Research On The Co-excitation Control Method For Four Degrees Of Freedom Magnetic Levitation Switched Reluctance Motor

Magnetic Bearing Switched Reluctance Motor(MBSRM)is composed of magnetic bearings and SRM(Switched Reluctance Motor),which can suspend the motor while satisfying its rotation,fully utilizing the high-speed performance of SRM and solving the problem of bearing wear in traditional high-speed motors.However,the traditional MBSRM composed of magnetic bearings and SRM requires independent control of the motor and magnetic bearings,resulting in a large control system and high cost,which is not conducive to applications in cost sensitive fields.Therefore,studying SRM,magnetic bearings,and their low-cost control strategies is of great significance.This article first proposes an MBSRM co-excitation control system,which consists of two 4/2-pole SRMs,two quadrupole radial magnetic bearings(AMB),and eight low-cost asymmetric half bridges.Two SRMs and two magnetic bearings form a four phase MBSRM,which controls the four radial suspension forces.The motor has a simple structure and strong high-speed adaptability.Each SRM is connected in series with the windings of each magnetic bearing to form a winding,which is controlled by a common excitation method,greatly reducing the cost of the control system and solving the problem of high cost in MBSRM systems under traditional control methods.Secondly,under the premise of neglecting magnetic flux leakage,based on the original mathematical model,a new interval division was carried out to derive a more accurate full cycle mathematical model.Simulation comparisons between the two mathematical models were conducted using Simulink,fully verifying the superiority of the full cycle mathematical model.Once again,electromagnetic design of a four degree of freedom MBSRM based on co-excitation control mainly includes motor structure,motor parameter selection,electromagnetic field analysis,and so on.Analyze and optimize the electromagnetic field of the motor through finite element analysis,mainly including magnetic flux distribution,magnetic field strength,inductance,torque,suspension force,and so on.Based on the selection of motor parameters and the results of electromagnetic field analysis,optimize the design of the motor to improve its efficiency,performance,and reliability.Finally,in order to reduce the control cost of the MBSRM system,a co-excitation constant conduction control strategy was proposed.When solving the winding current,corresponding constraint conditions were introduced,and the required current values for each phase and interval were solved based on a full cycle mathematical model.Finally,a four degree of freedom MBSRM motor model was built in Simulik to simulate the operating conditions of the motor under different conditions,and the feasibility of the control algorithm was verified through simulation analysis.