Search Results (22)

This article proposes a high-efficiency isolated three-port resonant converter for DC microgrids, combining a dual active bridge (DAB)–LLC topology with hybrid Pulse Width Modulat-Pulse Frequency Modulation (PWM-PFM) phase shift control. Specifically, the integration of a dual active bridge and LLC resonant structure with interleaved buck/boost stages eliminates cascaded conversion losses. Energy flows bidirectionally between ports via zero-voltage switching, achieving a 97.2% efficiency across 150–300 V input ranges, which is a 15% improvement over conventional cascaded designs. Also, an improved PWM-PFM shift control scheme dynamically allocates power between ports without altering switching frequency. By decoupling power regulation and leveraging resonant tank optimization, this strategy reduces control complexity while maintaining a ±2.5% voltage ripple under 20% load transients. Additionally, a switch-controlled capacitor network and frequency tuning enable resonant parameter adjustment, achieving a 1:2 voltage gain range without auxiliary circuits. It reduces cost penalties compared to dual-transformer solutions, making the topology viable for heterogeneous DC microgrids. Based on a detailed theoretical analysis, simulation and experimental results verify the effectiveness of the proposed concept. Full article

Battery energy storage systems are essential for grid stability and the efficient integration of renewable energy sources. Their performance is influenced by the efficiency of bidirectional converters, particularly under varying load conditions. This study presents a novel current-adaptive control strategy for a two-stage non-isolated bidirectional DC-DC converter designed to dynamically adjust the number of active branches based on real-time load variations. The proposed approach introduces a current-adaptive algorithm for branch activation and deactivation, combined with real-time temperature-based control decision making, which has not been explored in existing studies. The validation was conducted using real-time Hardware-in-the-Loop simulation with the Typhoon HIL 402 system, ensuring accurate system representation. The results show an increase in average efficiency from $77.69\%$ to $83.15\%$ in Buck mode and from $81.00\%$ to $83.71\%$ in Boost mode, with a reduction in average power losses by $8.67\%$ and $13.31\%$, respectively. These findings underscore the need for further research on temperature-adaptive control for efficiency optimization and thermal management, which is currently ongoing and will be expanded in future work. Future efforts will focus on experimental validation using a physical prototype and further refinement of temperature-adaptive control strategies. Full article

This paper presents the analysis and design of an isolated bidirectional DC-DC converter for applications where both input and output voltages may vary in a wide range. The proposed topology is derived from the integration of an isolated Current-Fed Dual-Active-Bridge (CF-DAB) stage with a Four-Switch Buck-Boost cell (4SBB), sharing one switching leg. Detailed design procedures are outlined for both CF-DAB and 4SBB stages, allowing to achieve Zero-Voltage turn-on of all devices while minimizing the inductor current RMS values. An optimized design of the CF-DAB coupled inductors allowed to achieve the desired leakage inductance value without the need for an additional magnetic component. Experimental results taken on a 5 kW prototype interfacing two voltage ports with V_L ∈ [42 V, 72 V], V_H ∈ [225 V, 435 V] validate the proposed design procedure. Full article

In this paper, to achieve versatile, cost-effective charging for dual-motor EVs, a multi-functional integrated onboard charger is constructed using a dual-motor driving system. In the driving mode, a five-phase flux-switching permanent-magnet (FSPM) motor powers the front, while a three-phase FSPM motor drives the rear. While in the charging mode, different topologies are adopted for different application scenarios, such as the single-phase AC charging mode, the three-phase AC charging mode, and the DC charging mode. The five-phase FSPM motor and its inverters serve as a boost-based AC/DC converter in both single-phase and three-phase AC charging modes, transforming grid power to DC. In the DC charging mode, they are reconfigured to function as a buck converter. During the three-phase AC charging mode, the three-phase FSPM motor and its inverters take on the role of a rear-stage buck converter. They function to regulate the rectified DC voltage, ensuring it meets battery charging needs. The performance of the integrated charger is validated through simulation and experiment results. Full article

A new four-port non-isolated SEPIC converter intended for hybrid renewable energy systems is presented in this study. The suggested converter minimizes space and expense by integrating two inputs and two outputs in a single-stage structure with fewer components. The converter retains important characteristics including continuous input current, buck/boost capability, non-inverting output, and enhanced power factor because it is based on the fundamental SEPIC topology. It effectively combines an energy storage system (ESS) with a variety of energy sources that have different voltage and current characteristics. The converter can be configured to operate in unidirectional or bidirectional topologies depending on whether storage elements are included. Performance is examined in two operating modes, with an emphasis on the ESS’s charging and discharging processes. System equations are produced by steady-state analysis, and the design of a closed-loop controller for accurate input power and output voltage regulation is informed by dynamic analysis performed with the state-space approach. Through real-time hardware implementation and MATLAB/Simulink simulations, the efficacy of the suggested design is verified, demonstrating the open-loop unidirectional topology’s theoretical and practical validity. Full article

A novel integrated DC-DC converter is proposed for the first stage of two-stage grid connected photovoltaic (PV) systems with energy storage systems. The proposed three-port converter (TPC) consists of a buck–boost converter, interposed between the battery storage system and the DC-AC inverter, in series with PV modules. The buck–boost converter in the proposed TPC is utilized for maximum power point tracking by regulating two power switches. The output power of the proposed converter is regulated by controlling the DC-AC converter. During the battery-charging mode, partial power regulation is employed with a direct power flow path (the series-connection of the PV panel, the battery and the output). As resistances in this path are almost negligible, the power conversion efficiency is higher than existing topologies. During battery-discharging mode, the power conversion is processed through a buck–boost converter with only two active power switches and one inductor. With fewer components, higher power conversion efficiency is also achieved. The circuit operation and analysis are presented in detail. To illustrate the simplicity of the converter control, the performance of the converter is tested with a straightforward maximum power point tracking on a PV system with battery cells. Simulation and experimental tests are carried out to demonstrate circuit operation and power conversion efficiency. Full article

The composite converter allows integrating the high-efficiency converter modules to achieve superior efficiency performance, becoming a prominent solution for electric transport power conversion. In this work, the versatile buck–boost dc–dc converter is proposed to be integrated into an electric vehicle composite architecture that requires a wide voltage range in the dc link to improve the electric motor efficiency. The inductor core of this versatile buck–boost converter has been redesigned for high voltage applications. The versatile buck–boost converter module of the composite architecture is in charge of the control stage. It provides a dc bus voltage regulation at a wide voltage operation range, which requires step-up (boost) and step-down (buck) operating modes. The PLECS thermal simulation of the composite architecture shows a superior power conversion efficiency of the proposed topology over the well-known classical noninverting buck–boost converter under the same operating conditions. The obtained results have been validated via experimental efficiency measures and experimental transient responses of the versatile buck–boost converter. Finally, a hardware-in-the-loop (HIL) real-time simulation system of a 4.4 kW powertrain is presented using a PLECS RT Box 1 device. The HIL simulation results verified the accuracy of the theoretical analysis and the effectiveness of the proposed architecture. Full article

This paper presents the stability improvement of the three-phase four-wire (3P-4W) grid-tied PV-hybrid energy storage system (HESS) using chaotic grew wolf optimization (CGWO) for DC bus voltage $\left(V_{dc}\right)$ and AC bus voltage $\left(V_{pcc}\right)$ control. The CGWO tuned fractional order proportional–integral (FOPI) controllers reduce the $V_{dc}$ and $V_{pcc}$ variations during diverse, dynamic conditions, i.e., sudden irradiation variations, deep voltage sag/swell, etc. The DC bus is responsible for the current injection/extraction control, maximum PV power extraction, bi-directional power flow, dc second-harmonics component elimination, and active power balance. At the point of common coupling (PCC), the AC bus is accountable for bi-directional power flow and active and reactive power control. The two-level voltage source converter (VSC) is controlled by a novel variable step-size incremental least mean square (VSS-ILMS) in zero voltage regulation (ZVR) mode. Due to its varying step size, VSC control is less prone to noise signals offers better stability, improved convergence rate, dc offset rejection, and tracking speed during dynamics, i.e., large oscillations. A battery and ultracapacitor are coupled to the DC link by buck-boost converters in the HESS. To regulate power transit between the DC bus and the grid, the HESS current control technique is designed to shift frequently from charging to discharging stage and vice versa. The novelty of the PV-HESS system lies in CGWO tuned VSS-ILMS control of VSC, which effectively and efficiently filter out the active fundamental constituents of load current and eliminate dc offset from VSC output. The HESS control maintains the DC bus voltage profile by absorbing and delivering energy (during dynamic conditions) rather than curtailing it. The presented system is simulated in a MATLAB/SIMULINK environment. The simulation results in graphical and numerical forms verify the stable and satisfactory operation of the proposed system as per IEEE519 standard. Full article

A cascaded-like high-step-down converter (CHSDC) is proposed in this article, which can steeply convert a high voltage to a much lower level without the utilizing of extreme turns ratio or duty ratio. The proposed converter integrates two buck-boost converters and one forward converter to form a single-stage architecture containing only a single low-side driving switch, which, as a result, can lower the cost and reduce the complexity of the associated control driver. Even in a single-stage single-switch structure, the ability to step down input voltage is as effective as the cascade of two buck-boosts and one forward converter. Meanwhile, the proposed converter can avoid the low efficiency caused by a cascaded structure. Without an additional clamp circuit, the leakage energy stored in the transformer of the CHSDC can be still recycled so as to raise the efficiency of the converter and suppress voltage spikes at the power switch. Converter operation principle and key parameter design are discussed. Moreover, a 200 W prototype is built and then tested to validate the proposed converter and verify the theoretical analysis. Full article

Microinverters for Building Integrated Photovoltaic (BIPV) systems must have had a small number of components, be efficient, and be reliable. In this context, a single-phase Buck-Boost Single-stage Microinverter (BBSM) for grid-connected BIPV systems is presented. The concept of topology is extracted from the buck-boost converter. The leakage current in the system is kept under control. It uses an optimal number of active and passive components to function at a high-efficiency level. The suggested topology provides a high level of reliability due to the absence of shoot-through problems. To validate the findings, a simulation in combination with an experimental system for a 70 W system is developed with the design approach. The efficiency of the microinverter, total harmonic distortion of the grid current are measured as 96.4% and 4.09% respectively. Finally, a comparison study has indicated the advantages and disadvantages of the suggested inverter. Full article

The universal paradigm shift towards green energy has accelerated the development of modern algorithms and technologies, among them converters such as Z-Source Inverters (ZSI) are playing an important role. ZSIs are single-stage inverters which are capable of performing both buck and boost operations through an impedance network that enables the shoot-through state. Despite all advantages, these inverters are associated with the non-minimum phase feature imposing heavy restrictions on their closed-loop response. Moreover, uncertainties such as parameter perturbation, unmodeled dynamics, and load disturbances may degrade their performance or even lead to instability, especially when model-based controllers are applied. To tackle these issues, a data-driven model-free adaptive controller is proposed in this paper which guarantees stability and the desired performance of the inverter in the presence of uncertainties. It performs the control action in two steps: First, a model of the system is updated using the current input and output signals of the system. Based on this updated model, the control action is re-tuned to achieve the desired performance. The convergence and stability of the proposed control system are proved in the Lyapunov sense. Experiments corroborate the effectiveness and superiority of the presented method over model-based controllers including PI, state feedback, and optimal robust linear quadratic integral controllers in terms of various metrics. Full article

The problem of voltage regulation in unknown constant resistive loads is addressed in this paper from the nonlinear control point of view for second-order DC-DC converters. The converters’ topologies analyzed are: (i) buck converter, (ii) boost converter, (iii) buck-boost converter, and (iv) non-inverting buck-boost converter. The averaging modeling method is used to model these converters, representing all these converter topologies with a generalized port-Controlled Hamiltonian (PCH) representation. The PCH representation shows that the second-order DC-DC converters exhibit a general bilinear structure which permits to design of a passivity-based controller with PI actions that ensures the asymptotic stability in the sense of Lyapunov. A linear estimator based on an integral estimator that allows reducing the number of current sensors required in the control implementation stage is used to determine the value of the unknown resistive load. The main advantage of this load estimator is that it ensures exponential convergence to the estimated variable. Numerical simulations and experimental validations show that the PI passivity-based control allows voltage regulation with first-order behavior, while the classical PI controller produces oscillations in the controlled variable, significantly when the load varies. Full article

Paralleled boost asymmetric configurations operating in discontinuous conduction mode (DCM) are suitable for integrating dissimilar green energy generating sources and control algorithms in versatile scenarios where voltage step-up, low cost, stable operation, low output ripple, uncomplicated design, and acceptable efficiency are needed. Unfortunately, research has mainly been conducted on the buck, sepic, switched-capacitor, among other asymmetric configurations operating in continuous conduction mode (CCM), to the authors’ knowledge. For asymmetric boost type topologies, achieving simultaneous CCM is not a trivial task, and other problems such as circulating currents arise. Research for interleaved converters cannot be easily extended to asymmetric boost topologies due to the dissimilarity of control algorithms and types of sources and parallel stages. This paper analytically establishes properties of stability, output ripple, output voltage, and design for asymmetrical paralleled boost converters operating in DCM with simultaneous or phase delayed (sequential) triggering. A 300 W experimental design and the respective tests allow validation of such properties, resulting in an easy-to-implement configuration with acceptable efficiency. Full article

A novel single-switch single-stage high power factor LED driver is proposed by integrating a flyback converter, a buck–boost converter and a current balance circuit. Only an active switch and a corresponding control circuit are used. The LED power can be adjusted by the control scheme of pulse–width modulation (PWM). The flyback converter performs the function of power factor correction (PFC), which is operated at discontinuous-current mode (DCM) to achieve unity power factor and low total current harmonic distortion (THDi). The buck–boost converter regulates the dc-link voltage to obtain smooth dc voltage for the LED. The current–balance circuit applies the principle of ampere-second balance of capacitors to obtain equal current in each LED string. The steady-state analyses for different operation modes is provided, and the mathematical equations for designing component parameters are conducted. Finally, a 90-W prototype circuit with three LED strings was built and tested. Experimental results show that the current in each LED string is indeed consistent. High power factor and low THDi can be achieved. LED power is regulated from 100% to 25% rated power. Satisfactory performance has proved the feasibility of this circuit. Full article

The advancement of power electronic-based sensitive loads drives the power utilities’ devotion to power quality issues. The voltage disturbance could be happening due to fault conditions, switching of loads, energizing of transformers, or integration of highly intermittent energy sources such as PV systems. This research work attempts to enhance the voltage fluctuation of a sensitive load connected to a grid-integrated PV system using a battery-based dynamic voltage restorer (DVR). The proposed battery energy storage-based DVR has two separate controlling stages that are implemented at the DC–DC buck/boost converter of the battery and voltage source converter (VSC) system. Charging and discharging of the battery is operated based on the state-of-charge (SOC) value of the battery and the measured root mean square (RMS) voltage at the point of common coupling (PCC). The VSC of the DVR detection and reference generation control is done appropriately. In the detection control of the VSC, a combination of RMS and dq0 measurement techniques is used, whereas in the reference generation control, pre-fault strategy is implemented to restore both phase jump and magnitude distortions. Symmetrical and asymmetrical voltage sags scenarios are considered and the compensation demonstration is carried out using power system computer-aided design (PSCAD/EMTDC) software. Full article