The Design Of High Power Devices’ Parallel Structure And The Research Of Their Crafts

In order to provide the requested power rating, insulate gate bipolar transistor (IGBT) modules could be connected in parallel. Unfortunately, due to the interconnection of the switches, the parameter of the devices and the delay times in the driving circuits, an unbalanced current would occur. As a result, the switch with bigger current may be overheated and would even be broken. Therefore, the IGBT modules are usually derated, which would increase number of devices required and the cost in the industry.To solve the problem discussed in the paper, at first, the operating mechanism of IGBT, dynamic characteristics and static characteristics are studied. Through the theoretical analysis and the result of simulation in this paper, it reveals that the parameter VCE(sat) plays an essential role during static period. If the VCE(sat)is different, each IGBT of the parallel module fails to share equal current. In this paper, based on the theory about voltage-current feedback, a current control circuit is proposed. Furthermore, the circuit is simulated and parameters of the circuit are optimized. The simulation shows that the proposed circuit could regulate current well and the current balancing could be achieved automatically.Secondly, IGBT would be usually regarded as a simple switch in the library of Spice, which may fail to take into account the parameter variation, especially VCE(sat), caused by junction temperature. Therefore, combined with experiments, the impacts on static current caused by junction temperature are discussed. In addition, the model of IGBT including the relationship between VCE(sat) and junction temperature is established and the proposed circuit is applied. Finally, the simulation reveals that the current control circuit presented a satisfactory result and this method for static current balancing proposed in this paper would be valuable and significant for high-power applications in parallel.