Fast Direct Torque Control of an Open-End Induction Motor Drive Using 12-Sided Polygonal Voltage Space Vectors

This Letter proposes a unified space vector pulse width modulation (SVPWM) for a dual two-level inverter system with two isolated DC voltage sources. The gate pluses for the dual inverter are generated by the concept of one unified SVPWM in accordance with the voltage-second integral principle and the ratio of the two DC-link voltages can be an arbitrary positive value. This proposed technique also simplifies the region identification in sectors and reduces total switching frequency of the dual inverter. The beneficial performance of this proposed technique is verified experimentally. Index Terms-Dual-inverter, Unified space vector pulse width modulation (SVPWM), Switching frequency

Section: Introductionmentioning

confidence: 99%

A Unified Space Vector Pulse Width Modulation for Dual Two-level Inverter System

Chen

Sun

2017

“…As per author in [17], a discrete SVM technique with predefined switching instants and extended switching tables is described for the DTC strategy. Even if this scheme can operate with fixed switching frequency, it is only suitable for induction motor (IM) drives.…”

Section: Introductionmentioning

confidence: 99%

Feedback Linearization Direct Torque Control With Reduced Torque and Flux Ripples for IPMSM Drives

Choi

Jung

2016

113

This paper designs a feedback linearization direct torque control (FL-DTC) based on the space vector modulation (SVM) which can noticeably reduce the electromagnetic torque and stator flux ripples that affect the system efficiency on interior permanent magnet synchronous motor (IPMSM) drives. First, a decoupled linear IPMSM model with two state variables (i.e., the stator flux and electromagnetic torque) is derived to implement the proposed FL-DTC strategy that preserves some advantages such as fast torque control, high torque at low speed, and fast speed response. Also, the proposed technique greatly alleviates the torque and stator flux ripples which are the major concerns of the classical hysteresis based DTC scheme and have an effect on the stator current distortion. The system stability with the designed FL-DTC method is mathematically analyzed using the Lyapunov stability theory. Finally, the effectiveness of the proposed control law is validated through simulation results with MATLAB/Simulink and experimental results obtained from a prototype 1-HP IPMSM drive with TI TMS320F28335 DSP. The verification results demonstrate that the proposed FL-DTC scheme achieves faster torque response, smaller torque ripple, and lower stator flux ripple than the conventional SVM-based PI-DTC approach under parameter uncertainties and external disturbances.Index Terms-Direct torque control (DTC), feedback linearization control (FLC), interior permanent magnet synchronous motor (IPMSM), torque and stator flux ripple reduction. 0885-8993 (c)

“…The well-known major problems that are normally associated with DTC utilizing hysteresis torque controller (which will be referred to as DTC-HC in this paper) are (1) poor stator flux regulation at low speed operation, also referred as flux droop [5], (2) high torque ripples [6][7][8], and (3) variable switching frequency [9][10][11]. Problems (2) and (3) have been addressed by various researchers and as a result several variations to the basic DTC structure have been proposed over the past few decades; among the widely accepted methods are the ones which are based on space vector modulation -known as the DTC-SVM.…”

Section: Introductionmentioning

confidence: 99%

Simple Flux Regulation for Improving State Estimation at Very Low and Zero Speed of a Speed Sensorless Direct Torque Control of an Induction Motor

Alsofyani

Idris

2016

118

This paper presents a simple flux regulation for a direct torque control (DTC) of induction motor (IM), to improve speed and torque estimations at low and zero speed regions. To accomplish this, a constant switching frequency controller (CSFC) is used to replace the3-level hysteresis torque comparator of a DTC IM. The DTC of IM utilizing CSFC (DTC-CSFC) retains the simple structure of a look-up table based DTC drive. With DTC-CSFC, constant switching frequency is maintained, and at the same, the flux droop problem that normally occurs in DTC with the hysteresis controller (DTC-HC) at low speed is solved; subsequently, the stator flux and torque estimations at low speed are also improved. In the proposed system, the speed feedback for the closed loop speed control is estimated using an extended Kalman filter (EKF), which requires heavy real-time computation. However, due to the simple structure of DTC-CSFC, small sampling time, hence large control bandwidth is possible. The performance of the speed sensorless DTC-HC and DTC-CSFC are compared experimentally under different operating conditions. With the improved stator flux regulation, experimental results of the DTC-CSFC showed a significant improvement in speed and torque estimations at very low and zero frequency operations. Index Terms-Constant switching frequency controller, direct torque control, extended Kalman filter, flux regulation, induction motor.S 0885-8993 (c)