An Exponential Reaching Law Sliding Mode Observer for PMSM in Rotating Frame

ABSTRACT

In order to solve chattering problem of conventional sliding mode observer (SMO), this paper proposes a exponential reaching law sliding mode observer (ERL-SMO) for a permanent magnet synchronous motor (PMSM) which substitutes exponential reaching law for constant reaching law. The ERL-SMO estimates the rotor position and the angular velocity from the back electromotive force (EMF) based on rotating frame instead of fixed frame. A phase locked loop (PLL) replaces low-pass filter which commonly leads to a phase delay. The stability of the proposed exponential reaching law was verified using the Lyapunov function. The simulation results show that ERL-SMO hasn’t only achieved a precise identification of PMSM speed and position, but also significantly weakened the signal chattering.

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