mathematical analysis and Fourier decomposition. image