TABLE OF CONTENTS Part V of this text deals with a class of converters whose operation differs significantly from the PWM converters covered in Parts I to IV. Resonant power converters [1 36] contain resonant L-C networks whose voltage and current waveforms vary sinusoidally during one or more subintervals of each switching period. These sinusoidal variations are large in magnitude, and hence the small ripple approximation introduced in Chapter 2 does not apply.
Dc-to-high-frequency-ac inverters are required in a variety of applications, including electronic ballasts for gas discharge lamps [3,4], induction heating, and electrosurgical generators. These applications typically require generation of a sinusoid of tens or hundreds of kHz, having moderate or low total harmonic distortion. A simple resonant inverter system is illustrated in Fig. 19.1(a). A switch network produces a square wave voltage v s( t). As illustrated in Fig. 19.2, the spectrum of v s( t) contains fundamental plus odd harmonics. This voltage is applied to the input terminals of a resonant tank network. The tank network resonant frequency f 0 is tuned to the fundamental component of v s( t), that is, to the switching frequency f s, and the tank exhibits negligible response at the harmonics of f s. In consequence, the tank current i s( t), as well as the load voltage v( t) and load current i( t), have essentially...
