Discretization error compensation method in high-speed motor drive system by using direct torque control

In this paper, a discretization error compensation method in a motor drive system by using direct torque control (DTC) is proposed. Similar to a conventional current control system, DTC allows an efficient drive and a wide range drive. Furthermore, it has the advantage that its control system can be simple and theoretically it can realize sensorless position control. Therefore, a reference flux vector calculator (RFVC) DTC is studied as a system for the ultra-high-speed drive control of permanent magnet synchronous motors (PMSMs). In high-speed drive, we revealed that a discretization error in the DTC generates an error in the instruction magnetic flux and stator magnetic flux. In addition, we revealed that current detection timing generates an error in the estimated torque and real torque. Then, we propose a compensation method to cancel the flux and torque error focusing on the phase of the stator magnetic flux and experimentally verifying its effectiveness. © 2016 The Institute of Electrical Engineers of Japan.