Parallel operation of IGBTs modular converter system for high power high frequency induction heating applications

The aim of this work is to develop a modular converter system for induction heating application, which considerably reduces the expenditure, while covering the whole range of power at high frequency (400 KHz). Such a system shall consist of identical converter-modules, which are combined to produce the desired power. To increase the power, parallel connection of modules was employed. At high power high frequency, the IGBT losses are very important and the IGBT losses are totally dominated by the turn-off losses. The maximum output power rating of the inverter is manly limited by the IGBT losses. For parallel operation of IGBTs modules, which used to increase the output power, there are two ways used to distressing of IGBTs, normal parallel operation method and cycle control parallel operation method. This paper presents the influence of these two different methods which used for IGBTs modules operate at 400 KHz and 100 KW for one bridge on the maximum output power.