Research On Fault Diagnosis Of Voltage Source Inverter For Permanent Magnet Synchronous Motor System Based On Vector Control

Permanent Magnet Synchronous Motor(PMSM) has been widely applied in the speed control system fields because of its many advantages such as simple structure, small size, large torque inertia ratio, high power density, high efficiency, low loss, and so on.Inverter is one of the important components of PMSM driven system and it plays an important role for the normal operation of PMSM driven system, but statistics show that inverter power tube open-circuit and short-circuit failure accounting for 82.5% of the speed control system. Once inverter in the event of failure, it will cause the system outage or huge economic loss, even endanger the life safety, so the fault diagnosis of inverter is of great significance.Inverter fault mainly include short-circuit fault and open-circuit fault, short-circuit fault has been taken measures on the hardware and turned it into open-circuit fault because its lasting time is too short to diagnose, so the inverter fault diagnosis is primarily open-circuit fault diagnosis of inverter.This thesis do relatively research on any single tube and double tube IGBT open-circuit fault diagnosis of inverter, the main contents are as follows:(1) PMSM vector control system is designed by using the method of vector control. PMSM vector control system based on Mixed Logic Dynamic(MLD) is designed combining with MLD. PMSM vector control system based on MLD can achieve the effect of PMSM vector control system and simulation experiments verify it. PMSM vector control system based on MLD at the condition of inverter open-circuit fault is analyzed theoretically and the simulation experiment show that PMSM vector control system based on MLD at the condition of fault is consistent with theoretical analysis, which lays the foundation for the further fault diagnosis.(2) A healthy state observer of PMSM system driven by normal inverter is constructed based on MLD and compare the health state observer with actual PMSM system driven by normal inverter, and healthy state observer can reconstruct three-phase current when PMSM driven by normal inverter, and the simulation experiments demonstrate the validity of the health state observer mentioned above.(3) The characteristic expressions of three-phase current residuals of single tube and double tube at the condition of open-circuit fault(21types) are analyzed, and the intervals of fault characteristic are distinguished, and three-phase current residuals threshold is obtained by simulation experiments, combining threshold of residual current and fault characteristic expressions to diagnose open-circuit fault of inverter in PMSM vector control system based on MLD, and this method can accurately locate any single tube and double tube open-circuit fault IGBT of inverter, and mutations in the motor speed and sudden load will not result in a false diagnosis and the diagnosis time as short as one fundamental cycle. Simulation experiments verify the correctness and feasibility of this method.