Study And Implementation Of Closed-Loop Control Current-Sharing Method For Paralleled IGBT Modules

In order to solve the problem exists in the areas such as the large capacity storage system, new energy and especially in traction and power transmission that a single switch device rated capacity is insufficient, there is no doubt that to use switching devices with small and medium-sized power levels in parallel rather than the device with large flow capacity has higher cost performance and be more safer and reliable?It is well known as IGBT parallel expansion technology.In the research of IGBT parallel expansion technology, we found that the differences of the switch parameters, the asymmetry between driver circuit and main power circuit that will bring some application problems to system. The leading problem is that the output static and dynamic flow are unbalanced. Consequently, the system flow ability to be reduced, working state to be not stable and even the device to be damaged. Therefore, it makes a barrier to IGBT module parallel expansion application. Hence, to research the mechanism and parallel flow control method of the unbalanced output static and dynamic flow of the IGBT parallel modules, contributes to better use of IGBT expansion.This paper's research object is based on IGBT parallel expansion technology. In view of the uneven static flow phenomenon, put forward a IGBT static flow equalize strategy based on closed-loop adjustment grid voltage; In view of the uneven dynamic flow phenomenon, put forward a IGBT dynamic flow equalize strategy based on series adjustable inductance. This article's main research content includes:(1) The working principle and characteristics of IGBT type PT and IGBT type NPT were compared and analyzed by this paper, and analysis and summarize comprehensively the factors of affecting the static characteristics and dynamic characteristics.(2) According to analysis the output characteristic of IGBT and the factors that affect the parallel flow, it puts forward a method of the gate voltage closed-loop controlled to improve static current sharing, constructs Pspice software simulation model based on BUCK circuit, and carries out the corresponding feasibility.(3) To make sure parallel IGBT module static current sharing, focused on analyzing the effect of delay time and other parameters for high power IGBT parallel dynamic current, pointed out deficiencies of improving the dynamic flow equalize by adjusting delay time, and proposed a method of cascading adjustable inductance in the emitter to achieve parallel IGBT module dynamic current sharing, and demonstrates the correctness of the method in Pspice simulation model and the experiment.