Research On High Quality Operation Control Of Permanent Magnet Linear Motor Servo System Under Fault Condition

With the development of precision manufacturing and military industry,the reliability of servo system is becoming more and more important.Compared with the traditional linear servo system with rotating motor and roller screw mode,on the one hand,the primary permanent magnet linear motor(PPMLM)servo system adopts direct drive transmission structure to directly convert electric energy into mechanical energy.On the other hand,PPMLM places all permanent magnets and windings on the primary side,while inheriting the characteristics of small volume and high power density of permanent magnet linear motor(PMLM),it also has the characteristics of simple structure and convenient maintenance.However,due to the complexity of motor operating conditions,the sensors of servo system have the possibility of failure.Therefore,it is of great significance to study the high quality operation control of permanent magnet linear motor servo system under fault conditions.Aiming at the current sensor fault and position sensor fault that may occur in the PPMLM servo system,the research on high quality operation control under fault conditions is carried out in this thesis.The main research contents are as follows:(1)The background and significance of the topic are introduced,the origin and development of servo system and PMLM are described,the research status of fault-tolerant control methods of current sensor and position sensor in motor servo system are expounded.(2)The topology,mathematical model in natural coordinate system,two-phase stationary coordinate system and synchronous rotating coordinate system,and common vector control strategies of PPMLM are introduced.(3)High quality operation control of permanent magnet linear motor under current sensor fault is studied.Firstly,a traditional fault-tolerant control(C-FTC)method is introduced.For C-FTC,the hysteresis current control is adopted in the current inner loop.In the hysteresis comparator,the reference value and measured value of healthy phase current remain unchanged,and the reference value of fault phase current remains unchanged,while the measured value is replaced by the estimated value calculated by the mathematical model.C-FTC has good dynamic performance,but poor robustness,and its steady-state performance is greatly affected by the variation of motor parameters.On this basis,a phase-shifting fault-tolerant control(PSFTC)method is proposed,which breaks through the technical bottleneck of poor robustness of model control methods.In the hysteresis comparator,the reference value and measured value of healthy phase current remain unchanged,while the measured value of the fault phase current is replaced by the estimated value calculated by the mathematical model,and the reference value is replaced by the phase-shifting value of the estimated value of the healthy phase current.PS-FTC has strong robustness and excellent steady-state performance,and is no longer affected by the variation of motor parameters,but its dynamic performance is poor.Finally,combined with the advantages of C-FTC and PS-FTC,a hybrid method is proposed.The hybrid method realizes the flexible switching between the two fault-tolerant methods by setting an appropriate threshold,switching to C-FTC in dynamic state and switching to PS-FTC in steady state.(4)High quality operation control of permanent magnet linear motor under position sensor fault is studied.A position sensor fault-tolerant algorithm based on sliding mode observer method is proposed.Compared with the traditional sliding mode observer method,the proposed algorithm adopts a new reaching low.On the one hand,the traditional symbolic function is replaced by the hyperbolic tangent function,that is,the discontinuous function is converted into a continuous function.On the other hand,the state variable is introduced based on the exponential reaching law,when the state variable gradually reaches zero,the bandwidth also reaches zero.The adoption of the new reaching law not only reduces the chattering of the system,but also speeds up the approach speed in the approach motion stage.(5)The PPMLM servo system experimental platform is established.Taking d SPACE DS1103 controller as the core,the software and hardware facilities of the experimental platform are designed.The hardware part is mainly divided into motor body part and control circuit part,and the software part is mainly the design process of motor servo system based on DS1103 control and Control Desk software.