Coping with Poor Dynamic Performance of Super-Junction MOSFET Body Diodes

Abstract

Poor dynamic performance of body diodes in Super Junction MOSFETs may cause difficulties when utilised in high frequency conversion circuits. Excessive reverse recovery as well as forward recovery may in the best case result in high conversion losses and EMI pollution where as in the worst case they may completely disrupt the converter operation. In this paper, using an auxiliary snubber circuit to control the reverse recovery and connecting a fast diode in parallel to a super junction switch to reduce the forward recovery is proposed. As documented by numerous experimental results, both proposed concepts work well and both recoveries may be largely avoided. Implementation of the proposed concepts in a forward boost, reverse buck circuit resulted in efficiencies close to 98.5% in 3-12.5kW load range while operating at 62.5kHz.