Frame-Angle-Based Direct Torque Control for 3ϕ Induction Motor Drives

This paper presents the performance evaluation of the frame-angle-based (FAB) direct torque controller (DTC) for 3φ induction motor drives (IMDs), which are fed by 3φ, 6-pulse wavelet modulated (WM) dc-ac power electronic converters (PECs). The tested DTC is designed to adjust the d - q-axis components of the voltages (v
_ds
and v
_qs
) applied to a 3φ IMD. The adjustments in v
_ds
and v
_qs
are created in response to changes in the load torque, command torque, drive speed, and/or system parameters. Desired adjustments in v
_ds
and v
_qs
are set by regulating the angle ϑ of the frame created by v
_ds
and v
_qs
. This frame produces reference modulating signals that are required to generate wavelet modulated switching pulses for operating the 3φ dc-ac PEC in the IMD. The complete IMD system, incorporating the FAB-DTC, is implemented for a 10-hp IMD system for performance evaluation. Tests of the FAB-DTC for the 10-hp IMD are conducted for various changes in the load torque, command torque, drive speed, and system parameters. Simulation and experimental test results demonstrate fast, accurate, reliable, and dynamic responses with minor sensitivity to variations in system parameters.