Advanced Digital Control Research Articles

Review of Advanced Digital Technologies, Modeling and Control Applied in Various Processes

This special issue reviews advanced digital technologies in modeling and control of technological processes [...]

A robust PIλDµ controller for enhancing the width of the molten pool and the tracking of welding current in gas metal arc welding (GMAW) processes

ABSTRACT By utilizing advanced power electronic devices and digital control techniques in a high-speed welding power supply, it is possible to achieve self-regulation of the electrode contact tube to work-piece distance. This innovation offers a range of customizable features that can enhance and automate the gas metal arc welding (GMAW) process. The focus of this paper is on investigating the dynamic characteristics of a self-regulated consumable electrode, under step changes in the distance between the torch and the work-piece over time. The key components of arc welding processes have been examined, and a fractional PID (PIλDµ) regulator has been developed to maintain the welding current within a predetermined range during both the melting phase and the short-circuiting of the electrode wire. In this study, a weighted sum multi-objective fitness function is utilized to optimize the parameters of a fractional PID regulator using the Bacterial Foraging Optimization (BFO) algorithm. The fitness function incorporates various error criteria, such as Integral Absolute Error (IAE), Integral Time Absolute Error (ITAE), Integral Time Square Error (ITSE), and Integral Square Error (ISE), each with its own assigned weight. To demonstrate the effectiveness of the proposed PIλDµ controller over a conventional PID controller, numerical simulations are performed using MATLAB/SIMULINK software. The simulations also aim to provide insights into the mechanisms that govern the changes in arc voltage and current as the arc length varies, also shedding light on the underlying mechanisms involved. Based on the simulation outcomes, it can be concluded that the automatic arc welding control system utilizing the optimal PIλDµ controller is capable of delivering excellent performance.

The Analysis of DCDC BUCK Circuit based on Arduino

With the development of the times, digitally controlled power supplies are becoming the trend of today's DC power supplies. This paper details a step-down circuit with Mosfet switch controlled by Arduino. This power supply and DC-DC adopts advanced semiconductor technology and digital control technology, featuring small size, light weight, simple and easy adjustment, high efficiency, wide voltage range and complete shutdown of zero-point adjustment. First, this paper details the structure, principle, and many features of the Arduino platform. Second, this paper explains the principle of BOOST circuit for boost and BUCK circuit for buck with equations and structure diagrams, and presents real-life applications. By reading this article, beginners will have a basic understanding of the use of Arduino and know what the exact principles of this circuit are, as well as circuit design and software programming ideas.

Advanced digital repetitive control of shunt active power filter

Advanced digital repetitive control of shunt active power filter

Hardware-software co-design of an open-source automatic multimodal whole slide histopathology imaging system.

Advanced digital control of microscopes and programmable data acquisition workflows have become increasingly important for improving the throughput and reproducibility of optical imaging experiments. Combinations of imaging modalities have enabled a more comprehensive understanding of tissue biology and tumor microenvironments in histopathological studies. However, insufficient imaging throughput and complicated workflows still limit the scalability of multimodal histopathology imaging. We present a hardware-software co-design of a whole slide scanning system for high-throughput multimodal tissue imaging, including brightfield (BF) and laser scanning microscopy. The system can automatically detect regions of interest using deep neural networks in a low-magnification rapid BF scan of the tissue slide and then conduct high-resolution BF scanning and laser scanning imaging on targeted regions with deep learning-based run-time denoising and resolution enhancement. The acquisition workflow is built using Pycro-Manager, a Python package that bridges hardware control libraries of the Java-based open-source microscopy software Micro-Manager in a Python environment. The system can achieve optimized imaging settings for both modalities with minimized human intervention and speed up the laser scanning by an order of magnitude with run-time image processing. The system integrates the acquisition pipeline and data analysis pipeline into a single workflow that improves the throughput and reproducibility of multimodal histopathological imaging.

A Cyclic True Triaxial with Rigid-Rigid-Flexible Boundary for Determination of Cross-Anisotropic Nature of Geomaterials

Abstract This paper describes a custom-designed Soil Poly-Axial Test System, SPAX-3000, developed to investigate the cross-anisotropic material properties of geomaterials under varying loading conditions. SPAX-3000, a mixed-boundary type of large-scale cyclic true triaxial apparatus (CTTA), is capable of applying a wide range of principal stress combinations on prismatic specimens of dimensions 152 × 152 × 304 mm. Two vertical and two horizontal load actuators on two opposite faces apply principal major (σ1) and intermediate (σ2) stresses independently to evaluate the performance of pavement structures under anisotropic stress states through resilient modulus (MR) testing. SPAX-3000 is controlled through software (CATS Software, provided by the manufacturer to provide advanced digital servo control of stresses and deformations). In this study, SPAX-3000 capabilities were evaluated through MR testing of both isotropic (urethane rubber) and cross-anisotropic materials (base, subbase, and subgrade) for the development of stress histories. The test results showed that SPAX-3000 is capable of determining MR independently of the anisotropy characteristics of the tested materials. Stress-hardening and stress-softening behaviors were observed for the coarse- and fine-grained geomaterials under different loading conditions. Anisotropy ratios (ratio of horizontal MR [MhR] to the vertical MR [MvR]) were determined for the base, subbase, and subgrade materials. MR test results showed that higher MvR results were obtained than that of MhR regardless of the loading conditions. The anisotropy ratios ranged from 0.08 to 0.21, 0.38 to 0.87, and 0.05 to 0.50 for the base, subbase, and subgrade materials, respectively. The highest MvR values (200–590 MPa) were obtained for the base material, whereas subbase material yielded the highest MhR (35–169 MPa). In general, stress-hardening behavior was observed for the geomaterials tested in both directions except for the stiffness of subgrade and subbase materials in the vertical direction.

Benchmarking Real-Time Control Platforms Using a Matlab/Simulink Coder with Applications in the Control of DC/AC Switched Power Converters

In the control of DC/AC switched power converters (SPC), one of the most important aspects to be considered is the selection of the real-time control platform. The real-time control platform must be able to meet the high performance efficiency and regulation requirements of the DC/AC SPC, as these typically operate at switching frequencies in the order of kHz to MHz. For this reason, the hardware characteristics of the ADC and PWM, and the processing capacity of the real-time control platform are of vital importance when implementing advanced digital controllers that maintain voltage and current levels within regulatory standards. In this context, we aimed to perform a comparative study of the computation times of different real-time control platforms when implementing different control strategies for DC/AC switched power converters. We also analyzed the impact of the real-time control platforms on the THD of the voltages generated by the DC/AC switched power converters. With the help of this paper, researchers and developers will have criteria to select which real-time control platform to use in real-time control for DC/AC SPC applications.

Digital Predictive Current-Mode Control for Asymmetrical Half-Bridge LED Constant-Current Driver

In this paper, we propose three advanced digital predictive current-mode control (DPCC) algorithms based on a simplified estimation method of duty cycle lost time for asymmetric half-bridge (AHB) LED constant-current driver. They are the digital predictive peak current mode control(DPPCC) algorithm based on leading-edge modulation, the digital predictive quasi-valley current mode control(DPqVCC) algorithm based on trailing-edge modulation, and the digital predictive quasi-average current mode control(DPqACC) algorithm based on double-edge modulation. Simulation and experimental results demonstrate that the three DPCC algorithms can effectively offset the effect of delay on digital control performance, which confirms the superiority of DPqACC. When the DPqACC is applied, the series-load-jump transition times are below 4.5 ms, the maximum load adjustment rate is 0.5%/ V, and the output current can be tuned continuously between 0.3 A and 4.5 A with the longest transition time of 1 ms. Moreover, the three DPCC algorithms are capable of compensating for low-frequency ripples due to the rapid regulation speed of the inner loop. With the electrolytic capacitance removed without additional ripple compensation, the maximum peak-to-peak value of the low-frequency secondary ripple is 0.1163 A (2.91%) when the input is 400 53sin(2ω <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>lin</i></sub> <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> ) V and the output is 4 A. This approach provides an excellent solution for the digital design of low-ripple AC-DC LED constant-current drivers without electrolytic capacitance.

Electromagnetic Bearings With Power Electronic Control for High-Speed Rotating Machines: Review, Analysis, and Design Example

This article reviews electromagnetic bearings with power electronic control for high-speed machinery, which are termed active magnetic bearings (AMBs). AMB is a contactless-type bearing, which uses magnetic force to support the rotor. This is suitable for high-speed applications, harsh operating conditions, and also clean environments. However, the AMB has nonlinear characteristics and is inherently unstable. Due to recent advancements in fast-switching power devices, high-switching-frequency power converters, high-bandwidth current control, nonlinear control strategies, advanced digital controllers, and sensors, AMBs have become promising for high-speed aerospace, industrial, and energy applications. This article contains a brief tutorial on the AMB, covering its operating principle, system-level block diagram, magnetic-circuit-based analysis, dynamic load due to rotor mass unbalance, load capacity, force slew rate, and response to large force disturbance. Furthermore, a design example of an eight-pole AMB with four excitation coils is presented to achieve a load capacity of 180 N. A preliminary design, based on magnetic circuit analysis, is seen to fall short in terms of load capacity. Iterative changes to the AMB dimensions achieve the required load capacity, but the characteristics are still nonlinear. Finite-element analyses bring out the effects of magnetic saturation on load capacity, linearity between force and current, force slew rate, and relationships between maximum force generated and AMB dimensions. An improved design procedure is presented to achieve both desired load capacity and linear characteristics, while balancing the compactness requirement. The improved design also achieves the desired slew rate besides faster response and improved stability.

Modeling digital main control room operator’s resilience under extreme conditions: An Experiment design scheme

Human reliability is one of the most important factors that make effects in nuclear power plant(NPP) operation. In advanced digital NPP main control room with high levels of automation, the systematic operation which require a sufficient mental workload to address those undesired events has become a critical challenge for operators. The aim of this research is to identify the operator’s reliability by developing a resilience model. In this work, a seven-stage technique framework is proposed, which includes the skeleton of theoretical analysis, experimental design and hardware setting to how to establish the model for NPP operator in a downsize main control room cabin. The resilience model for operators’ reliability via assessing their basic skill tasks performance and evaluating their cognitive workload in the framework hence can be used for assessing the level of training of the new employed operators as well as human reliability in other critical process industries.

Design and Implementation of a SiC-Based VRFB Power Conditioning System.

An energy storage system using secondary batteries combined with advanced power control schemes is considered the key technology for the sustainable development of renewable energy-based power generation and smart micro-grids. The performance of energy storage systems in practical application mainly depends on their power conditioning systems. This paper proposes a silicon carbide-based multifunctional power conditioning system for the vanadium redox flow battery. The proposed system is a two-stage circuit topology, including a three-phase grid-tie inverter that can perform four-quadrant control of active and reactive power and a bi-directional multi-channel direct current converter that is responsible for the fast charging and discharging control of the battery. To achieve the design objectives, i.e., high reliability, high efficiency, and high operational flexibility, silicon carbide-based switching devices, and advanced digital control schemes are used in the construction of a power conditioning system for the vanadium redox flow battery. This paper first describes the proposed system topologies and controller configurations and the design methods of controllers for each converter in detail, and then results from both simulation analyses and experimental tests on a 5 kVA hardware prototype are presented to verify the feasibility and effectiveness of the proposed system and the designed controllers.

ПРОСТОЙ МЕТОД ПОЛУЧЕНИЯ ТОЧНОГО РЕШЕНИЯ ЗАДАЧИ СИНТЕЗА ЦИФРОВЫХ ОПТИМАЛЬНЫХ РЕГУЛЯТОРОВ ДЛЯ ОДНОМЕРНЫХ ОБЪЕКТОВ С ЗАПАЗДЫВАНИЕМ

Models of aperiodic and integrator links with delay are traditional representations of controlled objects of various processes. In this case, the PID-family algorithms are traditionally used as control algorithms for which standard technical means have been developed. At the same time, the appearance of powerful miniature controllers with unified interfaces predicates the control quality improvement in the base of more advanced digital control systems usage. Such systems can be designed using the developed approach for the synthesis of optimal digital controllers with observers. Such an approach, in the traditional formulation, is impossible without the usage of specialized software which often substantially overload computer resources. At the same time, it is desirable to have a simple tuning method for customizing the controller at the control object, as well as for use in adaptive control systems. Obtaining such rules is described in this article. The theoretical result that follows from the obtained rules is that the parameters of the optimal state regulator do not depend on the delay and are determined solely by the object time constant and the selected sample period.

A smart component methodology for reliability analysis of dynamic systems

The new generation of nuclear power plants are being designed with passive safety systems and advanced digital Instrumentation & Control (I&C) systems for achieving required operational performance and improved reliability. Digital I&C systems often perform complex tasks while interacting with time dependent process dynamics. Similarly, in passive decay heat removal systems, the time dependence arising from the variation of heat load and interaction between redundant loops are important. Since static reliability methods cannot model these systems without significant approximations, dynamic reliability methods are preferred. Dynamic methods improve the correctness of modeling and shift the burden of proof for correctness from the modeling expert to the methodology. Though a number of dynamic reliability methods have been developed, they have not been adopted widely, like that of the traditional event tree/fault tree methods. A significant reason is due to the lack of an intuitive simulation framework to translate and represent the system structure and functional aspects by a faithful system reliability model. Therefore, we propose in this paper a methodology known as Smart Component Methodology (SCM) for reliability modeling of dynamic safety systems. The methodology is based on an intuitive object oriented framework for the representation of the components, system structure, behavior and reliability data of a safety system. A suitable Monte Carlo simulation algorithm is embedded into this framework to quantify the system reliability. The SCM architecture for dynamic system representation and the general Monte Carlo simulation algorithm used for driving the object oriented framework are presented. The method is applied to example I&C systems, passive heat removal systems involving human actions. The results are compared with traditional methods to validate the results and to demonstrate the improved accuracy and ease and generality of modeling.

An Advanced Digital Predictive Valley Current Control Algorithm for a Boost Converter

An advanced digital predictive valley current control algorithm for a boost converter is proposed. The control algorithm predicts the inductor current in a future period by sampling the voltages including input and output, and inductor current of the current period, which overcomes the problem of hardware periodic delay. Under the premise of ensuring the stability of the system, the control algorithm has a faster response speed as compared to the traditional digital proportional-integral (PI) control algorithm. In addition, it is not only algorithm simple, but also easy to implement on DSP of digital control chips. Finally, the proposed control algorithm is verified using simulations software and experimental measurements.

Advanced Digital Controller for Improving Input Current Quality of Integrated Active Virtual Ground-Bridgeless PFC

This paper presents a new digital control scheme for active virtual ground-bridgeless PFC (AVG-BPFC), which is able to obtain an optimized solution between the system efficiency and electromagnetic interference performance in the PFC stage. However, a resonant characteristic is generated from the input LCL filter structure of the converter. In addition, there is a phase difference between two inductor currents which also leads the controller design in the AVG-BPFC to become challenging, especially on the system stability and current quality. Thus, a triple loop control's architecture together with an integrated state machine is proposed as the control methodology of the AVG-BPFC. Under the simple control structure in the digital platform, a stable system is achieved together with a precise grid current tracking function. Such control scheme was implemented digitally on a 1.5 kW prototype. In this paper, theoretical models of the whole system were analyzed and the system performance was successfully verified in both steady state and transient state conditions. The experimental results show a good agreement with the theoretical knowledge.

Cyber‐physical robust control framework for enhancing transient stability of smart grids

Transient stability of power systems has become even more critical due to increasing complexity created by large penetration of renewable energy sources and massive deployment of information and communication technology. Fortunately, the two-way real-time data exchange capacity of smart grids allows designing advanced digital control schemes to better address the power system stability. In this study, a non-linear model-free-based robust controller in conjunction with a state estimation architecture is designed to enhance transient stability margins. The designed controller addresses uncertainties arising from communication and control input delay, sensor errors, varying plant parameters, and unmodelled dynamics effects. A novel time-delay compensation technique is presented in the control development to mitigate the effect of delay and the robustness of the proposed controller is proven by conducting a Lyapunov stability analysis with respect to additive disturbance and time delay. Furthermore, the proposed control framework is validated on the IEEE 39 bus test system through MATLAB simulation. The results show that the proposed framework is capable of stabilising the power system after a fault, also showing robustness to noise, latency in communication, delay in control input, and malicious data injection.

CBM Experiment Local and Global Implications

Abstract The research area of the compressed baryonic matter - CBM experiment (FAIR/GSI in Darmstadt) is subnuclear physics, thus hadron-baryon and quark-gluon, and the essence of phase transitions in the area of hot nuclear matter, and dense strongly interacting matter. Our interest in this paper are mainly considerations on the impact of such large infrastructural experiments and possibilities they give to local, smaller but very active, university based research groups and communities. Research and technical input from such groups is depicted on the background of the CBM detector infrastructure and electronic instrumentation just under design and test fabrication for this experiment. An essential input to this research originates from Poland via the agreed in-kind contribution. The areas of expertise of these groups are: superconductivity, structural large scale cabling, precision machined parts, RF and microwave technology, analog and advanced digital electronics, distributed measurement and control systems, etc.

Small-Signal Modeling of Uniformly Sampled Phase-Shift Modulators

Phase-shift modulation (PSM) is a commonly used technique for controlling the active power flow in resonant dc–ac and dc–dc converters. Although traditionally developed as an analog modulation scheme, PSM is being increasingly implemented digitally in conjunction with advanced multivariable digital controllers and online efficiency optimization algorithms. While analog PSM is known not to introduce additional dynamics from a small-signal standpoint, the analysis disclosed in this study indicates that discrete-time, or uniformly sampled , PSM introduces a transport delay of small-signal nature. Furthermore, and in close analogy with the theory of uniformly sampled pulse width modulators, such delay depends on the modulator carrier type as well as on the converter operating point. This paper first clarifies the modeling procedure for describing the small-signal dynamics of uniformly sampled phase-shift modulators. Second, it provides an extension of the traditional phasor modeling to digital phase-controlled converters, allowing to account for the additional modulator dynamics in the design of the closed-loop compensation. Theoretical findings are validated via simulation and experimental results.

Guest Editorial Optimal Design of Electric Machines

The papers in this special section cover the advances in multi-objective design and optimization based on genetic algorithms, surrogate, polynomial regression, and particle swarm optimization techniques. Design of novel trans-rotary magnetic gear, hybrid machines for dc generation, and two degrees of freedom split-stator induction machines highlight new magnetic configurations and their performance evaluations. Multiphysics analysis of magnetothermal and magnetostructural behavior of Switched Reluctance Machine (SRM) and brushless doubly fed machines shed light on analytical and practical aspects of design in electromechanical converters. Finally, control of torque undulation, loss minimization, low speed high torque operation, and advanced digital control of adjustable speed motor drives conclude this unique collection of papers.

Special Issue on Smart Grid and Emerging Technology Integration

Special Issue on Smart Grid and Emerging Technology Integration