scholarly journals An LQR-Based Controller Design for an LCL-Filtered Grid-Connected Inverter in Discrete-Time State-Space under Distorted Grid Environment

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2062 ◽  
Author(s):  
Thuy Tran ◽  
Seung-Jin Yoon ◽  
Kyeong-Hwa Kim
Keyword(s):  
State Feedback ◽  
System State ◽  
State Variables ◽  
Linear Quadratic ◽  
Control Approach ◽  
Distorted Grid ◽  
Control Scheme ◽  
Full State ◽  
Full State Feedback ◽  
Grid Connected Inverter

In order to alleviate the negative impacts of harmonically distorted grid conditions on inverters, this paper presents a linear quadratic regulator (LQR)-based current control design for an inductive-capacitive-inductive (LCL)-filtered grid-connected inverter. The proposed control scheme is constructed based on the internal model (IM) principle in which a full-state feedback controller is used for the purpose of stabilization and the integral terms as well as resonant terms are augmented into a control structure for the reference tracking and harmonic compensation, respectively. Additionally, the proposed scheme is implemented in the synchronous reference frame (SRF) to take advantage of the simultaneous compensation for both the negative and positive sequence harmonics by one resonant term. Since this leads to the decrease of necessary resonant terms by half, the computation effort of the controller can be reduced. With regard to the full-state feedback control approach for the LCL-filtered grid connected inverter, additional sensing devices are normally required to measure all of the system state variables. However, this causes a complexity in hardware and high implementation cost for measurement devices. To overcome this challenge, this paper presents a discrete-time current full-state observer that uses only the information from the control input, grid-side current sensor, and grid voltage sensor to estimate all of the system state variables with a high precision. Finally, an optimal linear quadratic control approach is introduced for the purpose of choosing optimal feedback gains, systematically, for both the controller and full-state observer. The simulation and experimental results are presented to prove the effectiveness and validity of the proposed control scheme.

scholarly journals Frequency-Adaptive Current Controller Design Based on LQR State Feedback Control for a Grid-Connected Inverter under Distorted Grid

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2674 ◽  
Author(s):  
Rizka Bimarta ◽  
Thuy Vi Tran ◽  
Kyeong-Hwa Kim
Keyword(s):  
Feedback Control ◽  
Discrete Time ◽  
State Feedback ◽  
State Feedback Control ◽  
Frequency Variation ◽  
Grid Voltage ◽  
Frequency Information ◽  
Full State ◽  
Full State Feedback ◽  
Grid Connected Inverter

This paper proposes a frequency-adaptive current control design for a grid-connected inverter with an inductive–capacitive–inductive (LCL) filter to overcome the issues relating to both the harmonic distortion and frequency variation in the grid voltage. The current control scheme consists of full-state feedback control to stabilize the system and integral control terms to track the reference in the presence of disturbance and uncertainty. In addition, the current controller is augmented with resonant control terms to mitigate the harmonic component. The control scheme is implemented in the synchronous reference frame (SRF) to effectively compensate two harmonic orders at the same time by using only one resonant term. Moreover, to tackle the frequency variation issue in grid voltage, the frequency information which is extracted from the phase-locked loop (PLL) block is processed by a moving average filter (MAF) for the purpose of eliminating the frequency fluctuation caused by the harmonically distorted grid voltage. The filtered frequency information is employed to synthesize the resonant controller, even in the environment of frequency variation. To implement full-state feedback control for a grid-connected inverter with an LCL filter, all the state variables should be available. However, the increase in number of sensing devices leads to the rise of cost and complexity for hardware implementation. To overcome this challenge, a discrete-time full-state current observer is introduced to estimate all the system states. When the grid frequency is subject to variation, the discrete-time implementation of the observer in the SRF requires an online discretization process because the system matrix in the SRF includes frequency information. This results in a heavy computational burden for the controller. To resolve such a difficulty, a discrete-time observer in the stationary reference frame is employed in the proposed scheme. In the stationary frame, the discretization of the system model can be accomplished with a simple offline method even in the presence of frequency variation since the system matrix does not include the frequency. To select desirable gains for the full-state feedback controller and full-state observer, an optimal linear quadratic control approach is applied. To validate the practical effectiveness of the proposed frequency-adaptive control, simulation and experimental results are presented.

scholarly journals Full-State Feedback Control Design for Shape Formation using Linear Quadratic Regulator

2020 ◽  
Vol 2 (2) ◽  
pp. 83
Author(s):  
Muhamad Rausyan Fikri ◽  
Djati Wibowo Djamari
Keyword(s):  
Feedback Control ◽  
State Feedback ◽  
Linear Quadratic Regulator ◽  
State Feedback Control ◽  
Linear Quadratic ◽  
Shape Formation ◽  
Full State ◽  
Full State Feedback ◽  
Input Response ◽  
Agent Coordination

This study investigated the capability of a group of agents to form a desired shape formation by designing the feedback control using a linear quadratic regulator. In real application, the state condition of agents may change due to some particular problems such as a slow input response. In order to compensate for the problem that affects agent-to-agent coordination, a robust regulator was implemented into the formation algorithm. In this study, a linear quadratic regulator as the full-state feedback of robust regulator method for shape formation was considered. The result showed that a group of agents can form the desired shape (square) formation with a modification of the trajectory shape of each agent. The results were validated through numerical experiments.

scholarly journals Application of LQR Full-State Feedback Controller for Rotational Inverted Pendulum

2021 ◽  
Vol 2111 (1) ◽  
pp. 012006
Author(s):  
N Setiawan ◽  
G N P Pratama
Keyword(s):  
State Feedback ◽  
Inverted Pendulum ◽  
Equilibrium Points ◽  
Linear Quadratic Regulator ◽  
Feedback Controller ◽  
Control Law ◽  
Linear Quadratic ◽  
State Feedback Controller ◽  
Full State ◽  
Full State Feedback

Abstract The rotational inverted pendulum is an interesting subject for some researchers, especially control engineers. Its nonlinear and underactuated characteristic make it quite challenging to stabilize it. Hence, a proper control law is a must to make it stable. Here, in this paper, we present a control law using LQR (Linear-Quadratic Regulator) to stabilize the rotational inverted pendulum. The experiments are carried out by linearizing the model and simulate the response in MATLAB. The results show that the controller succeeds to stabilize the states of rotational inverted pendulum to their respective equilibrium points. Even more, it provides zero settling errors.

scholarly journals Sistem Kendali Eddy Current Brakes Dinamometer menggunakan Linear Quadratic Regulator (LQR)

2021 ◽  
Vol 9 (4) ◽  
pp. 923
Author(s):  
MUHAMMAD ARROFIQ ◽  
LUKMAN SIDIQ NUGROHO ◽  
FAHMIZAL FAHMIZAL ◽  
ESA APRIASKAR
Keyword(s):  
Eddy Current ◽  
Pid Control ◽  
State Feedback ◽  
Linear Quadratic Regulator ◽  
Control Technique ◽  
Linear Quadratic ◽  
Matlab Simulink ◽  
Braking Performance ◽  
Full State ◽  
Full State Feedback

ABSTRAKMakalah ini memberikan analisis perbandingan antara teknik kendali klasik yaitu kendali PID dengan teknik kendali modern pada sistem Eddy current brakes dinamometer. Eddy current brakes merupakan sistem pengereman modern yang membutuhkan sebuah sistem kendali untuk menunjang kinerja pengereman. Selama ini kendali PID lebih sering digunakan, namun di beberapa kondisi dinilai kurang optimal. Dengan demikian, diperlukan pengembangan kendali yang modern dan optimal yaitu full state feedback Linear Quadratic Regulator (LQR). Perbandingan respon waktu pengereman disimulasikan menggunakan Matlab/Simulink. Hasil simulasi menunjukkan respon waktu pengereman pada kendali LQR lebih baik dibandingkan dengan kendali PID, dengan Ts = 2.12 detik, Tr = 1.18 detik, dan tanpa overshoot. Adapun kendali PID, meskipun menghasilkan Ts = 0.27 detik dan Tr = 0.18 detik, namun demikian masih terdapat overshoot sebesar 0.7%.Kata kunci: Eddy brakes, PID, LQR, Matlab ABSTRACTThis paper provides a comparative analysis between PID control as a classical control technique and modern control technique in the dinamometer Eddy current brakes system. Eddy current brakes is a modern braking system that requires a control system to support the braking performance. PID control is often used to be implemented but in some conditions it is less optimal. Therefore, it is necessary to develop a modern and optimal control, such as a full state feedback Linear Quadratic Regulator (LQR). The comparison of the braking time responses were simulated using Matlab/Simulink. The simulation results show that the response of LQR control is better than the PID, with Ts = 2.12 seconds, Tr = 1.18 seconds, and without overshoot. On the other side, PID control, although having Ts = 0.27 seconds and Tr = 0.18 seconds, there is still an overshoot about 0.7%.Keywords: Eddy brakes, PID, LQR, Matlab

An Active Suspension Strategy Using State Reconstruction

1990 ◽  
Author(s):  
P. K. Warner ◽  
M. J. Vanderploeg ◽  
J. E. Shannan
Keyword(s):  
Kalman Filter ◽  
State Feedback ◽  
Active Suspension ◽  
Response Surfaces ◽  
State Variables ◽  
Ground Vehicles ◽  
Suspension Systems ◽  
Full State ◽  
Full State Feedback ◽  
The Ideal

Abstract Many studies have shown that active suspensions using full state feedback can significantly improve the ride performance of ground vehicles. Using a seven degree of freedom vehicle model and a Kalman filter, this paper investigates the effects of reduced state feedback on active and semi-active suspension systems. Particular attention is given to control of pitch motion, which is usually considered to be the most uncomfortable of rigid body motions. The effects of phase differences between the tires is presented using frequency response surfaces. The Kalman filter, which reconstructs the state variables from a reduced set of observed variables, yields improvements in ride which compare well with the ideal active suspension without the need to measure all states. The Kalman filter system with active dampers instead of ideal actuators also yields ride improvements approaching the ideal systems.

scholarly journals Suboptimal Regulation of a Class of Bilinear Interconnected Systems with Finite-Time Sliding Planning Horizons

2008 ◽  
Vol 2008 ◽  
pp. 1-26 ◽  
Author(s):  
M. de la Sen ◽  
Aitor J. Garrido ◽  
J. C. Soto ◽  
O. Barambones ◽  
I. Garrido
Keyword(s):  
Control Law ◽  
State Variables ◽  
Linear Quadratic ◽  
Equivalent Representation ◽  
Quadratic Performance Index ◽  
Matrix Sequence ◽  
Control Scheme ◽  
Quadratic Performance ◽  
System Equations ◽  
Riccati Matrix

This paper focuses on the suboptimization of a class of multivariable discrete-time bilinear systems consisting of interconnected bilinear subsystems with respect to a linear quadratic optimal regulation criterion which involves the use of state weighting terms only. Conditions which ensure the controllability of the overall system are given as a previous requirement for optimization. Three transformations of variables are made on the system equations in order to implement the scheme on an equivalent linear system. This leads to an equivalent representation of the used quadratic performance index that involves the appearance of quadratic weighting terms related to both transformed input and state variables. In this way, a Riccati-matrix sequence, allowing the synthesis of a standard feedback control law, is obtained. Finally, the proposed control scheme is tested on realistic examples.

Flexible-Joint Humanoid Balancing Augmentation via Full-State Feedback Variable Impedance Control

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Emmanouil Spyrakos-Papastavridis ◽  
Jian S. Dai
Keyword(s):  
State Feedback ◽  
Position Control ◽  
Impedance Control ◽  
Humanoid Robots ◽  
Flexible Joint ◽  
Model Free ◽  
Floating Base ◽  
Full State ◽  
Full State Feedback ◽  
Series Elastic Actuators

Abstract This paper attempts to address the quandary of flexible-joint humanoid balancing performance augmentation, via the introduction of the Full-State Feedback Variable Impedance Control (FSFVIC), and Model-Free Compliant Floating-base VIC (MCFVIC) schemes. In comparison to rigid-joint humanoid robots, efficient balancing control of compliant bipeds, powered by Series Elastic Actuators (or harmonic drives), requires the design of more sophisticated controllers encapsulating both the motor and underactuated link dynamics. It has been demonstrated that Variable Impedance Control (VIC) can improve robotic interaction performance, albeit by introducing energy-injecting elements that may jeopardize closed-loop stability. To this end, the novel FSFVIC and MCFVIC schemes are proposed, which amalgamate both collocated and non-collocated feedback gains, with power-shaping signals that are capable of preserving the system's stability/passivity during VIC. The FSFVIC and MCFVIC stably modulate the system's collocated state gains to augment balancing performance, in addition to the non-collocated state gains that dictate the position control accuracy. Utilization of arbitrarily low-impedance gains is permitted by both the FSFVIC and MCFVIC schemes propounded herein. An array of experiments involving the COmpliant huMANoid reveals that significant balancing performance amelioration is achievable through online modulation of the full-state feedback gains (VIC), as compared to utilization of invariant impedance control.

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