Sliding Mode Speed Controller Research Articles

Composite Sliding Mode Speed Control for Sinusoidal Doubly Salient Electromagnetic Machine Drives Using Fast Reaching Law and Disturbance Compensation

The proportional-integral speed controller is widely used in field-oriented control due to its simplicity in implementation; however, parameter variations and load disturbance easily lead to the deterioration of its dynamic performance. To address the above problem, a composite sliding mode speed control (CSMSC) is proposed in this article, which is composed of a sliding mode controller based on a new fast reaching law (FRL-SMC) and an extended state observer (ESO). The FRL-SMC can effectively solve the contradiction between response time and chattering amplitude, which is superior to the traditional SMC approaches; the lumped disturbance is estimated online by the ESO, and then the estimated value used as feedforward compensation is introduced into the FRL-SMC to enhance the disturbance reject ability. The sinusoidal doubly salient electromagnetic machine (SDSEM) speed regulation system applying the proposed CSMSC obtains a fast startup response and load step response, an excellent anti-disturbance performance, and a small <i>q</i>-axis current steady chattering. Finally, the effectiveness of the proposed method is verified by experimental results for a SDSEM test platform.

Model Predictive Current Control for IPMSM Drives With Extended-State-Observer-Based Sliding Mode Speed Controller

Aiming at the characteristics that the classical proportional-integral (PI) controllers and the model predictive current control (MPCC) is extremely dependent on the motor parameters, and PI controllers are sensitive to the changes of the load torque, a novel extended-state-observer-based sliding mode speed control (ESO-SMSC) scheme and an extended-state-observer-based MPCC (ESO-MPCC) scheme are proposed to improve the speed and current tracking performance of the interior permanent magnet synchronous motor (IPMSM) under the disturbances of the internal parameter mismatch and the external load change. Firstly, the reaching law of the SMSC will be redesigned, and an ESO is designed to estimate the total disturbance to update the control law of the SMSC in real-time. Secondly, the stability of the closed-loop IPMSM drive system with the ESO-SMSC is proved by the Lyapunov theory. Thirdly, in the prediction part of the MPCC, another ESO real-time estimation of total disturbance is designed to compensate for the disturbance, which improves the strong robustness of the MPCC to the disturbance caused by parameter mismatch. Finally, experimental comparisons of the ESO-SMSC scheme, the ESO-MPCC scheme, and the ESO-SMSC+ESO-MPCC scheme are compared experimentally. The analysis and results show that the ESO-SMSC+ESO-MPCC scheme has good speed response and current characteristics, which proves the superiority of the proposed scheme for disturbance rejection.

A Fast Sliding Mode Speed Controller for PMSM Based on New Compound Reaching Law With Improved Sliding Mode Observer

To reduce the convergence time and improve the anti-disturbance capability of the permanent magnet synchronous motor (PMSM) drivers, a fast sliding mode speed controller based on a new compound reaching law (NCRL) and disturbance observer compensation technique is proposed. Firstly, to solve the conflict between fast convergence rate and chattering reduction in the existing solutions, the NCRL is proposed by introducing the exponential function and the power term piecewise function. The convergence of NCRL is proved and the reaching time is certified to be independent of the system’s initial state. The proposed NCRL can effectively reduce the reaching time, and smooth the output signal while maintaining the high tracking performance of the controller under different conditions. However, external load disturbances may degrade the performance of the proposed NCRL-based speed controller. The proposed controller is then combined with an improved sliding mode observer (ISMO), named the NCRL+ISMO method, to improve the estimation accuracy of the lumped disturbance and the robustness of the system. The stability of the proposed method is analyzed by the Lyapunov function. Experimental results show that the proposed method can reduce speed fluctuation and convergence time, and enhance anti-disturbance capability.

Improved Adaptive Terminal Sliding-Mode Reaching Law for Speed Control of TPMLSM With Disturbance Observer

This paper investigates the speed regulation issue of the tubular permanent magnet linear synchronous motor (TPMLSM) control system based on sliding-mode control (SMC) and disturbance compensation technology. By introducing the terminal attractor on the basis of exponential reaching law, an improved adaptive terminal sliding-mode reaching law (IATSMRL) is proposed to ensure the state variables of the control system to reach their equilibrium points quickly and suppress the chattering effectively. Based on the IATSMRL, the sliding-mode speed controller is designed to improve the dynamic performance of the TPMLSM control system. To further compensate the lumped disturbance in the TPMLSM control system, the paper utilizes an extended sliding-mode disturbance observer (ESMDO) to obtain the estimated lumped disturbance. Then an anti-disturbance sliding-mode speed controller is designed to strengthen the disturbance rejection capability of the TPMLSM control system and further improve the dynamic performance. The stability of the controller is proved by the Lyapunov stability theory. Comprehensive simulation and experimental results have been carried out to demonstrate the superiority of the proposed method.

Application of a new type of super twist sliding mode control in flywheel energy storage

Aiming at the error problem in estimating the speed of a permanent magnet synchronous motor (PMSM) using a sliding mode observer in a flywheel energy storage system, a super twist sliding mode observer (SMO) is used to replace the traditional sliding mode observer. A new saturation function is designed to replace the sign function. In addition, a constant sliding mode gain may lead to a decrease in observation accuracy during speed switching. An adaptive sliding mode gain is proposed to reduce chattering, The accurate estimation of the comprehensive speed range observer is enhanced, and the stability of the proposed observer is proved. On this basis, a super twist sliding mode speed controller is designed to replace the traditional PI controller to improve the observation performance of the system. The flywheel energy storage system’s simulation model is built, and the flywheel energy storage system’s constant speed standby and charging conditions are simulated. The simulation results verify the correctness and effectiveness of the improved super twist sliding mode observer in the flywheel motor.

Encoderless Five-phase PMa-SynRM Drive System Based on Robust Torque-speed Estimator with Super-twisting Sliding Mode Control

In this paper, a robust torque speed estimator (RTSE) for linear parameter changing (LPC) system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor (5-phase PMa-SynRM). This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem, as the feedback speed information is obtained directly from the virtual sensor. In addition, this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation. The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis. Furthermore, for improving the 5-phase PMa-SynRM performance, five super-twisting sliding mode controllers (ST-SMCs) are employed with providing a robust response without the impacts of high chattering problem. A super-twisting sliding mode speed controller (ST-SMSC) is employed for controlling the PMa-SynRM rotor speed, and four super-twisting sliding mode current controllers (ST-SMCCs) are employed for controlling the 5-phase PMa-SynRM currents. The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance, parameters variations, single open-phase fault, and adjacent two-phase open circuit fault conditions.

Sliding-Mode-Based Deadbeat Predictive Current Control for PMSM Drives

Deadbeat predictive current control (DPCC) has become a research hotspot for permanent magnet synchronous motor (PMSM) drive systems due to its advantages of short dynamic response time and superior current tracking performance. However, the speed controller in traditional deadbeat current control usually consists of a linear proportional-integral (PI) controller, which cannot quickly limit uncertain disturbances from internal or external sources. Moreover, DPCC is more sensitive to model parameters. In order to reduce the parameter sensitivity of the DPCC method and improve the fast-limiting disturbance capability of the speed controller, a sliding-mode-based deadbeat predictive control method is presented in this article. First, the traditional DPCC is introduced; then, a variable-speed sliding-mode reaching law is designed, and a sliding-mode speed controller is developed using this law to improve the antidisturbance capability of the speed controller. Moreover, in order to suppress the negative impact of the parameter mismatches on the control performance, the parameter mismatches are considered when building the system model, and a sliding-mode-based deadbeat current controller based on the same sliding-mode reaching law as the speed controller is presented. Finally, the experimental results show that the proposed method has a better control performance.

Adaptive Sliding Mode Control With Disturbance Observer for Speed Regulation System of Permanent Magnet Synchronous Motor

In order to improve the robustness and speed tracking performance of a permanent magnetic synchronous motor (PMSM) system, under the framework of PMSM vector control, a nonlinear speed control method based on improved sliding mode control (SMC) and disturbance observer is proposed in this paper. First, a novel fast reaching law is designed to make the system trajectory reach the sliding mode surface within a finite time and to alleviate the chattering phenomenon. Second, a nonlinear integral terminal sliding mode surface is proposed by introducing sign and fractional error integration, which achieves finite-time convergence of the speed tracking errors and integral errors without the singular problem. Then, based on the proposed reaching law and the proposed sliding mode surface, an adaptive sliding mode speed controller with disturbance observer which adaptively compensates the output of the improved sliding mode speed controller, is developed not only to guarantee the finite-time convergence performance of the state trajectories, but also to demonstrate stronger robustness, higher precision and lower chattering compared to conventional sliding mode controller. Finally, the simulation and experimental results confirm the validity of the proposed method for practical applications.

Improved Super-Twisting Non-Singular Fast Terminal Sliding Mode Control of Interior Permanent Magnet Synchronous Motor Considering Time-Varying Disturbance of the System

To solve the problems that control performance of high torque traction interior permanent magnet synchronous motor (IPMSM) is degraded by parameter perturbation and unknown disturbance, this paper proposes a novel Improved Super-Twisting non-singular fast terminal sliding mode control strategy (IST-NFTSMC) for IPMSM based on Extended Nonsingular Fast Terminal Sliding Mode Disturbance Observer (ENFTSMDO). Firstly, the mathematical model of IPMSM under parameter perturbation is established; Then, an improved Super-Twisting nonsingular fast terminal sliding mode speed controller (IST-NFTSMC) based on extended nonsingular fast terminal sliding mode disturbance observer (ENFTSMDO) is designed, in which the improved Super-Twisting control law designed can effectively weaken the chattering of traditional NFTSMC, and ENFTSMDO can more accurately observe the unknown disturbance part of the system in real-time than ESMDO; Finally, compared with PI control and traditional NFTSMC control by simulations and experiments, the method proposed has merits of accelerating convergence, improving steady-state accuracy and minimizing the current and torque pulsation.

Sliding mode speed control of permanent magnet synchronous motor based on improved reaching law

PurposeThis paper aims to present a sliding mode control method based on disturbance observer (DO) for improving the reaching law of permanent magnet synchronous motor (PMSM).Design/methodology/approachAiming at the insufficiency of the traditional exponential reaching law used in sliding mode variable structure control, an exponential reaching law related to the speed error is proposed. The improved exponential reaching law can adaptively adjust the size of the constant velocity term in the reaching law according to the size of the speed error, so as to adaptively adjust the speed of the system approaching the sliding mode surface to overcome the control deviation and improve the dynamic and steady state performance. To improve the anti-interference ability of the system, a DO is proposed to observe the external disturbance of the system, and the observed value is used to compensate the system. The stability of the system is analyzed by Lyapunov theorem. The effectiveness of this method is proved by simulation and experiment.FindingsSimulation and experiment show that the proposed method has the advantages of fast response and strong anti-interference ability.Research limitations/implicationsThe proposed method cannot observe the disturbance caused by the change of internal parameters of the system.Originality/valueA sliding mode control method for PMSM is proposed, which has good control performance. The proposed method can effectively suppress chattering, ensure fast response speed and have strong anti-interference ability. The effectiveness of the algorithm is verified by simulation and experiment.

Development of Closed-Loop Permanent Magnet Synchronous Motor Drive System Prototype

Permanent magnet synchronous motors (PMSM) are widely used in low to mid-power applications and high-performance drives. They are preferred over brush-type motors and gradually replacing induction motors in various fields of application due to its advantages. Many researchers are proposing new control methods of PMSM drive system. However, the PMSM system is nonlinear and consists of time-varying parameters with high-order complex dynamics. Due to these factors, researchers cannot rely only on simulation results to prove superiority of their proposed controllers. To validate the results obtained by simulation, experimental validation is necessary, where a closed-loop PMSM drive system prototype has to be developed. This paper describes the development of a PMSM drive system prototype with closed-loop current, speed and position feedback using dSpace DS1104 controller board for a 1.93kW three-phase interior-mounted permanent magnet synchronous motor used for experimental validation of a proposed modified fractional order sliding mode speed controller. Using this prototype, the performance of any newly proposed control methods in real applications can be verified. Appropriate signal acquisition procedures of the feedback signals, as described in this work, are crucial to ensure the accuracy of closed-loop performance of the developed drive system.

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.

IM Fed by Three-Level Inverter under DTC Strategy Combined with Sliding Mode Theory

The classical direct torque control (CDTC) of the induction motor (IM) drive is characterized by high ripples in the stator flux and the electromagnetic torque waveforms due to the use of hysteresis comparators. Furthermore, the motor speed in this control strategy is ensured through a proportional integral (PI) regulator, due to its simple structure. Nonetheless, this controller is sensitive to load disturbances. Hence, it is not robust against parameter variance, which can degrade the motor performance. To overcome this deficiency, many endeavors have been conducted in the literature to ensure a high dynamic response of the motor in all speed ranges, with minimum flux and torque undulations. Thus, the DTC of an IM associated with a three-level inverter based on sliding mode (SM) flux, torque and speed controllers was adopted to substitute the hysteresis comparators and the traditional PI regulator, since the SM speed controller is able to prevail against external disturbances. The second contribution of this manuscript is to develop the proposed DTC_SM approach using the Xilinx System Generator (XSG) in order to implement it on a field programmable gate array (FPGA) Virtex 5 on account of its ability to adopt parallel processing. The hardware co-simulation results verify clearly the merits of the suggested modified DTC strategy.

Periodic Event-Triggered Terminal Sliding Mode Speed Control for Networked PMSM System: A GA-Optimized Extended State Observer Approach

This article proposes a novel periodic event-triggered terminal sliding mode speed regulation scheme for the networked permanent-magnet synchronous motor (PMSM). The novel speed regulation strategy combines advantages of both terminal sliding mode control (TSMC) and periodic event-triggered mechanism. The satisfied speed regulation performance can be guaranteed by using TSMC to compensate the external disturbances and parameter uncertainties. The communication burden between the central controller and the remote motor is reduced by the periodic event-triggered protocol. To reduce the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">chattering</i> in the TSMC signal, an extended state observer (ESO) is further introduced to estimate all possible perturbations, in which the upper bound of the estimation error is analyzed explicitly. Then, a binary-based genetic algorithm (GA) is adopted to find the optimal observer parameters. A key challenge here is how to estimate the actual bound of the triggering error under the periodic event-triggered mechanism. To this end, an explicit selection criterion of the periodic sampling period is developed by utilizing the known constrained information of the PMSM. It is proven that the proposed novel periodic event-triggered TSMC with a proper selection of the control gain can guarantee the reachability of the sliding region and the ultimate boundedness of the regulation errors simultaneously. Finally, the effectiveness of the proposed novel periodic event-triggered TSMC via a GA-optimized ESO is demonstrated in both simulation and experiment results for a real PMSM platform.

Direct torque control based on second order sliding mode controller for three-level inverter-fed permanent magnet synchronous motor: comparative study

Introduction. The permanent magnet synchronous motor (PMSM) has occupied a large area in the industry because of various benefits such as its simple structure, reduced moment of inertia, and quick dynamic response. Several control techniques have been introduced for the control of the PMSM. The direct torque control strategy associated to three-level clamped neutral point inverter has been proven its effectiveness to solve problems of ripples in both electromagnetic torque and stator flux with regard to its significant advantages in terms of fast torque response. Purpose. The use of a proportional integral speed controller in the direct torque control model results in a loss of decoupling with regard to parameter fluctuations (such as a change in stator resistance value induced by an increase in motor temperature), which is a significant drawback for this method at high running speeds. Methods. That is way a second order sliding mode controller based on the super twisting algorithm (STA) was implemented instead of PI controller to achieve a decoupled control with higher performance and to insure stability while dealing with parameter changes and external disturbances. Results. The simulation results carried out using MATLAB/Simulink software show that the model of direct torque control based on a three-level inverter-fed permanent magnet synchronous motor drive has better performance with second order sliding mode speed controller than the proportional integral controller. Through the response characteristics we see greater performance in terms of response time and reference tracking without overshoots. Decoupling, stability, and convergence toward equilibrium are all guaranteed.

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.

Permanent Magnet Synchronous Generator Connected to a Grid via a High Speed Sliding Mode Control

Wind power generation has recently received a lot of attention in terms of generating electricity, and it has emerged as one of the most important sources of alternative energy. Maximum power generation from a wind energy conversion system (WECS) necessitates accurate estimation of aerodynamic torque and system uncertainties. Regulating the wind energy conversion system (WECS) under varying wind speeds and improving the quality of electrical power delivered to the grid has become a difficult issue in recent years. A permanent magnet synchronous generator (PMSG) is used in the grid-connected wind-turbine system under investigation, followed by back-to-back bidirectional converters. The machine-side converter (MSC) controls the PMSG speed, while the grid-side converter (GSC) controls the DC bus voltage and maintains the unity power factor. The control approach is second-order sliding mode controls, which are used to regulate a nonlinear wind energy conversion system while reducing chattering, which causes mechanical wear when using first-order sliding mode controls. The sliding mode control is created using the modified super-twisting method. Both the power and control components are built and simulated in the same MATLAB/Simulink environment. The study successfully decreased the chattering effect caused by the switching gain owing to the high activity of the control input.

Robust adaptive direct speed control of PMSG-based airborne wind energy system using FCS-MPC method

Electricity generation using airborne wind energy system (AWES) tends to be more efficient than that of conventional wind turbines due to their ability at extracting higher speeds from wind at higher altitudes by the tethered kite generator system (TKGS). The speed regulation of a permanent synchronous machine (PMSM) attached to a kite to maximize harvested power from wind is the topic of the present research. To track the optimal speed produced by TKGS, a finite-control-set model predictive control (FCS-MPC) with a new cost function is directly employed to generate appropriate gate signals for a 3-level neutral point clamped (3-L NPC) inverter that drives a PMSM. A novel adaptive algorithm is also provided for adjusting the weight coefficients of the cost function to improve the system’s performance across a wider range of change in the operating conditions. Moreover, a terminal sliding mode disturbance observer (TSMDO) is designed to estimate the load torque. A terminal sliding mode speed controller (TSMSC) is also used to produce the current reference for the optimizing algorithm in FCS-MPC. The proposed control scheme eliminates the need for a cascade structure while significantly reduces current deformation and torque oscillations. Additionally, the controller operates as fast as a traditional direct speed controller without the use of a cascade structure and is more robust against parameter uncertainties. To illustrate the success of the suggested controller, the results of simulations are presented in MATLAB/SIMULINK® software. The performance of the proposed technique is evaluated in three situations which simulates a grid-connected PMSM fed by a back to back 3-L NPC. In the first scenario, it is demonstrated that the suggested technique performs well when the system’s operational conditions vary. The performance of the adaptive tuning mechanism of the cost function weight factors is investigated in the second scenario, which takes into account model parameter uncertainty. The impacts of the disturbance observer (DO) on the system performance are explored in the final scenario, and it is discovered that the disturbance observer may increase the speed response and DC link voltage tracking performance. All of the simulation results show that the new technique outperformed the traditional FSC-MPC.

Robust Sliding Mode Control of the Permanent Magnet Synchronous Motor with an Improved Power Reaching Law

To improve the suppression ability of uncertain disturbance of the sliding mode control driving system of the surface-mounted permanent magnet synchronous motor (SPMSM) and to reduce the chattering of the control output, a robust sliding mode control strategy with an improved power reaching law (IPRL) is proposed in this paper. Compared with the traditional fast power reaching law (FPRL), the IPRL incorporates the sum of the power terms of the system state variables into the conventional power terms, and uses hyperbolic tangent saturation function to replace the piecewise function, which can effectively suppress the sliding mode chattering and improve the convergence speed of the system state to the sliding mode surface. Furthermore, the robust sliding mode speed controller and sliding mode current controller of the SPMSM are designed separately with the IPRL, and detailed simulation verification is carried out to reveal the effectiveness of the IPRL. Simulation and experimental results show that compared with the FPRL, the proposed IPRL can reduce the inherent chattering phenomenon in sliding mode control, and the IPRL-based speed and current control strategy can effectively improve the dynamic performance and robustness of the system.

Parameter Tuning of Sliding Mode Speed Controller of Induction Motor Drive Using Teaching-Learning Based Optimization Algorithm

The optimal settings of the Sliding Mode Controller for three-phase Induction Motor speed regulation are proposed in this paper using a Teaching-Learning Based Optimization Algorithm. It is a straightforward metaheuristic algorithm that simulates the teaching-learning processes in a classroom. Indirect Field Oriented Control is used in this induction motor drive, which allows the motor torque and the flux to be separated, similar to a DC motor. The inner loop uses proportional-integral current controllers, whereas the outside loop uses a sliding mode speed controller. In this paper, the sliding mode controller uses a tanh function as a switching function. Integral Time Absolute Error and Zwe-Lee Gaing's parameters are used as objective functions for tuning sliding mode controller settings. Performances of the proposed scheme in terms of the transient response analysis are compared with the swarm intelligence-based algorithms, namely the modified Particle Swarm Optimization and Grey Wolf Optimization. MATLAB/ SIMULINK software is used to build the three algorithms and sliding mode controller-based induction motor drive models, which are then analysed using simulation experiments. In comparison to the modified Particle Swarm Optimization and the Grey Wolf Optimization algorithms, Teaching-Learning Based Optimization yields the lowest value of the objective function Zwe-Lee Gaing's parameter and it converges quickly.