PI Compensator Research Articles

Design and testing of fabric-based portable soft exoskeleton glove for hand grasping assistance in daily activity

Hand exoskeleton robots have been developed as rehabilitation robots and assistive devices. Based on the material used, they can be soft or hard exoskeletons. Soft materials such as fabric can be used as a component of the wearable robot to increase comfortability. In this paper, we proposed an affordable soft hand exoskeleton based on fabric and motor-tendon actuation for hand flexion/extension motion assistance in daily activities. On-off control and PI compensator were implemented to regulate finger flexion and extension of the soft exoskeleton. The controllers were embedded into a microcontroller using Simulink software. The input signal command comes from the potentiometer and electromyography (EMG) sensor to drive the flexion/extension movement. Based on the experiments, the proposed controller successfully controlled the exoskeleton hand to facilitate a user in grasping various objects. The proposed soft hand exoskeleton is lightweight, comfortable, portable, and affordable, making it easily manufactured using available hardware and open-source code. The developed soft exoskeleton is a potential assistive device for a person who lost the ability to grasp objects.

Analysis and Implementation of a Switched Reluctance Generator in Connection with the Three-Phase Power Grid and Proposal of an Anti-Islanding Strategy

This paper presents a dynamics study of the Switched Reluctance Generator (SRG) dynamics when connected to a three-phase AC power grid. A mathematical model that includes magnetic saturation is used to represent the SRG, which is driven by an asymmetric half bridge converter. Output generated voltage is smoothed with a shunt capacitor leading to a DC link voltage. This voltage is regulated using a PI compensator that controls the magnetizing angle of the generator phases. It is shown that putting a freewheeling stage between the magnetizing and the demagnetizing states per phase, allows the best use for a better usage of the mechanical power in electromechanical conversion process. Injection of active power in the grid is performed by two PI compensators that determine the modulation indexes to each sinusoidal PWM modulators that drive the three phases of the converter. This work also proposes the implementation of an islanding detection method for distributed generation (DG) systems. This method is based on voltage and frequency parameters detection. It proved to be robust and useful to detect the islanding under different load conditions and the output of the power grid.

Design and Optimization of Voltage Mode PWM Control of DC-DC Buck Converter with a PI-Lead Compensator Using the Simulated Annealing Algorithm

This paper presents a method for improving the performance of DC-DC Buck Converter Systems using voltage mode Pulse Width Modulation (PWM) control. We explore the effectiveness of Proportional-Integral (PI) and Lead Compensator controllers in enhancing system stability, minimizing voltage fluctuations, and improving load response. The system is modeled through transfer functions, and the controllers' impacts are analyzed both individually and in tandem. A key contribution of this work is the optimization of the PI-Lead Compensator parameters utilizing the Simulated Annealing Algorithm, which is fine-tuned to improve phase margin, gain crossover frequency, and steady state error. These parameters are critical for optimizing the system’s output performance. Through MATLAB simulations, we demonstrate the iterative process of parameter optimization and validate the algorithm's efficacy in managing the DC-DC Buck Converter. The results highlight the enhanced performance achieved with the optimized parameters, providing a viable solution for effective control of DC-DC Buck Converter Systems.

A novel fractional-order dead-time compensating controller for the wireless networks

Wireless technology is becoming increasingly critical in industrial environments in recent years, and the popular wireless standards are WirelessHART, ZigBee, WLAN and ISA100.11a, commonly used in closed-loop systems. However, wireless networks in closed-loop control experience packet loss or drops, system delay and data threats, leading to process instability and catastrophic system failure. To prevent such issues, it is necessary to implement dead-time compensation control. Traditional techniques like model predictive and predictive PI controllers are frequently employed. However, these methods’ performance is sluggish in wireless networks, with processes having long dead times and set-point variations, potentially affecting network and process performance. Therefore, this paper proposes a fractional calculus-based predictive PI compensator for wired and wireless networks in the process control industries. The proposed technique has been simulated and evaluated on industrial process models, including pressure, flow, and temperature, where measurement and control are carried out wirelessly. The wireless network’s performance has been evaluated based on packet loss, reduced throughput, and increased system latency. The proposed compensator outperformed traditional methods, demonstrating superior set-point tracking, disturbance rejection, and delay compensation characteristics in the performance evaluations of the first, second, and third-order systems. Overall, the findings indicate that the proposed compensator enhances wireless networks’ performance in the process control industry and improves system stability and reliability by reducing almost half of the overshoot and settling an average of 8.3927% faster than the conventional techniques in most of the systems.

Modeling and simulation of electrical generation systems based on PEM fuel cell-boost converter using a closed loop PI controller

This paper presents dynamic modeling and control of a proton exchange membrane fuel cell (PEMFC). The system consists of a DC–DC Boost converter, DC–DC regulator, and DC load. The goal of the research is the construction of an emulator of the PEM Fuel Cell stack, that of a device having the same behavior as the real system, and evaluates performances of a stand-alone power system. Since the fuel cell produces DC output voltage that is unregulated. PWM (pulse width modulated) DC–DC converters are assumed to operate in continuous-conduction mode and the PI compensator in the feedback path is designed with voltage-mode control to convert the unregulated voltage into a desired voltage level, during different load variations. The results show the output voltages of the studied PEMFC connected with PWM DC–DC converters during a DC load change are stable. A PEMFC system is modeled using Matlab/Simulink and is interfaced with the mathematical model of fuel cell and various waveforms are presented in the paper.

Design and Analysis of a Buck–Boost DC–DC Converter with Delta-Sigma Modulator Controller

This paper presents a low-ripple and high-efficiency buck–boost DC–DC converter with delta-sigma modulator controller that converts 1.8 V to 1.2 V and 3.3 V. A current and voltage closed-loop controller has been designed to achieve better performance simultaneously such as lower settling-time, steady-state error and over shoot and under shoot. The converter is started in the current controller mode initially, when the output voltage approaches the desired value, the power stage is controlled with the voltage controller mode. PI compensator and a third-order delta-sigma modulator are utilized in the voltage mode. Also, the closed-loop stability of the designed converter has been analyzed with Lyapunov method using converter nonlinear model. This work has been simulated in MATLAB-SIMULINK environment. The performance results show that the maximum efficiency of the closed-loop DC–DC converter is 90% at 5[Formula: see text]MHz switching frequency, and the output voltage ripple is 0.5% and 0.6% for the buck and boost modes, respectively. Also, the simulation results demonstrate the closed-loop stability of the converter in the presence of 10% load variation.

Development of DSP-based TPS fully digital correction magnet power supply

The Taiwan Photon Source (TPS) is a third-generation 3 GeV synchrotron accelerator light source. After successfully operating for ten years since its first light in 2013, various subsystems are undergoing updates. In the context of magnet power supply upgrades, the trend toward digitization and high-precision modulation control is driving advancements worldwide. This study focuses on developing a fully digital correction magnet power supply (FDCMPS) based on a digital signal processor (DSP). The prototype utilizes a low-power, floating-point DSP with multiple communication functionalities as the core control unit. The output current is converted into digital values using current sensors and high-precision analog-to-digital converters. Discrete PI compensator algorithms are implemented within the DSP to generate pulse-width modulation (PWM) waveforms, driving a full-bridge (H-bridge) converter configuration with metal-oxide-semiconductor field-effect transistors (MOSFET). This forms a complete, fully digital closed-loop current control system. A virtual control interface is designed to operate the FDCMPS state. The control loop design of the prototype has been validated and demonstrates stable output bipolar current performance. When tested with a 0.1 V input reference signal, the prototype achieves a -3 dB bandwidth of 2.03 kHz. Finally, a hardware prototype circuit was constructed in the power supply laboratory, with an input voltage of 48 V, an output current of 10 A, and a maximum power of 400 W. Overall, the developed fully digital correction magnet power supply prototype showcases stable and high-performance output bipolar current performance. The system achieves total harmonic distortion of output current ripple within 0.3 mA peak to peak and long-term stability within ± 15 ppm. The successful implementation of the prototype establishes a solid foundation for advancing magnet power supply technology at the TPS.

Adaptive qXE-LMF Filter for Improving Power Quality Using Grid-Supporting Photovoltaic System

In practice, nonlinear electrical loads pose various power quality (PQ) challenges. Driven by these challenges, a parallel combination of a nonlinear load and a photovoltaic (PV) inverter with adaptive quantum normalized-least mean fourth ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF) filter is proposed and experimentally validated to detect and compensate for the harmonics in harmonically contaminated currents. A scheme with an adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF using fundamental weight components is used to generate the harmonics in the inverter output current thereby improving the PQ of the grid supply. The resulting grid current is pure and balanced; the PV inverter connected in parallel with the nonlinear load provides reactive and harmonic current support. Practically, the adaptive feature enables the online learning of filter weights of the load current harmonics to guarantee unconditionally balanced sinusoidal grid current. The proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF filter ensures fast convergence and minimum steady-state oscillations in the grid reference currents. An improved anti-windup PI compensator is used to ensure dc-link voltage stabilization. The practicality of the proposed adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF filter is experimentally demonstrated using a three-phase four-wire uncontrolled rectifier-based nonlinear load. The experimental results also demonstrate the robustness of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> XE-LMF filter against changes in solar insolation level and nonlinear loads.

Simplified MIMO design of observer-based PI control in view of input saturation

Abstract In observer-based control integral or controller windup can systematically be prevented by the observer technique, i.e., by feeding the saturated plant input signal into the observer. This prevents all windup effects caused by the dynamics of the compensator. The possibly remaining windup effects are then the same as if constant state feedback control had been applied. When using the classic approach for robust rejection of persistent disturbances the state-plus-disturbance observer is subdivided into the state observer and the controlled signal model. Thus the observer technique is only applicable when taking additional measures or when resorting to a recently published dual design method. Here, a very simple design for MIMO PI compensators is suggested which directly yields the basis for the observer technique.

Large-Signal Stability Analysis and Design of Finite-Time Controller for the Electric Vehicle DC Power System

In the electric vehicle dc power system (EVDCPS), a motor or converter can be regarded as a constant power load (CPL) when tightly controlled. Different from the resistive load, CPL may make the EVDCPS unstable. Thus, in addition to less overshoot and shorter setting time, the controller of the converter applied in EVDCPS should maintain the system stable. In this article, the finite-time controller (FTC) is proposed based on exact feedback linearization (EFL) to stabilize the EVDCPS feeding CPL. First, to handle the nonlinearity caused by the CPL, the affine nonlinear model of EVDCPS is transformed into the Brunovsky canonical form by using EFL. Then, the finite-time control is adopted and a PI compensator is designed to eliminate the steady-state error. Under the proposed control algorithm, rigorous proofs indicate that not only the closed system can be large-signal stable, but also the EVDCPS bus voltage can converge the reference in finite time. Furthermore, to reduce the design difficulty of FTC, the backstepping method is adopted to design a backstepping finite-time controller(BFTC). Finally, simulations and experiments of FTC and BFTC are carried out. Results indicate that both FTC and BFTC have large-signal stability, and although the robustness of BFTC is inferior to FTC, the setting time and overshoot are greatly improved compared with the traditional linear feedback controller.

Design and implementation of an internal model controller applied to MPPT PV systems using phase‐shift full‐bridge DC–DC converter

AbstractThis paper presents the design of an internal model controller with one degree of freedom (1DOF‐IMC) that will be applied to a full‐bridge DC–DC converter driven by phase‐shift PWM. This DC–DC converter will be used in photovoltaic systems for maximum power point tracking (MPPT), with the objective of developing a single‐phase micro‐inverter connected to the grid integrated to the photovoltaic module. It will be presented the mathematical modeling of this converter to control the input voltage aiming the application in MPPT and the design of the respective controller. The proposal testing and validation strategy was performed by comparison with a PI compensator. Simulations and experimental results will be presented and the performance of both controllers are evaluated and discussed. Both control strategies were discretized with the sampling frequency at 20 kHz and implemented in a floating point using the Texas Instruments® DSC TMS320F28335.

Design and Implementation of an IMC-1DOF Controller Applied to MPPT Photovoltaic Systems Using ZVS Full-Bridge DC-DC Converter

This paper presents the design of an Internal Model Control – 1 Degree of Freedom (IMC-1DOF) controller applied to a Zero Voltage Switching (ZVS) Full-Bridge DC-DC converter that will be used in photovoltaic systems for Maximum Power Point Tracking (MPPT), with the objective of developing a single phase micro inverter. It will be presented the mathematical modeling of this converter to control the input voltage aiming the application in MPPT and the design of the respective controller IMC-1DOF. The proposal testing and validation strategy was performed by comparison with a PI compensator. The performance of both controllers are evaluated and discussed.

Implementation and Control of Two Input Boost Converter with Voltage Multiplier Cell Based on PI Compensator for High Voltage Applications

Implementation and Control of Two Input Boost Converter with Voltage Multiplier Cell Based on PI Compensator for High Voltage Applications

Simple Circuits Recognize Parametric Blames in Multi-Input Simple Circuits

The point of this paper is to recognize parametric blames in multi-input simple circuits by addressing for the coefficients of a polynomial relapse model utilizing conventional direct least squares strategies, with some consideration applied in the arrangement. The multi-input circuit yield is communicated as far as more than one info factors utilizing polynomial coefficients. In the proposed approach, the worth of every part of the circuit under test (CUT) is differed inside its resistance limit utilizing Monte-Carlo reproduction to figure its deficiency free polynomial coefficient limits. The CUT is then proclaimed flaw free or broken dependent on the aftereffect of the examination of its assessed polynomial coefficients with the issue free coefficients. As far as we could possibly know, parametric flaw recognition in multi-input simple circuits utilizing polynomial relapse demonstrating is endeavored without precedent for the writing. The adequacy of the proposed strategy is exhibited by means of two contextual investigations, in particular, a lead slack circuit and the PI compensator of a pinnacle current-modecontrolled buck-type exchanging converter.

Design and Implementation of a Fuzzy Control System Applied to a 6 × 4 SRG

This article presents an experimental methodology to control the voltage generated from a switched reluctance generator (SRG) using fuzzy logic control. The generated voltage is controlled by varying the demagnetization angle ( θ off), maintaining the magnetization angle ( θ on) fixed. The developed strategy operates on the upper switches of the asymmetric half-bridge converter. The converter topology is used in conjunction with an intermediate freewheeling stage between the steps of magnetization and demagnetization of the phases. The control algorithm was developed in a DSP/FPGA with high processing capacity using LabVIEW graphical platform. Results in open loop and closed loop are presented, subjecting the SRG to variable speeds and load application. For the purpose of performance comparison, a PI compensator has been implemented and tuned for this specific application and the results for both controllers are presented and discussed. For the open-loop tests, the SRG was subjected to variations in the rotor speed, namely, shaft speed varying sinusoidally and triangularly. In these tests, it was observed that the bus voltage suffered great variations. Load variations were also implemented in open loop and, once again, the bus voltage varied significantly. In laboratory tests in closed loop, the SRG was again subjected to variations in sinusoidal and triangular speed and still under load step. In all these experiments, comparisons of results were made between PI controllers and using fuzzy logic control. At the end, it was observed that the imposition of a control loop allowed the bus voltage to be maintained at the preestablished value.

V/f with Stabilizing Loops and MTPA versus Sensorless FOC for PMSM Drives

In this article, a V/f control with two stabilizing loops and maximum torque per ampere (MTPA) control for spoke-PM synchronous motor drives is proposed, and experimentally compared against a sensorless field-oriented control (FOC) strategy based on active flux observer. To improve the drive dynamics, the standard V/f control is enhanced with two stabilizing loops, which provide corrections for stator voltage vector amplitude and phase. The novel voltage amplitude correction is based on MTPA method employing the magnetic energy and active flux concepts. The voltage angle correction employs the active power variation and works only in transient operations, to preserve the synchronism. The sensorless FOC, used for comparison, is based on an active flux observer which uses a PI compensator with the active flux error correction between the voltage and current models. Extensive comparative experimental results in sensorless large speed range, minimum speed being 100 rpm (0.022 p.u.), with speed reversal and quick load torque, validate the two control systems. Good close performances are obtained, FOC being more stable and less influenced by parameter variations.

Design and control of the accelerator grid power supply-conversion system applied to CFETR N-NBI prototype

The acceleration grid power supply (AGPS) rated 200 kV/25 A is a key component devoted to supply the acceleration grids of the China fusion engineering test reactor negative-ion-based neutral beam injector (N-NBI) prototype system. This paper focused on the design and control of the AGPS conversion system (AGPS-CS), with emphasis on the requirement of the wide range output voltage and rise time. A voltage regulation switch at the front of step-down transformer is applied to optimize the grid current and DC-link voltage. Moreover, a new feedforward control strategy with piecewise PI compensator is proposed to improve the characteristics of AGPS. The simulation results of the proposed AGPS-CS are presented, proving the performance of the power supply to achieve the desired requirements.

Simple and Effective Digital Control of a Variable-Speed Low Inductance BLDC Motor Drive

This paper presents a simple digital control applied to a low inductance 5 kW/48 V three-phase brushless DC motor. Controlling the VSI as a full-bridge converter allowed the use of unipolar switching strategy, increasing the output equivalent frequency up to 100 kHz. The aforementioned strategy has made it possible to control the three-phase currents using a single deadbeat controller without a back-EMF feed-forward compensation. Stability analysis is performed to show that the proposed current control presents good transient response under reasonable parametric variations, as well as zero steady-state error. Precise regulation with no overshoot was obtained using an IP controller to regulate the motor speed. Experimental results are presented to validate the theoretical analysis and to compare with a conventional PI compensator and a predictive controller.

Circuit Topology and Small Signal Modeling of Variable Duty Cycle Controlled Three-Level LLC Converter

With a view to regulate the output voltage with fixed frequency, without using any additional component or complex modulation technique, a topology of a variable duty controlled three-level LLC converter is proposed and an equivalent small signal model for Electric Vehicle (EV) charger applications is deduced in this paper. The steady state equations of each operating region are derived in time domain. Based on an Extended Describing Function (EDF) approach, a small signal equivalent circuit is modeled which includes both frequency and duty controlled terms. The equivalent circuit is further simplified to derive a transfer function of duty control to output voltage. The transfer function is verified through simulation software. Analyzing the transfer function, a voltage controller is designed and implemented with a PI compensator. The simulation results of the proposed control schemes are illustrated and discussed. The topology is compared to a conventional frequency control topology and the merits of the proposed topology are presented.

Design and digital implementation of power control strategy for grid connected photovoltaic inverter

&lt;p class="Abstract"&gt;This paper presents the optimization design and a detailed implementation in FPGA (Field-Programmable Gate Array) of a power control strategy. This strategy is based on the phase shift angle of the inverter output voltage with respect to the grid voltage and DSPWM (Digital Sinusoidal Pulse Width Modulation) patterns “Phase shift angle-DSPWM” for an inverter for photovoltaic system connected to the grid. The proposed control can synchronize a sinusoidal inverter output current with a grid voltage and control the power injected into the grid. Detailed development of a digital controller with lower hardware and computation requirement is proposed. Description on the digital implementation of the A/D converter, the PI compensator, the phase shift and the DPWM, is provided. This digital control exhibit simplicity, reduction of the memory requirements and power calculation for the control. The functional structure of this system with digital control has been validated with simulations and experimental results.&lt;/p&gt;