| A bearingless permanent magnet synchronous motor(BPMSM)is a new type of motor which combines the magnetic bearing technology with traditional permanent magnet synchronous motor.BPMSM has the advantages of no mechanical friction,no lubrication,long working life and low noise,overcoming the problem of speed limitation caused by the bearing friction in traditional motors,which is suitable for various high-speed fields.However,the traditional speed control method of permanent magnet synchronous motors is still adopted in the current speed control system of the BPMSM,which lacks the special research on the speed control of the BPMSM.And the speed control method of the BPMSM above the base speed is also rarely studied.Furthermore,because the BPMSM rotor is supported by the suspension forces,the mass imbalance of the rotor can produce the eccentric force proportional to the square of the speed,which seriously affects the stability of the rotor suspension under the high-speed operation of the BPMSM.In order to solve the above problems,a novel speed control method of the BPMSM based on flux strengthening and voltage regulation is presented in the dissertation.The flux-weakening control strategy is applied to the BPMSM to realize the speed control above the base speed,and the suspension force compensation control research is carried out on the mass unbalance of the BPMSM rotor.The dissertation is supported by Key Research and Development Program of Jiangsu Province(BE2016150).In this dissertation,the structure,operational principle,mathematical model,design of speed control system and rotor vibration compensation of the BPMSM have been researched.The main works and achievements are as follows:1.The basic structure of the BPMSM is introduced in detail and the electromagnetic force rotor subjects as well as the function is analyzed.Then the suspension force principle of the BPMSM is expounded.Moreover the mathematical models of the BPMSM suspension force and torque are derived based on the principle.Finally the mathematical models are verified by the finite element analysis.2.To reduce the speed fluctuation of the BPMSM,and considering the effect of suspension force load on the suspension performance,a novel speed control method of the BPMSM based on flux strengthening and voltage regulation is presented in the dissertation.Based on themathematical models of the BPMSM,the principles of flux strengthening and voltage regulation control are analyzed.Besides,the effect of the flux strengthening control method on the suspension performance is illustrated.The control system of the BPMSM is designed on the foundation of flux strengthening and voltage regulation,and the cooperation strategy of flux strengthening and voltage regulation control is proposed to improve the speed performance.Then the BPMSM flux-weakening control strategy based on the voltage regulation method is proposed to realize the speed control above the base speed,and the precise feedback linear decoupling control is adopted to improve the dynamic performance of the speed.Finally,the effectiveness of the proposed control method is verified by simulation experiments.3.In order to solve the problem of rotor synchronous vibration caused by the rotor mass imbalance,a compensation control method of rotor unbalanced vibration is proposed based on the unbalance mass-radius product which is obtained by adaptive search method and the compensation control signal is generated according to this.Compared with the direct compensation of the unbalanced force,the unbalance mass-radius product of the rotor is independent of the speed so that it is unnecessary to sample the synchronous signal of the speed in real time.Finally,the effectiveness and feasibility of the proposed vibration compensation control method based on the unbalance mass-radius product search is verified by simulation experiments.4.In the basis of the principle and control requirement of the BPMSM,the software and hardware of the digital control system are designed respectively,and the digital control experimental platform of the BPMSM is established by using TMS320F2812 DSP as the control chip.The basic experiments are conducted on the experimental platform,which confirms the feasibility of the control system.Finally,the proposed speed control method is effectively verified by prototype experiments. |
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