Model Of Converter Research Articles

Single‐Phase Single‐Stage Integrated Ćuk Inverter Operating in Discontinuous Conduction Mode for Autonomous Operation

ABSTRACTDC microgrids are required to supply energy to AC local loads in many applications. To address this need, integrated inverters have been rising as an excellent solution for interfacing AC loads with the microgrid due to their good conversion efficiency, lower costs, and enhanced reliability. Thus, this paper explores and analyzes the single‐phase single‐stage integrated Ćuk inverter (ICI). The ICI is designed to operate in discontinuous conduction mode with an improved switching strategy. The inverter's output voltage is regulated by a single‐loop control system employing a proportional integral multiresonant controller. This paper presents a comprehensive qualitative and quantitative mathematical analysis of the ICI, such as the main system equations, component sizing, and the converter modeling using the state‐space technique associated with the small‐signal analysis. The ICI distinguishes itself by (i) reduced number of electrical/electrical components; (ii) operation with a single high‐frequency switch, while the remaining bridge switches operate at low frequency; and (iii) ability to step up the input voltage while supplying an AC voltage in its output. The feasibility and functionality of the ICI are demonstrated from computational simulation and experimental results. The ICI provides an AC output voltage with low harmonic distortion and presents an efficiency greater than 96%.

Enhanced disturbance mitigation in nonlinear time delay systems with applications to double boost converters in microgrid environments

This study proposes an enhanced Smith Predictor (ESP) based Modified repetitive control (MRC) technique to develop a precise tracking performance of the input delayed double boost converter model, which is highly influenced by disturbances and saturation nonlinearity. A group of inequalities is derived on the basis of Lyapunov stability concept, which are in the form of linear-matrix-inequalities (LMIs) to guarantee the asymptotic stability and tracking performance of the considered delayed double boost converter. To be more specific, the proposed Lyapunov method not only provides the asymptotic stability of the system but also design the controller parameters when the feasibility of the derived LMIs are analyzed. The validation of the suggested ESP based MRC technique is confirmed through the simulation analysis and the corresponding outcomes from the considered double boost converter model. Moreover, the recommended control procedure yields better accuracy in tracking performance and disturbance elimination when comparing with the existing active disturbance methods such as improved equivalent-input-disturbance (IEID), parallel EID (PEID), higher-order EID (HEID) and EID based Smith predictor (SP) techniques.

Large-Signal Nonlinear Average Model for a Voltage-Controlled Flyback Converter

Large-Signal Nonlinear Average Model for a Voltage-Controlled Flyback Converter

Full-bridge DC-DC Converter based on Linear Active Disturbance Rejection Control

Dual Active Bridge (DAB) converter has been a research hotspot in recent years. It is widely used in distributed power generation system, DC microgrid system and power management system. Traditional PI controllers do not perform well in the face of nonlinear loads and external disturbances, so a more advanced control method is needed to improve the stability and performance of the system. In this paper, a control strategy based on active disturbance rejection control (ADRC) is proposed to improve the control performance of full-bridge DC-DC converter. First of all, the small signal mathematical model of full-bridge DC-DC converter is established, and the function relationship between input, output, control quantity and disturbance quantity in the system is obtained. Then, the extended state observer of ADRC core module is designed, and its parameters are adjusted and simulated, compared with the traditional PI controller. The simulation results show that the full-bridge DC-DC converter based on LADRC has faster dynamic response and better disturbance immunity, which can effectively improve the stability and robustness of the system.

Experimental evaluation of DC-DC buck converter based on adaptive fuzzy fast terminal synergetic controller

This study suggests an enhanced version of the adaptive fuzzy fast terminal synergetic controller (AF-FTSC) for controlling the uncertain DC/DC buck converter based on the synergetic theory of control (STC) and newly developed terminal attractor technique (TAT). The benefits of the proposed SC algorithm involve the features of finite-time convergence, unaffected by parameter variations, and chattering-free phenomenon. A type-1 fuzzy logic system (T1-FLS) make the considered controller more robust and is utilized to estimate the undefined converter nonlinear dynamics without resorting to the usual linearization and simplifications of the converter model. Taking a switching DC-DC buck converter as a demonstration, the suggested AF-FTSC is thoroughly analyzed and executed on a dSPACE ds1103 controller board. The outcomes of the experiment confirm the competence and applicability of the suggested regulator.

Small‐Signal Modelling of Bidirectional CLLC Converters for Onboard Charging Application in Electric Vehicles

ABSTRACTA two‐stage onboard battery charger with an CLLC resonant converter is a widely adopted configuration in the automotive industry. The ZVS and ZCS capability of the switching devices with high operating frequency of the CLLC converters encourages its application in various EV platforms to improve efficiency. In the literature, various authors proposed many methods to control the CLLC converters efficiently, but up to now, no simple and accurate small‐signal equivalent circuit modelling is available. As dynamic networks are load‐dependent, closed‐loop voltage and current controllers provide more stable operations in these converters. In this paper, a detailed mathematical modelling of the CLLC converters with time domain analysis has been presented. The proposed mathematical model accurately predicts the small‐signal behaviors seen in pulse‐frequency‐modulated (PFM) CLLC resonant converters whether the switching frequency is below, near to, or above the resonant frequency. Stable closed‐loop controllers for both current and voltage loops in battery charging applications are designed and detailed. A prototype hardware is been built and the experimental results with the load variations with the designed controllers are tested and the results are been discussed in the paper.

Proposing a new rotating frame‐based method for dynamic modelling of resonant converters

AbstractResonant converters are widely used in various industrial applications due to features such as wide input voltage range, high efficiency, and high‐power density. Mathematical modelling of these converters is crucial because they simultaneously exhibit AC and DC modes, complicating the design of their controllers. This paper proposes a new method for modelling of resonant converters based on the rotating frame theory. The proposed model possesses two essential features for controller design: being dynamic and having all DC states. The complexity of the model is significantly lower than other methods, such as MHA methods. Also compared to first harmonic approximation, Dp and generalized state space averaging methods, the proposed dq model has not any approximations for the inverter output voltage and transferred output voltage in the transformer primary side. The proposed method is compared with conventional modelling methods for such converters, including the first harmonic approximation, generalized state space averaging, nonlinear equation models, and circuit simulation models. According to the presented results, the proposed model demonstrates superiority in terms of accuracy and simplicity over the methods. Simulation results along with practical results from a prototype circuit are provided, highlighting the effectiveness of the proposed method.

Impedance modelling and stability analysis of modular multilevel converter under two droop control strategies

Impedance modelling and stability analysis of modular multilevel converter under two droop control strategies

Surrogate Modeling for Drive Co‐Simulation Including Local Irreversible Demagnetization Knowledge

ABSTRACTIn order to survey possible local demagnetization of permanent magnet drives during transient operations and/or faulty functioning in case of multi‐phase drives, co‐simulation including converter, vector control, and finite element model could be investigated. Nevertheless, expensive simulation time limits practically this solution. To solve this problem, the paper proposes a surrogate model of an electrical machine taking into account locally the irreversible demagnetization effect. In case of a multi‐phase machine working in transient operations and irreversible demagnetization, the proposed surrogate model gives large benefit in computational time in comparison with an finite element approach.

The digital twin of complex shipboard DC microgrids: The high‐performing synergy of compiled models and HIL platform in the dynamics emulation of zonal power electronic power distribution systems

AbstractNowadays, resilience is a crucial attribute to be pursued in advanced shipboard DC microgrids. When the power distribution is zonal, the presence of autonomous‐controlled converters guarantees both power use and resiliency improvement. The adoption of bidirectional controlled devices ensures power routing among generating units, storage, and loads. Moreover, zonal electrical distribution systems are effective in applying the optimization algorithms for green, safe, and high‐performing ship operation. In zonal DC microgrids, real‐time cooperation among controlled converters through properly set communication protocols enables the ship mission achievement. To this aim, functional tests are to be done on such complex power infrastructure. The digital twin approach provides the de‐risking step before the onboard deployment for controlled systems and communication. A zonal DC shipboard microgrid is the case study to test the synergy between compiled models and power converters on two hardware in the loop platforms, then verified by experiment in this paper. The first platform exploits the Linux real time application interface on the average value models of converters. This solution is then compared with a platform that utilizes the Typhoon hardware in the loop environment, proposing a combination of average value models and detailed switching models for the real‐time emulation of controlled grid.

Development of a Mathematical Model of a Two-stage DC-DC Converter

Development of a Mathematical Model of a Two-stage DC-DC Converter

Dynamic Modeling of LLC Resonant Converter Using Extracted Two‐Harmonic Approximation and Comparative Analysis With Other Approaches

ABSTRACTResonant converters are widely used in various applications due to their wide input voltage range, high efficiency, and high power density. The mathematical modeling of these converters has great importance because they have both AC and DC states, simultaneously, which poses challenges for controller design. In this paper, a dynamic mathematical model of the LLC resonant converter is extracted by developing the common first harmonic approximation (FHA) model to a two‐harmonic approximation (THA) model, and its accuracy is compared with other conventional models, including the FHA, the dynamic pharos (DP), non‐linear mathematical models. As a reference model, circuit experimental model has been used for comparison. The comparison metric is the sum of squared errors in transient and steady‐state modes, expressed as a percentage of the steady‐state peak value. Furthermore, the output of the mathematical models and simulations is evaluated against practical results from a prototype.

Analysis and Modeling of Fractional Order LC Series Resonant Boost Converter Based on Fractional Calculus and Laplace Transform

ABSTRACTBased on the fractional‐order (FO) characteristics of inductors and capacitors, many basic PWM DC–DC converters are defined and modeled by FO calculus in previous studies, but the research of FO resonant dc converters is still in its early stage. Therefore, this paper adopts FO calculus and Laplace transform to model and analyze a ZCS boost converter with an LC resonant tank, which mainly focuses on the influence of the FO component on the soft switching characteristics, converter efficiency, and output voltage gain of this isolated dc converter. This paper extends the topology to the fractional order domain and conducts FO modeling. The order of the resonant inductor and capacitor will affect the amplitude/phase of the resonant current and then affect the converter ZCS characteristic. The analysis demonstrates that the reduction of FOI and FOC order is not conducive to the ZCS of switching devices and converter efficiency. Based on the voltage and current relationship of the FO LC resonant tank, a parameter design guideline is presented. Numerical tools are used to solve the FO output voltage gain and draw the gain curve. And the order of FOI and FOC provides new flexibility for the converter output gain and soft switching design. Finally, simulations and a 360 W hardware experimental prototype are conducted to verify the accuracy and effectiveness of theoretical analysis.

Event-triggered boost converter model predictive control with Kalman filter

Event-triggered control has been gaining popularity as a method to reduce the computational burden of model predictive control (MPC). Existing literature reports its successful use in power converter applications. In our survey, event-triggered model predictive control (ET-MPC) is used to improve the computational performance of an enumeration-based MPC controlled boost converter. ET-MPC solves an optimal control problem (OCP) to generate an optimal actuating value only when an event is triggered as opposed to solving the OCP at every time step, and hence reduce the computational load. In addition, a Kalman Filter-based estimator is added to the control system to ensure accurate voltage tracking even in the presence of model mismatch, which commonly occurs during load transients. The novelty of this work lies in the selection of the actuating control signal, where the control actions are selected from the optimal switching sequence as opposed to upholding the last value of the optimal actuating value as reported in prior literature. Extensive simulation evaluations are conducted to compare the performance of conventional time-triggered MPC and the proposed event-triggered MPC, where the event-trigger threshold is used as a tuning parameter to balance computation and control performance.

Sensorless MPPT Algorithms for PV Systems in Partially Shaded Scenarios

This manuscript presents current sensorless algorithms for maximum power point tracking (MPPT) in partially shaded photovoltaic (PV) systems. The necessity of a current sensor is eliminated with the use of mathematical modeling of the power electronics converter. This approach significantly reduces the implementation cost and the inherent disadvantages in the current sensor circuitry. MPPT techniques based on soft computing are employed, in addition to Perturb and Observe (P&O), due to their ability to explore a larger search space. This feature is advantageous because it minimizes convergence risk to a local maximum, a limitation of traditional techniques. Simulation and experimental results are presented and each algorithm is evaluated through different metrics, such as search time for the global maximum power point (GMPP) and efficiency. The tests consider dynamic irradiance profiles, producing a tracking factor (TF) above 99% and a remarkable fast convergence time.

Neural ODE Model of Power Electronic Converters With Accelerated Computation and High Fidelity

Neural ODE Model of Power Electronic Converters With Accelerated Computation and High Fidelity

Research on characteristics of a two-dimensional piston pump with magnetic motion converters

A new type of two-dimensional piston pump with magnetic motion converters is proposed, which uses a pair of magnetic motion converters capable of generating a periodic axial force to replace the original roller-cam rail two-dimensional converters of the pump. By establishing the analytical model of the magnetic motion converters, the motion law of the two-dimensional piston under the magnetic motion converters is analyzed, and the efficiency model of the pump is established according to the principle of pump. The magnetic field simulation model of the magnetic motion converters is established based on Maxwell, and the simulation model of the piston pump is established based on AMESim. The simulation results verify the validity of the analytical model. The prototype pump and test rig were built, and the volumetric efficiency and mechanical efficiency of the pump under various working conditions were obtained. The deviation between the test results and the simulation results was less than 5%, which verified the correctness of the theoretical analysis.

Thermodynamic modeling of converter sludge sintering

Currently, a promising area is the development of technologies for sintering or briquetting of converter sludge. Recycling of this sludge into production will allow solving a number of important tasks for modern metallurgy in the utilization of man-made waste, saving raw materials and reducing the cost of steel. The efficiency of utilizing useful components in the composition of briquettes is significantly higher than in any other state (in a fine or polydisperse fraction, in sorted form). In this paper, we consider the development and justification of an integrated approach to thermochemical sintering of converter sludge based on conditioning of iron-containing sludge by non-thermal adsorption dehydration and thermochemical sintering with simultaneous reduction of iron from oxides. Adsorption dehydration to a moisture content of 2 – 3 % is provided by a short-term contact of iron-containing slimes with a porous energy carrier, brown coal semi-coke, which is separated by pneumoseparation and sent for energy technological use, and the iron-containing product mixed with coals is subjected to thermo-oxidative coking. Coking is carried out in an annular furnace with a rotating hearth, where, when temperatures reach 1050 – 1100 °C, a large and durable lump material is formed with 55 – 60 % of the iron-containing product with almost complete reduction. Thermodynamic modeling of converter sludge sintering with coals was carried out. A tool for performing computational experiments using methods of thermodynamic modeling of the studied object was the Terra software package designed to calculate the thermodynamic properties and composition of the phases of equilibrium state of arbitrary systems with chemical and phase transformations. The results of thermodynamic modeling were fully confirmed by the experimental studies. The obtained material is an analog of ferrocox containing 35 – 39 % of iron and 45 – 49 % of carbon, while the zinc oxide content does not exceed 0.017 %.

Optimal Control of Nonlinear, Nonautonomous, Energy Harvesting Systems Applied to Point Absorber Wave Energy Converters

Pursuing sustainable energy solutions has prompted researchers to focus on optimizing energy extraction from renewable sources. Control laws that optimize energy extraction require accurate modeling, often resulting in time-varying, nonlinear differential equations. An energy-maximizing optimal control law is derived for time-varying, nonlinear, second-order, energy harvesting systems. We demonstrate that sustaining periodic motion under this control law when subjected to periodic disturbances necessitates identifying appropriate initial conditions, inducing the system to follow a limit cycle. The general optimal solution is applied to two point absorber wave energy converter models: a linear model where the analytical derivation of initial conditions suffices and a nonlinear model demanding a numerical approach. A stable limit cycle is obtained for the latter when the initial conditions lie within an ellipse centered at the origin of the phase plane. This work advances energy-maximizing optimal control solutions for nonautonomous nonlinear systems with application to point absorbers. The results also shed light on the significance of initial conditions in achieving physically realizable periodic motion for periodic energy harvesting systems.

Analysis and Fuzzy Neural Networks‐Based Inertia Coefficient Adjustment Strategy of Power Converters

ABSTRACTWith the development of new energy generation technology and power electronic technology, power electronic equipment occupies an increasing proportion of the power system, and its control flexibility makes the power system complicated, bringing problems such as low inertia, low damping, high harmonics, low reliability, and weak anti‐interference ability. Especially the influence of converter on inertia of power system, even causing excessive frequency fluctuations, leading to the collapse of the power system. In view of the inertia problem of converters, this article starts with the principle of converters and analyzes the inertia transmission characteristics of different types of converters in power systems by three types of control strategies. Based on the influence of the inertia parameters of converters on system frequency and power, a converter inertia target function is established, and a neural network adaptive adjustment strategy for converter inertia coefficient is proposed to achieve self‐adaptive optimization of converter output power and system frequency. The corresponding converter model is established, and the simulation circuit and control model are built by Simulink to verify the inertia transfer characteristics. The simulation results show the correctness of the relevant theories and provide theoretical support for the inertia design of high‐proportion power electronic systems.