Zero Steady-state Error Research Articles

Automobile active tilt control based on active suspension

The rolling control of a car that focuses on reducing the roll angle passively has limited performance of increasing handling stability, passing speed, ride comfort, and rollover prevention while turning. This project presents a method for controlling an automobile to tilt toward the turning direction using active suspension. A 6-degree-of-freedom vehicle model with a 2-degree-of-freedom steering model and a 4-degree-of-freedom tilting model is established. The active tilt sliding mode controller, which causes zero steady-state tilt angle error, is established after the desired tilt angle is determined by dynamic analysis. Simulation results confirm the effectiveness of the control method. The proposed controller reduces the perceived lateral acceleration and the lateral load transfer rate, thereby effectively improving handling stability, ride comfort, and vehicle speed, meanwhile decreasing the possibility of rollover while turning.

A Modified Multifrequency Passivity-Based Control for Shunt Active Power Filter With Model-Parameter-Adaptive Capability

The passivity-based control (PBC) has a better control performance using an accurate mathematical model of the control object. It can offer an alternative tracking control scheme for the shunt active power filter (SAPF). However, the conventional PBC-based SAPF cannot achieve zero steady-state current error with the inaccurate model. In order to handle the steady-state current error of the conventional PBC-based SAPF, a modified PBC scheme is proposed, where an error proportional-integral regulator is inserted into the coupling loop. The design of the modified PBC is implemented in the dc model, transferred from the ac model by using a fast Fourier transform. A comparative performance analysis is carried out between the conventional and modified PBC-based SAPFs. A 380-V/75-A prototype is developed, where the results demonstrate that by using the modified PBC, the zero steady-state current error of SAPF can be achieved at the selected frequency or frequencies, even though the model used is not so accurate.

Variable- and Fixed-Switching-Frequency-Based HCC Methods for Grid-Connected VSI With Active Damping and Zero Steady-State Error

This paper presents variable- and fixed-switching-frequency-based hysteresis current control (HCC) methods for single-phase grid-connected voltage-source inverters with LCL filter. The main feature of the proposed HCC methods is that the reference inverter current is generated through a proportional-resonant (PR) controller for achieving zero steady-state error in the grid current. The consequence of using the PR controller is eliminating the need for using derivative operations in generating the reference inverter current. Furthermore, the active damping method is employed to damp the LCL resonance. An equation is derived for variable-switching frequency. Fixed-switching frequency operation is achieved by modulating the hysteresis band. The performance of both HCC methods has been validated by simulation and experimentally. It is reported that the proposed HCC methods not only preserve the inherent features of the conventional HCC methods, but also damp the LCL resonance using an active damping method and guarantee zero steady-state error in the grid current.

English

English

Predictive control strategies for wind turbine system based on permanent magnet synchronous generator

In this paper, Model Predictive Control and Dead-beat predictive control strategies are proposed for the control of a PMSG based wind energy system. The proposed MPC considers the model of the converter-based system to forecast the possible future behavior of the controlled variables. It allows selecting the voltage vector to be applied that leads to a minimum error by minimizing a predefined cost function. The main features of the MPC are low current THD and robustness against parameters variations. The Dead-beat predictive control is based on the system model to compute the optimum voltage vector that ensures zero-steady state error. The optimum voltage vector is then applied through Space Vector Modulation (SVM) technique. The main advantages of the Dead-beat predictive control are low current THD and constant switching frequency. The proposed control techniques are presented and detailed for the control of back-to-back converter in a wind turbine system based on PMSG. Simulation results (under Matlab-Simulink software environment tool) and experimental results (under developed prototyping platform) are presented in order to show the performances of the considered control strategies.

Generic Nonsmooth <inline-formula> <tex-math notation="LaTeX">$\mathcal {H}_{\infty }$ </tex-math></inline-formula> Output Synthesis: Application to a Coal-Fired Boiler/Turbine Unit With Actuator Dead Zone

Actuator nonidealities, such as backlash, dead zone, and others, present in a number of industrial systems, are known to severely degrade system performance. Providing nonconservative closed-loop robust performance guarantees for these systems in a consistent manner has been an open problem. For example, in boiler/turbine units, the turbine valve position actuation for manipulating steam flow rate is characterized by a small mismatch between the turbine valve command and the actual valve position, producing a small steady-state regulation error in the plant outputs. The standard linear $\mathcal {H}_{\infty }$ controller designed to provide zero steady-state error regulation drives this error to zero, producing the undesirable oscillations in the control signals and the plant outputs. This paper develops a nonsmooth $\mathcal {H}_{\infty }$ output regulator theory addressing this problem and applies this theory to the experimentally validated boiler/turbine model with actuator dead zone. The simulation results showing a considerable performance improvement are given.

DC-Link Voltage Coordinated-Proportional Control for Cascaded Converter With Zero Steady-State Error and Reduced System Type

Cascaded converter is formed by connecting two subconverters together, sharing a common intermediate dc-link voltage. Regulation of this dc-link voltage is frequently realized with a proportional-integral (PI) controller, whose high gain at dc helps to force a zero steady-state tracking error. Such precise tracking is, however, at the expense of increasing the system type, caused by the extra pole at the origin introduced by the PI controller. The overall system may, hence, be tougher to control. To reduce the system type while preserving precise dc-link voltage tracking, this paper proposes a coordinated control scheme for the cascaded converter, which uses only a proportional dc-link voltage regulator. The resulting converter is thus dynamically faster, and when compared with the conventional PI-controlled converter, it is less affected by impedance interaction between its two subconverters. The proposed scheme can be used with either unidirectional or bidirectional power flow, and has been verified by simulation and experimental results presented in this paper.

General Unified Integral Controller With Zero Steady-State Error for Single-Phase Grid-Connected Inverters

Current regulation is crucial for operating single-phase grid-connected inverters. The challenge of the current controller is how to fast and precisely track the current with zero steady-state error. This paper proposes a novel feedback mechanism for the conventional proportional integral controller. It allows the steady-state error suppression with no need of additional complex control algorithms such as the synchronous reference frame transformation. Five alternative implementation methods are comparatively evaluated from the viewpoint of the steady-state and dynamic responses. Further, the theoretical analysis done indicates that the widely used P+Resonant control is just a special case of the proposed control solution. The time-domain simulation in MATLAB/Simulink and experimental results from a TMS320F2812 DSP-based laboratory prototypes are in good agreement, which verify the effectiveness of the proposed generalized method.

Zero‐steady‐state‐error compensation method in application of peak current mode buck converter with fast transient response

A novel zero-steady-state-error (ZSSE) compensation technique based on an accurate small signal model of peak current mode buck converter is proposed for optimising the microprocessors with low power consumption needing high-definition voltage scaling. This technique eliminates the steady-state error of output voltage without negatively affecting the transient response. The main parasitic parameters of the buck converter are taken into consideration to design an excellent ZSSE compensation module; the relationships between the parameters of the compensation circuit and parameters of the other parts of the converter have been derived in this study. This technique has been implemented on a prototype. The validity of this method is shown and confirmed by test results.

Robust voltage‐mode controller for DC–DC boost converter

In this study, a robust voltage-mode controller for DC–DC boost converter subject to time varying parameters is presented. The time-varying parameters of the boost converter are considered as the input voltage, the load resistance and the passive components (inductor and capacitor). The proposed controller, designed in discrete time, is based on the sliding mode control combined with the model-reference approach. In addition to this controller structure, the system dynamics are augmented by integral action to ensure zero steady-state tracking error. Experimental results, obtained from prototype operating at the fixed frequency, are provided to demonstrate the excellent robustness of the designed controller against wide input voltage variations and large load transients and also variation in passive components.

The Static Analysis of Pilot Type Zero Steady-State Error of Water Hydraulic Pressure Reducing Valve

The Static Analysis of Pilot Type Zero Steady-State Error of Water Hydraulic Pressure Reducing Valve

The Static Analysis of Pilot Type Zero Steady-State Error of Water Hydraulic Pressure Reducing Valve

The static-state error is existed in the pressure valve, coupled with the characteristics of high vaporization pressure, low viscosity, and small compressibility, so that the fluid dynamics and friction force of hydraulic pressure valve are increased. The pressure valve will easily come up with produce cavitation erosion and wire drawing. Those appearances would seriously affect the performance of the pressure valve and its life cycle. A new type of static water pressure reducing valve is designed in this paper. It has a special structure which can complete the internal dynamic pressure feedback of the valve. The static mathematical model of value is established. And the static characteristic is analysed by using MATLAB simulation, which provides the static pressure characteristic curve, static pressure flow curve. It comes up with a result that this valve has good static pressure, and high precision pressure regulator.

The Optimal Controller Design of Zero Steady-State Error for Nonlinear Systems with Composite Disturbances

This paper considers the optimal rejection with Zero Steady-State Error for nonlinear systems with step and ramp composite disturbances. Firstly, the nonlinear system model with composite disturbances is transformed into linear system with disturbances, then we construct an augmented linear system without disturbances. With respect to the quadratic performance indexes of infinite horizon, consequently, the problem of disturbance rejection with zero steady-state error is transformed into the problem of designing an optimal controller for the augmented plant without disturbances, which can eliminate static error. Thus the disturbances can unfold of the signal through the Taylor series for the form of polynomial function of time, and obtain optimal controller design approach to eliminate the general disturbance. Finally, a practical example is given to illustrate the effectiveness of the theory.

Current Control of Grid-Connected Boost Inverter With Zero Steady-State Error

This paper proposes a current control strategy with zero steady-state tracking error for grid-connected boost inverters. Two boost converters are controlled separately to achieve both output current tracking and balanced output voltages. Based on cascading control and feedback linearization, the inner- and outer-loop controllers are as the combination of the inversion of boost converter model and the output error compensation. After the boost converter model is linearized, proportional and resonant controllers are derived from the internal model principle to achieve zero tracking error. Experimental results confirm that the proposed control achieves good current tracking to meet stringent grid-connection harmonics standards.

A Modified Stationary Reference Frame-Based Predictive Current Control With Zero Steady-State Error for LCL Coupled Inverter-Based Distributed Generation Systems

This paper proposes a modified stationary reference frame-based predictive current controller with zero steady-state error for LCL coupled inverter-based distribution generation systems. Analytical expressions for the predictive current control error sources are investigated. The stability margin for the predictive current gain is derived. Online adaptive control for the grid voltage is embedded in the control system to eliminate steady-state real and reactive power errors. The grid voltage estimation expressions for sensorless operation are employed to enhance system robustness and performance. Finally, simulated and practical results verify the derived expressions and the proposed control system performance.

Determining maximum load-carrying capacity of robots using adaptive robust neural controller

SUMMARYIn this paper, the combination of neural network (NN), proportional derivative (PD), and robust controller are used for determining the maximum load-carrying capacity (MLCC) of articulated robots, subject to both actuator and end-effector deflection constraints. The proposed technique is then applied to articulated robots, and MLCC is obtained for a given trajectory. In the practical simulations, it's impossible to determine the parameters of robot model exactly, so the trajectory tracking performance of the proportional integral derivative (PID) and computed torque methods significantly decrease. The PD control of robot has major problem, it cannot guarantee zero steady state error. For this reason, the NN controller with PD and robust controller are used. The multilayer neural network is also used to compensate gravity and friction effects. By using Lyapunov Direct Method it is shown that the stability of closed loop system would be guaranteed, if the weights of multilayer had certain learning rules. Standard back propagation algorithm is used as a learning algorithm to update the connection weights of the NN controller. The simulation results of the proposed adaptive robust neural network (ARNN) controller are compred with sliding mode and feedback linearization methods for flexible joint robot, and compared with open loop controller for 3D industrial robot. The obtained results assured the robustness and improvement in MLCC in the presence of uncertainties in dynamic model of the robot arm and external disturbances. In fact, adaptive robust NN controller suppresses disturbances accurately and achieves very small errors between commanded and actual trajectories.

Load frequency control strategies: A state-of-the-art survey for the researcher

Global analysis of the power system markets shows that load frequency control (LFC) is one of the most profitable ancillary services of these systems. This service is related to the short-term balance of energy and frequency of the power systems and acquires a principal role to enable power exchanges and to provide better conditions for electricity trading. The main goal of the LFC problem is to maintain zero steady-state errors for frequency deviation and good tracking of load demands in a multi-area power system. This paper provides an overview of control strategies for researchers, as well as of their current use in the field of LFC problems. The history of control strategies is outlined. Various control methodologies based on the classical and optimal control, robust, adaptive, self-tuning control, VSC systems, digital and artificial intelligent/soft computing control techniques are discussed. We make various comparisons between these approaches, and the main advantages and disadvantages of the methods are presented. Finally, the investigations of the LFC problem incorporating BES/SMES, wind turbines and FACTs devices have also been discussed.

PD Control of robot with velocity estimation and uncertainties compensation

Normal industrial PD control of Robot has two drawbacks: it needs joint velocity sensors, and it cannot guarantee zero steady-state error. In this paper we make two modifications to overcome these ...

PD CONTROL OF ROBOT WITH VELOCITY ESTIMATION AND UNCERTAINTIES COMPENSATION

Normal industrial PD control of Robot has two drawbacks: it needs joint velocity sensors, and it cannot guarantee zero steady-state error. In this paper we make two modifications to overcome these problems. High-gain observer is applied to estimate the joint velocities, and an RBF neural network is used to compensate gravity and friction. We give a new proof for high-gain observer, which explains a direct relation between observer gain and observer error. Based on Lyapunov-like analysis, we also prove the stability of the closed-loop system if the weights of RBF neural networks have certain learning rules and the observer is fast enough.

CAutoCSD-evolutionary search and optimisation enabled computer automated control system design

This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of “computer-aided control system design” (CACSD) to novel “computer-automated control system design” (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency domains. Such performance-prioritised unification is aimed at relieving practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-commitment to such schemes. With recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytical and practical, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, and meets multiple objectives in the design of an LTI controller for a non-minimum phase plant and offers a high-performance LTI controller network for a non-linear chemical process.