A practical series connection technique for multiple IGBT devices

Although IGBT device manufacturers are working hard to provide higher and higher voltage ratings, presently available IGBT devices still do not meet voltage requirement for building common medium voltage power electronic equipment. Direct series connection is the most compact and cost effective way of meeting such a requirement. However, existing techniques for series connection are either too expensive, easily oscillating, lossy or even retarding IGBT fast switching advantage. This paper proposes a practical approach by combining device terminal clamping and gate signal delay control. Together they are able to handle both dynamic and steady state operation of the series chain. Experimental results verify such approach's effectiveness.