Efficiency improvement by frequency modulation of carrier signal for an inductor commutation soft-switched PWM inverter

The inductor communication soft switched PWM inverter (ICSI) gives good output waveforms and allows high carrier frequencies. However, to realize soft switching, a circulating current must always flow, so that the efficiency is not as good as in the conventional hard‐switched PWM inverter (CHSI). In this paper, to alleviate the efficiency deterioration due to the circulating current, we propose a technique which uses frequency modulation (FM) of the carrier signal. The frequency is designed to be higher at zero of the input signal and lower at its peak. By this technique, the circulating current is suppressed efficiently without sensing of the voltage and current of the main circuit, and efficiency is greatly improved. We quantitatively investigate this FM method and analyze the loss and efficiency of ICSI based on the FM method (FM‐ICSI). We also compare it with ICSI without the FM method and discuss the effectiveness of the FM method.