T-type Three-level Inverter With Reverse Blocking IGBT

In recent years, the three-level inverter is developing rapidly with the advantages of its low harmonic. The T-type three-level topology with RB-IGBT power module featured with lower conduction loss and higher efficiency, is widely concerned not only in low voltage applications, but also in high voltage and high power applications.The thesis introduces the topology of T-type three-level inverter with RB-IGBT power module. Operation mode was analyzed and then detailed system power loss calculation was conducted firstly. The dc-link capacitor voltage unbalance is one of the important problems of this kind of topology. Based on analysis of the unbalance mechanism of the dc-link capacitor voltages, an improved voltage balance control strategy was then proposed with PI controller for controlling the balance of the voltage of the midpoint. Moreover, the modulation methods including the PD-SPWM and POD-SPWM have been analyzed in comparison. The output performance and FFT analysis results verified with MATLAB simulation model.Because of the specific electrical characters and features, the existing developed gate drives for conventional IGBT cannot be used for RB-IGBT directly because the reverse voltage on RB-IGBT during operation will destroy the gate drive circuit and power semiconductor device. Thus the over-voltage protection and over-current protection circuit of the common IGBT’s driver has been improved.What is more, this thesis also presents a detailed derivation of the circuit’s parameters of dc-link capacitor and parameters of filter circuit. The hardware setup of the experimental platform with the laminated bus bar has been designed, constructed. The corresponding experimental results verify the feasibilities and effectiveness of the theory analysis and the proposed control strategies.