유도 가열용 Half-Bridge 인버터 시스템의 신뢰성 향상 및 최적제어에 관한 연구

A Study on the Reliability and Optimal Control of Half-Bridge Inverter for Induction Beating System

The purpose of this paper is to obtain the improved reliability and optimal control of the half-bridge inverter for induction heating system. Parasitic inductance components within the inverter circuit for induction heating including the loss-less turn-off snubber capacitor considerably affect stable operation and noise level of the system. This paper analyzes the effect of the inductance in detail and presents a new snubber configuration suitable for the half-bridge inverter to effectively reduce it. In the half-bridge inverter for induction heating the capacity of the loss-less snubber capacitor determines the switching losses because the zero voltage turn-on switching is used. However, the increase of the capacitor is limited by the system specifications, so that it is not easy work to reduce the switching loss. To effectively overcome the limitation, this paper introduces an active auxiliary resonant circuit suitable for the half-bridge inverter circuit, which operates actively according to the variation of load condition. It is also one of the most important study issues for the half-bridge inverter driven induction heater that the development of optimal control scheme considering varied load condition should be achieved. The control strategy ensures a very stable operation of overall inverter system and zero voltage turn-on switching irrespective of sensitive load parameter variations, in particular, even under the non-magnetic materials.