Sliding Mode Direct Torque Control Research Articles

Research on Sliding Mode Direct Torque Control of Asynchronous Motor for Electric Vehicles

Research on Sliding Mode Direct Torque Control of Asynchronous Motor for Electric Vehicles

Sliding Mode Direct Torque Control of SPMSMs Based on a Hybrid Wolf Optimization Algorithm

Direct torque control has been widely used to control surface-mounted permanent magnet synchronous motors (SPMSMs). To reduce the torque ripple and improve the flux tracking accuracy of SPMSM drives, sliding mode direct torque control (SMDTC) was developed. However, its optimal performance is hardly obtained by trial and error tuning of the control parameters. Hence, a hybrid wolf optimization algorithm (HWOA) is proposed to automatically adjust the controller's parameters of SMDTC for SPMSMs in this article. This algorithm combines the grey wolf optimization algorithm and coyote optimization algorithm. A conversion probability is designed to use them simultaneously. The proposed HWOA holds the advantages of the two algorithms. It converges very fast and can avoid local optimums effectively. Furthermore, a special fitness index with penalty terms is designed to enhance flux tracking accuracy and reduce the torque ripple of SPMSM drives. The superiority of the proposed control method is verified by an experiment.

Robust SVM-direct torque control of induction motor based on sliding mode controller and sliding mode observer

This paper proposes a design of control and estimation strategy for induction motor based on the variable structure approach. It describes a coupling of sliding mode direct torque control (DTC) with sliding mode flux and speed observer. This algorithm uses direct torque control basics and the sliding mode approach. A robust electromagnetic torque and flux controllers are designed to overcome the conventional SVM-DTC drawbacks and to ensure fast response and full reference tracking with desired dynamic behavior and low ripple level. The sliding mode controller is used to generate reference voltages in stationary frame and give them to the controlled motor after modulation by a space vector modulation (SVM) inverter. The second aim of this paper is to design a sliding mode speed/flux observer which can improve the control performances by using a sensorless algorithm to get an accurate estimation, and consequently, increase the reliability of the system and decrease the cost of using sensors. The effectiveness of the whole composed control algorithm is investigated in different robustness tests with simulation using Matlab/Simulink and verified by real time experimental implementation based on dS pace 1104 board.

Second-order Sliding-mode Control Approaches to Improve Low-speed Operation of Induction Machine under Direct Torque Control

Direct torque control is a powerful approach widely used for the control of electrical machines. However, this approach is sensitive to several problems, such as the stator flux demagnetization phenomenon and the appearance of undesirable torque ripples, especially at low-speed operation. To overcome these problems, a variable structure control approach for a direct torque control–space vector modulation system, with a constant switching frequency, is proposed in this article. The proposed sliding-mode direct torque control–space vector modulation method can (i) enhance the system robustness, (ii) reduce the torque ripples, and (iii) prevent the demagnetization problem, which penalizes the stator flux regulation. To reduce the chattering phenomenon that appeared on the control law, a second-order sliding-mode approach, which is a new second-order procedure, has been proposed. Simulation results dealing with low-speed operation of the induction motor under variable structure control direct torque control–space vector modulation strategy is presented and compared to those yielded by the direct torque control–space vector modulation strategy using hysteresis controllers.

Sliding-mode direct torque control and sliding-mode observer with a magnetizing reactance estimator for the field-weakening of the induction motor drive

The paper deals with the sliding-mode control and the sliding-mode speed observer for the induction motor drive. The main interest of the paper is high speed operation, during the field-weakening, where the machine magnetizing characteristic is of great importance. Therefore the magnetizing reactance estimator, based on the magnetizing curve identification is used. The sliding mode technique is applied to design the direct control of the induction motor torque. A unified designing approach for control as well for the state space variables estimation is shown. Simulation and experimental results are shown to illustrate described problems.

Integral Sliding-Mode Direct Torque Control of Doubly-Fed Induction Generators Under Unbalanced Grid Voltage

An integral sliding-mode direct torque control (ISM-DTC) scheme with space-vector modulation for wind-energy conversion systems based on doubly-fed induction generators (DFIGs) under unbalanced grid voltage is proposed. The torque and power pulsations at twice the grid frequency caused by unbalanced grid voltage can be minimized by the proposed ISM-DTC scheme. Compared with existing control schemes of DFIGs under unbalanced grid voltage, the parametric uncertainties are included into the design procedure of sliding-mode controller, which guarantees the robustness of the controller. Because the torque and reactive power are directly controlled by the rotor voltage, the measurement, coordinate transformation, and symmetrical component extraction of rotor current are eliminated, which simplifies the structure of the controller. Simulation and hardware implementation results validate the effect and parametric robustness of the proposed ISM-DTC scheme.