The Development and Performance Evaluation of a Frame-Angle-Based Direct Torque Controller for PMSM Drives

This paper presents the development and performance evaluation of a direct torque controller (DTC) for permanent-magnet synchronous motor (PMSM) drives fed by a 3φ 6-pulse wavelet-modulated dc-ac power electronic converters. The developed DTC is designed to adjust the d - q-axis components of stator voltages (v
_d
and v
_q
) of a PMSM in response to changes in the load torque or drive speed. The desired adjustments in v
_d
and v
_q
are achieved by changing the angle ϑ of a frame created by v
_d
and v
_q
. This frame is responsible for updating or changing the reference modulating signals that are required by the wavelet modulation technique to generate switching pulses. The complete PMSM drive system incorporating the developed DTC is implemented for a 10-hp PMSM drive system. The performance of the frame-angle-based DTC is investigated for different changes in the command torque and drive speed. Simulation and experimental test results demonstrate stable, fast, and accurate responses that are complimented by negligible sensitivity to variations in the system parameters.