Permanent Magnet Synchronous Motor Direct Torque Control Research Articles

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.

PI-based direct torque control of PMSM for torque ripple reduction

This paper addresses the challenge of torque ripple in Permanent Magnet Synchronous Motors (PMSMs) through the implementation of a Proportional-Integral (PI)-based Direct Torque Control (DTC) strategy. Torque ripple, a phenomenon affecting motor performance, is mitigated by leveraging the simplicity and fast response of DTC, augmented by the precision of PI controllers. The objectives encompass a comprehensive understanding of PMSM characteristics, the design and implementation of the PI-based DTC system in MATLAB Simulink, and an in-depth analysis of its performance in torque ripple reduction. The paper also involves comparative studies with traditional control methods, parameter tuning for optimization, and assessments of versatility under varying conditions. By achieving these objectives, the research contributes to the advancement of control strategies for PMSMs, enhancing their efficiency and adaptability in industrial applications. The outcomes are documented and presented, providing valuable insights for future advancements in electric motor control.

A Novel Duty-Controlled DTC of a Surface PMSM Drive With Reduced Torque and Flux Ripples

Direct torque control (DTC) is a widely used method for the control of permanent magnet synchronous motor (PMSM) drive. DTC suffers the drawback of high ripples in torque and flux. Various duty-cycle-controlled DTC methods have been introduced in the recent past to improve the steady-state response of the PMSM. However, the existing duty-cycle-controlled DTC methods are complex and result in higher switching frequencies. This article introduces a novel duty-controlled DTC for reducing the ripple in torque and flux without giving considerable rise in the switching frequency and computation burden. The proposed DTC applies two separate voltage vectors (VVs) for individual control of stator flux and torque during two different sampling intervals. A look-up table is proposed to select candidate VVs and their duty ratios are calculated to achieve the reference values of stator flux and torque in two sampling intervals. This causes a major reduction in the torque and stator-flux ripples. Also, the proposed method decides the sequence of candidate VVs to reduce the number of switching and thereby reduce the switching frequency. The proposed method is experimentally tested and compared with conventional DTC, an existing duty-based DTC, and deadbeat DTC to verify its effectiveness.

Five-Level Inverter Fed DTFC-SVM of Permanent Magnet Synchronous Motor Drive

In this paper, a five-level diode clamped inverter fed DTFC-SVM of Permanent Magnet Synchronous Motor (PMSM) drive is proposed for high power industrial applications. In Direct Torque and Flux Control with Space Vector Modulation (DTFC-SVM) technique, the speed of PMSM drive is regulated by controlling stator flux and electromagnetic torque directly and independently such that it abandons the use of direct torque control for PMSM Drive. The proposed multilevel inverter fed DTFC-SVM based PMSM drive gives very less ripples in stator flux and electromagnetic torque and also gives very less total harmonic distortion (THD) in the stator winding voltages and currents which consequences excellent dynamic and steady-state performance of drive. The five-level inverter switching pulses are designed using five-level space vector modulation (SVM) based on two-level SVM, so that it reduces the complexity of the SVM and also gives very good performance under all environmental conditions. The proposed model is simulated in MATLAB/SIMULINK software under various conditions, such as, No-load, load, reversal speed, and change in speed. In order to show the feasibility and effectiveness of the proposed model, it is also implemented in the experimental setup under various conditions.

Reduction of torque and flux ripples in direct torque control for three‐level open‐end winding PMSM drive

The direct torque control (DTC) of permanent magnet synchronous motor (PMSM) drives is a noticeable practice in industrial applications due to its quick dynamic performance. However, due to the presence of hysteresis controllers and inaccurate switching tables especially for the multilevel fed DTC drives are facing higher ripples in torque and flux response. An improved DTC for three-level open-end winding PMSM drive is proposed in this article and features reduction of flux and torque ripples. The torque and flux performances of the PMSM are directly controlled by the calculated reference voltage vector in the stationary reference frame. The voltage vector tables are proposed based on the length of the voltage space vectors and the actual voltage vector nearer to the calculated reference voltage vector is selected so that the minimum ripples exist in flux and torque responses. The steady-state and dynamic conditions of the proposed DTC method are verified in the real-time experiment and also compared with the conventional DTC as well as the recently developed control methods.

Dead-beat control of permanent magnet synchronous motor based on extended voltage vectors set

Simplified models to calculate the change of stator flux and torque of permanent magnet synchronous motor (PMSM) on stator flux coordinate system are proposed. In order to solve high torque ripples of PMSM direct torque control (DTC) system, dead-beat (DB) control of stator flux and torque is proposed. The calculation of ideal voltage vector (VV) for the DB control of stator flux and torque using simplified models are given, and a simplified VV selecting method is used to implement the DB control. In order to improve control performances, a novel way to expand VVs based on both angle and amplitude is proposed. The angle and amplitude of ideal VV are used to determine the angle and amplitude of output VV and the look-up table is used to generate output VVs. Simulation results show this novel method can decrease stator flux and torque ripples dramatically, but increase switching frequency.

Enhanced Voltage Switching States for Direct Torque Controlled Open End Winding Permanent Magnet Synchronous Motor Drive

Direct torque control (DTC) is most popular technique used in industries for adjustable speed of drives. It has simple control algorithm without any pulse width modulation technique and vector transformations involvement. Two level voltage source inverter (VSI)-fed permanent magnet synchronous motor (PMSM) operated with DTC has higher torque and flux ripple problems due to the limited voltage vectors availability, which affects the performance of drive. To alleviate these problems, more number of voltage space vectors should be available for DTC of PMSM drive. In this article, DTC for open-end winding PMSM drive (OEW-PMSM) is proposed. A two level dual VSI-fed OEW-PMSM drive configuration attains three level inversion with an equal dc link voltage to VSIs. Similarly four level inversion can also be attained with an unequal dc link voltage of 2:1 ratio given to dual VSIs. Therefore availability voltage space vectors are increased for PMSM drive operation. The effective voltage switching tables for DTC operated OEW-PMSM drive at different speed conditions are proposed to make its performance more satisfactory, thus achieving less torque and flux ripples and also reduced common mode voltage (CMV). To validate this, Simulink/MATLAB and real time experimentation are performed on 3.7 kW PMSM drive.

Direct torque control of permanent magnet synchronous motor for electric vehicles

Permanent magnet synchronous motors (PMSM) are highly preferred in electric vehicles due to their high efficiency, good torque-speed characteristics, simple structure and long life. In this paper, the simulation study of direct torque controlled PMSM for electric vehicles was performed in MATLAB by direct torque control (DTC) method using different speed control and speed estimation methods, because output parameters of DTC method such as torque and current, have high ripple, and this ripple should be reduced for electric vehicle. Due to the simple structure of the DTC and its low dependence on the system parameters, it is widely used in alternative current motors. When DTC is used in PMSM drive, it is known that although it has fast dynamic response when it is compared to other vector control methods, the ripple in the torque and flux increases. In this study, direct torque controlled PMSM is tried to be minimized by using different speed control methods and speed estimation methods. For this purpose, proportional-integral (PI), fuzzy logic and sliding mode speed controller are used as speed controllers and their performances are compared. In addition, speed sensor less direct torque control of PMSM was performed by using sliding mode observer and model reference adaptive system (MRAS) observer. As a result of the simulation studies, it was found that sliding mode speed control method provides less ripples in the torque, better speed control and less energy consumption. Furthermore, as a speed observer, the sliding observer gives better results in speed estimation and provides less energy consumption.

Direct Torque Control of PMSM with Modified Finite Set Model Predictive Control

A direct torque control (DTC) with a modified finite set model predictive strategy is proposed in this paper. The eight voltage space vectors of two-level inverters are taken as the finite control set and applied to the model predictive direct torque control of a permanent magnet synchronous motor (PMSM). The duty cycle of each voltage vector in the finite set can be estimated by a cost function, which is designed based on factors including the torque error, maximum torque per ampere (MTPA), and stator current constraints. Lyapunov control theory is introduced in the determination of the weight coefficients of the cost function to guarantee stability, and thus the optimal voltage vector reference value of the inverter is obtained. Compared with the conventional finite control set model predictive control (FCS-MPC) method, the torque ripple is reduced and the robustness of the system is clearly improved. Finally, the simulation and experimental results verify the effectiveness of the proposed control scheme.

Extending the Frame-Angle-Based Direct Torque Control of PMSM Drives to Low-Speed Operation

This paper extends the application of a frame-angle-based (FAB) direct torque controller (DTC) for permanent magnet synchronous motor (PMSM) drives to low and very low speeds. The FAB-DTC is intended for PMSM drives that are fed by $3\phi$ six-pulse wavelet-modulated dc–ac converters. The foundations of the FAB-DTC are based on regulating the $d\text{--}q$ -axis stator voltages, in response to variations in the load torque and/or drive speed. The adjustments in $d\text{--}q$ -axis stator voltages are created by changing the angle $\vartheta$ of the frame spanned by the $d\text{--}q$ -axis stator voltages. In order to extend the FAB-DTC to low and very low speeds, the changes in $\vartheta$ are accompanied by changes in the maximum scale. The values of maximum scale and $d\text{--}q$ -axis stator voltages are used to update or change the reference signals employed by the wavelet modulation to generate switching pulses to operate a $3\phi$ dc–ac converter. The complete PMSM drive system incorporating the modified FAB-DTC is implemented for a 10-hp PMSM drive system. The performance of the FAB-DTC is investigated for different changes in the command torque for various low and very low speeds. Performance results demonstrate stable, fast, dynamic, and accurate responses, which have minor sensitivity to variations in load torque and/or drive speed.

Comparison between Modified MPC and DTC Control Method for Permanent Magnet Synchronous Motor

Direct torque control (DTC) and model predictive control (MPC) are widely used in the control of permanent magnet synchronous motor (PMSM). However, DTC for PMSM can cause large torque ripples and flux ripples, high harmonic distortion of the stator current, and high acoustic noises. Compared to DTC, MPC considers all possible switching states which can reduce the ripples of torque and flux. MPC with one-step delay compensation for PMSM and DTC with one-step delay compensation and two hysteresis comparators for PMSM have been proposed to solve some drawbacks of these two controllers. This paper makes a detailed comparison between these two improved control methods through Simulink and hardware experiments results to analyse the four indicators-torque ripple, flux ripple, transient time and THD of inverter current.

Performance Improvement for PMSM DTC System through Composite Active Vectors Modulation

In this paper, a novel direct torque control (DTC) scheme based on composite active vectors modulation (CVM) is proposed for permanent magnet synchronous motor (PMSM). The precondition of the accurate compensations of torque error and flux linkage error is that the errors can be compensated fully during the entire control period. Therefore, the compensational effects of torque error and flux linkage error in different operating conditions of the PMSM are analyzed firstly, and then, the operating conditions of the PMSM are divided into three cases according to the error compensational effects. To bring the novel composite active vectors modulation strategy smoothly, the effect factors are used to represent the error compensational effects provided by the applied active vectors. The error compensational effects supplied by single active vector or synthetic voltage vector are analyzed while the PMSM is operated in three different operating conditions. The effectiveness of the proposed CVM-DTC is verified through the experimental results on a 100-W PMSM drive system.

Cuckoo Search Based DTC of PMSM

<p>Hysteresis controllers (HC) are used to limit the torque and flux in the control band in conventional configuration of direct torque control (DTC) while in the space vector pulse width modulated (SVPWM) DTC, the HC are switched to PI or PID controllers. This paper presents a modern approach for the speed control applied on a DTC of a permanent magnet synchronous motor (PMSM) using the Cuckoo Search Optimization (CSO) algorithm in order to optimize the PI speed controller parameters of the outer loop and PID flux and torque controllers of the inner loop. The system is tested at no load and with a step change in load.</p><p>The performance of the controllers is presented and the results of simulation indicate a very rapid dynamic response and the system achieves the steady state (SS.) in a very short time. Also it shows that both the SS. and dynamic performances are improved by applying of the CSO algorithm. The proposed DTC simulation model of the PMSM is presented using MATLAB / SIMULINK and capable of simulating both the steady-state and dynamic response. The CSO results are compared with another control strategy that incorporates fuzzy logic controller (FLC) with DTC.</p><p> </p>

Comparative study of conventional DTC and DTC_SVM based control of PMSM motor — Simulation and experimental results

In the conventional direct torque control (DTC) of a permanent magnet synchronous motor (PMSM), hysteresis controllers are used to choose the proper voltage vector resulting in large torque ripples, and the inverse voltage vector, employed in this system instead of the zero voltage vectors used in an induction motor, can accelerate the torque response but enlarges the torque ripples at the same time. To ameliorate the steady state effectiveness of the PMSM DTC system a SVM scheme is introduced in this paper. In the direct torque, control scheme using space vector modulation (DTC-SVM) for permanent magnet synchronous motor. The study of PMSM shows that the increase of electromagnetic torque is related to the increase of the angle between the stator and rotor flux linkages and therefore swift torque response can be obtained by increasing the rotating speed of the stator flux linkage as fast as possible. This paper presents a simulation and a practical implementation for the conventional DTC and the DTC-SVM based control of the PMSM, using a dSPACE-1104. To confirm the efficacy of the proposed technique, simulation and experimental results are presented. Besides, the system associated with these techniques can effectively decrease flux and torque ripples with better dynamic and steady performance. The results with the SVM technique show more performances than the results with the conventional DTC.

Direct torque control of PMSM using sliding mode backstepping control with extended state observer

Based on the nonlinear characteristics of permanent magnet synchronous motor (PMSM), a nonlinear speed and direct torque control (DTC) using sliding mode backstepping method for PMSM is presented in this paper. The sliding mode speed controller is implemented with exponential reaching law to improve the robustness of the system, and further a step-by-step recursive design for backstepping torque and flux controllers is presented. The system stability with proposed scheme is mathematically proved using Lyapunov stability criteria. At the same time, the load torque is observed with the extended state observer (ESO), and is fed-forward to the controller for rejecting the load disturbance and to mitigate the chattering affect due to the sliding mode controller. Finally, simulation test results are demonstrated to support the effectiveness and feasibility of the proposed strategy.

Direct Torque Control of PMSM Based on Fractional Order Sliding Mode Variable Structure and Experiment Research

A direct torque control method based on fractional order sliding mode variable structure (DTC-FOSMVS) was proposed for the speed control of a permanent magnet synchronous motor (PMSM). The proposed method in which the space vector pulse width modulation (SVPWM) with fixed switch frequency is applied, reduces the torque and flux ripple, and improves the speed control performance. In order to improve the energy efficiency and reduce the demagnetization effect, the DTC-FOSMVS method with dynamic flux reference was designed. The stability of the control method is proved by Lyapunov theory. The performance of the proposed method is verified through experiment which is based on hardware in loop and Simulink/QuaRC real time control software. The experiment results show the robustness and effectiveness of the proposed method.

Direct Torque Control for Permanent Magnet Synchronous Motors Based on Fuzzy Regulator

In this paper, a method of direct torque control (DTC) for permanent magnet synchronous motor (PMSM) based on fuzzy regulator is proposed. It overcomes the disadvantages such as speed drop with load, torque ripple etc., which happens in the DTC for PMSM based on conventional PI regulator. The simulation results show that, the DTC for PMSM based on fuzzy regulator can effectively improve the system loading capability and significantly reduce the torque ripple and the harmonic content of the system. Therefore, it can comprehensively improve the system performance.

Speed Estimation by Using EKF Techniques for Sensor-Less DTC of PMSM with Load Torque Observer

This paper proposes a Direct Torque Control (DTC) of a Permanent Magnet Synchronous Motor (PMSM) without mechanical speed and position sensors. These later are estimated by using the Extended Kalman Filter (EKF) only by measurement of the stator line voltages and currents. Moreover, DTC uses no current controller and no motor parameters other than the stator resistance, which yields a faster torque response and lower parameter dependence than with others motor control techniques. The Kalman filter is an observer for linear and non-linear systems. Also, due to an angle modification scheme with error tracking, the Sensor-less drive system is robust to parameter variations. A load torque can also be estimated by using Luenberger Observer. A simulation model is developed in MATLAB/SIMULINK and is used to verify the basic operation (performance) of the Sensor-less DTC of PMSM

Influence of flux estimation in performance of direct torque control of PMSM

Permanent magnet synchronous motors (PMSMs) are extensively used in high-performance industrial applications. High dynamic response can be achieved by means of direct torque control (DTC). The main advantage of DTC is that coordinate transformations and pulse width modulation (PWM ) generation are not needed, however, classical DTC produces high torque ripple. This paper presents a comparison of different flux estimation methods to implement DTC drive systems, and shows the influence of the choice of estimation method on torque ripple.

A Simplfied Voltage Vector Selection Strategy for Direct Torque Control

The direct torque control (DTC) for permanent magnet synchronous motor (PMSM) under the control of switching table suffers from high torque ripple and variable switching frequency. For PMSM DTC system, voltage vector selection strategy as the hysteresis control principle determines the system’s performance. The angle ( a ) between stator flux vector and the applying voltage vector determines effect of the voltage vector on the amplitude of stator flux and torque angle . The effect of the voltage vector on toque is dependent on a , torque angle and parameters of PMSM. A voltage vector selection strategy based on the technology of space vector modulation (SVM) is proposed to control stator flux, torque angle and torque . E xperimental results for a 15-kW interior PMSM show it can decrease stator current and torque ripples and fix the switching frequency.