Error Calibration of Current Reconstruction Considering Noncentral Sampling for OW-PMSM Drive With Single Current Sensor

In this article, a novel current error calibration scheme considering noncentral sampling is proposed for an open winding permanent magnet synchronous motor (OW-PMSM) drive with a single current sensor. To realize the current reconstruction using a single current sensor, the durations of measurement vectors need to last long enough. Besides, the pulsewidth modulation (PWM) of the dual inverters is complicated, where the switching signals of two inverters need to be calculated simultaneously. Hence, the modified PWM strategy is developed to simplify the PWM procedure and extend the duration of measurement vectors. Nevertheless, the sampling error exists, because the bus current samplings take place sequentially at the measurement vectors instead of simultaneously at the central point. This will lead to a significant error in the reconstructed current, degrading the operation performance. Therefore, an online current calibration scheme is proposed to compensate for the current sampling error, which requires neither observer nor offline measurement to obtain the back electromotive force (back EMF). With the proposed calibration strategy, the precision of the reconstructed current can be significantly improved. Experiments are performed on an OW-PMSM drive to verify the effectiveness of the proposed strategy.