Research On Diagnosis Scheme For Open-switch Fault Of Three-phase Voltage Source Inverter

Highly developed power electronics technology in modern society,three phase voltage source inverter applications ranging from small appliances to electric vehicles,aircraft,high voltage power plants and industrial production process of the electrical drive system,it is an integral part of the electrical energy conversion system.The reliability and safety of power electronic inverters are critical for any advanced industrial electrical system.Therefore,it is very meaningful to study the safe operation and reliable operation of the inverter in order to improve the stability of the system and avoid unnecessary losses.This paper mainly studies the open-switch fault diagnosis method of inverter.In order to solve the problems in these existent fault diagnosis methods based on voltage and current analysis,the improved method is proposed.In addition,the construction of experimental platform and experimental verification is completed.The main contents of this paper are as follows:(1)In order to propose an effective fault diagnosis method for inverter.Firstly,the operation mode of inverter is analyzed and characteristic change of current and voltage is analyzed before and after fault in inverter.(2)In order to overcome the disadvantages of the traditional fault diagnosis method based on current vector frequency which can not locate the fault switch and improve the speed of fault diagnosis method based on current,a new method for fast diagnosis and location of open-switch fault based on current vector is proposed in this paper.(3)In order to ensure the reliability of the open-switch fault diagnosis method based on voltage and reduce the cost and improve the reliability,the open-switch fault diagnosis method based on voltage characteristic analysis of inverter is proposed.Low switch voltage feature is extracted by high-speed optocoupler.Then,the fault location signal is obtained by using specific logic operation.(4)Finally,in order to verify the effectiveness of the proposed fault diagnosis method,four-bridge fault tolerant inverter topology of is built,load current sampling circuit and voltage sampling circuit are designed and the diagnostic circuit is designed based on the characteristics analysis of the lower switch voltage.Finally,the fault tolerant inverter experimental platform based on dSPACE control is built.Experimental and simulation results show: The proposed inverter fault diagnosis method is experimentally verified by four bridge fault tolerant topology based on the dSPACE;the proposed fault diagnosis and location method based on current vector characteristic analysis to locate the fault switch needs the shortest time less than 15% current period and needs the longest time less than 65% current period.In addition,the method overcomes the shortcoming that the traditional fault diagnosis method is slow,cannot locate the fault switch and often needs a fundamental period;the proposed method based on the characteristics of the lower switch voltage have low diagnostic cost,high speed and high reliability.