Research On Control Method Of Single-winding Bearingless Switched Reluctance Motor With Hybrid Rotor

Bearingless Switched Reluctance Motor(BSRM),which combines switched reluctance motor(SRM)with magnetic bearings,integrates functions of suspension and rotation.It has the characteristics of compact structure,low cost,convenient manufacture,easy maintenance,clean pollution and high speed limit,which make the HSBSRM very suitable for the feld of aerospace,flywheel power generation,etc.Traditional BSRM has strong coupling and non-linearity between torque and suspension force,which seriously restricts the high-speed performance of the motor,increases the difficulty of control,and it is difficult to achieve decoupling control from the control method.Due to structural constraints,there is a dead zone of suspension force during traditional BSRM operation,which limits the operating area of the motor and reduces the flexibility of control.In order to improve the above defects,this paper studies a single-winding bearingless switched reluctance motor with hybrid rotor(HSBSRM),which has decoupling structure and can realize full-period suspension.Firstly,the structure and operation principle of HSBSRM and 12/8-pole BSRM are introduced,and the operation characteristics of HSBSRM are described in detail.Under the condition of ignoring magnetic flux leakage and edge flux,based on the virtual displacement method,the mathematical model of levitation force under two-phase conduction is deduced,which lays the foundation for the control of HSBSRM.Secondly,based on the idea of equivalent control between single and double-windings BSRM,the mathematical model is optimized.Aiming at the characteristics of full-period levitation and natural decoupling of HSBSRM,a no-load control strategy of minimum inductance flat-top region with less torque ripple and simpler control is proposed.In order to realize the decoupling control of torque and suspension force,two decoupling control strategies of dual-phase conduction are proposed,and the two decoupling control strategies are compared and analyzed in terms of torque ripple,control difficulty and suspension accuracy.In order to improve the controllability of torque and suspension force under high speed operation,an optimized decoupling control method is proposed.Based on MATLAB/Simlink,the dynamic simulation model of HSBSRM is built,and the above control strategies are analyzed in the simulation model.The simulation results coincide with the theoretical analysis,which verifies the effectiveness of the control method.Then according to the power level and control requirements of the HSBSRM prototype,a modular digital control system was designed and manufactured.The function and connection relationship of each analog block in the digital control system are introduced,and the design of important modules in the digital control system is described in detail.Finally,according to the control strategy of HSBSRM,the program of DSP2812 and CPLD is designed;a prototype of 1.5kW is processed.Based on the above hardware platform and software design,the symmetrical excitation experiment,no-load and decoupling suspension experiment of HSBSRM are carried out,and the stable suspension of motor is realized;the experimental results are analyzed in detail.The correctness and effectiveness of the mathematical model,control strategy,hardware platform and software design were confirmed by experiments.