Study On Design And Control Of Flux Reversal Linear Rotary Permanent Magnet Actuator

Flux reversal linear and rotary permanent magnet actuator(FR-LRPMA)is a novel electromagnetic actuator integrating the features of flux reversal principle and linear-rotary permanent magnet actuator,which can achieve the rotary,linear or spiral motion.It has great requirement in the field of industrial control such as digital control machine tools,medical equipment,robots,aerospace and so on Therefore,it has greatly theoretical significance and practical engineering application value in its design,analysis and drive control.The paper synthesisly analyses the state of the art for the design and drive control system of linear rotary actuator(LRA).The typical topologies and performance of LRA are summarized.A novel FR-LRPMA topology is proposed,and the basic working principle and the main electromagnetic parameters are studied.An ideal linear model is built to analyse the inductance and flux linkage characteristics of the FR-LRPMA,which is verified by 3-D finite element method.A 3-D analytical method is used to analyse the no-load air gap magnetic field of FR-LRPMA.Assuming that the stator and the mover are slotless,the tubular structure is transformed to a planar one,a 3-D analytical magnetic field of the planar model is calculated in the Cartesian coordinate system,and then the curvature coefficient is used to reduce the error between the analytical magnetic field in the planar model and the tubular model.The air gap relative permeance is calculated to analyse the influence of the difference between the permanent magnet pole and the ferromagnetic pole on the air gap magnetic field and the influence of the stator slot and the mover slot on the air gap magnetic field.The no load air gap magnetic flux density is deduced.The analytical functions of the cogging torque,the linear detent force,the torque and the thrust are derived based on the Maxwell stress tensor method and virtual power method.The parameters of the topology are optimized according to the minimization of the amplitude of the cogging torque,linear detent force and torque ripple and the maximization of the amplitude of the torque.The main demagnetization factors of the permanent magnet material of FR-LRPMA are analyzed according to the mechanism of irreversible demagnetization and the demagnetization model of the permanent magnets.In order to reduce the possibility of irreversible demagnetization of permanent magnet,a fitting function is proposed to determine the minimum work point of the permanent magnet,which takes the thickness of permanent magnet,the temperature,the mover rotary position and the current into consideration,and then the optimized value of permanent magnet thickness and the maximum current value are obtained.The difference of control model between the flux reversal machine and the traditional permanent magnet synchronous machine is analyzed,and the mathematic model of FR-LRPMA in the nine-phase stator coordinate system and the control model in the dual dq mover coordinate system are derived.A simulation model of the control system is built in the Matlab/Simulink software according to space vector pulse width modulation(SVPWM),and then linear,rotation or spiral motion are carried out.A prototype is manufactured according to the results of the design and control simulation.The experimental drive control system is set up using digital signal processer.The static characteristics and the main performance parameters of the prototype is tested based on the dual dq transform and SVPWM.The decoupling control of FR-LRPMA is realized.The prototype design,analytical method and control strategy are correct.It lays a good theoretical foundation for further engineering applications of FR-LRPMA.