The Parameters Selection Methods for Turn-off Capability in IGBTs
IGBT devices ensure their turn-off capability by connecting a large number of chips in parallel.However,when the parameters of parallel chips vary significantly,the turn-off capability of the devices inevitably degrades.Thus,it is significant to investigate the parameters selection methods for the turn-off capability enhancement in the IG-BT devices.In this paper,we firstly analyze features and key factors in turn-off failure for two parallel IGBT chips,and demonstrate the waveforms in dynamic latch-up failures for the first time.The waveforms indicate that uneven current redistribution during turn-off results in different stress levels being applied to the parallel chips,which subsequently leads to degradation in the turn-off capability of IGBT devices.Additionally,this process is significantly influenced by various parameters,including the threshold voltage and transfer characteristic curves of the chips,so it is necessary to improve the turn-off capability by multi-parameters selection.Therefore,we summarize the experimental results from 300 sets of parallel chip turn-off tests,and investigates the relationship between variations in parallel chip parameters and current sharing during turn-off process.Lastly,we propose the parameters selection method for the current sharing during the turn-off period,which can improve the turn-off capability in the IGBT devices.Experimental results show that the threshold voltage,transfer characteristics curves and the equivalent transconductance are necessary.Based on the proposed method,the peak value of the current mismatch at 1.8 times rated current can be effectively reduced to less than 10％,which verifies the effectiveness of this method.
万方数据
维普
