Research On Fault Tolerant Control Of PMSM Drive System

Permanent Magnetic Synchronous Motor(PMSM for short),because of its many advantages,is widely used in electric vehicles,servo systems,precision equipment and other fields.The drive system usually works under various complicated working conditions,and the inverter and important sensors face the danger of failure at any time.Once a fault occurs,it will force the system into an abnormal state,which will cause the system’s output performance to degrade or even shut down,which not only endangers life,production,and even causes catastrophic accidents.This paper’s research on fault-tolerant control of PMSM drive system is mainly to find a low-cost inverter fault-tolerant method with high fault coverage.At the same time,in order to deal with the failure of the speed sensor,a sliding mode observer is used to provide accurate speed and angle feedback to the system.In order to further maintain low jitter in a wide velocity domain,an improved parameter adaptive second-order sliding mode observer is used.Based on the above,in order to verify that the system is fault-tolerant,the use of fault-tolerant control scheme can still keep the system running stably and have better output performance,this paper has done a lot of simulation and experimental work.Firstly,the evaluation criteria of fault-tolerant systems are given.Based on the comprehensive consideration of the cost,fault coverage and reliability of the fault-tolerant system,a new topology circuit is reconstructed in the paper for the problem of poor fault-tolerant performance of traditional fault-tolerant inverters.This topology can fully cover the single-tube and double-tube failures of the inverter,and can deal with some of the three failures,thereby improving the reliability of the fault-tolerant inverter.After the first fault occurs,the normal three-phase six-switch mode can be used for operation.A six-switch four-vector non-continuous SVPWM control strategy is proposed for the secondary fault.The modulated wave formula is derived.At this time,the system operates in the degraded mode.At the same time,inthe paper,the transient response of the DC component of the capacitor neutral point offset voltage is studied,and the DC component of the capacitor neutral point voltage is compensated to the voltage vector at the stator two-phase coordinates.At the same time,the fault tolerance of the permanent magnet synchronous motor is carried out in the paper Control system simulation and experimental verification.Secondly,the high-performance modern AC speed regulation system requires high control accuracy,and generally cannot do without the measurement feedback device.However,the permanent magnet synchronous motor speed sensor is generally installed on the end shaft with the body,and the influence of high temperature and vibration cannot be avoided.Once the speed sensor fails or the signal is lost,the control accuracy of the system degrades.At this time,using the observer’s rotor position estimate to replace the faulty hardware speed sensor not only has low cost but also meets basic performance requirements.Aiming at the problem of large shake in the traditional first-order sliding mode observer,a second-order sliding mode observer based on parameter adaptation is proposed in the paper.According to the theoretical analysis of the Super-Twisting algorithm,and considering that the fixed parameter of the sliding mode observer based on this algorithm leads to the problem of narrow speed regulation range of the permanent magnet synchronous motor,a high-order sliding mode that can adjust the sliding mode parameters online is designed Observer,and use the saturation function instead of the switching function used in the algorithm.The proposed parameter-adaptive second-order sliding mode observer obtained from the experimental and simulation results can more effectively suppress the sliding mode chattering.In view of the excellent dynamic performance and low cost,it can be used as a software fault-tolerant way for speed sensor failure.The simulation results under inverter faults also show the characteristics of fast torque response,low torque harmonic distortion rate,and strong fault coverage of switch tubes.After the offset voltage of the neutral point is compensated,the attenuation process of the DC component is greatly accelerated.In summary,the method proposed in this paper has very good fault tolerance performance,and the system can operate safely and reliably.Finally,the design of PMSM fault-tolerant control system is given.The main circuit and auxiliary circuit design of fault-tolerant inverter are introduced in detail.