Search Results (26)

This work contains the results of the research carried out on the framework of the design of the resonant power module of DAB. The peculiarity of this device is that it is supposed to be used as part of the basic element of a scalable power storage system, the load of which is an industrial three-phase network. The paper proposes a method of designing such devices based on preliminary analytical calculations and the development of numerical models. This method includes three stages. In the first iteration, the parameters of the resonant CLLC converter. In the second iteration, in the course of performing more accurate calculations and development of numerical models, the output parameters and the adjustment characteristic of the converter are determined, taking into account the specifics of the load. At the third stage, a numerical model of a high-frequency transformer is developed to determine the number of losses in the core and estimate the values of magnetic induction. Full article

This paper introduces a novel switching method called copolar switching, designed to maintain high power efficiency in CLLC bidirectional chargers across different modes of operation. The proposed method sets the switching frequency close to the resonance of the LC tank within the CLLC circuit, ensuring efficient power conversion in both the forward (charging) and reverse (discharging) modes. Using Fourier series analysis and circuit theory, the necessary duty cycle for achieving the target efficiency is derived and applied to the full bridge on the high-voltage side in reverse mode. Copolar switching ensures that the entire CLLC circuit operates at a single resonant frequency, addressing the conventional issue of unbalanced efficiency between forward and reverse power conversions. A prototype circuit was designed for power conversion between 400 V and 48 V. Experimental results demonstrate 1 kW power conversion with 97% efficiency in forward mode and 800 W conversion with the same efficiency in reverse mode. Additionally, the copolar switching method shows potential for applications requiring voltage output adjustments, such as converting between 400 V and 50 V. Full article

In conventional CLLC topologies, CC/CV charging is typically implemented using closed-loop control strategies based on phase shift modulation. This not only increases control complexity but also requires additional voltage and current sensing circuits, thereby raising the overall system cost. To address these issues, this paper proposes a novel CC/CV charging strategy. By analyzing the inherent characteristics of the coupled network, the switching frequencies corresponding to the CC and CV operating points are derived. By jointly applying frequency modulation and phase shift control to the CLLC converter, the system not only realizes CC/CV charging, but also enables the regulation of both the magnitude and the direction of power flow. Furthermore, to improve the system’s efficiency, a fine frequency tuning method is introduced to ensure operation under the critical zero-voltage switching (ZVS) condition. Finally, a 500 W prototype is constructed to validate the effectiveness of the proposed control strategy. Full article

The growing market penetration of Electric Vehicles (EVs) requires very efficient bidirectional on-board chargers. These converters must allow the power transfer from the grid to the battery of the vehicle and vice versa, since Vehicle to Grid (V2G) applications enable a mitigation of the peak demand and help regulate both the voltage and the frequency of the grid. In this paper, an innovative double asymmetric modulation was studied and applied to a resonant Dual Active Bridge (DAB), CLLC resonant filter configuration. The results of the study showed a significant efficiency boost and an easier controllability of the converter with respect to more traditional modulations or variable frequency techniques, maintaining Zero-Voltage Switching (ZVS) conditions for all the switches in a wide operating range, from 28 to 100% of the maximum power (4–14 kW). A map of optimum points, where converter losses are minimized, is calculated offline through an algorithm in MATLAB R2024a and a proper interpolation between these points allows any output power for each possible voltage level of the battery to be achieved: from 250 V up to 400 V. The modulations are compared and evaluated through simulations carried out in PLECS, both offline and using hardware-in-the-loop (HIL), as well as through experimental tests. Full article

This paper presents the design and implementation of a bidirectional resonant converter with enhanced dynamic response to electric vehicles (EV). The proposed system comprises an assembly of four switches, a capacitor, and an inductor on both the primary and secondary sides of the transformer. The value of C-L-L-C was calculated using the first harmonic approximation method. Moreover, the small-signal analysis method was used to design the control system and analyze the dynamic performance of the system. Closed-loop control algorithms for voltage and current loops with synchronous rectifiers (SRs) were designed and implemented on a 32-bit microcontroller (STM32G474RET6). A 70 kHz, 400 W prototype is built with a peak conversion efficiency of 95.05% using SR in the forward mode. Without SR, the peak conversion efficiency was 93.57% in the forward mode and 93.04% in the reverse mode. In the forward mode, the proposed algorithm reduced the settling time to 15 ms, in contrast to the 40 ms associated with the conventional algorithm; in the reverse mode, the proposed algorithm reduced the settling time to 10 ms, in contrast to the 15 ms associated with the conventional algorithm. Full article

This study introduces a Multiscale Dual-Attention U-Net (TS-MSDA U-Net) model for long-term time series synthesis. By integrating multiscale temporal feature extraction and dual-attention mechanisms into the U-Net backbone, the model captures complex temporal dependencies more effectively. The model was evaluated in two distinct applications. In the first, using multivariate datasets from 70 real-world electric vehicle (EV) trips, TS-MSDA U-Net achieved a mean absolute error below 1% across key parameters, including battery state of charge, voltage, acceleration, and torque—representing a two-fold improvement over the baseline TS-p2pGAN. While dual-attention modules provided only modest gains over the basic U-Net, the multiscale design enhanced overall performance. In the second application, the model was used to reconstruct high-resolution signals from low-speed analog-to-digital converter data in a prototype resonant CLLC half-bridge converter. TS-MSDA U-Net successfully learned nonlinear mappings and improved signal resolution by a factor of 36, outperforming the basic U-Net, which failed to recover essential waveform details. These results underscore the effectiveness of transformer-inspired U-Net architectures for high-fidelity multivariate time series modeling in both EV analytics and power electronics. Full article

The synchronous rectification (SR) strategy in CLLC resonant converters can effectively enhance operational efficiency, meeting the stringent requirements of application scenarios such as renewable energy systems, DC distribution systems, and electric vehicle-to-grid (V2G) technology. However, due to the complex mathematical model, achieving precise SR directly in CLLC resonant converters is challenging. To realize high-precision and low-complexity SR in CLLC resonant converters, this paper proposes a state-trajectory-based SR strategy. By leveraging geometric principles and tailored simplifications, the expression for SR timing is derived. The proposed SR strategy exhibits excellent versatility and is suitable for the entire frequency range of CLLC resonant converters. The feasibility and accuracy of the proposed SR strategy are validated through an 800 W CLLC resonant converter prototype, demonstrating a robust dynamic performance and achieving a rated efficiency of 97.38%. Full article

This paper introduces a new two-stage multi-parallel-channel LED driver using a CLL-C resonant converter as the first stage and a Time Division Multiple Control circuit as the second stage. The first stage of the proposed converter topology has been developed from CLL-C topology with an additional inductor in the primary side and a capacitor in the secondary side. The converter provides a constant current at a resonant frequency with a Zero Phase Angle (ZPA), thus achieving Zero Voltage Switching (ZVS) turn-on, nearly Zero Current Switching (ZCS) turn-off for the switches, and ZCS for the diodes. The Time Division Multiple Control (TDMC) circuit was applied in the second stage to share the balanced current to each LED string. A 200 W prototype with five output channels was implemented to verify the superior advantages of the proposed topology with a maximum efficiency of 95.05%. Full article

The integration of hybrid alternating current (AC) and direct current (DC) networks has gained relevance due to the growing demand for more flexible, efficient, and reliable electrical systems. A key aspect of this integration is the parallelization of power converters, which presents several technical challenges, such as current sharing imbalances, circulating currents, and control complexity. This paper proposes a distributed control architecture for parallel resonant CLLC dual active bridge (DAB) converters to address these issues in hybrid AC–DC networks and microgrids. The approach includes a master voltage controller to regulate the output voltage and distributed local current controllers to ensure load balance. The approach minimizes the difference between the output and input voltages, allowing for independent control of power flow. Simulation and experimental results show significant improvements. The system stability has been demonstrated experimentally. Transient response has been improved with response time 80% lower using the feed-forward term. The system maintained stability with current sharing deviations below 3% under full and low load conditions. Finally, scalability is ensured by the proposed distributed controller because the central power controller is not affected by the number of units in parallel used in the application. This solution is suitable for advanced hybrid networks and microgrid applications. Full article

Optimized guidelines for the design of power converters are crucial to achieve the expected goals in terms of performance, efficiency, power density, etc. Therefore, they are the basis for industrial success or failure. Resonant converters based on Dual Active Bridges (DABs) are particularly sensitive to the design process due to their inherently nonlinear behaviour; thus, they are in the spotlight for research and development at present. Plenty of design methodologies can be found in the literature but each of them is specific to the perspective of the authors, the performed analysis, the assumptions made, and the design objectives. It is critical to understand the Key Performance Indicators (KPIs) and design methodologies of a resonant DAB converter. There is a significant lack of articles that concisely and clearly summarize this. Different design methodologies are analyzed and compared with respect to the most important KPIs, and the most relevant demos and experiences are pointed out so that designers can select the best choice for their assignment. These results will help designers understand the design methodologies and carefully choose one based on the application, analysis, and design objectives. Full article

In recent years, the trend in power electronics has been toward high-efficiency and high-power-density converters. Additionally, this trend has allowed electric vehicles to accommodate larger batteries, which necessitate bi-directional capabilities not only for driving but also for vehicle to grid (V2G), etc. This article proposes a comparative analysis of GaN-based bi-directional topologies, namely the dual active bridge (DAB) converter and the CLLC converter. To ensure a fair analysis of the proposed topologies, prototypes with the same target of efficiency above 97.5% and a power density of 5.5 kW/L have been constructed. This research can support the adoption of 10.9 kW bi-directional topologies in GaN-based on-board chargers (OBCs) for EVs. Full article

This paper presents an electric vehicle (EV) switched reluctance motor (SRM) drive with incorporated operation capabilities integrated into the utility grid, the microgrid, and another EV. The motor drive DC-link voltage is established from the battery through an interleaved boost/buck converter with fault tolerance. The varied DC-link voltage can improve driving performance and reduce battery energy consumption over a wide speed range. Through a well-designed current control scheme, speed control scheme, and dynamic commutation tuning scheme, the established SRM drive possesses good performance in the motor driving mode. During deceleration, the regenerative braking energy can be effectively recovered to the battery. When the EV is in idle mode, the grid-to-vehicle (G2V) charging operation can be conducted through the bidirectional switch mode rectifier (SMR) and CLLC resonant converter. Satisfactory charging performance with good line drawn power quality and galvanic isolation is preserved. Conversely, the vehicle-to-grid (V2G) discharging operation can be performed. The EV can make movable energy storage device applications. Finally, the interconnected operations of the developed EV SRM drive to vehicle and microgrid are presented. Through vehicle-to-vehicle (V2V) operation, it can supply energy to the nearby EV when the battery is exhausted and needs roadside assistance. In addition, microgrid-to-vehicle (M2V) and vehicle-to-microgrid (V2M) operations can also be conductible. The EV battery can be charged from the microgrid. Conversely, it can also provide energy support to the microgrid. Full article

In this paper, a high-efficiency and low-cost active cell-to-cell balancing circuit for the reuse of electric vehicle (EV) batteries is proposed. In the proposed method, a battery string is divided into two legs to transfer the charge from each cell in one leg to that in the other and a bidirectional CLLC resonant converter is used to transfer energy between the selected cells. Thanks to the proposed structure, the number of bidirectional switches and gate drivers can be reduced by half compared to the conventional direct cell-to-cell topologies, thereby achieving lower cost for the system. The CLLC converter is used to transfer the charge, and it is designed to work at resonant frequencies to achieve zero-voltage zero-current switching (ZVZCS) for all the switches and diodes. Consequently, the system’s efficiency can be enhanced, and hence, the fuel economy of the system can also be improved significantly. To verify the performance of the proposed active cell-balancing system, a prototype is implemented for balancing the three EV battery modules that contain twelve lithium-ion batteries from xEV. The maximum efficiency achieved for the charge transfer is 89.4%, and the balancing efficiency is 96.3%. Full article

In DC microgrids, CLLC topology is commonly applied for battery integration. It provides galvanic separation, the ability to integrate a high-frequency transformer into the resonance circuit, and the ability to operate in a wide range of voltage. Moreover, it assures zero voltage switching conditions for all switches and zero current switching conditions for secondary side switches, which enables obtaining high efficiency. This paper presents a clear and effective approach to design a methodology for a CLLC DC/DC converter, especially a resonant tank. High-frequency transformer is fully integrated in a resonant tank. Its size is minimal and based on area product parameter $A_p$. An equivalent scheme for first harmonic approximation analysis is presented with inclusion of parasitic elements. Based on it, the analytical formulas are provided, which enable graphical determination of working characteristics. It was proved that the model increases the accuracy of the results. The conditions of ZVS and maximal magnetizing inductance are established, including parasitic capacitances of secondary side switches and transformer parasitic capacitances. Based on the proposed design methodology, as the proof of concept, a small-power prototype with a GaN transistor was built operating at 364 kHz. Converter losses were determined through analytical expressions and compared with the experimental and simulation results. Full article

The original system, designed as a combination structure of a linear machine and a wireless power transmission transformer, was designed to overcome the limitations of the wired power supply method used for working robots and transportation equipment in existing smart factories, and improvements in magnetic coupling and power transfer efficiency are needed. In this work, we study the efficiency improvement of a system that can supply wireless power to track-type transportation equipment. For this purpose, electromagnetic properties such as magnetic equivalent resistance, inductance, magnetic coupling rate, and core loss are analyzed using the finite element method. In addition, the results of magnetic field finite element analysis are applied in electrical equivalent circuit modeling to analyze the voltage transfer ratio and input/output characteristics of a CLLC resonant converter designed for wireless power transmission. The efficiency improvements of the proposed model are verified through a comparison of experimental and simulation results after fabricating a prototype. From the results of this study, a more optimized wireless power transmission system design based on the analysis results from an electromagnetic perspective can be realized to improve the efficiency of wireless power transmission. Full article