Research On Switch Open Circuit Fault Detection Of Permanent Magnet Motor Drive System

The motor drive system is widely used in industrial production and defense industry because of its high efficiency and flexible control,and the safety and reliability requirements of some important applications are increasing,so it is necessary to study fast and accurate fault detection methods.For the open-circuit fault of the inverter power electronic switching device,current investigations mainly focus on characteristics analysis of fault signals and fault mode to construct fault indicator.However,there are relatively few studies on the fault features generation mechanism and the extraction of optimal fault signals.It is essential to understand the mechanism clearly and then put forward the fault detection method with the high signal-to-noise ratio.In this paper,we intend to analyze the opencircuit fault voltage characteristics of inverter power tubes,deduce the causes of open-circuit fault characteristics,explore the key fault characteristics signals,and then construct the optimal fault detection signals.Firstly,in this paper,the basic structure,mathematical model and electromagnetic performance characteristics of PMSM are analyzed.The electromagnetic simulation software and control simulation software are combined and simulated by the look-up table method to establish the closedloop simulation model of PMSM drive system.By analyzing conduction state of the power electronic switching device,midpoint voltage characteristics of the fault bridge,SVPWM switching states and synthetic space voltage vectors,the causes of the open-circuit fault characteristics of the inverter are theoretically deduced,and it is obtained that the key fault characteristics of the open circuit fault are the mismatch between the reference voltage and the actual output voltage,and the -axis residual voltage remains unchanged in fault condition.Then,two detection techniques which based on the residual harmonic components and -axis residual voltage are proposed.They do not require any additional voltage sensors.The two methods use the residual harmonic components and -axis voltage between the model predictive voltage and controller reference voltage,respectively.The rapidity,accuracy and robustness of the fault diagnosis methods are simulated and analyzed.The average diagnosis time of the two fault diagnosis methods is 0.44 and 0.38 fundamental cycle,respectively.Compared with the traditional current signal detection method,the diagnosis speed is improved,and the robustness of the diagnosis method is improved.At the same time,the normalization of the residual results eliminates the influence of load on the diagnosis results and improves the robustness of the diagnosis method.Finally,the proposed method is proved to be correct under different load and speed conditions by a multi-phase motor drive system experimental platform,and a joint test experiment of opencircuit fault diagnosis and fault-tolerant operation is conducted.The experimental results show that the proposed fault diagnosis algorithm is fast and robust,with low algorithm complexity and no additional hardware cost of the system,and has important practical engineering application value.