Independent Control Scheme Research Articles

Finite Time Disturbance Observer Based on Air Conditioning System Control Scheme

A novel robust finite time disturbance observer (RFTDO) based on an independent output-finite time composite control (FTCC) scheme is proposed for an air conditioning-system temperature and humidity regulation. The variable air volume (VAV) of the system is represented by two first-order mathematical models for the temperature and humidity dynamics. In the temperature loop dynamics, a RFTDO temperature (RFTDO-T) and an FTCC temperature (FTCC-T) are designed to estimate and reject the lumped disturbances of the temperature subsystem. In the humidity loop, a robust output of the FTCC humidity (FTCC-H) and RFTDO humidity (RFTDO-H) are also designed to estimate and reject the lumped disturbances of the humidity subsystem. Based on Lyapunov theory, the stability proof of the two closed-loop controllers and observers is presented. Comparative simulations are carried out to confirm that the proposed controller outperforms conventional methods and offers greater accuracy of temperature, humidity, and carbon dioxide concentration, having superior regulation performance in terms of a rapid finite time convergence, an outstanding disturbance rejection property, and better energy consumption. In addition to presenting the comparative simulation results from the control applications on the VAV system, the quantitative values are provided to further confirm the superiority of the proposed controller. In particular, the proposed method exhibits the shortest settling time of, respectively, 15 and 40 min to reach the expected temperature and humidity, whereas other comparative controllers require a longer time to settle down.

Q-learning–based practical disturbance compensation control for hypersonic flight vehicle

Aiming at the attitude control problem of hypersonic flight vehicle, a compound control strategy based on the disturbance compensation technique and Q-learning optimization is proposed. Firstly, a three-channel independent control scheme based on the super-twisting extended state observer (STESO) is proposed such that coupling among channels, uncertainties, and external disturbances can be estimated and compensated in real time. Secondly, the Q-learning mechanism is introduced to optimize the control parameters while keeping the control structure unchanged. Lastly, the convergence of the STESO is analyzed by the Lyapunov theory, and some numerical simulation results are carried out to verify the effectiveness of the proposed strategy. Compared with the traditional linear active disturbance rejection control, the proposed method can avoid a lot of manual parameter tuning process and also has better performance.

Observer-based independent joint control for a coupled rigid-flexible manipulator with actuator saturation based on distributed parameter model

This study is concerned with an observer-based independent joint control scheme for a coupled two-link rigid-flexible robotic manipulator considering the effects of actuator saturation and external disturbances. A distributed parameter model of the robotic manipulator system described by ordinary and partial differential equation (ODE-PDE) is derived by using Hamilton’s Principle. An anti-saturation controller is developed to cope with the input saturation problem by using hyperbolic tangent and hyperbolic secant function. Considering the external disturbance, a disturbance observer is designed to estimate the external disturbance. The observer-based independent joint controller can adjust the joint angle and suppress the vibration simultaneously without the need for end-mounted actuators. The extended LaSalle’s Invariance Principle is adopted to strictly prove the asymptotic stability of the robotic manipulator system. The simulation comparisons validate the effectivity of the proposed controllers and observers.

Cascaded boost buck converter for solar power driven stand-alone PMSM drive

This paper deals with the boost-buck converter employed solar power based PMSM (Permanent Magnet Synchronous Motor) drive for variable speed compressor of a refrigeration system. A cascaded boost-buck converter is used as a non-inverting DC-DC converter in between solar PV panel and the PMSM drive. An independent control scheme for cascaded boost-buck converter is used to achieve non-inverting output DC bus voltage with maximum power tracking. It allows variable voltage control at PV panel with reduced voltage stress across the boost-buck converter switches under a desired voltage gain and system efficiency. The ZDC (Zero Direct Current) based vector-oriented control is employed for the VSI (Voltage Source Inverter) for speed control of non-salient pole PMSM drive. A DSC (Digital Signal Controller) dSPACE 1104 is used for real time validation. Simulation results are obtained to validate the performance of proposed control algorithms and test results are obtained with a rooftop solar PV panel.

Enhanced dynamic performance in grid tied bidirectional converter with direct power model predictive control

A direct power control of grid tied converters is proposed here as a preferable future choice. Removal of additional power computations will improve the dynamic response of the control thereby aptly fitting to fast acting micro-grids. The work presented tweaked the basic model predictive control to provide a reference computation directly from the power references. This added feature uses the predictive model to estimate grid voltage in contrast to the conventional sensing method, and further computes the current references directly from the applied power references. While keeping other merits of model predictive control like good harmonic profile and accurate reference tracking, the proposed control ensures a seamless bidirectional power flow between inverter and rectifier modes of operation. A detailed analysis of the proposed control in multiple applications has been presented which validates its potential and proves its efficacy to be a fast, comprehensive and independent converter control scheme.

An Enhanced Control Strategy for AC–DC Matrix Converters Under Unbalanced Grid Voltage

Under unbalanced grid voltage conditions, an ac-dc matrix converter (MC) induces ripple on the dc side, as well as severe grid current harmonics. To overcome these problems, an enhanced control strategy for an ac-dc MC based on an independent control scheme for the active and reactive powers is proposed in this paper. The generated current reference is directly synthesized from instantaneous power analysis in a stationary frame, and a constant dc voltage and current and sinusoidal grid current are obtained. Moreover, the input power factor (IPF) becomes almost unity due to the reactive power control, in spite of unbalanced grid voltage conditions. There is no need to extract grid voltage components such as the positive and negative sequences, and a controller for the grid current is not required, in contrast to previous methods. Thus, the proposed control method can be implemented easily without a large storage requirement. Simulation and experimental results are presented to verify the effectiveness of the proposed control strategy.

Regulation of Linear Input Delayed Systems without Delay Knowledge

In this paper, we propose a delay independent control scheme that regulates to zero the state and the control input of a linear input delayed system whose open loop poles are at the origin or in th...

Flow Control and Scheduling Algorithm of Air-Space-Ground Integrated Networks

Air-space-ground integrated networks are the combine network of the air, space and ground. The ASG-IIN has the problem of level isolated in Multi-level architecture. This article design an Air-space-ground integrated networks layered independent flow control scheme, based on the Air-space-ground framework, which analyze the problems of satellite network flow control, spacecraft flow control and land mobile communications networks flow control. According to the research of complex networks’ situation of establishment in WIT120, secure campus and sturdy power grid, we obtain a high service flow control demand of blend networks. Basing on the token, game theory and neural network, we put forward a series of new method to control the flow in Air-space-ground integrated networks.

Investigation on the potential of individual blade control for lifetime extension

In recent years the focus of wind energy industry is on reducing levelized cost of energy by rotor upscaling. Moreover, a current topic of interest to both industry and academia is the extension of lifetime to existing wind turbines approaching the end of initial design span. Thus, the need for load alleviation technologies integrated in the design process or for retrofit purposes is becoming more relevant. One of these is individual blade pitch control, a recurring topic in research, with known advantages and weaknesses namely the pitch actuator and bearing wear. The present work suggests such a system incorporating three independent controllers with input the root bending moments on the rotating frame. The linear system used for controller design is based on black box identification of non-linear simulations and filters are used both for the input and output. Different setups of the independent blade control scheme are applied on a 10 MW reference turbine, with a large and highly flexible rotor representative of the current industrial status, under wind conditions as defined by relevant certification standards. The investigation aims on evaluating the system’s performance based on the fatigue load alleviation potential for different components as well as identifying the tradeoff for each design choice. Finally, based on basic assumptions the reductions are translated to possible life time extension for each component based on a combined operation where the new controllers are applied for a percentage of the initial 20 year lifetime.

Partially independent control scheme for spacecraft rendezvous in near-circular orbits

Due to the complexity and inconstancy of the space environment, accurate mathematical models for spacecraft rendezvous are difficult to retrieve, which consequently complicates the control tasks. In this paper, a linearized time-varying plant model with consideration of the external perturbations is developed to approximate the spacecraft rendezvous in near-circular orbits. In order to achieve the robust stability with optimal performance cost, a partially independent control scheme is proposed, which consists of a robust anti-windup controller for the in-plane motion and a H∞ controller for the out-of-plane motion. The effectiveness and advantages of the partially independent control scheme are verified by comparing with other control schemes in a numerical example.

Enhanced Independent Pole Control of Hybrid MMC-HVdc System

This paper presents an enhanced independent pole control scheme for hybrid modular multilevel converter based on a full-bridge submodule and half-bridge submodule. A detailed analysis of the power distribution between upper and lower arms under asymmetrical dc pole voltages is presented. It is found that the fundamental ac currents in the upper and lower arms are asymmetrical. To enable operation under asymmetrical dc pole voltages, an enhanced independent pole control scheme is proposed. The controller is composed of two dc control loops, two ac control loops, and circulating current suppression control based on current injection. Six modulation indices are presented to independently control the upper and lower arms. With this controller, the dc voltage operating region is significantly extended. To ride through a pole-to-ground dc fault without bringing dc bias at the neutral point of the interface transformer, a pole-to-ground dc fault ride through strategy is proposed. The feasibility and effectiveness of the proposed control scheme are verified by simulation results using PSCAD/EMTDC.

Independent MPPTracking Method of Hybrid Solar-Wind Power Conditioning Systems Using Integrated Dual-Input Single-PWM-Cell Converter Topology

This paper proposes the modeling and control strategy to track the MPPs of hybrid PV and Wind power systems, using a new dual input boost converter. The dual input power conditioning system with an independent MPPT control scheme is introduced with minimum number of circuit elements in order to reduce the switching loss, size and cost of the system. Since the operating conditions for the PV and Wind power systems are very distinct from each other, an efficient and superior control system is required to track the MPPs of both renewable sources with the use of a simply-structured single-ended single-inductor converter. The design of Power-Conditioning System (PCS) and detail control strategy are presented in this paper. To provide independent tracking of MPPs, a variable duty-cycle control strategy is employed for the wind system and a variable frequency strategy is employed for the PV system. Finally, the proposed dual-input converter for hybrid power conditioning system is implemented and the hardware test results are presented. From the hardware experiment, it is concluded that the proposed system successfully tracks the MPPs of both of the renewable power systems independently.

Channel Estimation and IQ Imbalance Compensation for Uplink Massive MIMO Systems With Low-Resolution ADCs

In this paper, two techniques to compensate inphase/quadrature-phase imbalance (IQI) are investigated in the uplink-quantized massive multiple-input and multiple-output (MIMO) systems for different models of randomized IQI parameters. One is referred to as combined-signal-based channel estimation and compensation (CCEC) and the other is denoted by effective channel estimation and compensation (ECEC). First, an independent automatic gain control (AGC) scheme is proposed to calibrate the dynamic range of both the I branch and the Q branch. By doing that, different quantization steps are used for analog-to-digital converters following the AGCs in these two branches at each receive antenna. Second, considering the impacts of both quantization and IQI, we give the details of channel estimation and IQI compensation for both the CCEC and the ECEC using bilinear generalized approximate message passing (Bi-GAMP). Moreover, to exploit the Bi-GAMP for ECEC reasonably, we theoretically derive the probability density function PDF of the elements in the effective channel for the case where only RX IQI is considered. Furthermore, we extend the ECEC to the case where both RX IQI and TX IQI are incorporated into the systems and derive the similar pdf as well. Finally, we use the numerical results to testify the validity of our theoretical analysis and the fact that the analytic PDF can be approximated by a Gaussian distribution when the IQI parameters are relatively small. Compared with other classical methods, the proposed methods can obtain better performance based on the Monte Carlo simulation results.

A forward fast media independent handover control scheme for Proxy Mobile IPv6 (FFMIH-PMIPv6) over heterogeneous wireless mobile network

Proxy Mobile IPv6 (PMIPv6) is a networked-based handover protocol for the IP layer, i.e., the layer 3 mobility management protocol. In this work, we integrate fast handover and IEEE 802.21 Media Independent Handover (MIH) Services with PMIPv6 to improve the handover performance over the heterogeneous wireless network environment. Since it may have multiple candidate destination networks to which a Mobile Node can select for handover, it needs to consider not only the signal strength but also the corresponding networking situation for the proper selection of the next network. To reduce the packet loss situation, the multicast mechanism is adopted to forward packets to these candidate destination networks during the handover processing period. In this work, a Forward Fast Media Independent Handover Control Scheme for Proxy Mobile IPv6 (FFMIH-PMIPv6) is proposed based on the aforementioned concerns. Through the simulations for performance analysis, it shows that the proposed FFMIH-PMIPv6 can have better handover performance in terms of handover latency, packet loss rate and throughput.

Efficient rate control scheme using modified inter-layer dependency for spatial scalability

Scalable video coding extension has been added to H.264AVC to support compression and encoding of multiple resolution video sequences, having different frame rates and fidelities in a single bit stream. The motion vectors and the residual data of the enhancement layers are derived from up-sampling the co-located macroblock (MB) of the base layer. The peak signal to noise ratio (PSNR) across the enhancement layers is degraded as up-sampling introduces distortion of high-frequency components. In this paper, a spatial-resolution-ratio-based MB mode decision scheme is proposed for spatially enhanced layers. The scheme uses the motion estimated at the base layer, to encode the respective MBs in the enhancement layers. The spatial–temporal search schemes at the enhancement layers are used to derive motion vectors and residues that are encoded using a quantization parameter obtained using independent rate control (IRC) scheme. The IRC from the prior art is modified to achieve better rate control per layer by recursive updates for mean absolute difference values of each basic unit. Proposed modified inter-layer dependency shows improvement in the PSNR for enhancement layers while the updated IRC enforces better IRC for all the layers.

Adaptive control for a rewinding process of a roll-to-roll system

In this paper, transverse vibration and transport velocity controls of a moving web in a rewinding section of a roll to roll system are investigated. The moving web is modeled as an axially moving beam. Two independent adaptive control schemes are proposed. The first control scheme using a control force exerted from a hydraulic actuator is to suppress transverse vibrations of the moving web of unknown mass per unit length under a spatially varying tension and a time-varying transport velocity. The second control scheme using a control torque applied to the rewind roller is to maintain the transport velocity levels of the moving web in spite of disturbances such as the variations of rotating elements and unknown bearing friction. From the decentralized control viewpoint, the uniformly exponential stability for suppressing the transverse vibrations and the uniformly asymptotic stability for maintaining the transport velocity are achieved. However, as a whole, the uniformly asymptotic stability is concluded. Simulations for demonstrating the effectiveness of the proposed control schemes are presented.

Control of Suspending Force in Novel Permanent-Magnet-Biased Bearingless Switched Reluctance Motor

Recently, bearingless switched reluctance motor (BLSRM) has been received more and more attention. To realize the stable levitation and rotation, the corresponding suspending force and torque should be controlled. In this paper, different from the conventional bearingless SRM control, one independent control scheme for levitation force and torque is presented. In the control, a complex control algorithm based on a lookup table is not needed. Torque control is separated from radial force control, and each channel of radial force is independently controlled. Therefore, the control is very simple to be implemented. First, based on the brief introduction of the BLSRM structure and operating principle, the mathematical relationship of levitation force with respect to current and displacement is derived. Furthermore, the rotor dynamics model, in which levitation force in four degrees of freedom is considered, is established. Based on the given analysis, the digital control system, which includes torque and suspending force, is designed by means of TMS320F28335, and an experimental platform is established. According to the experimental results, the proposed BLSRM can be steadily levitated in the static and rotating conditions.

Binocular Suppression-Based Stereoscopic Video Coding by Joint Rate Control With KKT Conditions for a Hybrid Video Codec System

Asymmetric video coding based on binocular suppression provides a prospect for improving coding efficiency since one view in stereoscopic video can be encoded at lower bitrates than the other view without a loss of perceptual video quality. In this paper, we propose a joint rate control scheme for asymmetric stereoscopic video coding in a hybrid video codec system, which supports binocular suppression-based asymmetric stereoscopic video coding in a theoretical basis within an optimization framework. To obtain an optimal solution to quantization steps for joint rate control, we apply the Karush-Kuhn-Tucker (KKT) conditions in minimizing the perceptual distortion of decoded video under the conditions that: 1) the sum of bits generated from two video encoders is constrained within a given bit budget; 2) the quality of a primary view is superior to that of an auxiliary view with an allowable difference between two view qualities; and 3) the distortion of an auxiliary view is less than a given threshold value for high bitrate encoding. As a result, the proposed rate control scheme effectively enhances the perceptual quality based on an optimization framework by taking into account the binocular suppression and also simultaneously controlling the rates of both the left and right views of stereoscopic video under the constraints with a given target bit budget and an allowed quality difference. Experimental results demonstrate that, compared with the independent rate control scheme, the proposed joint rate control scheme with KKT conditions for asymmetric stereoscopic video coding not only demonstrates comparable 3-D perceived visual quality with an overall gain of 0.33 dB, but also attains 2-D visual quality gain by an average of 2.49 dB while accurately satisfying the given constraints in the proposed optimization framework

A Joint Rate Control Scheme in a Hybrid Stereoscopic Video Codec System for 3DTV Broadcasting

In this paper, a frame-level joint rate control scheme for both intra- and inter-predictive coding is first introduced for a hybrid video codec system that independently encodes the two-view sequences of a stereoscopic video. The proposed rate control scheme jointly works on the left view encoder of MPEG-2 Video and the right view encoder of an H.264/AVC for stereoscopic video input, and is formulated as optimization problems that allow control of the output bit rates of both encoders in the sense that: 1) the sum of the two decoded video qualities is maximized, and 2) the quality difference is maintained around a desired level for a given target bit budget at the same time. In order to verify the effectiveness of the proposed joint rate scheme, it is compared with an independent rate control scheme. The experimental results show that the joint rate control scheme effectively regulates the output bitstreams of the hybrid encoders based on MPEG-2 Video and H.264/AVC. The joint rate control scheme achieves average 0.71 dB gain in PSNR and 67.07% reduction in the MSE of PSNR difference for I-frame only, average 0.54dB gain and 91.08% reduction for IPPP coding, and average 0.32dB gain and 79.01% reduction for IBBP coding.

Study on the Performance of Cascaded STATCOM Based on DC-Link Voltage Balancing Method

DC-link voltage balancing method is the key technique of cascaded static synchronous compensator (STATCOM) while safety and reliability is required previously. However, independent control scheme is necessary for each H-bridge in consideration of the voltage balancing strategy, which is different from the assumption of carrier phase shift modulation algorithm. The influence of voltage balancing strategy on cascaded STATCOM was analyzed in detail and several feasible solutions were proposed, experiment results were shown to validate the presented analysis in the end.