A Restarting Strategy for Back-EMF-Based Sensorless Permanent Magnet Synchronous Machine Drive

Abstract

Safely starting a spinning position sensorless controlled permanent magnet synchronous machine is difficult because the current controller does not include information regarding the motor position and speed for suppressing the back-electromotive force (EMF)-induced current. This paper presents a restarting strategy for back-EMF-based sensorless drives. In the proposed strategy, the existing back-EMF and position estimator are used and no additional algorithm or specific voltage vector injection is required. During the restarting period, the current controller is set to a particular state so that the back-EMF estimator can rapidly estimate motor voltage without using rotor position and speed. Then, this voltage is used to decouple the back-EMF of the motor in the current controller in order to suppress the induced current. After the back-EMF is decoupled from the current controller, sensorless control can be restored with the estimated position and speed. The experimental results indicated that the induced current can be suppressed within four to five sampling periods regardless of the spinning conditions. Because of the considerably short time delay, the motor drive can restart safely from various speeds and positions without causing overcurrent fault.

Permanent Magnet Synchronous Machines

“…This trend can be seen in this special issue as a majority of the papers deals with PM motors with an emphasis on motor control. Five of the fifteen contributions target renewable energy sources [2][3][4]9,10], whereas the rest are focused on electric motors, with most examining electric vehicles [1,[5][6][7][8][11][12][13][14][15]. Three of the papers address brushless DC (BLDC) motors [7,11,12].…”

“…Three of the papers address brushless DC (BLDC) motors [7,11,12]. Six of the contributions present work on motor control, with the work of all six being experimentally verified [1,[6][7][8]11,15]. One paper is focused on fault diagnosis for hydropower generators [2].…”

“…However, alternatives exist and novel magnets have been heavily researched. Almost all the papers in this special issue are based on NdFeB-magnets, as stated by the authors in references [10][11][12][13] or as assumed from the contents in references [1,[4][5][6][7][8][9]14,15]. However, paper [3] investigates a span of magnetic properties, which could fit any magnet material.…”

“…Control of motors commonly requires a speed and position sensor, however, it would be beneficial to not be dependent on a sensor and therefore different types of sensorless control are subject to research. This issue is addressed in reference [1], where a restarting strategy is presented for a back EMF-based sensorless drive for a PM synchronous machine, and the motor voltage is estimated without using the rotor position and speed. The method is experimentally verified and it is concluded that the induced current can be suppressed for various conditions within four to five periods and therefore will not lead to overcurrent fault.…”

“…This special issue contains the successful invited submissions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] to a Special Issue of Energies on the subject area of "Permanent Magnet Synchronous Machines". Interest in permanent magnet (PM) synchronous machines is continuously increasing worldwide.…”