Direct Instantaneous Torque Control Research Articles

Direct Instantaneous Torque Control for Six-Phase SRM With Nonsingular Fast Terminal Sliding Mode Controller

Direct Instantaneous Torque Control for Six-Phase SRM With Nonsingular Fast Terminal Sliding Mode Controller

Torque Ripple Minimization of Six-Phase Switched Reluctance Motor Based on Enhanced Direct Instantaneous Torque Control

Torque Ripple Minimization of Six-Phase Switched Reluctance Motor Based on Enhanced Direct Instantaneous Torque Control

Modeling of nonlinear characteristics of switched reluctance motor based on optimized RBF neuron network

The strong nonlinearity of switched reluctance motor (SRM) makes it difficult to establish an accurate mathematical model of its electromagnetic characteristics. In this paper, an artificial neural network modeling method is adopted to estimate the nonlinear flux linkage characteristics of a four-phase SRM. Based on the samples obtained by experimental measurement, a radial basis function neural network is trained and further optimized using the K-Means algorithm. The modeling accuracy of the optimized flux linkage model is analyzed in detail and also verified by dynamic simulation of a direct instantaneous torque control system of the motor.

Torque ripple reduction of switched reluctance motor using direct instantaneous torque control and adaptive turn‐on technique for electric vehicle applications

AbstractDirect Instantaneous Torque Control (DITC) with an adaptive turn‐on angle technique is presented in this paper to improve the torque ripple of the Switched Reluctance Motor (SRM) for Electric Vehicle applications. Torque ripple suppression is achieved by employing two operating modes during the commutation interval. First, both the outgoing and incoming phase states are modified to track the required torque during the incoming phase's minimum inductance area. As soon as the incoming phase leaves its minimum inductance zone, the outgoing phase is demagnetised, and only the incoming phase state is modified for torque tracking. In addition, a closed‐loop regulator is used to dynamically control the turn‐on angle that drives the incoming current to reach its first peak at the instant of switching between the two operation modes when the rotor and stator poles initiate overlap, thus increasing the motor's efficiency. Simulation results showed that the proposed control method has superior advantages over the traditional DITC and Average Torque Controller. Furthermore, the simulation results were verified experimentally using a four‐phase 4kW, 8/6 SRM prototype.

Direct Instantaneous Torque Control of SRM Based on a Novel Multilevel Converter for Low Torque Ripple

The torque ripple of a switched reluctance motor (SRM) limits its application in electric vehicles. This paper proposes a DITC system for SRMs based on a novel multilevel converter (MLC), which aims at the problem that the torque ripple cannot be effectively suppressed for the conventional direct instantaneous torque control (DITC) of an SRM due to the limitation of the DC bus voltage in the asymmetric half-bridge converter (AHBC) and the single control strategy formulated in the commutation region. Based on the advantages of fast excitation and fast demagnetization for the proposed MLC and the torque distribution characteristics for each phase winding in the commutation region, a novel torque hysteresis control strategy is developed to improve the torque-following ability of the DITC and achieve the purpose of minimizing the torque ripple in the commutation region. In addition, multiobjective optimization control of the motor is carried out to improve the efficiency of the DITC system while suppressing the torque ripple. The effectiveness of the proposed SRM drive scheme is verified by experiment, which is of great significance for the application of SRMs in electric vehicles.

An enhanced direct instantaneous torque control of switched reluctance motor drives using ant colony optimization

The highly nonlinear characteristics of switched reluctance motors (SRMs) are the drawback that complicates their control and modeling. Hence, obtaining the best performance becomes a challenging task. Therefore, this paper presents an upgraded methodology of the ant colony optimization (ACO) technique. The proposed multistage ant colony optimization (MSACO) enhances the search capability of the classical ACO. Therefore, it helps to find the best switching angles without violating pre-specified constraints. The optimized angles are used to implement an improved high-performance direct instantaneous torque control (DITC) drive. This work focuses on reducing torque ripple, improving motor efficiency, and preventing generating a considerable amount of negative torque. Moreover, a current detector is used to provide information about negative torque production and thus helps to find optimal angles and avoid the set of solutions that give a considerable amount of negative torque. Furthermore, a new switching strategy is utilized to implement an efficient hysteresis torque controller, where the selection of the switching mode of the power converter is entirely determined based on the inductance profile of the SRM. The utilized switching strategy guarantees accurate torque tracking over the entire phase excitation period; thus, the machine's torque profile is improved further. The simulation results showed the superiority of the proposed control method over the traditional control method. In addition, the experimental measurements have been carried out to verify the simulation findings using a three-phase 750 W, 12/8 SRM prototype.

A Hybrid Control Strategy for Multimode Switched Reluctance Motors

A hybrid control strategy based on the principle of dynamic coordination control is proposed for switched reluctance motors (SRMs) in this article. The proposed controller can obtain a small torque ripple in a wide speed range. An SRM with 12/10 poles is considered as a multimode SRM as it can be used as a six-phase or a three-phase motor. In the three-phase mode, direct instantaneous torque control based on the torque sharing function is applied, which can achieve a small torque ripple and a large instantaneous torque. In the six-phase mode, the torque ripple of the multiphase SRM is small, but the system stability is insufficient. Angle position control based on active disturbance rejection control is applied to improve the stability of torque output. In order to reduce the energy loss and torque ripple caused by the switching process of the two modes, an improved dynamic coordination principle is designed to control the switching between different modes. The effectiveness of the control method is confirmed by both experiment and simulation results.

Optimal Direct Instantaneous Torque Control for SRMs Using Advanced Sliding Mode Controller

In this paper, an optimal direct instantaneous torque control scheme using terminal sliding mode control is proposed to achieve better control performance for switched reluctance motors. To obtain faster convergence speed and better chattering suppression, the terminal sliding mode speed controller based on an advanced reaching law is proposed. Moreover, the hybrid wolf optimization algorithm is employed to tune the adjustable parameters for optimum performance. The experimental results show that the torque ripple range of the proposed scheme can be reduced by 25% and 17% under 0.3 Nm compared with PI and conventional sliding mode controllers. Meanwhile, the transient response can be improved by 50% and 31% in the initial stage, respectively. The proposed controller can perform well in aspects of speed tracking, torque ripple suppression, dynamic performance, and anti-interference capability of the system, which was validated by experimental results under different conditions.

A Novel Universal Torque Control of Switched Reluctance Motors for Electric Vehicles

Due to their advantages, switched reluctance motors (SRMs) are interesting solutions for electric vehicle (EV) propulsion. However, they have the main drawback of high torque ripple. This paper develops a universal torque control (UTC) technique for SRM that can fulfill all vehicle requirements under a wide range of speeds. The developed UTC involves two different control techniques. It utilizes the direct instantaneous torque control (DITC) strategy in a low speed region, and the average torque control (ATC) strategy in high speeds. The selection of DITC and ATC is made based on their performance regarding torque ripple, torque/current ratio, and efficiency. Moreover, a novel transition control between the two control techniques is introduced. The results show the ability of the proposed UTC to achieve vehicle requirements while obtaining all the benefits of torque control over the possible range of speeds. The proposed UTC provides the best performance regarding minimum torque ripple, maximum torque/current ratio, and maximum efficiency over the whole speed range. The transition control achieves a smooth operation without any disturbances. The transition control helps to simplify the overall control algorithm, aiming to have a feasible and practical UTC without a complicated control structure.

Four-Quadrant Model Following Sliding Mode Cruise Control for SRM With DITC Applied to Transportation Electrification

The ability of the four-quadrant operation is essential for transportation electrification applications. Switched reluctance machines (SRMs) have been increasingly considered an option for electric vehicles’ traction. However, achieving higher efficiency and low torque ripple may be a challenge for this type of machine, especially at low speeds. This article proposes a cruise control for SRM with the four-quadrant operation for extended autonomy. The cruise control is realized with a model following sliding mode speed controller and direct instantaneous torque control (DITC) for direct torque control. The proposed generating mode DITC aims for higher efficiency. An asymptotic stable model is developed for mode transition. The developed control system is Lyapunov stable in motoring, generating, and transition modes. Furthermore, an online multiobjective optimum point tracker (OPTPT) based on the steepest descent method is proposed aiming for efficiency maximization and torque ripple minimization. The experimental results show that the OPTPT convergence time is 1.25 s for a speed step and 1.2 s for a load step. The proposed control was submitted to an EUDC driving schedule, showing good speed regulation. The speed MAE of the cruise controller was 1.1344%. The transition between operation modes (motor–generator) occurs smoothly, which substantiates the proposed system for four-quadrant transportation electrification applications.

Improved DITC strategy of switched reluctance motor based on adaptive turn-on angle TSF

Aiming at the problem of large torque ripple and low efficiency of traditional direct instantaneous torque control (DITC) of switched reluctance motor (SRM), an improved DITC method based on adaptive turn-on angle torque sharing function (TSF) is proposed. This method not only introduces TSF, but also divides a working cycle into six sectors, and gives the corresponding candidate voltage states of different sectors. In addition, the adaptive turn-on angle function is designed, so that the TSF curve and the sector position of DITC can be adjusted adaptively according to the changes of speed and load torque, so as to suppress torque ripple and improve efficiency. Finally, in order to prove the correctness of the proposed method, the traditional DITC and improved method are simulated and compared. The results confirmed that the improved method avoids the negative torque of the traditional DITC method at high speed, limits the torque ripple and improves the operation efficiency of the drive system.

Performance improvement based on adaptive commutation strategy for switched reluctance motors using direct torque control

This research presents an improved direct instantaneous torque controller (DITC) for switched reluctance motors (SRMs). It incorporates a novel adaptive real-time commutation mechanism. The proposed method can effectively enhance the torque profile and efficiency of the machine by proper real-time adjustment of both the turn-on and the turn-off angles. First, an initial value of the turn-on angle is selected to achieve the highest torque generation capability. Then, with a real-time adjustment around the pre-selected initial angle, the instantaneous torque error can be further compensated. Hence, the torque ripple is minimized.Regarding the turn-off angle, an initial value is selected to satisfy the minimum required conduction angle of SRM. Then, this value is continuously adjusted at each electrical cycle by utilizing a phase current detector to force the outgoing phase current to decay to a less effective value before the negative slope of the inductance profile. Therefore, this prevents serious negative torque generation. The proposed strategy fully utilizes the torque generation capability of the motor with a minimized torque ripple, besides the phase currents, are generated in optimal conduction range to enhance the motor efficiency. The simulations and experiments have been carried out on a 3-phase 750 W 12/8 SRM to validate the proposed method's feasibility and effectiveness.

An Improved Direct Instantaneous Torque Control Based on Adaptive Terminal Sliding Mode for a Segmented-Rotor SRM

In this article, an improved direct instantaneous torque control (DITC) based on adaptive terminal sliding mode control (ATSMC) is proposed to suppress torque ripple and enhance the anti-interference ability for switched reluctance motors (SRMs). The proposed speed controller used in the outer loop of DITC is based on the rate of change in load torque. The state of the system converges quickly to the equilibrium point and realizes fast output of the given torque without known disturbance upper bound. Moreover, a novel reaching law is proposed to reduce torque ripple and startup time. The stability of the adaptive terminal sliding mode motion is verified by using the Lyapunov function. The improved DITC system is implemented on a 16/10 segmented-rotor SRM. Compared with sliding mode control and terminal sliding mode control, the proposed ATSMC in the DITC system behave with better performances in aspects of the speed and torque response, antiinterference ability, robustness, and torque ripple suppression. Simulation and experimental results are given to verify the effectiveness of the improved DITC.

Modified PWM Direct Instantaneous Torque Control System for SRM

Torque ripple is a defect of switched reluctant motors. DITC (direct instantaneous torque control) is harnessed to solve the problem as a traditional method, which is superior to TSF (torque sharing function). In this paper, a new controller is proposed with modified hysteresis and PWM in DITC. With the modified algorithm, the torque error will be reduced with PWM in DITC. The proposed algorithm is effective to improve sample and 0 status in a period. The modified algorithm is based on application of zero in the asymmetric half bridge, which is implemented as the buffer zone. In case of big torque error, hysteresis will mitigate error under the characteristic of fast responding. In case of small errors, the modified PWM will solve torque error in the equivalent strategy, which has adopted the essence of the impulse equivalent method. The modified controller is designed to reduce responding time and minimize the torque ripple under the proposed algorithm, which has been designed to harness different functions in different torque errors. Based on final simulation and experimental results, responding speed and reduction of output torque ripple are enhanced effectively.

Overview of multi-phase switched reluctance motor drives for electric vehicles

Switched reluctance motor (SRM) provide a potential candidate for electric vehicle (EV) applications due to rigid structure, potentially low production cost, the absence of permanent magnets, excellent power-speed characteristics, and high reliability and robustness. This paper aims to review the current research on the design, winding topologies, converter topologies, and control methods of switched reluctance motors (SRMs). Torque ripple and vibration are the main drawbacks of SRMs, which constrain their application. To conquer these drawbacks, multi-phase SRMs (MSRMs), optimum structure, and control methods of SRMs have been utilized over the past decades. In this paper, MSRMs with multiple combinations of stator/rotor poles and winding arrangements are investigated. Different converter topologies are compared, and a full-bridge converter is suitable for SRMs used in EVs. Torque sharing function, direct torque control, and direct instantaneous torque control are the main control methods to reduce the torque ripple of SRMs, which have been comprehensively summarized.

Control System Design for 16/6/8 Double-Stator Bearingless Switched Reluctance Motor

The 16/6/8 double-stator bearingless switched reluctance motor (DSBSRM) is used as the object of study in this paper. To solve the problem of torque and levitation force ripples in this motor, a control system direct force control (DFC) and direct instantaneous torque control (DITC) based on the torque sharing function (TSF) are proposed. With the strong nonlinearity and approximation capability of radial basis function neural networks, the torque and levitation force observer are designed. The observed torque and levitation forces are used as feedback for the internal loop control, which is combined with the external loop control to make a double closed-loop control. In order to further improve the output torque and system robustness and suppress the torque ripple in steady-state process, the motor winding method is optimized and a set of switching angles is added on the basis of TSF. The simulation results verify the effectiveness and superiority of the proposed control method. It effectively suppresses speed ripple and reduces torque and levitation force fluctuations and rotor radial displacement jitter.

Minimization of torque ripple in switched reluctance motor based on MPC and TSF

In this paper, a novel control method based on model predictive control (MPC) and torque sharing function (TSF) is addressed to minimize the torque ripple of switched reluctance motor (SRM). Firstly, an accurate SRM model is established based on flux‐linkage characteristic curves obtained from the locked rotor test, which can predict the future operation state of the SRM drive system. Secondly, an improved TSF curve is proposed, and genetic algorithm is used to optimize TSF parameters to reduce torque ripple in commutation region. Besides, the MPC is integrated into the TSF control framework to replace the traditional hysteresis controller, and establishes a new TSF‐based model predicted torque control (MPTC) method, which avoids the frequency conversion problem caused by torque or current hysteresis controller. Further, a sector division scheme is addressed to decrease the number of candidate voltage states, whereby the computation of the controller in each sampling period is effectively reduced. Finally, in order to verify the correctness of the MPTC method, it is compared with the traditional direct instantaneous torque control (DITC). Both simulations and experiments on a three‐phase 12/8 pole SRM have confirmed that MPTC scheme can not only decreases torque ripple and stator copper losses, but also has higher efficiency than DITC. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

A single-winding BSRMWR direct instantaneous torque control and direct levitation force control method

The stator and rotor of the bearingless switched reluctance motor are both double salient pole structures, when the traditional current chopping control method is used, the torque and levitation force of the motor will have large fluctuations. To solve this problem, this paper studies a direct instantaneous torque control and direct levitation force control (DITC&DFC) method suitable for single-winding bearingless switched reluctance motors. This method takes the instantaneous torque and the instantaneous levitation force of the motor as the directly controlled object, eliminates the current loop, and simplifies the control algorithm while suppressing the fluctuation of the motor torque and levitation force. A 12/8-pole singlewinding bearingless switched reluctance motor with wide rotor teeth drive system is constructed, the Matlab/Simulink system simulation verifies the effectiveness and feasibility of the method.

Comparative Evaluation for an Improved Direct Instantaneous Torque Control Strategy of Switched Reluctance Motor Drives for Electric Vehicles

Due to the expected increase in the electric vehicles (EVs) sales and hence the increase of the price of rare-earth permanent magnets, the switched reluctance motors (SRMs) are gaining increasing research interest currently and in the future. The SRMs offer numerous advantages regarding their structure and converter topologies. However, they suffer from the high torque ripple and complex control algorithms. This paper presents an improved direct instantaneous torque control (DITC) strategy of SRMs for EVs. The improved DITC can fulfill the vehicle requirements. It involves a simple online torque estimator and a torque error compensator. The turn-on angle is defined analytically to achieve wide speed operation and maximum torque per ampere (MTPA) production. Moreover, the turn-off angles are optimized for minimum torque ripples and the highest efficiency. In addition, this paper provides a detailed comparison between the proposed DITC and the most applicable torque control techniques of SRMs for EVs, including indirect instantaneous torque control (IITC), using torque sharing function (TSF) strategy and average torque control (ATC). The results show the superior performance of the proposed DITC because it has the lowest torque ripples, the highest torque tor current ratio, and the best efficiency over the low and medium speed ranges. Moreover, the comparison shows the advantages of each control technique over the range of speed control. It provides a very clear overview to develop a universal control technique of SRM for EVs by merging two or more control techniques.

A Sliding Mode DITC Cruise Control for SRM With Steepest Descent Minimum Torque Ripple Point Tracking

Switched reluctance motors are frequently quoted for electric and hybrid electric vehicle traction. However, high torque ripple is a common restraining disadvantage. This article proposes a design method for model following sliding mode as cruise controller, considering a direct instantaneous torque controller as part of the controlled plant. In addition, a back-electromotive force cancelation is incorporated by modifying the torque reference using the developed model. A minimum torque ripple point tracking (MTRPT) that actuates over the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> angle is proposed through an adaptation from the steepest descent maximum power point tracking algorithm. The turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> angle is also controlled, aiming for enhanced torque regulation. The cruise controller is Lyapunov stable, robust to parameter variations, and is capable of rejecting load disturbances. Experimental results show that the MTRPT convergence time is around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{2.5 s}$</tex-math></inline-formula> for a load step and around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{1.625 s}$</tex-math></inline-formula> for a speed step. Besides, the speed tracking capability of the proposed system returns an MAE of 0.9223% and 1.0884% for the ECE-R15 and for the EUDC driving schedules, respectively. The MTRPT is capable of reducing the torque ripple by 14.6% in low speeds (ECE-R15) and by 10.1% at high speeds (EUDC). The results show that the proposed system is well founded for electric and hybrid electric vehicles applications.