Improved Three-Phase Current Reconstruction Technique for PMSM Drive with Current Prediction

In this article, we present an improved current reconstruction technique with current prediction for a permanent magnet synchronous motor drive system. In some conventional single current sensor techniques, current fluctuations occur at the sector-switching period (SSP) due to current holding between two adjacent sampling intervals, which can cause current distortion and introduce many current harmonics, especially when the motor speed is very high. Focusing on that, a current prediction method is proposed in this article to prevent the current fluctuation happening at SSP. The SSP is divided into two independent parts for the accurate calculation of the output voltage vector and the actual three-phase currents at SSP are determined on account of both the predicted dq-axis currents and the measurable ones. As a result, compared with the previous current-holding strategy, the current fluctuations can be fundamentally eliminated under the proposed method with less current harmonics introduced, further improving the control performance of the whole system. The accuracy and practicability of the proposed method are verified by the experimental results.