A novel 1000 V/40 A IGBT power supply unit for a plasma hardening and chemical vapor deposition plant

Due to its relatively low environmental pollution, plasma based surface hardening (e.g. of automotive components) is becoming increasingly important. This paper presents a novel 40 kW (20 kW) power supply unit for hardening/chemical vapor deposition (CVD) plants, as one plant can be used for both hardening and CVD, e.g. for coating cutting tools to increase tool life. The topology and the realization of the IGBT output stage, which has to generate voltage pulses with amplitudes up to 1 kV and a maximum repetition rate of 30 kHz (50 kHz with reduced output power) are described in detail. Furthermore, the construction of the high-frequency power transformer (which is necessary for potential separation) is discussed. Finally, measurement results are shown which also demonstrate the high dv/dt-stress of some system components in case an arc discharge occurs