ABSTRACT
This chapter introduces the soft-switching technique in DC/AC inverters. Multilevel inverters are a different method to construct DC/AC inverter. Multilevel inverters are a different technique from pulse-width-modulation method, which requires vertically chopping a reference waveform to achieve the similar output waveform multilevel inverting technique involves horizontally accumulating the levels to achieve the waveform. There are numerous ways of implementing soft-switching methods, such as zero-voltage switching and zero-current switching, to reduce the switching losses and to increase efficiency for different multilevel inverters. For capacitor- or diode-clamped inverters, however, the choices of soft-switching circuit can be found with different circuit combinations. In electric motor drive applications, soft-switching inverters are usually classified into three categories, namely, resonant pole inverters, resonant DC link inverters, and resonant AC link inverters. The chapter discusses a specially designed resonant pole inverter that is suitable for Brushless DC motor drive systems and is easy to apply in industry.
