| Switched reluctance motor(SRM)is a new type of speed control system developed in the past 30 years.The motor rotor is made of laminated silicon steel sheets without windings and permanent magnets.The structure is simple and can be used in high-speed rotation occasions.It has high fault tolerance,small motor starting current,suitable for frequent forward and reverse rotation,and has been widely used in many fields.As the core of the speed control system,the power converter is mainly composed of power electronic devices,and is often in high-frequency working conditions or harsh working environments.If the electrical fault of the power converter is not dealt with in time,it will lead to further deterioration of the system fault and irreparable damage.Therefore,the accurate diagnosis of the fault of the SRM power converter is of great significance.This paper analyzed and researched the above problems,and proposed a method of using variational mode decomposition(VMD)for fault diagnosis of SRM power converters,and introduced the multi-scale energy entropy rule to better quantify the fault information of nonlinear unstable fault signals at different scales.After extracting the fault feature vector,the support vector machine was used to realize fault diagnosis.Aiming at the problem that the number of decomposition modes needs to be pre-set for variational mode decomposition,this paper improved the VMD fault diagnosis method,which used the adaptive decomposition characteristics of empirical mode decomposition and the center frequency judgment method to select the number of modes to improve the practicability of variational mode decomposition.Firstly,the paper expounded the research background and significance of the subject,introduced the working principle of the switched reluctance motor,and summarized the research status of the fault diagnosis technology of the switched reluctance motor system at home and abroad,analyzed the basic working mode of the power converter,the fault types of the switch tube and its main characteristics,proposed a fault feature extraction method centered on the variational mode decomposition.Aiming at the problem of setting the number of modal components,this paper improved the variational modal decomposition method and applied it to fault diagnosis of SRM power converters.Secondly,the paper used MATLAB/Simulink software to build the fault occurrence module of the SRM drive system,established the fault diagnosis simulation model,collected the characteristic data of fault diagnosis of SRM drive system,analyzed the characteristics of the obtained signal in time domain and frequency domain,compiled the fault diagnosis algorithm program,and verified the validity of the fault diagnosis method by simulation.Finally,the paper developed a 45 k W switched reluctance motor controller based on the DSP chip,built an experimental platform and conducts a power converter fault diagnosis experiment,set up two modes of open-circuit fault and short-circuit fault,and collected the DC bus current and three-phase winding current in normal state,open-circuit fault and short-circuit fault.DSP operation results showed that the fault diagnosis method proposed in this paper has strong anti-interference ability and good fault diagnosis performance. |
