Modified PI Controller Research Articles

High current density DC-DC converter with Modified PI controller for fast charging applications in EVs

As electric vehicles (EVs) become increasingly prevalent, the demand for efficient and high-performance DC–DC converters in the charging infrastructure is paramount. Electric vehicles, powered by rechargeable batteries or fuel cells, hence is necessary to have a cost-effective and efficient battery charger to deliver the consistent output current needed for the designated EV's battery. This paper adds a new and more effective approach of design and control of a DC–DC converter with bidirectional capability appropriate for incorporation in EV charging systems aimed at enhancing the current density and control issues inherent in the charging /discharging process. It appears to provide the necessary high current density besides battery out as soon as possible and also to impose an unimportant overshooting of the charging time for demanded lithium-ion battery system while charging it. The converter circuit contains the following equipment in its construction include single phase AC voltage source, linear transformer, passive component that includes the inductor and capacitor and bridge rectifier. Usually, Simulink/MATLAB is used for the purpose of various simulations. Using the MATLAB simulation the design of the concept system offered in this proposal has been proved. Monitored the current in amperes that the battery charger is supplying to the battery, closely observed the condition and voltage of the battery.

Stabilization of Linear Delay Systems With Two Unstable Poles by Modified PI Controller

Stabilization of Linear Delay Systems With Two Unstable Poles by Modified PI Controller

Disturbance and Uncertainty Attenuation for Speed Regulation of PMSM Servo System Using Adaptive Optimal Control Strategy

This paper proposes an adaptive optimal control scheme to minimize the effect of disturbances and uncertainties of permanent magnet synchronous motor (PMSM). In the speed regulation loop, an adaptive speed controller is designed, which not only regulates the speed perfectly but also is robust against wide range variation of parameters and external disturbance of PMSM. Unlike the traditional speed controller, the proposed controller includes an adaptive law to compensate the distorted model parameters and disturbances in real-time, enhancing speed performance. The stability of the proposed speed controller is fully proven by using Lyapunov theory. Meanwhile, a PI-type optimal current controller is established in the inner control loop to achieve the current tracking and limitation. By easily selecting appropriate performance indexes, the proposed controller can balance between control input magnitude and current tracking error. Finally, the validity of the proposed control scheme is verified through simulations and experiments. For a comparative study, four different control strategies, that is, the proposed control, super twisting sliding mode control, PI control and disturbance observer-based control, are carried out to demonstrate the superiority of the proposal.

Research On Adaptive Sliding Mode Control of PMSM Based On Novel Reaching Law

Based on the jitter and slow convergence speed caused by the conventional approach law SMC, a new exponential approach rate is proposed to optimize dynamic characteristics of the PMSM control system. The approach law is based on the conventional exponential adience law, and the variable of state the system are added. It can ceaseless adapt to the changes of the controlled system, ensure the high tracking function of the system and reduce the jitter caused by the control input. Meanwhile, based on the new exponential approach law, an self-adaption SMC is designed to estimate the uncertain parameters of the control process, and the stability of the make better approach law and control algorithm is analyzed by the function. Finally, The designed controller is compared with traditional sliding mode control and PI control through simulation experiments. The results show that the new exponential approach law can effectively suppress chattering and improve the dynamic characteristics of the system.

An optimal motion path planning control of a robotic manipulator based on the hybrid PI-sliding mode controller

This paper proposes a hybrid proportional-integral (PI-sliding) mode controller to improve and adjust the point-to-point path planning of a three-link robotic arm with three degrees of freedom. The main objectives of the proposed control unit are to control the tracking process to reach the desired path handle the outgoing vibrations, and dampen them in the links of the robotic arm during its movement to ensure accuracy in completing the work. Seventh-degree polynomial paths represented the segments of locomotion connecting the first, middle, and last points at the combined space through predefined route points via minimal travel time. While not exceeding a predetermined maximum torque, without hitting any obstacle in the robot's workspace. The results showed that the proposed control design provides a robust control performance and fast response corresponding with conventional sliding mode controller (SMC) and PI controller. Then the outcomes provide the best results for the demanded mission according to the whished intakes with minimal error. The system equations are solved using the techniques available in MATLAB software then the results of the model are validated by the results of simulations.

A Modified PI-Controller Based High Current Density DC–DC Converter for EV Charging Applications

Electric vehicles (EVs) are getting more popular in the field of automobiles due to environmental factors and others. Since electric vehicles manage their power from the rechargeable battery so it’s essential to have a reliable, efficient, and economical battery charger that can provide stable required output for the specified EV’s battery. In this paper, a DC-DC converter with a modified PI controller has been presented which helps to achieve the required output voltage and high current density with negligible overshoot for the specified lithium-ion battery system to minimize the charging time. Apart from minimizing the power loss of the active switches, the proposed system minimizes the junction temperature which eventually improves the life cycle of the converter. The analysis of the proposed converter is performed both in ideal and non-ideal conditions. The power loss of the active switches and the junction temperature have also been analyzed. An economical and effective dc and ac side inductor has been designed and perform the total power loss and the temperature rise. The analysis results show that the proposed converter can maintain a power factor of more than 90% and a total harmonic distortion of less than 0.46%, which is ideal for the high-density load current. The reliability of the dc-dc converter is also evaluated. A hardware prototype has also been implemented to confirm its viability for EV battery charging applications.

A Bi-Sliding Mode PI Control of DC-Link Voltage of Three-Phase Three-Wire Shunt Active Power Filter

A novel bi-sliding mode PI control (bi-SMPIC) of the dc-link voltage of a three-phase three-wire shunt active power filter (APF) is proposed in this article. One SMPIC having an improved reaching law function in the reaching phase can make the speed of the state variables reaching the sliding surface approach zero. The other SMPIC possessing an improved reaching law function with a boundary layer in the sliding phase can render the state variables asymptotically stable at the origin of the sliding surface. Thus, the proposed bi-SMPIC can effectively reduce system chattering. Moreover, it is proven that the system has reachability and asymptotic stability. Further, a formula for determining the PI control parameters is obtained. From the formula, the proposed bi-SMPIC can have ideal control effects in both the reaching phase and the sliding phase. Finally, the high control performance of the bi-SMPIC is confirmed by both experimental and simulation results.

Active Disturbance Rejection Control of a Magnetic Screw Motor for High Tracking Performance

A magnetic screw motor integrated by a magnetic screw and a permanent magnet synchronous motor offers high thrust density without friction and loss. However, its internal structure is complicated, resulting in difficulty to control its linear displacement to track the given signal in time and even getting out of control due to interference. In this article, to improve the tracking performance and anti-interference performance of the system, an active disturbance rejection controller (ADRC) is adopted to improve the current loop and makes up for nonlinear regional control in the closed-loop control system. To ensure the stability of the proposed scheme in the entire operation range, the design and the stability analysis are carried out in the continuous-time domain. The novel control algorithm enhances the flexibility of the magnetic screw motor by optimizing the nonlinear function in ADRC. In addition, to highlight the high-performance control of the ADRC for the magnetic screw motor, sliding mode control and PI control are added to compare with it. Finally, the reciprocating motion control is added to show the diversity of the functions of the magnetic screw motor, which verifies the effectiveness and feasibility of the control algorithm.

Pattern recognition based movement control and gripping forces control system on arm robot model using LabVIEW

Most arm robot has an inefficient operating time because it requires operator to input destination coordinates. Besides, main problem of arm robot is object’s vulnerability when it is manipulated by the robot. This research goals is to develop an arm robot control system which has ability to automatically detect object using image processing in order to reduce operating time. It is also able to control gripping force for eliminating damage to objects caused by robot gripper. This research is implemented in LabVIEW 2011 software to control arm robot model which can represent industrial scale robot. The software is designed with informative visualization to help user learn and understand robotic control concept deeply. The system can automatically detect object position based on pattern recognition method which has four steps: pre-processing process to initialize picture taken by camera, segmentation process for separating object from the background, classification process to determine characteristics of object, and position estimation process to estimate object position in the picture. The object’s position data are then calculated by using kinematic equation to control the robot’s motion. The results show that the system is able to detect object and move the robot automatically with accuracy rate in x-axis is 95.578 % and in y-axis is 92.878 %. The system also implements modified PI control method with FSR as input to control gripping force with maximum overshoot value `10 %. Arm robot model control system developed is successfully meet the expectation. The system control can be implemented to industrial scale arm robot with several modification because of kinematic similarity between model and industrial scale robot.

Study on influence of switching frequency on sliding mode control performance of permanent magnet synchronous motor

Aiming at the deficiencies of the speed loop PI control algorithm of permanent magnet synchronous motor (PMSM) in variable working conditions, a new fast reaching law sliding mode control algorithm based on double-power is proposed. Firstly, a new sliding mode reaching law is proposed, and the reaching law includes system state variables and the power function of the terminal attractors. It can reach the sliding mode surface at a faster speed, reduce chattering and improve system performance. Secondly, the reachability and existence of the new reaching law are proved by the Lyapunov function, and a new reaching law sliding mode controller (NRLSMC) is designed. Then, the theoretical analysis of the switching frequency of the system is carried out, and the effects of different switching frequencies on the performance of sliding mode control (SMC) of PMSM are explored. Simulation and experimental results demonstrate that the proposed NRLSMC can effectively attenuate the disadvantages of large overshoot and long transition time under variable working conditions compared with ordinary sliding mode controller (OSMC) and PI controller. Moreover, the relative optimal switching frequency that improves the above performance is obtained, and the existence of the optimal sampling period for stable convergence of the system is proved.

Design of Robust Decentralized Control Systems for Distillation Columns

This paper is devoted to the development of a decentralized control system design method with improved robustness, applicable to distillation columns control problem. The aim is attained by solving the following tasks: selection of representative models of columns; development of an effective transfer function identification algorithm; development of a decentralized controller design algorithm, which takes into account the cross-links impact; verification of the developed method for the selected models of columns. The most important result is the developed design method, which includes two algorithms. The first algorithm can be used to identify simplified models of the effective transfer functions. The second algorithm makes it possible to design a decentralized control system based on the ratio between the diagonals of the original model and effective transfer functions. Modified PI controller is used. The achievement of the distillation column control system robustness to the synchronous technologically conditioned deviation of the model parameters by up to three hundred percent of the nominal value is the paper significant result. The digital implementation of the designed controllers is simple. The analysis of the literature shows that none of the previously proposed methods for designing decentralized automatic control systems solved such a problem. The efficiency of the developed algorithms is illustrated using the known models of dynamics of distillation columns. The analysis of limitations of the method as well as its significant differences to the Biggest Log Tuning and H∞ loop shaping methods is presented.

Research on PMSM Sliding-mode Vector Combined Speed Controller Based on Improved Exponential Reaching Law

Abstract Sliding mode control has good robustness, but the traditional sliding mode has the problem of chattering. Aiming at the conflict between velocity and chattering in the approach stage of sliding mode control, a new reaching law is put forward. By improving the isokinetic approach term of the traditional exponential reaching law, the system’s requirements in different stages of sliding mode motion are met, and this contradiction has been effectively improved. At the same time, to better improve the control effect of permanent magnet synchronous motor (PMSM) speed regulation system, combined with the traditional PI control with no static error and no overshoot, a combined speed controller combining sliding mode control and PI control is designed to enhance the robustness of the system. By building a model in Matlab/SIMULINK for simulation, the effectiveness of the improved exponential reaching law and the improvement of the system performance brought by the combined speed controller are verified respectively.

Enhancement of PHB Production Process in a Fed-batch Bioreactor Using Input-output Linearization Technique with Optimal Setpoints

Polyhydroxy butyrate (PHB) is a polyester that has been widely applied to formulate bioplastics. A challenge for the PHB production is the enhancement of PHB accumulation in bacterial cells, which can be conducted through the nutrient feeding strategy. A control system based on an input/output (I/O) linearization technique for the PHB production in a fed-batch bioreactor is proposed in this work. The concept of feast/famine phase is employed to provide the optimal desired targets for each time instant through optimization problems. The developed controller is applied to regulate the controlled output to follow the desired setpoints by manipulating the feed flow rate of nutrients. Simulation results show that the proposed control system attempts to follow the optimal desired targets (discrete-time approach) during the process operation. The accumulation of PHB in bacterial cells is around 25% higher than that of the process with a modified PI controller. Control performance tests indicate that the proposed control strategy successfully regulates the process according to the desired targets and handles the process disturbance effectively.

A High Step-Down DC–DC Converter With Reduced Inductor Current Ripple and Low Voltage Stress

This article presents a buck converter with a large step-down voltage conversion ratio, reduced ripple in inductor current and low semiconductor voltage stress. The proposed converter produces a lower output voltage at a sufficiently higher duty ratio compared to the conventional buck converter. The step-down voltage conversion ratio is modified by a series-parallel transition of two identical capacitors of a switch-capacitor cell. Two parallelly placed switches and two cross-connected identical capacitors are utilized to design the cell. An extra inductor is placed at the input side to oppose the sudden change in input current due to the series-parallel transition of the two identical capacitors. Therefore, two inductors are required to design the converter. These two inductors are coupled directly. The modified voltage conversion ratio reduces the ripple in inductor currents and output voltage. Direct coupling between the two inductors helps to further reduce the ripple in inductor currents and output voltage. The operating principle, analysis of ripple in inductor currents, and ripple in output voltage are discussed. The analysis of small-signal modeling is carried out and a voltage mode PI-controller is designed to enable the closed-loop operation. Finally, the proposed converter is implemented in hardware and the performance of the proposed converter is verified experimentally.

Fuzzy Sliding Mode Hybrid Control MPPT Strategy and PI Control as a Controller for a Battery Integrated with PV System

Fuzzy Sliding Mode Hybrid Control MPPT Strategy and PI Control as a Controller for a Battery Integrated with PV System

Dual Sliding Mode with PI Controller Based Switched Reluctance Motor Drive

In this paper, a Dual Sliding Mode with Proportional Integral (DSM-PI) controlled Switched Reluctance Motor drive circuit is proposed with closed loop speed control. An asymmetric half bridge converter is used to drive SRM which is fed by a front-end circuit. The dual sliding mode PI controller is utilized for better time response. With variable proportional and integral gains in DSM-PI controller the error generation value is altered with faster values making the speed of the motor to settle faster with reduced ripple and disturbances. The topology is modelled in MATLAB/Simulink environment and the simulation results on a three-phase 6/4 SRM are presented.

Stability analysis and a hybrid controller design of grid‐connected offshore wind farm through a VSC‐HVDC transmission link

AbstractThis paper proposes a hybrid controller which is a combination sliding mode control and PI control techniques for AC grid integrated offshore wind farm (OSWF) with voltage source converter ‐ high voltage direct current system. The controller must be capable of controlling AC voltage, DC‐link voltage, reactive power and effective power transfer. To examine the FRT capability, a symmetrical fault is applied at onshore AC grid side and compared the performances of the studied system based on the hybrid and PI controllers. The dynamic modelling and linearized system by state‐space modelling for the studied system are explained in detail. The small signal stability analysis and controller stability are observed with the help of the eigenvalue analysis. The analysis of the studied system with a hybrid and conventional controllers are conducted in the software environment of the MATLAB/SIMULINK. The effect of parameter uncertainty on total system stability is examined with the help of eigenmatrix of the studied system.

MIMO Fuzzy Sliding Mode Control for Three-Axis Inertially Stabilized Platform.

In this paper, a MIMO (Multi-Input Multi-Output) fuzzy sliding mode control method is proposed for a three-axis inertially stabilized platform. This method is based on the MIMO coupling model of the three-axis inertially stabilized platform in which the dynamic coupling among the three frames, namely the azimuth frame, the pitch frame and the roll frame, is fully considered. Firstly, the dynamic equation of the three-axis inertially stabilized platform is analyzed and its linearized model is obtained. After this, the controller is designed based on the model, during which fuzzy logic is introduced to deal with the frame coupling and the adaptive fuzzy coupling compensation factor is designed to be part of the algorithm. A complete proof of the stability and convergence is also provided in this paper. Finally, the performance of the platform with a MIMO fuzzy sliding mode controller and PI controller is analyzed. The simulation results show that the proposed scheme can guarantee tracking accuracy and effectively suppress the coupling interference between the three frames.

Extended Kalman Filter Based Sliding Mode Control of Parallel-Connected Two Five-Phase PMSM Drive System

This paper presents sliding mode control of sensor-less parallel-connected two five-phase permanent magnet synchronous machines (PMSMs) fed by a single five-leg inverter. For both machines, the rotor speeds and rotor positions as well as load torques are estimated by using Extended Kalman Filter (EKF) scheme. Fully decoupled control of both machines is possible via an appropriate phase transposition while connecting the stator windings parallel and employing proposed speed sensor-less method. In the resulting parallel-connected two-machine drive, the independent control of each machine in the group is achieved by controlling the stator currents and speed of each machine under vector control consideration. The effectiveness of the proposed Extended Kalman Filter in conjunction with the sliding mode control is confirmed through application of different load torques for wide speed range operation. Comparison between sliding mode control and PI control of the proposed two-motor drive is provided. The speed response shows a short rise time, an overshoot during reverse operation and settling times is 0.075 s when PI control is used. The speed response obtained by SMC is without overshoot and follows its reference and settling time is 0.028 s. Simulation results confirm that, in transient periods, sliding mode controller remarkably outperforms its counterpart PI controller.

Investigation Into the Nonlinear Characteristics of a High-Speed Drive Circuit for a Proportional Solenoid Controlled by a PWM Signal

This paper analyzes the unique nonlinear characteristics of a high-speed drive circuit for proportional solenoid, i.e., the inverse discharging drive circuit (IDDC), which has a faster discharging speed than a traditional drive circuit. The experimental results clearly show the piecewise nonlinear relationship between the current and the pulse-width modulation (PWM) duty ratio of the control signal of the IDDC. The mathematical model of the IDDC working processes in one PWM period is constructed in detail to analyze the IDDC nonlinear characteristics. The computational equations of the significant nonlinear features, including the critical PWM duty ratio, the steady-state current, the amplitude of the current oscillation, and the response time of the circuit, are deduced through algebraic analyses, which are verified by a comparison between the experimental and calculated results. These analyses aid the design and control of a solenoid drive circuit for a hydraulic proportional valve. Finally, a modified PI controller that considers the nonlinear characteristics of the IDDC is designed, and the experimental results show that the designed controller significantly improves the response speed of the solenoid current.