Universal Restart Strategy for High-Inertia Scalar-Controlled PMSM Drives

In many industrial settings, momentary power disruptions commonly occur, resulting in tripping of large electric machines, which then have to be brought to zero speed before the machine can be restarted. This can result in frequent interruptions in an industrial process, which can have negative effects on productivity. A more practical approach would restart the machine back to the original speed as soon as power is restored, not having to wait for the machine to be at a standstill. This concept is known as flying restart. In this paper, we propose an approach to implement the flying restart for permanent magnet synchronous machines (PMSM) by using an identification algorithm that determines the speed and position of the machine back-electromotive force so that the correct voltage vector can be applied, thus minimizing the inrush current during the restart. The novelty of the proposed method is that its implementation only requires nameplate machine parameters and needs no machine-specific tuning, making the approach suitable for implementation with both vector- and scalar-controlled PMSM.