Sliding mode vector control of non-sinusoidal permanent magnet synchronous machine

Abstract

This work presents a sliding mode controller for the speed control of a surface-mount permanent magnet synchronous machine (PMSM) with non-ideal trapezoidal back-EMF, using vectorial non-sinusoidal modeling. The calculus of vector-based machine model considers an ideal trapezoidal back-EMF waveform, i.e., all control calculation is based on ideal back-EMF, but they are applied to a machine with a real back-EMF waveform, which can be considered a distorted trapezoid. For the sliding controller, this paper shows the use of a sigmoidal function, the hyperbolic tangent, instead of the signal function and uses a proper sliding surface that presents combined integrative action and anti-windup effect, which is applied to the vector-based model of the non-sinusoidal machine. The final system consists in a high performance controller, robust to machine parameters and disturbances, and light in its design as shown by the results. The chosen sliding surface with integrative control action, combined to an anti-windup feature and the torque ripple free vector-based model, give zero steady state speed error, minimizes the system speed output overshoot and ripple.