Research on H∞ control strategy of vertical hoist system driven by permanent magnet linear synchronous motor

The vertical hoist system directly driven by permanent magnet linear synchronous motor (PMLSM). It eliminates auxiliaries such as the mechanical couplings, rotary-to-linear translators, and reduction gears, but any change or disturbance will be directly reflected to the motor and control syetem. It will cause large deterioration in the motion profile. In order to reduce the disturbances of load and motor parameter variation, this paper converts control problem of PMLSM into a standard H_∞ control problem. The H_∞ robust controller was built based on choosing suitable weighting functions and solving matrix Riccati inequality with symmetrically positive solution. The simulation results were got by using of MATLAB toolbox. From the results, it can be seen that velocity comes back to the given scope quickly. The dynamic adjustment rate and stability time of system are relatively small. The system has good robustness. The improvement response speed and overshoot suppression performance are satisfactory. Thus the proposed method is reasonable and effective.