Modulation-Index-Adjustment-Based Dead-Time Compensation Method in Voltage Angle Regulation for PMSM Drive

The field-weakening control method with voltage angle regulator (VAR) has the advantages of better efficiency and power capacity by improving the voltage modulation index (MI). However, the control error of MI, which is mainly caused by the dead-time effect, results in the current operation points deviating from the optimal ones. It increases motor thermal loss and reduces system efficiency. But the applications of dead-time compensation methods are limited by the difficult problem of current polarity judgment. To solve this problem, a modulation-index-adjustment-based (MIAB) dead-time compensation method is proposed in this article, where the current polarity judgment is not necessary. Firstly, the quantitative relationship between MI and dead time is analyzed. Then, it provides the theoretical foundation of the target MI adjustment to eliminate the control error of MI, allowing the current operation points return to the optimal ones. Therefore, the influence of dead-time effect on MI is suppressed. Finally, the adaptability of the proposed method is verified by PMSM bench experiments.