Research On Transient Failure Mechanism And Reliability Of 3L-NPC Inverter Based On Power Device

At present,three-level NPC inverter is widely used in the field of power electronic inverter topology model.The topology has excellent performance in output waveform quality,power conversion efficiency and so on.At present,it is very popular in energy industry,motor drive industry and other fields.In this paper,the three-level NPC inverter is taken as the target,and the transient failure mechanism of the three-level inverter and the thermal reliability of the power device are studied.On this basis,a closed-loop dynamic selective tracking DSVPWM control method is proposed to improve the thermal reliability of the three-level NPC inverter.The main content structure of this article is as follows:Firstly,the article summarizes the domestic and international research and development status of the reliability of power electronic power switching devices and power electronic inverters.A brief introduction is given to several inverter topology models and inverter control strategies that are currently widely used.Secondly,parasitic parameters such as stray inductance have a significant impact on the switching characteristics of the inverter switching device.Based on the inverter topology with stray parameters,the article analyzes the electrical-thermal overshoot characteristics of the power device during the commutation transient.Studies have shown that the main cause of inverter transient failure is due to the presence of circuit stray inductance that causes the power device to generate excessively high electrical and thermal shocks during transient commutation,resulting in damage to its internal components.Thirdly,two different control methods,SVPWM and DSVPWM,are used to study the related losses and junction temperature of the three-level inverter switching device.And compare the difference between the loss and junction temperature under different control methods,it is concluded that the DSVPWM mode can improve the loss and junction temperature of the power device during operation.Based on DSVPWM,a closed-loop dynamic selection DSVPWM control method is proposed.The control method can improve the thermal reliability of inverter power devices to the greatest extent.Finally,The principle of hardware experimental equipment used during the study and the implementation of related control algorithms under different microcontrollers are introduced.The hardware platform is mainly used to verify the relevant theories in this article.