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Two methods for compensating motor-current-sensor offset error by using DC-voltage component included in phase-voltage command for current-controlled PMSM drive

Offset error of a motor-current sensor varies during motor drive and increases torque ripple. To maintain torque at a high quality, on-line methods for compensating that offset error are required. Accordingly, two methods for compensating offset error by using the DC-voltage components included in phase-voltage commands are proposed and evaluated by experiments and simulation respectively. The evaluation results reveal that the proposed methods can estimate and compensate for the offset error of a motor-current sensor without using motor parameters. The first proposed method (method I) applied to a two-phase-current-detection system was validated by the experimental results. The second proposed method (method II), established by adding an algorithm for estimating a zero-phase-sequence-offset-error component to method I, was evaluated by applying it to a three-phase-current-detection system, and its effectiveness for reducing torque ripple was demonstrated by the simulation results.