Active Gate Control for Parallel Operation of IGBT Devices

Asymmetry in power circuit layout, mismatch in gate drive circuits, and lack of carefully matched device selection commonly result in dynamic and static current mismatch during parallel operation of IGBT devices. This paper is aimed at presenting a technique for actively controlling the gate drive of the IGBT to ensure appropriate current sharing under transient and steady state conditions. The multiple stage active gate drive approach proposed here utilizes single drive for all the parallelconnected IGBT devices during the transient states and a separate drive for each of parallel-connected IGBT devices during static state. This will allow robust parallel operation of the devices, thus providing greater manufacturing flexibility, plug and play operation, and ease of maintenance. The paper presents results from experimental evaluation of the current mismatch problem among randomly selected IGBT devices and a demonstrated solution to the problem using the proposed multiple stage active gate drive approach.