Unipolar voltage-cancellation control of resonant inverters for induction cooking appliances

Generally, power inverters for induction cooking appliances are controlled by varying frequency to control current through the inductor coil. When more than one power converter is operated at different frequencies greater than audible noise upper threshold, low frequency interharmonics are generated in common impedance due to nonlinear effects. Suppression of audible noise in multiple-coils induction cookers leads to high-performance fixed-frequency control. This paper presents a new unipolar voltage-cancellation control for series resonant inverters. This control strategy is used in full-bridge topologies for induction cookers, allowing fixed frequency control with ZVS operation over a wide power range. Performance of current-mode and voltage-cancellation is improved. This control is implemented in a series-resonant full-bridge inverter for induction cookers using IGBTs and digital control implemented in a PLD which can be easily implemented in an ASIC for mass production.

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