Mode Variable Structure Control Strategy Research Articles

Grid-Connected PV Inverter Control Strategy Based on the Sliding Mode

The Photovoltaic grid-connected inverter is an essential equipment of photovoltaic grid-connected system. Due to the disadvantages of the traditional PI control method for grid-connected photovoltaic inverters, this paper adopts the integral sliding mode variable structure to control grid-connected inverters. Grid inverter DC control mode was introduced in detail in the sliding mode variable structure control strategy. Using Matlab simulation platform to compare and analyze the traditional PI voltage compensation control strategy and sliding mode variable structure control strategy. From the waveform of the simulation output, the current harmonic at the output of the grid-connected inverter is reduced, and the power factor is increased, with the power factor is close to 1. The control precision, robustness and anti-interference ability of grid-connected system are improved. Which proved the feasibility and the superiority of the proposed control strategy.

Self-Docking Characteristics and Sliding Mode Control on Space Electromagnetic Docking Mechanism

Electromagnetic docking technology can realize the flexible docking and safe separation of spacecraft, and presents broad application prospects. However, an electromagnetic force with nonlinearity and uncertainty properties increases the difficulties of the electromagnetic docking control. In this work, the magnetic dipole far-field model of a single coil has been established by simplifying the electromagnetic docking device. Afterward, the electromagnetic force and electromagnetic torque models were obtained during space electromagnetic docking. The space electromagnetic docking dynamics model was established by analyzing the influences of disturbance force and disturbance torque caused by a geomagnetic field. According to the one-dimensional docking reference trajectory, the sliding mode variable structure controllers based on exponential reaching law were proposed and verified. The quasi-sliding mode control method has been adopted to solve the chattering problem in sliding mode variable structure control. The simulation results show that it is necessary to design and add an electromagnetic controller to achieve flexible docking. The sliding mode variable structure controller based on quasi sliding mode can realize one-dimensional electromagnetic flexible docking, and have made good tracking effect on the reference trajectory. Compared with the control method based on exponential reaching law, it can reduce the chattering phenomenon in the control process. The sliding mode variable structure control strategy based on quasi sliding mode presented good robustness. Therefore, it can provide theoretical guidance and control reference for the flexible docking process between electromagnetic satellites.

Multi-Degree-of-Freedom Manipulator Joint Trajectory Tracking Control Method Based on Decision Tree

For industrial-grade manipulators, the study of trajectory tracking control issues provides an important guarantee for accurate and safe work. Therefore, the trajectory control input driving torque can meet the requirements of the robot arm to accurately track a given target trajectory, and the process of building a decision tree is a process of dividing the feature space. For a given training data set, a set of if-then is summarized the rule of. Based on this, this paper launches the research of multi-degree-of-freedom manipulator joint trajectory tracking control method based on decision tree. Based on the established kinematics and dynamics model of the manipulator, this paper uses a proportional-integral-derivative (PID) sliding mode controller based on the sliding mode surface of the manipulator to perform the trajectory tracking control of the end of the manipulator, and the simulation results of the improved sliding mode control are compared with the simulation results of the improved sliding mode control. The simulation results of the PID controller and the traditional sliding mode controller are compared. This paper finally verifies the effectiveness of the proposed new sliding mode controller based on the expanded state observer through the experimental platform. The speed and chattering problems of the trajectory tracking at the end of the manipulator are better than those of the controller on the experimental platform. Finally, this paper adopts the sliding mode variable structure control strategy combining the double-power reaching law and the improved terminal sliding mode surface to study the trajectory tracking control of the planar two-degree-of-freedom manipulator.

Position Control Study on Pump-Controlled Servomotor for Steam Control Valve

In steam turbine control and actuation, the steam control valve plays a key role in operability and reliability. The electrohydraulic regulating system for the steam control valve, usually called the servomotor, needs to be reliable and high performing under nonlinear excitation interference in actual conditions. Currently, electrohydraulic servo valve control technology is widely used in servomotors. Although this technology has good control performance, it still has some technical defects, such as poor antipollution ability, low energy efficiency, large volume size, and limited installation space. Aiming at the abovementioned technical shortcomings of electrohydraulic servo valve control technology, a servomotor-pump-hydraulic cylinder volume control scheme is proposed in this paper, forming a pump-controlled servomotor for the steam control valve. By analyzing the working principle of the pump-controlled servomotor position control in the steam control valve, the mathematical model of a pump-controlled servomotor for the steam control valve is established. The sliding mode variable structure control strategy is proposed, and the variable structure control law is solved by constructing a switching function. To verify the performance of the proposed control method, experimental research was conducted. The research results show that the proposed sliding mode variable structure control strategy has a good control effect, which lays the theoretical and technical foundation for the engineering application and promotion of pump-controlled servomotors for steam control valves and helps the technical upgrade and product optimization of steam turbines.

Dynamic Modeling and Error Analysis of a Cable-Linkage Serial-Parallel Palletizing Robot

The efficiency and accuracy for parallel robot play a significant role in the industrial production process. In order to further improve the motion performance of parallel robot, this paper focuses on the study of mechanism design, dynamic modeling and error analysis of a cable-linkage serial-parallel palletizing robot (CSPR). Firstly, the CSPR is designed as a series-parallel hybrid mechanism driven by flexible cables, which can effectively reduce the inertia and improve the dynamic response. As is known that kinematic design optimization of compliant mechanisms requires accurate yet efficient mathematical models, the kinematics and dynamic models are established by the homogeneous coordinate transformation method and Lagrange equation. Based on the dynamic mathematical model of the robot, a variety of sensors are chosen to construct the hardware control system and the sliding mode variable structure control strategy is also designed based on motion errors. Then, the motion performance and load carrying capacity of the CSPR were analyzed and compared in different operating conditions respectively, and the results verify the validity and efficiency of the mechanism.

Virtual synchronous motor based-control of Vienna rectifier

Vienna rectifiers are widely used because of their advantages of high power-factor, low voltage stress on the power semiconductor switches, high power density, stable output voltage, low current harmonic content, and good economics. And gradually applied to the front stage AC/DC part of the electric vehicle charger. Traditional Vienna rectifier control methods include double closed-loop control, hysteresis current control, and Sliding mode variable structure control strategy, but all strategies usually regulate DC-Voltage and keep the unity power factor. However, if it is used for the interface part of the electric vehicle charger with frequent load switching, it is necessary not only to ensure the stability of the output voltage and low THD of the current, but also to be able to respond to the fluctuation of the voltage and frequency of the power system and improve the inertia and damping at the interface. Thereby, the stability of the power grid is improved to a certain extent, and fast-charging is ensured while being grid-friendly. Therefore, this paper proposes to apply the virtual synchronous motor control to the Vienna rectifier to improve the adaptability of the grid to the large-scale access of electric vehicles. Build the topology of the Vienna rectifier in simlink and the modulation method using SVPWM to build a complete model on the basis of VSM.

An Approach to Improve System Performance in the Vehicle-Grid System Using Sliding Mode Control Under Multiple Operation Conditions

To improve the performance of vehicle-grid system under multiple operation conditions and suppress the low-frequency oscillation (LFO) in electrified railways, this paper proposed a control strategy of electric multiple units (EMUs) traction line-side converter (LSC) based on sliding mode control (SMC). First, the accurate model of EMUs is established and then the mathematical model of it in the d-q frame is derived. Then, the application of sliding mode variable structure control strategy in the LSC of EMUs is presented in detail, which includes the design of outer loop voltage sliding mode surface and inner loop current control law. Moreover, the control performance for EMUs based on SMC and traditional linear proportional integral (PI) control is compared under multiple operation conditions in the case of one traction drive unit of EMUs and multi-EMUs, respectively. Finally, experiments are implemented on the hardware in the loop simulation platform based on software StarSim. The experiments results show that, compared with PI control, SMC owns better control performance, such as the lower total harmonic distortion of traction line-side current under multiple conditions, lower voltage fluctuation when braking occurs, better anti-interference ability with the change of system parameters, and can effectively suppress the LFO occurs under operation mode.

Sliding Mode Variable Structure Control Strategy Applied on Position Servo System of EMA

This paper introduces the basic elements of Electronic-Mechanical Actuator (EMA), and gives the equations. The mathematical model-state equations is established based on the basic equations, and the sliding mode variable structure control strategy, based on the reaching law is applied to control the position servo of EMA. We design a position-speed integrated sliding mode variable structure controller. The models of EMA machinery, electrical motor and controller are established in AMESim and Matlab, and joint simulation is carried out. Finally, this control strategy is compared with the three loop PID control strategy, and the experiment is carried out. The result shows that the sliding mode variable structure control strategy based on reaching law used to control EMA can improve the frequency response and control accuracy of the system, can also improve the dynamic performance of the position servo system.

Fuzzy sliding mode control of servo control system based on variable speeding approach rate

In order to optimize the speed control performance of the permanent-magnet synchronous motor system with different disturbances and uncertainties, this paper proposes a fuzzy sliding mode variable structure control (fuzzy-SMC) strategy. First, a variable speed reaching rate is introduced to solve the deficiency of the exponential reaching rate widely used in conventional sliding mode variable structure control (SMC) strategy. Then, a fuzzy controller is designed to adjust the control parameters to overcome the control deviation and improve the dynamic performance of the system. Simulation and experimental results show that when the steady state is reached, the proposed fuzzy-SMC strategy has better response speed than the proportional integral differential strategy and the conventional SMC strategy. It has smaller speed fluctuation, is more robust, and effectively suppresses the chattering phenomenon.

Non‐linear extended state observer‐based sliding mode control for a direct‐driven wind energy conversion system with permanent magnet synchronous generator

Considering the internal and external disturbances of direct-driven wind turbine-based permanent magnet synchronous generation system, an extended state observer (ESO)-based sliding mode variable structure control strategy is proposed to improve the maximum power tracking performance of the system. The ESO is used to estimate the effects of the disturbances, such as dynamical uncertainties, modelling error, external forces, variety of wind speed and so on, and eliminate the disturbances by the feedforward compensation. The simulation results show that the control system not only effectively improves the anti-disturbance ability of the system, but also solves the chattering problem of sliding mode control system to a certain extent.

Direct Torque Control of Permanent Magnet Synchronous Motor Based on Sliding Mode Variable Structure

In order to solve the problem of large torque and flux ripple in the traditional direct torque control of permanent magnet synchronous motor, Super-Twisting sliding mode variable structure control strategy is adopted. Under the dl coor-dinate system, the torque and flux controller is designed. In the direct torque control, the problem of speed overshoot and considerable fluctuation during PI control is adopted. The synovial speed controller is designed, and the space vector pulse width modulation technology (SVPWM) is adopted to stabilize the inverter switching frequency. The simulation results demonstrate that the method can effectively reduce the torque and flux linkage and accelerate the system response.

Sliding mode variable structure control strategy of bearingless induction motor based on inverse system decoupling

A bearingless induction motor is a multivariable, nonlinear and strong coupling object. To achieve its dynamic decoupling control with high performance and improve the system stability, a sliding mode variable structure (SMVS) control strategy based on inverse system decoupling is proposed. First, taking the stator current as the control variable, by means of inverse system method, the bearingless induction motor system is decoupled into four pseudolinear subsystems, including motor speed subsystem, rotor flux‐linkage subsystem and two radial displacement component subsystems. Then, according to the SMVS control theory, the regulator is designed for each subsystem. To overcome the chattering problem of the system, an exponential reaching law is introduced to the SMVS regulator; based on Lyapunov theory, system stability is analyzed. From the simulation experimental results, it is clear that the system has better dynamic decoupling control performance, a stronger ability to resist load disturbance and stronger robustness to the variation of motor parameters. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Study on maximum power point tracking of photovoltaic array in irregular shadow

Abstract Traditional maximum power point tracking (MPPT) methods can hardly find global maximum power point (MPP) because output characteristics curve of photovoltaic (PV) array may have multi local maximum power points in irregular shadow, and thus easily fall into the local maximum power point. To address this drawback, Considering that sliding mode variable structure (SMVS) control strategy have such advantages as simple structure, fast response and strong robustness, and P&O method have the advantages of simple principle and convenient implementation, so a new algorithm combining SMVS control method and P&O method is proposed, besides, PI controller is applied to reduce system chattering caused by switching sliding surface. It is applied to MPPT control of PV array in irregular shadow to solve the problem of multi-peak optimization in partial shadow. In order to verity the rationality of the proposed algorithm, the experimental circuit is built, which achieves MPPT control by means of the proposed algorithm and P&O method. The experimental results show that compared with the traditional P&O algorithm, the proposed algorithm can fast track the global MPP, tracking speed increases by 60% and the relative error decreased by 20%. Moreover, the system becomes more stable near the MPP, the fluctuations of output power is greatly reduced, and thus make full use of solar energy.

Sliding Mode Variable Structure Control and Real-Time Optimization of Dry Dual Clutch Transmission during the Vehicle’s Launch

In order to reflect driving intention adequately and improve the launch performance of vehicle equipped with five-speed dry dual clutch transmission (DCT), the issue of coordinating control between engine and clutch is researched, which is based on the DCT and prototype car developed independently. Four-degree-of-freedom (DOF) launch dynamics equations are established. Taking advantage of predictive control and genetic algorithm, target tracing curves of engine speed and vehicle velocity are optimally specified. Sliding mode variable structure (SMVS) control strategy is designed to track these curves. The rapid prototyping experiment and test are, respectively, conducted on the DCT test bench and in the chassis dynamometer. Results show that the designed SMVS control strategy not only effectively embodies the driver’s intention but also has strong robustness to the vehicle parameter’s variations.

Efficiency Optimization of Asynchronism Motor Based on a Novel Reaching Law

To satisfy with the high-power control of the asynchronism motor control drive system, this paper devised a novel reaching law of sliding mode variable structure control strategy and analysed this control strategy for vector control system of asynchronism motor and the high-frequency chattering phenomenon in traditional sliding mode controllers. The simulation results demonstrate that the control strategy can ensure rapid dynamic speed response during the efficiency optimization at low loads and decrease chattering phenomenon effectively, greatly improve the robustness of asynchronism motor and improve control quality.