| The rotor of the conical bearingless motor can be fully levitated and rotate at the same time without magnetic bearings.The rotor critical speed can be higher because the motor axial length is shortened.The Conical Bearingless Switched Reluctance Motor(CBSRM)takes the advantages of the bearingless motor and the switched reluctance motor,therefore,it can be applied in many fields with the demand of high speed,high power density and high reliability.However,the CBSRM inherents the characteristics of intensive coupling and high nonlinearity because its angular velocity and five-axis positions need to be controlled simultaneously.It remains a difficult research topic to find out the control method of the torque and the levitation forces for the CBSRM especially the coordinate control method of the torque and the axial force.To solve the problem mentioned above,the paper takes a 6/4 CBSRM and two 6/4 CBSRMs as the targets and aims at the coordinate control methods for the CBSRM.Firstly,the paper presents the mathematical model of a 6/4 CBSRM considering two phases coupling due to its special structure.In the meanwhile,the paper presents a current equivalent control method for a CBSRM.Simulation results based on MATLAB/Simulink and experimental results based on the DSP+CPLD platform validate the theory.Then,the paper proposes three control methods for two CBSRMs,namely,the individual roleshare control for torque and axial force,the mutual role-share control for torque and axial force as well as the bias current ? control.The three methods can achieve the levitation and rotation of the CBSRM rotor at the same time.Theory analyses and comparisons are made and the simulation results also prove the methods.Finally,the motor structure,the hardware platform and software framework are introduced.Moreover,the auxiliary limitation for the motor parameter design is presented as a result of the complex machining problem for two CBSRMs. |
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