Steady-State Performance Degradation of a DTC IM Drive Under Parameter and Transduction Errors

Abstract

With direct torque control (DTC), the stator flux magnitude and the torque of an induction motor (IM) drive are controlled in a closed-loop way. The actual values of the controlled variables are estimated by processing the inverter dc-link voltage and the stator currents by means of the IM voltage model. Any error in the model parameter (the stator resistance) or in the voltage and current transduction degrades the drive performance. In this paper, a theoretical investigation of the effects of the various errors on a DTC IM drive is carried out. The investigation gives a proof of the drive instability due to some errors and provides, for the other errors, the amount of the deviation produced on the controlled variables in steady state. The theoretical findings are substantiated by experimental and simulation results.

Estimation of Stator Resistance in Direct Torque Control Synchronous Motor Drives

“…Stator resistance error in DTC induction and synchronous motor drives is studied in [7] and [8], respectively. The small-signal analysis presented in [7] and [8] shows that if the estimated stator resistance is greater than the actual resistance (negative error), the control system becomes unstable.…”

“…The small-signal analysis presented in [7] and [8] shows that if the estimated stator resistance is greater than the actual resistance (negative error), the control system becomes unstable. On estimated stator resistance is less than the actual resistance (positive error), the control system is stable, but the actual values of electromagnetic torque and stator flux modulus are different from their reference values.…”

“…On estimated stator resistance is less than the actual resistance (positive error), the control system is stable, but the actual values of electromagnetic torque and stator flux modulus are different from their reference values. Although a DTC induction motor drive can be stable even when the stator resistance is neglected [7], [9], a DTC synchronous motor drive becomes unstable with a high positive resistance error at low speeds [10]- [12]. Therefore, estimation of stator resistance is even more critical in DTC synchronous motors than in DTC induction motors.…”

Symmetrical and asymmetrical H-bridge multilevel inverter for DTC induction motor drive automotive applications

“…One of the methods that have been used by a major multilevel-level inverter manufacturer is DTC, which is recognized today as a high-performance control strategy for AC drives [10][11][12][13]. Several authors have addressed the problem of improving the behavior of DTC AC motors, especially by reducing the torque ripple.…”

Compensation Method of Current Measurement Error for Vector-Controlled Inverter of 2-Phase Induction Motor

“…이러한 오차들은 벡터제어에서 전동기 의 토크리플을 증가시키므로 이를 제거 또는 감소시키기 위한 많 은 연구가 진행되어 왔다 [6][7][8][9][10][11][12][13][14][15][16][17][18].…”