Research On The Power Devices Junction Temperature And Fault-tolerant Control Of T-type Three-level Inverter

In recent years,the new energy technology has developed rapidly.The reliability of the converter has become the bottleneck of its breakthrough development.In this thesis,the reliability of converter is studied.Taking T-type three-level inverter as an example,study is carried out on the junction temperature control of key devices and fault-tolerant control.Some new control strategies are proposed based on the summary of previous research results.The specific research contents of this paper are as follows:1.The working principle,modulation strategy and control method of T-type three-level grid connected inverter are analyzed.2.The switching loss model and the heat model of IGBT are combined to derive the quantitative relationship between the switching loss,the junction temperature and the switching frequency.It is proposed to reduce the IGBT junction temperature amplitude by using the multiple structure to reduce the switching frequency of the inverter,so as to improve the reliability of the converter.3.Based on SVPWM algorithm of voltage space vector,the principle of fault-tolerant control using redundancy vector is described,and a fault-tolerant strategy combination of topology reconstruction and fault-tolerant redundancy vector strategy is proposed,which can maintain the operation of system after failure.4.Based on the experimental.platform,the effectiveness of the proposed control strategy is verified.The experimental results are in good agreement with the theoretical analysis,which shows that the proposed control strategy can effectively improve the reliability of the converter.