Direct Torque Control Research Articles

Synchronous DTC for torque sub-harmonic reduction in low switching frequency induction motor drives

A direct torque control (DTC) algorithm with synchronous modulation for high-power induction motors is presented in this paper. While maintaining the dynamic response and robustness of a PI-based DTC operating in the stationary reference frame, the proposed scheme is able to keep an integer PWM modulation ratio, adjusting the stator flux angle and the switching period at each control step so that the synchronicity condition is always satisfied. In this way, it is possible to achieve an improvement of the very low-frequency harmonic spectrum of the torque, in particular by reducing torque sub-harmonics. These represent one of the main problems associated with low-frequency modulation typical of high-power drives and their reduction allows to avoid drawbacks such as resonance and mechanical stresses. The performance of the proposed algorithm is evaluated with experimental tests on a small-scale test bench.

Comparative study of the two DTC (6S - 12S) approaches applied to PMSM equipped with an IP regulator

Direct torque control was introduced in 1980 for induction machine for torque and flux control and developed for MSAP in 1990. DTC is gaining popularity due to its simple control structure and easy implementation. The principle of direct torque control (DTC) of the asynchronous machine was introduced in 1985 by I. Takahashi as an alternative to flux-directed vector control (FOC). It is thanks to its simple control structure that it gains popularity and its easy implementation that it has opened a new horizon in the field of variable speed control of electric drives. Indeed, direct torque control (DTC) has benefited in recent years from significant methodological advances in operation and technological development following the introduction of power electronics and digital electronics and the implementation of possible and very usable control algorithms. In conjunction with these technological advances, the scientific community has developed several control approaches to control the operation of electrical machines. In this context, this article presents a comparative study of the different direct torque control (DTC) strategies and structures of the permanent magnet synchronous machine (MSAP). We propose the algorithm of this control making it possible to provide solutions to the ripples of the torque and the stator flux in order to reduce them by adopting a method of compensating the effects of progression by passing from the six sector DTC (DTC – 6S: classic and modified) then develop the twelve-sector DTC (DTC-12S) whose purpose is to minimize ripples and control the switching frequency of the inverter. The simulation graphs presented will clearly show the difference between the different controls techniques cited.

Direct Torque Control Space Vector Modulation for Induction Motor Driven by Matrix Converter

This study proposes enhancing induction motor (IM) drive systems by developing a DTC-MC with SVPWM integration to reduce ripple. DTC-MC is effective for precise torque control in AC drives, offering high control accuracy by isolating stator flux and torque. The method excels in sensor-less speed control, maintaining unity input power factor at low speeds, and constant switching frequency for rapid torque adjustments. Combining DTC-MC with SVPWM improves simplicity, dynamic behavior, and torque response. The DTC-SVM approach further refines the torque response by correcting flux and torque discrepancies. MATLAB/SIMULINK simulations validated the approach, showing a robust dynamic response and significantly reduced motor torque ripple and control of speed.

Torque dynamic performance enhancement of five‐phase permanent magnet synchronous motor with open‐circuit fault

AbstractMultiphase permanent magnet synchronous motors (PMSMs) have attracted much more attention for their high efficiency, low torque ripple and good fault tolerance. However, open‐circuit fault results in asymmetrical motor behaviour, and deteriorates torque performance, especially dynamic response. This paper proposes a novel fault‐tolerant direct torque and flux control (DTFC) strategy to restrain fluctuating torque and enhance torque dynamic performance of a five‐phase PMSM with open‐circuit fault. The novelty of the proposed strategy is the development of DTFC based on stator flux orientation under the open‐circuit fault condition and the third harmonic current suppression with carrier‐based pulse width modulation technology. Consequently, the decoupling control of torque and stator flux can be achieved under the open‐circuit fault condition, and the third harmonic current can be restrained without additional control. Combined with deadbeat control, the heavy computation burden can be reduced. Thus, the proposed strategy not only can enhance torque dynamic performance under open‐circuit fault operation, but also keep smooth torque with circular stator flux trajectory before and after open‐circuit fault. The effectiveness of the proposed strategy is verified by the simulation and experimental results.

Direct Instantaneous Torque and Axial Force Control Method for Linear-Rotary Switched Reluctance Motor With Two Radial Windings

Direct Instantaneous Torque and Axial Force Control Method for Linear-Rotary Switched Reluctance Motor With Two Radial Windings

Direct torque control of a dual star induction generator based on a modified space vector PWM under fault conditions

Recent studies have shown that electrical systems in wind power conversion are subject to a 67 % failure rate, and conventional three-phase generators are considered to be the most sensitive to these faults. Induction generator current harmonics are a major source of torque ripples causing acoustic noise and vibrations. These ripples can progressively increase under faulty operating conditions. In six-phase machines, there is appearance of high harmonic currents in the air gap as space harmonics. Power electronic converters are also subject to faults, the most common being Short-Circuit (SC) and Open-Circuit (OC) faults. SC faults cause large peaks in the line currents, which trigger the protection devices, resulting in a complete shutdown of the production system. OC faults, on the other hand, cause imbalances in the phases, but the system remains in operation.Direct Torque Control (DTC) based on Space Vector Modulation (SVM) at constant switching frequency is an effective solution to tackle induction generator current harmonics. This paper proposes a DTC combined with a Proportional Integral Fuzzy Logic Controller (PIFLC) optimized by Particle Swarm Optimization (PSO) in order to overcome the problems of torque ripples. Furthermore, using Vector Space Decomposition (VSD) and the Modified Space Vector Pulse Width Modulation (MSVPWM) strategy, a significant reduction of harmonics in the air-gap can be achieved.Simulations were carried out under MATLAB/Simulink, and the results obtained demonstrate the superiority of the proposed DTC-PIFLC-PSO controller in terms of robustness against wind speed variations and under faulty switch conditions in the power converter of the Dual Star Induction Generator (DSIG) generator. In addition, a comparative study with the classical PI controller is presented to show the effectiveness of the DTC-PIFLC-PSO controller against faults with a significant reduction in the Total Harmonic Distortion (THD) during both faulty and non-faulty conditions.

Enhanced direct torque control based on intelligent approach for doubly-fed induction machine fed by three-level inverter

This paper presents an adaptive neuro-fuzzy inference system (ANFIS) based on 24 sectors direct torque command (DTC) for a doubly-fed induction machine (DFIM) by using a 3-level neutral point clamped inverter. The DTC approach is used in this paper with 24 sectors based on the ANFIS regulator to minimize the torque fluctuations, flux fluctuations, and stator stream THD (Total Harmonic Distortion) of the DFIM drive. The composed technique is accomplished by replacing the hysteresis controllers of the flux and torque with the ANFIS controller. On the other hand, the results of the designed approach based on ANFIS controls were obtained compared to the traditional approach that uses usual controls, as MATLAB was used to realize these approaches in different working conditions. In all tests, the designed method shows improved performance in minimizing torque and flux undulations while reducing the THD of the stator stream. These results highlight the extent of efficiency, high competence, and effectiveness in improving machine features compared to the conventional approach, where the designed approach minimized the THD of current by ratios of approximately 77.50%, 48.34%, 75%, and 81.43% in all tests. Also, the torque undulation value was reduced by 30%, 39.24%, 31.94%, and 59.31% in all tests compared to the DTC. The designed approach minimized the speed overshoot compared to the DTC by percentages estimated at 98.83%, 97.11%, 96.75%, and 95.56% in all tests. These percentages demonstrate the high efficiency and effectiveness of the 24 sectors DTC-ANFIS compared to the conventional approach in improving the features of the control system, making it a promising solution in all electrical fields in the future.

ANN-Based Improved Direct Torque Control of Open-End Winding Induction Motor

ANN-Based Improved Direct Torque Control of Open-End Winding Induction Motor

Acoustic Noise Mitigation in Slip Angle Controlled DTC of Open-End Winding Induction Motor Drive Using Dual Randomized AISPWM for EV Application

Low vibration and acoustical noise as well as effective DC link usage are the demands of industries and Electric Vehicles (EV). Direct Torque Control (DTC) of Induction Motors (IMs) meet the EV and other modern industry requirements. Still, flux as well as torque swings lead to higher acoustical noise. Consequently, EVs as well as working place noise have become major concerns, affecting the health of individuals. Efficiency of dc link use is improved by Space Vector Pulse Width Modulation (SVPWM). Yet, SVPWM is not efficient in lowering acoustical noise. Different RPWM techniques can lower acoustic noise. Still, the lower degree of randomisation makes the noise reduction difficult. This work presents a Hybrid Dual Random PWMs (HDRPWMs) based Alternate Inverter Switching (AIS) strategy for Slip-Angle Controlled Direct Torque Control of an Open End Winding IM Drive (OEWIMD). This technique is aimed to lower the acoustical noise for EVs. The intended PWMs seek to show how well HDRRPWMs distribute the acoustical noise spectra in contrast to conventional techniques.

Improved Performance of the Permanent Magnet Synchronous Motor Sensorless Control System Based on Direct Torque Control Strategy and Sliding Mode Control Using Fractional Order and Fractal Dimension Calculus

This article starts from the premise that one of the global control strategies of the Permanent Magnet Synchronous Motor (PMSM), namely the Direct Torque Control (DTC) control strategy, is characterized by the fact that the internal flux and torque control loop usually uses ON–OFF controllers with hysteresis, which offer easy implementation and very short response times, but the oscillations introduced by them must be cancelled by the external speed loop controller. Typically, this is a PI speed controller, whose performance is good around global operating points and for relatively small variations in external parameters and disturbances, caused in particular by load torque variation. Exploiting the advantages of the DTC strategy, this article presents a way to improve the performance of the sensorless control system (SCS) of the PMSM using the Proportional Integrator (PI), PI Equilibrium Optimizer Algorithm (EOA), Fractional Order (FO) PI, Tilt Integral Derivative (TID) and FO Lead–Lag under constant flux conditions. Sliding Mode Control (SMC) and FOSMC are proposed under conditions where the flux is variable. The performance indicators of the control system are the usual ones: response time, settling time, overshoot, steady-state error and speed ripple, plus another one given by the fractal dimension (FD) of the PMSM rotor speed signal, and the hypothesis that the FD of the controlled signal is higher when the control system performs better is verified. The article also presents the basic equations of the PMSM, based on which the synthesis of integer and fractional controllers, the synthesis of an observer for estimating the PMSM rotor speed, electromagnetic torque and stator flux are presented. The comparison of the performance for the proposed control systems and the demonstration of the parametric robustness are performed by numerical simulations in Matlab/Simulink using Simscape Electrical and Fractional-Order Modelling and Control (FOMCON). Real-time control based on an embedded system using a TMS320F28379D controller demonstrates the good performance of the PMSM-SCS based on the DTC strategy in a complete Hardware-In-the-Loop (HIL) implementation.

Adaptive PID controller based direct torque control of fuel cell fed BLDC drive for industrial drives applications

Fuel cell fed Brushless DC motors (BLDC) are widely used in electrical applications due to their more efficiency, simple and compact volume. With a simple traditional PID controller, it is challenging to adjust the settings and produce highlights with full power. In order to effectively regulate the torque and speed of a BLDC drive, the adaptive PID (APID) Controller based Direct Torque Control (DTC) is proposed in this paper. The proposed controller depended on the extra error of a spin around controller indication to understand non-linearity, parameter fluctuations, and burden transit difficulties that arise in the BLDC motor drive framework, to maintain good torque control performance, DTC is used as a suitable control technique in industrial drives systems. The comparison tests are step changes in the motor drive’s reference speed and torque. Simulations with MATLAB/Simulink and also experimental outcomes are utilized to validate the operation and performance of various vector control methods.

Improved Control Strategy for Dual-PWM Converter Based on Equivalent Input Disturbance

Aiming at the problems of jittering waveforms and poor power quality caused by external disturbances during the operation of a dual-pulse-width-modulation (PWM) converter, an improved terminal sliding mode control and an improved active disturbance rejection control (ADRC) are investigated. The method is based on mathematical models of grid-side and machine-side converters to design the controllers separately, and the balance between the two sides is maintained by the capacitor voltage. An improved terminal fuzzy sliding mode control and equivalent input disturbance (EID)-error-estimation-based active disturbance rejection control are presented on the grid side to improve the voltage response rate, and an improved support vector modulation (SVM)–direct torque control (DTC)–ADRC method is developed on the motor side to improve the robustness against disturbances. Finally, theoretical simulation experiments are built in MATLAB R2023a/Simulink to verify the effectiveness and superiority of this method.

Fuzzy logic based improved direct torque control of DFIG-based wind turbines

This paper investigates direct torque control with a fuzzy controller (F-DTC) for a two-level voltage source inverter feeding the rotor of a doubly-fed induction generator (DFIG) based on a variable-speed wind energy conversion system (VSWECS). The wind turbine's MPPT technology is used to obtain the torque reference. The proposed fuzzy logic-based direct torque control (F-DTC) is designed to eliminate the flux and electromagnetic torque ripples that are common with existing (DTC) controls, leading to smoother operation and improved efficiency in the wind energy conversion system. The fuzzy logic controller improves switching decision-making by handling uncertainties and non-linearities, resulting in smoother and more efficient control of the torque and flux. To validate the effectiveness of the proposed F-DTC method, simulations are conducted in MATLAB/SIMULINK, and the results are compared with those of the classical DTC approach. The findings demonstrate that the F-DTC strategy significantly reduces torque and flux ripples, enhances the dynamic response, and improves overall system performance.

Direct torque control of bearingless induction motor based on super-twisting sliding mode control

A bearingless induction motor (BIM) is an innovative magnetic levitation motor that incorporates torque system and suspension systems. Aiming to improve the anti-interference and levitation performance of the BIM, a second-order super-twisting sliding mode direct torque control strategy (STSM-DTC) is proposed. Initially, the basic principles and convergence conditions of the super-twisting algorithm are analysed. Subsequently, corresponding sliding mode surfaces are constructed according to speed, torque, and stator flux error, and the corresponding super-twisting sliding mode controllers (STSMC) are designed in the torque system. The STSMCs are designed based on the rotor radial displacement error and further enhanced by incorporating a differential loop in the suspension system. The hyperbolic tangent function tanh(x) is used as the switching function. Simulation and experimental of the BIM STSM-DTC system show that the STSM-DTC strategy effectively improves the anti-interference ability and suspension performance of the BIM, and show better dynamic response.

Direct torque control of switched reluctance motor driven by full bridge power converter

Direct torque control of switched reluctance motor driven by full bridge power converter

Robust fuzzy controller design with FPGA implementation for matrix converter based induction motor drive

This paper aims to design a controller for a matrix converter fed induction motor drive providing less torque ripples and eliminating peak overshoots with good transient and steady state responses utilizing fuzzy and direct torque control. The proposed controller utilizes Direct Torque Control (DTC) strategy with space vector modulation for regulating stator flux and electromagnetic torque. Due to the superior control capabilities of the matrix converter such as bidirectional power flow, sinusoidal input/output waveforms, high power density and lesser volume, it has attracted significant research interest in the field of adjustable speed drive. Hence the proposed matrix converter based controller is developed in MATLAB/Simulink and tested in different input/output conditions. To validate simulation results, a laboratory prototype is built around the Altium Nano Board 3000 equipped with a Xilinx Spartan using Field Programmable Gate Array (FPGA) is employed. The proposed control scheme, validated through simulation and hardware testing, ensures stable, robust drive system with significant reductions in input side harmonics and enhances induction motor drive's performance.

Experimental Implementation of a TD3 Agent Based Speed Controller for Direct Torque Control of PMSM Drives

This manuscript presents a novel control approach for Permanent Magnet Synchronous Motors (PMSMs) by integrating the widely used Direct Torque Control (DTC) method with Deep Reinforcement Learning (DRL), specifically the Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm. The TD3 algorithm is well-suited to address the challenges posed by high-dimensional state and action spaces in PMSM drives. The conventional Proportional–Integral (PI) controller in the outer loop of DTC is replaced with the DRL based TD3 agent to overcome the limitations of traditional PI controllers, such as model dependency and complex parameter tuning. The DRL technique allows the agent to learn optimal control policies from experience, making it suitable for complex and nonlinear control problems. Extensive simulation studies demonstrate the effectiveness of the TD3-based control in achieving accurate speed tracking under varying operating conditions. Real-time experimental validation using a TMS320F28379D digital signal processor confirms the feasibility of the proposed DRL based approach. The research offers new insights into improving the performance of PMSM drives and paves the way for future advancements in electric drive control.

Enhancing the efficiency of a dual three-phase permanent magnet synchronous motor with modified switching table for direct torque control

Enhancing the efficiency of a dual three-phase permanent magnet synchronous motor with modified switching table for direct torque control

Direct torque control of induction motor based on double-power-super-twisting sliding mode speed control for electric vehicle applications

Direct torque control of induction motor based on double-power-super-twisting sliding mode speed control for electric vehicle applications

Modified load angle direct torque control for dual star motor using fuzzy logic

Space Vector Modulation (SVM) has emerged as a prominent alternative for motor control, particularly within the framework of Direct Torque Control (DTC-SVM). SVM leverages variations in the load angle, which result from changes in motor torque, to generate the appropriate voltage vectors. The conventional approach to this method involves a single Proportional-Integral (PI) regulator, which is characterized by a constant switching frequency and the capability to reduce ripples in torque, flux, and current. Despite these advantages, the PI regulator may face challenges in maintaining optimal performance under varying load conditions. This study seeks to enhance the performance of the DTC-SVM strategy by integrating Fuzzy Logic into the PI regulator. The primary objective is to improve the accuracy and responsiveness of the load angle control, thereby optimizing the motor's operational efficiency. The proposed SVM-Fuzzy control scheme is designed to address the limitations of the traditional PI regulator, offering a more adaptive and robust solution for motor control. To evaluate the effectiveness of the proposed approach, extensive simulations were conducted using Matlab Simulink. The SVM-Fuzzy strategy was compared against the conventional SVM-PI approach to assess its performance in terms of torque, flux, and current regulation. The SVM-Fuzzy control scheme significantly enhances efficiency, stability, and load angle precision, particularly in Double Star Induction Motors (DSIM). It also ensures the durability and reliability of the motor control system under different operating conditions.