Research On Bearingless Permanent Magnet Synchronous Motor With Modular Pole And Its Predictive Control

Motor is the most important mechanical equipment in modern industrial production,which promotes the continuous improvement of social productivity.The problems of service life,operating performance,production cost have an important impact on the whole social production and economic development.The bearingless permanent magnet synchronous motor(BPMSM)integrates the advantages of magnetic bearing and permanent magnet synchronous motor(PMSM),which is difficult to be realized and replaced by traditional motors,and has become an important research direction in the field of special electrical transmission.In order to improve the sinusoidal shape of air gap magnetic density and obtain smaller torque and levitation force ripple,a special structure called modular permanent magnet poles is proposed in this dissertation.The BPMSM with modular pole is taken as research object.The principle of levitation force generation is analyzed.The mathematical model is deduced,the rotor is optimized and the predictive direct control strategy is put forward.1.The basic structure of BPMSM with modular pole is introduced.The internal electromagnetic force of motor is analyzed,including Lorentz force and Maxwell force.The mathematical model of BPMSM with modular pole with rotor offset is derived,and the mathematical model of rotor motion is given.The mechanical structure of the BPMSM with modular pole with five degrees of freedom is proposed,and the control block diagram of the BPMSM with modular pole is constructed,which lays a foundation for further research.2.The finite element model of BPMSM with modular pole is established.In order to improve the efficiency of the optimization design,an efficient optimization design method,taguchi method,is proposed.In order to reduce the torque ripple and the levitation force ripple,the thickness of permanent magnet,the ratio of the rotor magnetic pole to pole pitch of rotor,the ratio of the high remanence material to modular pole and magnetic pole material are optimized based on the finite element analysis.At last,the radial suspension force of the optimized BPMSM with modular pole is analyzed.In order to verify the effect of the optimization,the performance of BPMSM with common pole and BPMSM with modular pole is compared and analyzed,and the superiority of the designed motor performance is verified.3.In order to solve the problem of sampling time delay in traditional direct control,a predictive control algorithm model is proposed.The basic principle of predictive control is introduced,the mathematical model of predictive direct control algorithm is deduced,and the delay time is compensated.The predictive direct control system is established,and the simulation model is built in simulation software.The results of the simulations show that compared with the traditional direct control of the BPMSM,the predictive direct control strategy can effectively reduce the ripples of flux,torque and suspension force,and when the speed of the motor changes or is disturbed,the motor can resume stable suspension and operation more quickly after a short adjustment.4.Based on the working principle and control strategy of BPMSM with modular pole,the hardware and software of the control system are designed.The hardware circuit includes DSP2812 minimum system board,power drive board,interface circuit board and other hardware modules.The software includes torque interrupt service program,suspension force interrupt service program and man-machine interaction program.The debugging experiment is carried out on the experimental platform.