Design Issues for Permanent Magnet Machine Sensorless Drive Combining Saliency-Based and Back-EMF-Based Control in the Entire Speed Range

摘要

This paper addresses design issues on a position sensorless drive for permanent magnet (PM) synchronous machines in the entire speed range. At initial state, the rotor magnetic polarity is identified based on the flux saturation through a square-wave voltage injection. For low speed operation, the spatial information in the salieney is tracked for the closed-loop sensorless drive. The square-wave voltage is persistently injected to measure the salieney reflected current ripples for the position estimation. For high speed operation, the back-electromagnetic-force (EMF) voltage is estimated for the spatial saliency replacement to achieve the maximum speed under the same DC bus voltage. The rotor position is estimated from the spatial information in back-EMF through a sliding-mode observer (SMO). A transition algorithm based on a multi-input phase-lock loop by blending these two estimated position signals is proposed for a smooth dynamic operation. In this paper, all the design methods are verified on an interior PM motor with a saliency ratio of 1.37 (Lq/Ld=1.37).