High-efficiency parallel quasi-resonant current source inverter featuring SiC metal-oxide semiconductor field-effect transistors for induction heating systems with coupled inductors

Efficiency and reliability are the two key design parameters when designing induction heating (IH) systems. A parallel quasi-resonant current source inverter (CSI) is proposed to optimise the converter efficiency and to take advantage of the inherent protection of CSIs. The proposed converter uses a coupled inductor, already present in the system to produce the IH phenomena, in order to reduce the current through the power devices and to ensure zero voltage switching during turn on and turn off transitions. As a consequence, the proposed converter significantly improves the IH system efficiency. An analytical model is proposed to study both operating conditions and efficiency. In addition to this, a 2.2-kW prototype has been designed and implemented to verify the proposed model and to prove the converter feasibility. To utilise the converter at most, SiC metal-oxide semiconductor field-effect transistors have been used, obtaining up to 98.6% efficiency at resonant conditions.