Resonant Converter Research Articles

Optimized Design of Full‐Bridge LLC Planar Transformer Based on Variable‐Width Windings

ABSTRACTTo address the issue of significant loss increase in planar transformers at high frequencies in LLC resonant converters, the winding width of the transformer was optimized. This design minimizes losses due to eddy currents and skin effects, thereby optimizing the transmission efficiency of the LLC resonant converter. This paper developed a mathematical model of the transformer windings, analyzed the losses in the windings and the core of the planar transformer, and summarized the design rules for three commonly used winding geometries. By determining the optimal winding width, the transformer losses were optimized. Using the finite element simulation software Maxwell3D, a 3D simulation model of the transformer was constructed. The simulation results were compared, and a 500‐W full‐bridge LLC prototype was built to validate the principles summarized in the paper.

Research on the Isolated Three‐Port DC‐DC Converter with Resonant Parameter Compensation Capability and Its Performance Optimization

AbstractIn order to eliminate the adverse effects caused by power coupling of the isolated three‐port converter (ITPC), this paper proposes a three‐port resonant converter that uses a switch‐controlled‐capacitor (SCC) and an auxiliary inductor, which has resonant parameter compensation capability (RPC‐ITPC). The topology and operational principle of RPC‐ITPC are discussed in detail. To achieve resonant‐type power decoupling, it is usually necessary to ensure that the resonant frequency of the decoupling port resonant tank is consistent with the switching frequency, which puts high demands on the accuracy of the resonant components. To address the sensitivity of resonant‐type power decoupling to the parameters of resonant components, an SCC was adopted to solve the problem. The use of SCC enables the RPC‐ITPC to have resonant parameter compensation capability. In order to further optimize the performance of the RPC‐ITPC, a triple‐phase‐shift (TPS) modulation strategy is proposed to achieve the minimum RMS value of resonant current (MRMS‐TPSMS). Under the MRMS‐TPSMS, the switching devices of the power decoupling port have difficulty achieving ZVS turn‐on. To circumvent this problem, we realize ZVS of the decoupling port switching devices via auxiliary inductor current injection. Finally, a 1 kW experimental prototype was constructed to validate the theoretical propositions presented in this study. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

A Lightweight Artificial Neural Network Start-Up Controller for CLLC Resonant Converters

A Lightweight Artificial Neural Network Start-Up Controller for <i>CLLC</i> Resonant Converters

Surge Current Analysis and Reduction in LLC Resonant Converter With a New Hybrid Control Strategy of Pulse-Frequency Modulation and Phase-Shift Modulation

Surge Current Analysis and Reduction in LLC Resonant Converter With a New Hybrid Control Strategy of Pulse-Frequency Modulation and Phase-Shift Modulation

Three-Level Double LLC Resonant Converter with Ripple-Free Input Current for DC Microgrid Application

DC distribution systems have garnered interest in recent years due to their advantages over AC distribution systems, such as their high power conversion efficiency and lack of harmonic issues. An isolated DC-DC converter with low-input noise, high efficiency, and high-power density is required for DC microgrids within DC distribution systems. Although existing DC to DC converters have high efficiency and high power density, they still have input noise problems due to pulsating input currents. Thus, a large input filter should be inserted, which increases the cost and degrades the power density. In this study, a novel three-level double LLC resonant converter with zero-input-current ripple is presented for DC microgrid application with a high-voltage DC bus. The input-current ripple of the proposed converter theoretically decreases to zero without adding large input filters. Moreover, the voltage stress on each main switch is only half of the input voltage when using the modified three-level structure, which enables the use of low-voltage-rated power switches for high-voltage input applications. In addition, all the primary switches and secondary diodes are softly switched over a wide input voltage range. The experimental results of the prototype are presented to verify the performance of the proposed converter.

Energy injection and free resonance converter for AC–AC inductive power transfer

Energy injection and free resonance converter for AC–AC inductive power transfer

Wide voltage gain isolated LCC resonant converters for LED driver applications

AbstractThis article proposes an isolated high‐efficiency resonant LED driver with wide‐input voltage range. The proposed converter is developed by integrating LCC resonant converter and buck‐boost converter. In this topology, the LCC network provides many features including the integration of buck‐boost filter inductor and the transformer magnetizing inductance. In addition, the LCC network provides zero voltage switching (ZVS) operation of the main switches and zero current switching (ZCS) operation of the rectifier diodes over a wide variation of duty cycle operation. Also, load‐independent output current characteristic with improved efficiency is obtained at the resonant frequency operation which is well‐suited for LED applications. Other topology variations of the proposed converter generating step‐up and step‐down voltage gains are introduced for applications with different input voltage ranges. To validate the theoretical analysis and LED driver operation, a 50 W laboratory prototype of the proposed LED driver is implemented for the wide input voltage of 18–40 V to deliver 500 mA output current to a string of 1–30 LEDs, which corresponds to an output voltage range of 3.3–100 V.

Serial resonant converter (SRC) polynomial model implemented in a digital signal controller (DSC)

AbstractThis work describes the process of modelling resonant converters by means of polynomial equations, in such a way that they can be easily implemented in digital controllers as digital signal controller. As an example, the serial resonant converter is modelled and its implementation in the TMS320F28335 Texas Controller.

Universal Soft Switching Dual Active Bridge Converter for Electric Vehicle Charging Infrastructure towards Sustainable Electric Transportation

This paper introduces a modified Dual Active Bridge (DAB) converter integrated with an LLC2 resonant converter tailored for Electric Vehicle (EV) charging infrastructure, emphasizing a unidirectional power flow. The converter implements a two-stage power conversion process, leveraging the DAB’s suitability for high-power applications characterized by enhanced efficiency, low voltage stress, and universal soft switching (ZVS) across all switches. Distinguishing itself from conventional isolated and non-isolated DC-DC converters, the DAB-LLC2 configuration is systematically elucidated in terms of its operating principle, soft switching characteristics, steady-state attributes, output features and crucial design parameters. A meticulous design of a 3kW DAB-LLC2 converter is conducted using MATLAB/Simulink software and the comprehensive results are documented, providing valuable insights into the converter’s performance and applicability for EV charging infrastructure for sustainable electric transportation.

Bipolar to unipolar conversion in superjunction MOSFETs during resonant switching

Superjunction MOSFETs have been one of the promising switching components for realizing resonant converters. In spite of the numerous studies about the resonant converters in power electronics, the detailed current flow in the device has been still unclear, especially for the inner-current circulation between the body diode and the MOSFET. By employing five-terminals on the superjunction MOSFET, mixed-mode half-bridge resonant converter is simulated. During the turn-on of the MOSFET, the gate charging current flows into the drain-to-source capacitance to form a built-in depletion of the pillars. In the case of the turn-off, the source current reversely flows across the channel with a slightly negative drain-to-source bias and diverts to the gate discharging current.

Research on Cascaded On‐Board DC/DC Converter Based on Three‐Phase Interleaved LLC

ABSTRACTThe on‐board DC/DC converter proposed in this research consists of a Buck converter and a three‐phase interleaved LLC resonant converter. This paper analyzes the average current and output current ripple characteristics of the rear‐stage converter in addition to explaining the topology and working principles of the front‐stage Buck converter and the rear‐stage three‐phase interleaved LLC resonant converter. To establish a single‐phase fundamental equivalent circuit for the rear‐stage converter, apply the fundamental wave analysis method, and it is essential for comprehending the impact of relevant system parameters on voltage gain characteristics and resonant operating regions. Conducting research on the two‐stage on‐board DC/DC converter's control strategy involves establishing small‐signal circuit models for both front and rear stage converters, derivation of parameters for double closed‐loop control, and determination of the control strategy employing phase‐shifted current sharing for the rear‐stage converter in cases where significant tolerance exists in resonant components. The simulation for a two‐stage on‐board DC/DC converter results indicates that under various conditions of resonant component tolerance, the converter is capable of achieving balanced phase currents and demonstrates minimal output current ripple prior to capacitor filtering. A 1.5‐kW experimental prototype has been fabricated, and the experimental findings indicate that the output voltage remains stable at 13.8 V despite fluctuations in input voltage. The highest efficiency of the prototype is about 96.27%, and the utilization of phase‐shifting current balancing control results in a notable reduction in output current ripple. This provides more evidence that the design of a two‐stage on‐board DC/DC converter is correct.

On-State Voltage Measurement Circuit for Condition Monitoring of MOSFETs in Resonant Converters

This work aims to estimate the Metal-Oxide-Semiconductor Field-Effect Transistor’s (MOSFET) junction temperature, guessing in real time the dynamic drain-source resistance during MOSFET operation in LLC (Inductor-Inductor-Capacitor) converters usually adopted in Switched-Mode Power Supplies. The task is accomplished using an on-state voltage measurement circuit that allows clamping of the high-voltage drain-source voltage during the off-state. The results of this method have been compared with the temperature accurately measured using a co-packed die as a thermal sensor.

Improved Natural Current Sharing and Phase-Shedding Operation in LLC Resonant Converters With Voltage-Doubler Rectifier

Improved Natural Current Sharing and Phase-Shedding Operation in <i>LLC</i> Resonant Converters With Voltage-Doubler Rectifier

“E+Ǝ” Cores Magnetic Integrated Transformers for Two-Phase Parallel LLC Resonant Converter

“E+Ǝ” Cores Magnetic Integrated Transformers for Two-Phase Parallel <i>LLC</i> Resonant Converter

A Three-Port Resonant PV Converter With Adaptive Resonant Time and Optimized Gain Adjustment Path

A Three-Port Resonant PV Converter With Adaptive Resonant Time and Optimized Gain Adjustment Path

Fixed Frequency Highly Efficient Resonant Converter With Low Component Count for CC and CV Charges of Electric Vehicles Batteries

Fixed Frequency Highly Efficient Resonant Converter With Low Component Count for CC and CV Charges of Electric Vehicles Batteries

Partial Fluctuation Power Control of Resonant Converter in Solid-State Transformer

Partial Fluctuation Power Control of Resonant Converter in Solid-State Transformer

A Simplified Large-Signal Model-Based Control for Dual Active Bridge Series Resonant Converter to Achieve Uniform Dynamic Response

A Simplified Large-Signal Model-Based Control for Dual Active Bridge Series Resonant Converter to Achieve Uniform Dynamic Response

Conducted interference and voltage ripple suppression study in LLC resonant converter based on symmetric chaotic spread spectrum

ABSTRACT Spread-spectrum modulation technique can effectively reduce the peak value of conducted interference in automotive LLC DC/DC converters, but it will bring more serious ripple problems to Class E resonant converters. In this paper, we investigate the voltage ripple trend of LLC resonant converter when applying spread-spectrum modulation, and propose a chaotic signal sampling rule under the minimum output voltage ripple. A symmetric chaotic spreading method is proposed to reduce the output voltage ripple from the source by changing the distribution sequence of the chaotic signal to make it centrosymmetric. The symmetric chaotic spread spectrum is simulated and analysed to be able to suppress the conduction interference while reducing the voltage ripple, and is verified by experiments. This modulation strategy does not require the addition of auxiliary circuits and additional control links, which saves cost and reduces the difficulty of designing control links.

병렬 운전을 통한 4kW급 인공위성용 아날로그 LLC 공진형 컨버터 개발

A modular analog LLC resonant converter capable of delivering high power for aerospace applications with zero voltage switching turn on of power semiconductors has been proposed. The LLC converter utilizes a half bridge configuration, with top and bottom switches designed by paralleling two low capacity power semiconductors suitable for use in space, thereby increasing the current capacity to enable an output of up to 1.2kW. Each LLC converter module takes in 100V power and outputs 300V in a step up DC/DC converter configuration, designed to operate with regulated voltage and current. This paper describes the operating principles and steady state analysis of the proposed DC/DC converter. To validate its effectiveness, a prototype was constructed and tested. The tests yielded a max efficiency of 95.3% and an output of approximately 4kW, demonstrating the feasibility and output performance of high efficiency, high power supplies through load sharing of multiple modules in parallel.