Design considerations for three element L-LC resonant inverters for induction heating

This article presents the up-to-date conclusions concerning the design of the three element L-LC resonant inverters for induction heating applications. The main properties of the L-LC resonant tank are presented. The advantages of the L-LC circuit over the series resonant inverter (SRI) are explained: namely, its current gain and short-circuit robustness. Finally, a transformation algorithm is proposed which allows substitution of the SRI by an equivalent L-LC circuit, that is to say, an LLC which achieves the same output power at the same resonant frequency with the same heating coil and piece.