Research On Fault Diagnosis And Tolerant Control Technology In Five Phase Pmsm System

This paper takes five phase permanent magnet synchronous motor as the research object and has a deeply analysis about Five-Phase PMSM mathematic model, Five-Phase inverter pulse width modulation(PWM) technique, Inter-turn short circuit fault model, Five-Phase inverter open circuit fault diagnosis and fault tolerant control performance research.Firstly, the paper establishes mathematical model of Five-Phase PMSM and analyzes the PWM technique of Five-Phase inverter. Taking ITH-MMF Five-Phase PMSM as an example, the paper analyzes the stator inductance matrix, flux equation and motor mathematical model under natural coordinate system. And the paper establishes coordinate transformation matrix under Five-Phase system and mathematical model under rotating coordinate system. Besides, the paper discusses vector control scheme of Five-Phase PMSM and has any theoretical analysis and simulation verification about the Near Two Vectors and Near Four Vectors SVPWM algorithm. The result shows that Near Four Vectors SVPWM algorithm can ensure smaller harmonic content of motor output phase voltage and that the phase current is more similar to sine wave.Secondly, Inter-turn short circuit and Five-Phase inverter open circuit fault is researched. According to the Sin-MMF five phase PMSM, adding a fault factor into inter-turn short fault phase, the fault parameter and simulation model of Inter-turn short circuit is built. The simulation show that the stator current is proportional to the number of turns which occur Inter-turn short circuit fault. For the Five-Phase inverter switch open circuit fault, this paper gives two fault diagnosis algorithms: one can get the fault location table of inverter single tube and different phase two tubes open circuit by improved average current method, another one utilizes the normalized current method to solve the false diagnosis problem of average current method when the load is abrupt and can achieve inverter single open circuit fault diagnosis by using the phase angle of three times harmonic subspace α3-β3 fault current.Then, fault tolerance mechanism of Five-Phase PMSM is studied. Based on mirror symmetry principle to obtain mirror relation equation of a sinusoidal current, it reduces unknown variables of fault tolerance current, increases the solving speed of control system and reduces the motor abnormal state operation time. With zero torque pulsations, zero neutral current and minimum stator copper loss as constraint conditions, this paper analyzes active and reactive power of Five-Phase PMSM in open circuit fault of single phase, nonadjacent double phase and adjacent double phase respectively. Next, the optimal solution of fault tolerance current is acquired, which can maintain low torque pulsations and high output torque in Five-Phase PMSM open fault. And the conclusion is verified by using Ansoft simulation.Finally, Five-Phase PMSM drive control system platform is built with Infineon 32-bit MCU TC1767 as control chip. And experimental results show that Near Four Vectors SVPWM algorithm can ensure smaller harmonic content of motor output phase voltage and reduce the motor loss, both improved average current method and three times harmonic normalized current method can have accurate diagnosis about Five-Phase inverter open circuit fault, what’s more, it solves the false diagnosis problem of average current method when the load is abrupt, optimal fault-tolerant current can endure motor run smoothly and reduce furthest torque pulsations.