FREKVENSOMVANDLARE FOR INDUKTIONSUGN

摘要

A protection device for a thyristor inverter circuit of an induction heating cooking oven wherein commutation failure of a thyristor is detected by determining that the conduction period of the thyristor is outside a predetermined period or that a voltage applied to the thyristor is outside of a predetermined magnitude. The protection device deactuates the inverter to prevent breakdown of the thyristor and reduces the number of operations of the circuit breaker which is a final protection device. Additionally provided are linked switch actuator apparatus for placing a switch for actuating a thyristor control circuit in a state in which it is always actuated in advance of the actuation of a switch for a heating coil in order to prevent occurrance of a transient high voltage due to the switching of an inductive load in the inverter circuit, and an overheating protection circuit for detecting an abnormal temperature rise of the heating coil and an abnormal load condition to deactuate the inverter.