Current Sensor Fault Tolerant Control For Inverter Of Induction Motor And Performance Improvement Research

Induction moto(IM)has been widely used in industrial applications due to its advantages of low cost,high reliability,and mechanical ruggedness.The performance of induction motor has been improved with the development of rotor field-oriented vector control technology.Sensors has important effect in IM vector control system,and serious consequences may happen with the failure of sensors.The main content of this paper is the full fault tolerance control of the current sensor in the induction motor variable frequency speed control system.With the condition of single phase current sensor with no speed sensor and no current sensor with speed sensor,normal operation of IM drives system can be guaranteed with proposed tolerant control method,and proposed control method has high industrial application value.This paper firstly researches on the improvement of anti-disturbance capability in speed loop,because the stable speed operation of IM is directly determined with the performance of speed loop.Speed and torque are estimated with the disturbance observer based on extended state observer,and discuss the effect of the observer pole selection on control system performance.Torque feedforward compensation is introduced into speed loop with PI control to improve the anti-disturbance capability.Proposed method can reduce the speed fluctuation under load torque without affecting the stability of speed loop.Fault-tolerant control of the current sensor is respectively discussed for single phase current sensor with no speed sensor and no current sensor with speed sensor control modes.In single phase current sensor with speed sensorless control system,full-order state observer based on a mathematical model of IM is used to estimate and stator speed using flux as a state variable.Traditional speed adaptation law has been improved with the field current error based on the current relationship in rotation coordinate system and the stationary coordinate system,and corresponding error feedback matrix is redesigned to improve the low-speed performance of IM.Vector control method with single phase current is proposed with above control method and current compensation method.When all current sensors failure happens and only speed sensor can be acquired,close loop control of inner current loop cannot be realized.PWM prediction control(PPC)with control delay is proposed based on the mathematical model of induction motor.Virtual current loop is constitute with reference current value and Lunberger observer,and control method of PPC with no current sensor can be acquired.The effectiveness of proposed control method is demonstrated by experimental results based on 2.2k W IM experiment platform.The experimental results improve that the speed feedback anti-disturbance method based on the torque feedforward can reduce the speed fluctuation when the load torque changes.The fault-tolerant control scheme of single phase current sensor with no speed sensor and no current sensor with speed sensor can ensure stable operation of IM when the extreme sensor failure happens.