Gain PI Research Articles

ANFIS and MRAS-PI controllers based adaptive-UPQC for power quality enhancement application

This paper presents a novel heuristic based adaptive control technique (ACT) for improved compensation capability of the unified power quality conditioner (UPQC). The compensation capability of UPQC is enhanced by the optimal regulation of DC link voltage. Among all power quality (PQ) distortions, voltage sag is the severe PQ problem that significantly deteriorates the regulation of DC link voltage. The conventional approaches utilize a fixed gain PI controller that increases the error between the reference and actual DC link voltage under sag condition. This ultimately results in poor compensation of PQ distortions at the point of common coupling. To enhance compensation capability, the performance of ACT is examined with analytical and artificial intelligence techniques. The model reference adaptive system (MRAS) is used in the analytical method for online self tuning PI controller. For artificial intelligence technique, the off-line trained ANFIS is processed in the simulation studies. The performance of ACT based UPQC is validated in Matlab/Simulink and the obtained results are compared with conventional scheme. To substantiate theoretical results of the proposed approach, the algorithm is tested in real time Xilinx system generator (XSG).

English

A brake system is a nonlinear system which applies different compressive force depending on the position of the brake pad. The EMB(electric mechanical brake) used in passenger vehicles cannot detect the compressive force without a sensor. Therefore, it has different operating times at the same distance because the brake caliper applies different force depending on the position of the brake pad. A position controller for the EMB system was developed to control the operating time robustly at the same distance. A vector control method was used to operate the motor. The result of the position controller was used as the Q axis reference for the vector control method. The PI gain of the position was defined differently to meet the same operating time of the motor on each sector. In addition, the interval value between each position was calculated using an interpolation method. A PI gain of the position controller was tuned using the MATLAB tool, and the reliability of the position controller was verified through a simulation in the MATLAB. The verified PI controller was installed in an EMB system. The operating times were measured on each sector, showing that they were nearly identical. The proposed PI scheduling method was confirmed to have robust characteristics in a nonlinear EMB system with different amounts of compressive force depending on the position of the brake pad.

High Performance PI Current Controller for a Switched Reluctance Motor

The most common current controller for the Switched Reluctance Motor (SRM) is the hysteresis controller. This method, however, suffers from such drawbacks as variable switching frequency, consequent audible noise and high current ripple. These disadvantages make this controlling method undesirable for many applications. The alternative solution is the PI controller. Since the fixed gain PI current controller can only be optimized for one operating point, and on the other hand, SR motor is highly nonlinear, PI controller gain should be adjusted according to incremental inductance. This paper presents a novel method for PI current controller gain adaptation which is simple and yields a good performance. The proposed controller has been implemented on a test bench using a eZdsp F28335 board. The performance of the current controller has been investigated in both simulation and experimental tests using a four-phase 8/6 4KW SRM drive system.

Fuzzy logic control of grid connected DFIG system using back-to-back converters

This paper deals with the power generation control in variable speed wind turbines. In this context, the wind energy conversion system is equipped with a doubly-fed induction generator (DFIG) and two back-to-back PWM voltage source converters in the rotor circuit. A vector control of the rotor side converter (RSC) provides an independent control of stator active and reactive power and optimal speed tracking for maximum energy capture. A vector control scheme for the grid side converter (GSC) gives an independent control of slip active and reactive power exchanged between the grid and the GSC, in order to ensure sinusoidal supply currents and to maintain DC-link voltage constant. In this paper, an intelligent fuzzy inference system is proposed as alternative of the conventional PI controller to overcome any disturbance, three fuzzy controllers are used in the RSC for the speed, active and reactive power control, another fuzzy inference system is proposed as PI gain tuner for the DC-link voltage control loop. Performances have been tested on 1.5 MW DFIG by using Matlab/Simulink software environment.

GA를 이용한 오일쿨러시스템의 최적 PI제어기 설계

This paper deals with optimum PI controller design using genetic algorithm to improve control performance and robustness for an oil cooler system. The optimum PI gain was found to minimize an object function, integrated absolute error, and to satisfy control design specifications such as overshoot and settling time based on practical transfer function of the oil cooler system. The control performance and robustness were investigated by comparing indicial responses and Bode diagram analysis with respect to three kinds of PI gains obtained from different gain decision manners. Moreover, the robustness against to input disturbances, sinusoidal wave form and abrupt single pulse, was evaluated. The computer simulation results showed that the suggested optimum gain can establish desirable control performance and strong robustness with easy design process.

DYNAMIC MODELING AND GAIN SCHEDULING CONTROL OF A CHIILLED WATER COOLING SYSTEM

ABSTRACT Dynamic Modeling and Gain Scheduling Control of a Chilled Water Cooling System Jun Liu In this thesis, a dynamic model of a chilled water (ChW) cooling system with a stratified ChW tank was developed. The model-based analysis of the energy consumption and the cost under different control strategies were studied. The dynamic model consists of a zone, a cooling coil, a chiller, a stratified ChW tank, and a cooling tower. Nonlinear differential equations were written to describe and evaluate the performance of the entire chiller plant with the ChW tank. A PI-based gain scheduling (GS) control was designed and its performance was compared with the constant gain PI control by subjecting to setpoint changes and load disturbances. The simulation results showed that the system with GS control gives good control and has more stable performance. Five different operation strategies were simulated for comparing the energy consumption and the cost of the ChW cooling system under full load and partial load conditions. The results showed that the operating strategy with optimized chilled water setpoint saved 7.16% energy (21.5% cost) compared to the case with constant setpoint. These savings were more significant (36%) under partial load conditions. The gain scheduling control with optimal setpoint has great potential for energy savings as demonstrated by the results presented in the thesis.

Sensorless Speed Control of Permanent Magnet Synchronous Motors by Neural Network Algorithm

The sliding mode control has the merits with respect to the variation of the disturbance and robustness. In this paper, the sensorless sliding-mode observer with least mean squared error approach for permanent magnet synchronous motor (PMSM) to detect the rotor position by counter electromotive force and then compute motor speed is designed and implemented. In addition, the neural network control is also used to compensate the PI gain tuning to increase the speed accuracy without regarding the errors of the current measurement and motor noise. In this paper, a digital signal processor TMS320F2812 utilizes its high-speed ADC module to get current feedback information and thus to estimate the rotor position and takes advantage of the built-in modules to achieve SVPWM current control so that the senseless speed control will be accomplished. The correctness and effectiveness of the proposed control system will be verified from the experimental results.

가변이득 PI 제어기를 이용한 BLDC 모터의 속도제어

This paper provides a technical review of speed control using variable gain PI algorithm for BLDC(Brushless DC) motor. Usually the PI control is used in many motor applications, but a general PI control has problems of overshooting and disturbance for response. By the change of PI gain in motor control operation, these problems can be solved. To find the optimized PI gains for BLDC motor control, many control methods have been proposed. In this paper, the control algorithm with a variable PI gain is applied to improve overshooting response in transient region and rapid load disturbance rejection. Fixed gain and variable gain PI controls are compared. The validity of the propose method is verified by experiment.

Design of Robust Speed Controller by Optimization Techniques for DTC IM Drive

Direct Torque Control (DTC) of induction motor is preferred control strategy recently, due to its quick torque response, simplicity, less sensitivity against motor parameter variation. In general, PI speed controllers are widely used in industrial applications due to their simple structure. Due to the continuous variation of machine parameters, model uncertainties, nonlinear dynamics and system external disturbance, fixed gain PI controllers may becomes unable to provide the required control performance. Genetic Algorithm (GA) is used to tune the PI controller gains to ensure optimal performance. GA is more attractive for applications that involve non smooth or noisy signals. GA is used to minimize speed error and attains optimal values of the PI controller gains. The efficient and effective speed controllers can be designed by using adaptive control techniques. In which the conventional PI controller is replaced by structures based on Sliding Mode Control (SMC) strategy. SMC is known for its capability to cope with bounded disturbance as well as model imprecision which makes it ideal for the robust nonlinear control of IM drives

Variable Gain PI Controller Design For Speed Control of a Doubly Fed Induction Motor Using State-Space Nonlinear Approach

This paper presents a comparison between a variable gain PI controller and a conventional PI controller used for speed control with an indirect field orientation control of a Doubly Fed Induction Motor (DFIM), fed by two PWM inverters with a separate DC bus link. By introducing a new approach for decoupling the motor’s currents in a rotating (d-q) frame, based on the state space input-output decoupling method, we obtain the same transfer function (1/s) for all four decoupled currents. Thereafter, and in order to improve control performance, the VGPI controller was used for speed regulation. The results obtained in Matlab/Simulink environment illustrate the effectiveness of the technique employed for the decoupling and for speed regulation.

High Response and Precision Control of Electronic Throttle Controller Module without Hall Position Sensor for Detecting Rotor Position of BLDCM

This paper describes the characteristics of Electronic Throttle Controller (ETC) module in BLDC motor without the hall sensor for detecting a rotor position. The proposed ETC control system, which is mainly consisted of a BLDC motor, a throttle plate, a return spring and reduction gear, has a position sensor with an analogue voltage output on the throttle valve instead of BLDC motor for detecting the rotor position. So the additional commutation information is necessarily needed to control the ETC module. For this, the estimation method is applied. In order to improve and obtain the high resolution for the position control, it is generally needed to change the gear ratio of the module or the electrical switching method etc. In this paper, the 3-phase switching between successive commutations is adapted instead of the 2-phase switching that is conventionally used. In addition, the position control with a variable PI gain is applied to improve a dynamic response during a transient period and reduce vibration at a stop in case of matching position reference. The mentioned method can be used to estimate the commutation state and operate the high-precision position control for the ETC module and the high response characteristics. The validity of the proposed method is examined through the experimental results.

A New State-Space Nonlinear Control Approach of a Doubly Fed Induction Motor Using Variable Gain PI and Fuzzy Logic Controllers

In this paper, the authors are interested on the field-oriented control with variable gain PI (VPGI) and fuzzy logic regulators of doubly fed Induction Motor (DFIM) fed by two PWM inverters with separate DC bus link. By introducing a new approach for decoupling the motor’s currents in a rotating (d-q) frame, based on the state space input-output decoupling method, we obtain the same transfer function (1/s) for all four decoupled currents. Thereafter and in order to improve the performances of the machine’s control, the VPGI and fuzzy logic controllers with seven subsets were used for the regulation speed. The Results obtained in Matlab/Simulink environment show well the effectiveness of the technique employed for the decoupling and the speed regulation of the machine.

Simulation of Non Linear Adaptive Observer for Sensorless Induction Motor Control

This paper presents a model reference adaptive system based sensorless induction motor drive. In this scheme, an adaptive full order flux observer is used. The simulation result show that with the large PI gain for the adaptive scheme, the convergence for the speed estimation is fast and very well, however higher harmonics and noises are included in the estimated speed. Usually noises caused by inverter. Simulation results show that proposed scheme can estimate the motor speed under various adaptive PI gains and estimated speed can replace to measured speed in sensorless induction motor.

Efficiency optimisation with PI gain adaptation of field-oriented control applied on five phase induction motor using AI technique

Improving flux vector control (FOC) drives performance is studied for five phase saturated model of induction motor. Fuzzy logic, genetic algorithm (GA) and particle swarm optimisation (PSO) are used for this purpose. Optimum flux reference identification by using FL, GA and PSO is used to minimise the motor input power to have the optimum motor efficiency. Selecting of the optimal gains using both methods is done to improve the motor response and behaviour. A comparison between the simulation results was done to evaluate the performance for the developed controller adopting (GA) and (PSO) algorithms. The results show that the proposed PSO controller algorithm has better optimisation performance than the proposed GA both for gain tuning and for the selection flux set point, while the fuzzy logic give the best performance for optimal flux set point selection.

Adaptive control of web guides

Web guides are mechanisms that are used in roll-to-roll material processing machines to control the lateral position of the material while it is transported over rollers in processing machinery; the flexible, continuous materials are often referred to in the industry as “webs”. The process of controlling the lateral position of webs on rollers is referred to as “web guiding”. With the increasing need to transport and process different types of materials under different operating conditions within the same processing machinery, the existing fixed gain control algorithms do not provide adequate performance under these changing conditions and must be re-tuned often to provide satisfactory guiding performance. A controller that will adapt to parameter changes resulting from changes in the material properties, operating conditions, and size and type of guide mechanisms is desired. This paper discusses the design and implementation of model-based adaptive control strategies for web guides based on the dynamic models which describe the lateral behavior of webs. Extensive experiments are conducted for the designed adaptive control strategies for two types of web guides, namely remotely pivoted guide and offset pivot guide. Practical implementation issues and methods to increase robustness of the adaptive strategies are discussed. Experimental results from the adaptive control strategies will be compared with the existing fixed gain PI controller.

퍼지 제어 알고리즘을 이용한 차량 조향 장치용 표면 부착형 영구자석 동기 전동기의 속도제어

This paper, we describe the vector control of surface mounted PMSM (Permanent Magnet Synchronous Motor) using the fuzzy controller which is suggested algorithm. In these days, when vehicle is operated or not, whether the road is covered or not, the sensitivity of the steering column is not stable. To make up for it, the PI gain of a steering column controller is adjusted by experience. It becomes the price because it need a lot of sensor. Also it is difficult to implement robust control because we need a lot of parameters for variable road conditions which are the off road, the on road, a low battery voltage, a high battery voltage, a vehicle speed. In this paper, we propose fuzzy controller using the suggested algorithm which suitable for steering system. We test the fuzzy controller with the various condition. We get the good performance of fuzzy controller even if it is nonlinear system. We check a robust the fuzzy controller using the suggested algorithm.

A SYSTEM FOR DISSOLVED OXYGEN CONTROL IN INDUSTRIAL AERATION TANK

The control system is developed for accurate set-point control of dissolved oxygen concentration in industrial aeration tank based on adaptation of PI controller to time-varying dynamics of the controlled process. The controller adaptation algorithm refers to the process state model-based transfer function that follows changes in process dynamics by updating the function parameters with on-line measurements of process variables, and the controller tuning rules developed for typical structure transfer function models. The control system was investigated via computer simulation of the dissolved oxygen concentration set-point control in an industrial aeration tank under process disturbances and set-point step changes. The control system demonstrates fast adaptation of PI controller parameters and noticeably higher accuracy control compared to that of ordinary fixed gain PI controller. DOI: http://dx.doi.org/10.5755/j01.itc.41.1.921

Improvement Of Load Frequency Control By Using Self–Tuning Controller

Since a Superconducting Magnetic Energy Storage (SMES) unit with a self–commutated converter is capable of controlling both the active and reactive powers simultaneously and quickly, increasing attention has been focused recently on power system stabilization by SMES control. This paper presents a novel control method of SMES with a self-tuned Fuzzy Proportional Integral (FPI) controller associated with the Automatic Generation Control (AGC) for improving Load Frequency Control (LFC) in a single area power system. Boiler dynamics and nonlinearities such as governor dead band (DB) and generator rate constraints (GRC) are considered in the developed comprehensive mathematical model of a single area isolated power system. The effects of the self–tuning configuration of FPI controller in AGC on SMES control is compared with that of fixed gain PI controlled AGC. It is seen that with addition of FPI controller, SMES can perform a more effective primary frequency control for single area power system. Key words: Load frequency control; single area power system; automatic generation control; superconducting magnetic energy storage unit; fuzzy proportional integral controller

Decentralized Control of Uncertain Fuzzy Large‐Scale System with Time Delay and Optimization

This paper studies the decentralized stabilization problem for an uncertain fuzzy large‐scale system with time delays. The considered large‐scale system is composed of several T‐S fuzzy subsystems. The decentralized parallel distributed compensation (PDC) fuzzy control for each subsystem is designed to stabilize the whole system. Based on Lyapunov criterion, some sufficient conditions are proposed. Moreover, the positive definite matrices Pi and PDC gain Kij can be solved by linear matrix inequality (LMI) toolbox of Matlab. Then, the optimization design method for decentralized control is also considered with respect to a quadratic performance index. Finally, numerical examples are given and compared with those of Zhang et al., 2004 to illustrate the effectiveness and less conservativeness of our method.

Modeling and simulation of InAs/GaAs quantum dot lasers

Based on the analysis of carrier dynamics in quantum dots (QDs), the numerical model of InAs/GaAs QD laser is developed by means of complete rate equations. The model includes four energy levels and among them three energy levels join in lasing. A simulation is conducted by MATLAB according to the rate equation model we obtain. The simulation results of PI characteristic, gain characteristic and intensity modulation response are reasonable. Also, the relations between the left facet reflectivity of laser cavity and threshold current as well as modulation bandwidth are studied. It is indicated that the left facet reflectivity increasing can result in reduced threshold current and improved modulation bandwidth, which is in accordance with experimental results. The internal mechanism of QD lasers is fully described with the rate equation model, which is helpful for QD lasers research.