Sensor Fault Diagnosis And Fault Tolerant Control Of Permanent Magnet Motor Drives

With the innovation of technology,the application of new materials and the advancement of control technology,the permanent magnet synchronous motor(PMSM)drive system is gradually becoming the mainstream in the current drive field.Fault diagnosis and fault-tolerant control technology can improve the reliability of the drive system and has become a research hotspot in recent years.For faults in the position sensor in the drive system,fault diagnosis based on model-based fault diagnosis is used and the position observer is used to control the motor after the fault.For the current sensor fault,the abnormal phase is detected and located based on the coordinate transformation method,and combined with the current observer to complete the motor control after the fault.For the composite sensor fault,a single current sensorless vector control method is used for control.In this thesis,fault diagnosis and fault-tolerant control of position and current sensors in permanent magnet motor drive system are studied.First,the common faults of the position sensor are analyzed.The faults of the position sensor are classified by approximate processing,and several position sensor faults are modeled according to different fault characteristics.Based on this,the change of the running performance of the motor caused by the abnormal value of the position sensor is analyzed.The common types of faults in current sensors are analyzed.These faults are classified and modeled by approximate processing,and the effects of current sensor faults on motor performance are analyzed.The simulation analysis and verification of the influence of two sensor faults on the operation of the drive system are performed.Then,the position observer based on the sliding mode control theory is studied to realize the fault diagnosis and fault tolerance control of the position sensor.According to the sliding mode control theory,a full-order sliding mode observer is designed,and the saturation function is used to replace the switching function in the traditional sliding mode observer,and the position information is extracted through the phase-locked loop structure.A model-based fault diagnosis method is used to design a fault diagnosis scheme and a fault flag is output when the position sensor fails.Fault-tolerant control signals are selected according to the fault flag to ensure that the motor can operate stably after the position sensor fails.Then,a model-based current reconstruction method is studied to complete the reconstruction of the fault phase current.The fault diagnosis method based on coordinate transformation is used to perform fault diagnosis,and a full-order current observer is constructed to ensure stable operation of the motor after a fault.When the position and current sensors both fail,a single-current,position-sensorless vector control method is used to control the motor when the composite sensor fails.The fault-tolerant control strategy of the current sensor and the composite sensor is designed respectively.The current and position information for the motor control are selected by the fault flag to complete the fault-tolerant control of the permanent magnet motor drive system.On the basis of simulation and verification,a digital control algorithm is implemented,and a 1.0 k W permanent magnet synchronous motor based on ARM chip is tested on a drag loading experimental platform to verify the control method studied.