Countermeasures against Radiated EMI for IH Cooker with Voltage Resonance Circuit Using Discrete IGBT

The limit levels of radiated EMI for IH cookers were revised to lower values in December 2018 by the Electrical Appliances and Materials Safety Act. In this study, a switching noise mechanism and its countermeasures for an IGBT loaded into a voltage resonance circuit of an IH cooker is analyzed. A device model is developed using a BSIM3 MOSFET model with voltage-dependent capacitors. The inductor and capacitor load switching operation, including the parasitic elements of a test circuit, is simulated, and switching noise generated during turn-off transient conditions is discussed. An effective method for EMI suppression is proposed based on optimization of the C-voltage characteristics and the addition of an external capacitor. The effect of reduced radiated EMI levels is discussed.