High frequency inverter including a boost chopper

This paper presents a new high frequency inverter for high power induction heating applications under a low utility voltage condition. This inverter realizes 2 functions in same time. One is a boost chopper function and other is a full bridge inverter. The boost chopper function of this inverter raises the DC bus voltage than an input voltage. Herewith, the boost chopper and one bridge realize an operation same as the full bridge inverter and a DC voltage is energized to the load resonant circuit positive and negative in turn. As this full bridge inverter operates under high DC bus voltage, the proposed inverter achieves high power without changing the input voltage to high. The proposed inverter has 6 switching modes including the voltage commutation mode for soft switching. The soft switching operations of S1 and S2 are obtained by connecting a small capacitor to S2 in parallel. Furthermore, the design rule of resonant capacitance is explained for tuning the resonant frequency appropriate by using some simple equations. Additionally, the maximum rated power also can be estimated by them, and it is verified by a simulation. The experimental results using a scale model of proposed inverter achieved about 3.2 times output power than the conventional full bridge inverter in a same load condition.