Research On Current Sensor Fault Tolerant Control Of Encoderless Ipmsm Drive System

With the development of the control theory and electronic devices,the encoderless based permanent magnet synchronous motor(PMSM)drive systems have been widely used in many field.However,the current sensors in the system are vulnerable to some interferences and become failed,causing the system crash,even to endanger the life of the operator.As a result,the current sensors fault diagnosis and tolerant control for the encoderless PMSM drive system have become a research focus in recent years.In order to improve the reliability of the encoderless PMSM drive system,and make the system can operate stably under the fault of the current sensor with a good dynamic performance,some corresponding solutions have been studied in this paper.First,the mathematical model under fault conditions of the current sensor is established,and the influence of the different types of faults for current sensors on the PMSM drive system is analyzed.Based on the faulted output characteristics of current sensor,four typical fault types are summarized,and corresponding mathematical models are set up.Then combining with the theoretical analysis results of the mathematical models and the simulation results,the influence of different types of current sensor's fault on PMSM drive system is studied.The characteristics of the faulted current are summarized,and the approp riate fault type is selected for the next research.Then,a full order position observer based on the sliding mode control theory is designed to realize the encoderless control of PMSM drive system.The parameters of the observer are designed according to Lyapunov theory,and the position and speed can be obtained through orthogonal phase-locked loop(PLL),then the encoderless control of the system can be achieved.Next,a current sensor fault diagnosis strategy based on axes transformation is studied.The fault detection and location of the current sensor can be realized by comparing the difference between the amplitude of the current residual and the preset threshold.To ensure the stable operation of the system,a current observer based on the projection of the current space vector error is studied to reconstruct the faulted current,and the fault tolerant control of the current senso r for encoderless PMSM drive system can be realized.Considering the parameter in the position and current observers is easy to change with the operating of the motor,the parameter sensitivity analysis for current fault tolerant control based encoderless PMSM drive system is performed in this paper.The influence of motor parameters and position error on observers and the current space error reconstruction is the research focus in this paper,and some corresponding conclusions are summarized as a reference for compensation.Finally,on the basis of theoretical analysis,the current sensor fault diagnosis and tolerant control strategy of the encoderless PMSM drive system is programed on the chip based ARM,and the performance of the researched strategy is ve rified at the platform with 1.0kW PMSMs.