Harmonic Current Suppression for PMSM Drives via Time-Shifting Harmonic Extraction

Multiple synchronous reference frame (MSRF) current control scheme is frequently utilized in permanent-magnet synchronous machine (PMSM) drive systems for harmonic current suppression. However, low-pass filters (LPFs) with relatively low cutoff frequencies are commonly used to separate the fundamental and the major current harmonic components, which can introduce significant delays in the control loop, degrading the system performance. To address this issue, this article proposes a rapid and efficient harmonic current suppression scheme for PMSMs by incorporating a fast harmonic extraction method based on numerical calculation. For the separation of fundamental, 5t<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sup> and 7<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> harmonic currents, the proposed method only requires the current data from three sampling moments for processing, essentially constituting a time-shifting operation. Then the current with different orders can be decoupled and transformed into different harmonic planes, and independent closed-loop control can be realized. Compared with the existing MSRF-based current harmonic regulation methods, the proposed scheme avoids the use of any digital filter and does not require a large amount of data storage. This approach mitigates delay effects, enhancing the dynamic performance of harmonic current regulation, and offers easy implementation. Finally, comparative experimental validation is conducted to validate the effectiveness of the proposed scheme.