Harmonic Optimization Method by SHEPWM for Contactless Power Transfer System with Seriesseries Compensation

Contactless power transfer (CPT) technology is developing rapidly in recent years. This paper introduces the circuit model of a typical CPT system with series-series (S/S) compensation topology. By analyzing the transfer function of a practical CPT system, with the load resistance changes, the bifurcation phenomenon might happen. In case of voltage source inverter with square wave modulation, there will be serious harmonic distortion in the primary and secondary current waveform, which might cause the drop of power factor. Using selective harmonic elimination pulse width modulation (SHEPWM) instead of square wave modulation could remedy this problem. With SHEPWM, the harmonic order will be increased, improving the waveform quality, and the requirement of filters also be decreased. Experimental results are provided to validate the harmonic problem, and show the effectiveness of the harmonic optimization method.