Control Of Permanent Magnet Synchronous Machines At High Speeds

Permanent magnet synchronous machines(PMSM)have been widely used in industry due to their advantages of high efficiency,high power density and wide speed range.In order to achieve the high-speed operation of PMSMs,it is of significance to apply the flux-weakening control,which is one of the hot topics for research on PMSMs.Based on the characteristics of permanent magnet synchronous machines and coordinate transformation principles,the mathematical models on the synchronous rotating reference frame for the SPM machines and IPM machines have been discussed respectively.Then,various control methods of PMSMs,such as V / f control,vector control and flux-weakening control are introduced.The flux-weakening control technique of PMSM based on single-current regulator(SCR)is presented.And the torque and the current trajectory of PMSMs at high speeds are analyzed.In order to solve the problem of the decreased operation efficiency of PMSMs with the constant-Vq SCR,a new flux-weakening scheme is proposed.In addition,an integral sliding-mode controller is designed for working with the new SCR.The stability analysis of the sliding-mode control is performed.Finally,the vector control and MTPA control of PMSMs are simulated in PLECS.Also the new flux-weakening scheme is simulated and compared with the fixed-Vq SCR.The effectiveness of the proposed flux-weakening and the integral sliding-mode control is verified by simulation results.