Switching frequency analysis of dynamically detuned ICPT power pick-ups

Dynamic detuning methods have been used in inductive contactless power transfer (ICPT) systems for power flow control. However, the highly variable switching frequency involved in the detuning operation will contribute to electromagnetic interference (EMI) and power losses. It is difficult to determine the detuning frequency precisely due to nonlinear features of power pick-ups. Uncertainty in the operating frequency can result in difficulties in designing filters with suitable bandwidths and choosing suitable switching devices. Based on detailed analytical analysis in four segments of the detuning process, a numerical method is developed in this paper to determine the boundaries of the switching frequencies. An iterative algorithm is presented using a flow chart to illustrate the process taken in the numerical analysis. Simulation and practical experiments are conducted to verify the algorithm so as to ensure the calculated results are sufficiently accurate for designing EMI filters and choosing suitable switching devices.