Fault Diagnosis And Fault-tolerant Control For Current Sensors In Permanent Magnet Servo Drive System

When the current sensor of the permanent magnet servo drive system is abnormal,the operation performance of the system will be declined,and serious consequences such as motor stall and overcurrent trippin even could be caused.In order to avoid the influence of the faulty current sensor on the drive systems,the fault diagnosis and fault-tolerant control of the current sensor have received extensive attention from scholars at home and abroad.In this paper,for the permanent magnetic synchronous motor(PMSM)drive system,the fault diagnosis and fault-tolerant control of the current sensor is realized by using the model-based fault diagnosis method and the fault-tolerant control method with reconstructed current.The main research content and innovations are as follows:(1)The mathematical model of the permanent magnet synchronous motor in the d-q rotating coordinate system is established.The stator current reconstruction method based on the current observer is studied.The performance of the reconstructed current of different observers is analyzed,and the effect of DC bus voltage fluctuation on the extended Kalman filter is studied.This paper proposes an improved stator current reconstruction method based on the DC bus voltage signal.(2)Several common faults of current sensors are briefly described.A fault diagnosis method for current sensors based on double EKF cross-current analysis is proposed.The effectiveness of the method and the performance of the fault diagnosis method under different working conditions are verified through the simulation and the built experimental platform.(3)A highly reliable operation framework of permanent magnet servo drive system based on DC-link current sensor is proposed.The current sensor of the servo drive system is monitored in real time through the DC-link current sensor.When the bus current sensor or the phase current sensor is faulty,the method can effectively diagnose the faulty sensor.(4)A fault-tolerant control of PMSM current sensor based on EKF reconstruction of stator current is proposed,and the influence of inaccurate motor parameters on the fault-tolerant control performance is analyzed.A fault-tolerant control of PMSM current sensor based on DC bus current signal is proposed.The measurement dead zone problem in this method is introduced and solved,and the fault-tolerant control performance is verified by simulation and experiment.(5)The requirements of PMSM electromagnetic parameters for the control framework of permanent magnet servo drive system is analyzed.The differential evolution algorithm to identify PMSM electromagnetic parameters is designed.The motor mathematical model solution,fitness equation and mutation crossover steps are improved.The theory is verified by simulation,and the performance of the parameter identification algorithm is analyzed.