Current Control Architecture Research Articles

A quantum computing measurement and control system with an FPGA-based scheduling system.

Large-scale qubit systems represent the future of superconducting quantum computing. As the number of qubits and functions increases, the current qubit control architectures struggle to achieve large-scale expansion. To address this issue, we have developed a field-programmable gate array-based scheduling system, which serves as a control architecture deployed on measurement and control hardware. This system achieves the generation of multi-channel long sequence pulses using minimal storage space, with reusable envelope and instruction designs. The envelopes and instructions are preloaded into the electronics, with each instruction corresponding to a different segment of the output waveform. The architecture we designed allows for extended pulse control lengths and more complex experiments without the requirement for external storage resources. We present the resource utilization of the implementation and compare it with previous measurements under different qubit counts. To verify the functionality of the system, we conducted a series of performance tests and characterization experiments on the deployed electronics. The measured single-qubit relaxation time T1 is 34.1 μs, and the dephasing time T2* is 25.8 μs. We characterized the quality of the control pulses using a randomized benchmarking protocol, achieving an average fidelity of 99.962%.

A General Purpose Transformerless Charging System Based on Fully Bridgeless Canonical Switching Cell High-Quality Rectifier for LVEVs

A general purpose transformerless charging system (CS) targeted for various class of low voltage electric vehicles (LVEVs) (24 V–72 V), is designed, analyzed, and implemented in this work. The presented CS employs a fully bridgeless canonical switching cell (FBLCSC) improved power quality rectifier (IPQR) at its front end stage, and a high gain buck (HGB) DC-DC converter at its back end stage. At front end, the presented FBLCSC IPQR does not employ diode bridge rectifier (DBR) circuit, and therefore, ensures better conversion efficiency while operating over wide range of AC mains conditions (110 V–265 V). Further, compared to conventional buck-boost derived IPQRs, the presented IPQR employs minimum component count and maintains low current ripples at its AC and DC ends. On one side, the minimum component count shrinks down the cost, size and losses of the complete CS; low current ripples characteristic on the other side lowers the size of AC and DC end filtering elements. Notably, the FBLCSC IPQR exhibits auto unity power factor operation during discontinuous current mode (DCM) design, and thus, facilitates simple and low cost control architecture. Apart from control simplicity, the DCM operation of FBLCSC IPQR leads to negligible switch turn-on and diode reverse recovery losses. Likewise, at the back end stage, the HGB converter realizes a transformerless DC-DC stage to ensure ripple free charging of different classes of LVEVs. Even if, the HGB DC-DC stage accomplishes transformerless steeper step down gain, its simple design and effective operation over wide battery voltages (24 V–72 V), are further ensured through flexible DC link voltage (150 V – 350 V) control of front end FBLCSC IPQR. At last, the design, operation, and performance of the presented CS are validated experimentally, and relevant results are discussed comprehensively in support of the performance validation of the presented CS.

Enhancing sustainability of acid gas treatment in a Waste-to-Energy plant via Model Predictive Control

The municipal solid waste fed to waste-to-energy (WtE) plants produces acid flue gas with a wide and volatile range of composition, a scenario which implies significant process disturbances for traditional control schemes. In this paper, a two-stage dry sorbent system in an Italian treatment plant is used as a case study. The focus was on the first stage of abatement, where calcium hydroxide is injected into a reactor to reduce the hydrogen chloride (HCl) content in the acid flue gas. A state-space model, identified and tested in a previous work, was here implemented in a model predictive control (MPC) structure. In particular, four different MPC solutions were derived and tested on routine data in order to increase the process performance. Three suitable key performance indicators were used to assess the quantitative comparison between the proposed advanced control approaches and the simulated architecture of the one implemented in the WtE plant. The analysis evidenced the benefits obtained by MPC structures with respect to the current sub-optimal control architecture. Controller tuning and the possibility to include the online HCl concentration in the model have been also tested to highlight the best solution. Overall, the advanced controllers allowed one to achieve a solid profit-safety trade-off, by strictly tracking set-point on outlet HCl concentration and, at the same time, by requiring minimal sorbent doses and then minimal solid residues, with limited stress on the actuation system.

Modeling and Design of a Multiport Magnetic Bus-Based Novel Wind-Wave Hybrid Ocean Energy Technology

This article proposes a multiport magnetic bus (MMB)-based novel wind-wave hybrid ocean energy technology (HOET). The ocean waves are mixed frequency waves and generate unique frequency spectra. The wave energy converters (WECs) connected to the linear permanent magnet generators generate voltages with varying amplitudes and frequencies due to the variation of the wind speed and direction. The proposed MMB of the proposed compact wind-wave HOET can provide galvanic isolation and allow a high-frequency operation of the MMB. A decoupled voltage and current control architecture is proposed to regulate the voltage and current waveforms in the high-frequency inverter modules of the MMB that can integrate multiple WECs. An Archimedes wave swing-based conversion method is utilized for the modeling and the design of the proposed WEC. A damping controller is designed to extract the maximum power from the irregular waves. For the wind-energy generation system, a doubly fed induction generator-based technology is considered. The simulation and the laboratory-scale experimental results validate the potential and the applicability of the proposed wind-wave HOET as an effective means to harness ocean energy.

Virtual charge‐based synchronisation and feedback linearisation‐based current control of a three‐phase grid‐connected inverter without grid voltage sensors

A conventional synchronous (rotating) reference frame control requires small-signal models and introduces cross-coupling terms. In this study, a virtual charge-based scheme for grid synchronisation with only current measurements has been proposed for a three-phase grid-connected inverter with a first-order filter. The methodology described in this study curbs the dependency of the inverter on the information of the grid voltage to generate unit vectors from the phase-locked loop. This kind of estimation is especially important during grid voltage sensor failures or a distant point common coupling or weak grid conditions. In the proposed estimation scheme, no noisy differentiation is involved and only the nominal values of the interfacing filter parameters are utilised, making the implementation easier in digital microcontrollers. Also, a current control architecture based on feedback linearisation concept has been explored and embedded with the proposed grid voltage estimation technique, and the corresponding performance has been evaluated via simulation and experimental studies.

Capacitor Voltage Ripple Suppression in a Modular Multilevel Converter Using Frequency-Adaptive Spatial Repetitive-Based Circulating Current Controller

In this article, a new circulating current control architecture is proposed to suppress the submodule capacitor voltage ripple in a modular multilevel converter (MMC). The proposed cascaded control architecture uses the spatial repetitive controller (SRC) in both the outer voltage loop and the inner current loop, and can effectively suppress the second harmonic component of the submodule capacitor voltage ripple even under variable line frequency conditions. The dual SRC-based circulating current controller injects a second harmonic component into the circulating current to suppress the submodule capacitor voltage ripple. The SRC, which is a frequency-adaptive periodic digital controller, incorporates a phase sampling technique to achieve dynamic change in the sampling frequency, can adaptively tune its gain characteristics according to operating line frequency of the MMC. Unlike the existing techniques, the proposed controller uses the submodule capacitor voltage information for circulating current harmonic reference generation and, hence, does not require additional sensing of the output current. Detailed mathematical analysis and architecture of the proposed controller are presented in this article. A 400-V, 1-kW MMC laboratory prototype is developed and experimental results demonstrating the performance of the proposed circulating current control architecture for variable frequency and load conditions are also presented.

Industry 4.0: contributions of holonic manufacturing control architectures and future challenges

The flexibility claimed by the next generation production systems induces a deep modification of the behaviour and the core itself of the control systems. Over-connectivity and data management abilities targeted by Industry 4.0 paradigm enable the emergence of more flexible and reactive control systems, based on the cooperation of autonomous and connected entities in the decision-making process. From most relevant articles extracted from existing literature, a list of 10 key enablers for Industry 4.0 is first presented. During the last 20 years, the holonic paradigm has become a major paradigm of Intelligent Manufacturing Systems. After the presentation of the holonic paradigm and holon properties, this article highlights how historical and current holonic control architectures can partly fulfil I4.0 key enablers. The remaining unfulfilled key enablers are then the subject of an extensive discussion on the remaining research perspectives on holonic architectures needed to achieve a complete support of Industry4.0.

Learning methodologies for wireless big data networks: A Markovian game-theoretic perspective

Wireless big data significantly challenges the current network management and control architecture, mathematical modeling techniques, and distributed algorithm design, in particular, in the promising cognitive, distributed, and ultra-dense networks. Motivated by the idea of divide-and-conquer, in this article, we first present a multiple cognitive agent-based divide-and-conquer network management and control architecture. Furthermore, a Markovian game-theoretic modeling framework is proposed to model the state big data-based decision-making problem. Then, we investigate various learning methodologies with respect to different kinds of the state information, in particular, we concentrate on the construction of state space, the state transition computation, and the convergence of parallel Q-learning technique. This work provides a suitable network management architecture, an effective modeling tool, and various learning techniques for wireless big data networks.

EU Merger Control: A Set of Proposals to Enhance the Operational Effectiveness of the Current Architecture of Separate Jurisdictional Zones

The paper documents the failure of the EU’s current merger control architecture to address the misallocation problem and proposes changes to the architecture which would virtually eliminate this major concern. This will streamline the working of the architecture by removing the need for correctives to either prevent misallocation or reassign cases that have been misallocated. Moreover, and just as importantly, the resolution of this problem will improve the application of the principle of subsidiarity in merger cases and bring to an end the multiple notification issue, thereby strengthening the operation of the one-stop shop approach. The changes to the architecture and how they interact to virtually end the misallocation problem and thereby bring about the aforementioned benefits are revealed. More specifically, it demonstrates how the use of the three or more Member state notification rule and the distinct market test, the retention of the existing two Community Dimension tests and the two-thirds rule, as well as the shared competence of the Competition Directorate and Member state regulators to apply EU merger law, albeit intentionally in different situations, reinforce each other to resolve the stated problem. Moreover, this limited sharing of the right to apply EU merger law—currently the EU Commission has the exclusive right—allied with other forms of envisaged cooperation between the regulators is not just simply a reinterpretation of the Commission’s most appropriate authority goal but also the possible beginnings of a more cooperative architecture, relative to the current architecture of separate jurisdictional zones, aimed at improving the efficacy and efficiency of merger control within the Union.

Fixed structure compensator design using a constrained hybrid evolutionary optimization approach

This paper presents an efficient technique for designing a fixed order compensator for compensating current mode control architecture of DC−DC converters. The compensator design is formulated as an optimization problem, which seeks to attain a set of frequency domain specifications. The highly nonlinear nature of the optimization problem demands the use of an initial parameterization independent global search technique. In this regard, the optimization problem is solved using a hybrid evolutionary optimization approach, because of its simple structure, faster execution time and greater probability in achieving the global solution. The proposed algorithm involves the combination of a population search based optimization approach i.e. Particle Swarm Optimization (PSO) and local search based method. The op-amp dynamics have been incorporated during the design process. Considering the limitations of fixed structure compensator in achieving loop bandwidth higher than a certain threshold, the proposed approach also determines the op-amp bandwidth, which would be able to achieve the same. The effectiveness of the proposed approach in meeting the desired frequency domain specifications is experimentally tested on a peak current mode control dc−dc buck converter.

EU Merger Control: From Separate Jurisdictional Zones to a More Cooperative Architecture—A Possible Way Forward?

The paper is a call to re-ignite the debate over the future shape of the EU’s concentration or merger control architecture in the longer-term. The paper contributes to this debate by considering the efficacy of replacing the current merger control architecture of separate jurisdictional zones with a more cooperative approach. It demonstrates that the adoption of the cooperative architecture would result in a number of benefits relative to the operation of the current architecture. For in effectively resolving a major problem that has dogged the operational effectiveness of the current architecture since it became law in 1990, the misallocation problem, the proposed architecture would also lead to a strengthening of the application of the principle of subsidiarity in this field, be supportive of the reinterpreted more appropriate authority goal, and resolve the multiple notification issue. Further, by ending the multiple notification issue, the valued one-stop shop approach to merger regulation would be reinforced. Yet the paper recognises that the cooperative architecture itself is not concern free, for the cooperative approach in granting Member state regulators the right for the first time to apply EU merger law, albeit in certain circumstances only, creates the possibility of inconsistent decision-making across this network. This would distort the regulatory level playing field, undermining what the architecture is supposed to guarantee, the Single European Market. With this in mind, necessary safeguards are explained. The paper concludes by briefly commenting upon key systems that need to be in place to ensure the operational effectiveness of the cooperative architecture. Of course, and at the cost of stating the obvious, improving the protection of competition in the field of merger control in the longer-term requires a willingness on the part of the key stakeholders to look beyond the current architecture of separate jurisdictional zones.

A DC Offset Current Compensation Strategy in Transformerless Grid-Connected Power Converters

A line frequency transformer is usually employed in grid-connected power converters, from both renewable and traditional energy sources, in order to suppress the DC current component and the ground leakage current. Solutions employing a high frequency transformer or employing no transformer at all have recently been investigated in order to reduce size, weight and cost. As a consequence, unless a suitable remedy is adopted, a DC current component exceeding the limits enforced by international standards may be injected into the grid. This paper proposes a simple and cheap solution to reduce the DC current component injected into the grid in the case of a full-bridge, single-phase, transformerless converter. The proposed strategy is intrinsically insensitive to offset measurement errors and can be utilized as a robust and dynamic offset compensator for the current transducer. The simulation results have confirmed the theoretical behavior of the proposed solution, while the experimental ones, performed for different values of output power and for different current control architectures, have shown its effectiveness.

Service Robotics as an Application for the Grand Challenges in Computer Enginering

Abstract Service robots have a very high potential for the future and are already today employed in a number of important applications. For exploiting this potential successfully progress has to be made in many disciplines. This article focuses on robot control architectures in hardware and software. Taking today existing robots as examples typical current control architectures are presented and the contribution of the Grand Challenges in Computer Science to their further development is discussed.

MOTION GENERATION AND CONTROL FOR THE PNEUMATIC BIPED "LUCY"

This paper reports on the control structure of the pneumatic biped "Lucy." The robot is actuated with pleated pneumatic artificial muscles which have interesting characteristics that can be exploited for legged machines. They have a high power-to-weight ratio, an adaptable compliance and they can reduce impact effects. The current control architecture focuses on the trajectory generator and the tracking controller, which is divided into a computed torque controller, a delta-p unit, a PI position controller and a pressure bang-bang controller. The trajectory generator provides polynomial joint trajectories while the computed torque, combined with the delta-p unit, calculates the required muscle pressure levels. The PI and bang-bang controller work at a pressure level to cope with modeling errors and to set the pressures in each muscle. The control design is divided into single support and double support, where specifically the computed torque differs for these two phases. The proposed control architecture is evaluated with a full hybrid dynamic simulation model of the biped. This simulator combines the dynamical behavior of the robot with the thermodynamical effects that take place in the muscle-valves system. The observed hardware limitations of the real robot and expected model errors are taken into account in order to give a realistic qualitative evaluation of the control performance and to test the robustness. A preliminary implementation of the presented controller on the real biped, representing a walking motion of the robot while both feet are in the air, is discussed. This first implementation shows already promising results concerning tracking performance of the proposed control architecture. It confirms that the pneumatic tracking system can be used for a dynamic application such as a biped walking robot.

A Multi-Objective Control Scheme for an ETBE Reactive Distillation Column

Reactive distillation is a bidirectional (i.e. the process gains change sign over the operating range) and highly non-linear process. These characteristics reduce the controllability of the process and suggest that the steady state benefits of reactive distillation might not be realized with a simple control scheme. There are also insufficient degrees of freedom to satisfy the reaction and separation objectives simultaneously. An integrated control scheme is proposed here, using an ETBE column as an example, to address these problems by permitting the control objectives to be changed online in order to reflect changing economic constraints. The careful selection of controlled and manipulated variables allows this scheme to be implemented with linear controllers only. More complex control systems can be built onto the current control architecture, if required. In these cases, the current control structure will maximize the effectiveness of the advanced control application.

Robust Nonlinear Missle Autopilot Design

A methodology incorporating both dynamic inversion and structured singular value synthesis is employed to design a robust nonlinear autopilot for an air-to-air missile. The nonlinear components include fast and slow inversion loops which approximately lin earize the system when closed in the absence of modeling errors. A feedback control law is designed for this closed-loop system in the presence of structured uncertainties. The current controller architecture differs from previous work in the following two respects: uncertainties and modeling errors in the slow dynamics are treated explicitly, and the autopilot accepts external commands in bank angle rather than stability-axis roll rate.