Research On Fault Diagnosis And Fault Tolerant Control Of BLDCM Drive System

Brushless DC motor(BLDCM)has the characteristics of high efficiency,small size,wide speed range,excellent speed regulation performance,strong safety and stability,and convenient maintenance,so it has been widely used in the fields of automobile,aerospace and industry.The reliability of the control system of BLDCM is greatly affected by the power electronic devices,because the problems caused by its destruction are difficult to solve,which limits its application in high reliability and high precision occasions.Therefore,scholars at home and abroad pay more and more attention to the research of fault diagnosis technology.This paper mainly studies the power tube short circuit and open circuit fault and fault-tolerant control in the control system.Firstly,the system composition and working principle of BLDCM are introduced,the mathematical model of BLDCM is established,and the corresponding waveforms are analyzed under normal operation.In this article,by comparing the advantages and disadvantages of current detection method and voltage detection method,a fault diagnosis method based on voltage and current detection and combining with converter signal is proposed.Analysis of various fault types and their working characteristics in various fault states,establish fault diagnosis table,realize the accurate diagnosis and positioning of fault power tube.Secondly,the fault-tolerant topology of inverter is studied,and a fault-tolerant structure of three-phase four bridge arm is given.The single tube open circuit fault and single-phase open circuit fault are analyzed,and the fault-tolerant control strategy is given.Through the combination of hardware and software control method,the fault location of the motor is isolated to ensure that the motor can return to normal operation after the fault.Finally,the fault diagnosis and fault-tolerant operation of the motor aresimulated and hardware experiments are carried out.In the software,the fault diagnosis method and fault-tolerant control strategy are modeled,and a fault-tolerant experiment platform for the main controller is built,and the hardware circuit debugging and software programming are carried out.Through the analysis of the simulation and experimental waveforms,it is verified that the fault diagnosis and fault-tolerant operation of the proposed method can be realized in the single tube short circuit fault and open circuit fault of power tube,as well as in the power tube short circuit fault and open circuit fault of the same bridge arm.