A Current Sharing Method Utilizing Single Balancing Transformer for a Multiphase LLC Resonant Converter With Integrated Magnetics

Noah, Mostafa; Endo, Shun; Ishibashi, Hiroki; Nanamori, Kimihiro; Imaoka, Jun; Umetani, Kazuhiro; Yamamoto, Masaaki

doi:10.1109/jestpe.2017.2777508

Cited by 62 publications

(28 citation statements)

References 25 publications

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“…Other methods interconnect the resonant tanks or transformers to change and match the equivalent impedance of each resonant converter [16], [20]- [22]. Additionally, it is possible to add a magnetic coupling to transfer energy between tanks, maintaining the same current amplitude for all tanks and a balanced operation [7], [23], [24]. However, these methods are complex, costly and bulky, have slow dynamic performance and do not maintain an even power distribution among all the units for the entire operating range.…”

Section: Introductionmentioning

confidence: 99%

Decoupled PI Controllers Based on Pulse-Frequency Modulation for Current Sharing in Multi-Phase LLC Resonant Converters

et al. 2021

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The LLC series resonant converter has emerged as a solution to applications requiring power conversion with isolation, reduced volume and high efficiency, such as PV systems and EV chargers. However, the LLC resonant converter is limited in power, so it requires a multi-phase configuration in order to provide higher currents. This configuration connects the outputs of two or more LLC converters in parallel, increasing the output current but introducing imbalance and circulating currents due to the mismatch and tolerance values of components in each resonant tank. This paper proposes a simple PI control scheme to compensate the current imbalance and eliminate circulating currents generated when several LLC resonant converters are connected in parallel. Unlike reported current sharing methods, the proposed control scheme is based on multiple current control loops operating independently, using the switching frequency of each parallel-connected unit as a degree of freedom of the overall converter. The proposed control scheme has been successfully validated under simulations and experimental assessment, implementing two resonant tanks with ±5% tolerance of parameters, providing excellent steady-state and transient performance.

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Section: Introductionmentioning

confidence: 99%

Decoupled PI Controllers Based on Pulse-Frequency Modulation for Current Sharing in Multi-Phase LLC Resonant Converters

et al. 2021

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“…The interleaved LLC resonant converter employing common inductors tends to suffer from a current imbalance under light load conditions [11]. The three-phase interleaved LLC resonant converter developed in [12] automatically balances three-phase currents by utilizing an integrated transformer and current balancing transformer. However, the existence of the integrated transformer not only increases its design difficulty but also impairs the LLC resonant converters' advantage of the simple structure.…”

Section: Introductionmentioning

confidence: 99%

Three-Phase Interleaved LLC Asymmetric Resonant Converter With Capacitive Current Balancing and Reduced Switch Voltage Stress

2020

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Interleaved converters are a typical solution to enhance a current capacity and to reduce current ripples of an input or output port. Conventional interleaved LLC resonant converters need additional switches and passive components with a feedback control loop for active current balancing, increasing the circuit complexity and cost. This paper proposes a novel three-phase interleaved LLC resonant converter with an automatic capacitive current balancing capability. Two flying capacitors are added to a conventional interleaved LLC resonant converter in order to realize not only the automatic capacitive current balancing but also the reduced switch voltage stresses and asymmetric resonant operations that contribute to reducing rms currents as well as copper losses of transformers. The detailed operation analysis, including the capacitive current balancing mechanism and gain characteristics derivation, are performed. The experimental verification using a 1-kW prototype demonstrated that the automatic capacitive current balancing could be achieved despite the significant mismatch in transformers' parameters.INDEX TERMS Asymmetric resonance, current balancing, flying capacitor, interleaved converter, LLC resonant converter.

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“…Nonetheless, higher switching frequencies allow for smaller passive components, and hence an overall smaller power supply, as well as higher bandwidth to better react to various load and line disturbances. Therefore, to improve on the switching frequencies, soft switching topologies have been receiving much attention in recent years [1][2][3][4][5][6][7]. One family of soft switching converters are the resonant converters [8].…”

Section: Introductionmentioning

confidence: 99%

An Improved Linear Model for High-Frequency Class-DE Resonant Converter Using the Generalized Averaging Modeling Technique

Dahl

Ammar

Knott

et al. 2020

IEEE J. Emerg. Sel. Topics Power Electron.

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As the operating frequency of power converters increases, the passive component values likewise decrease. This results in the effect of the parasitic components becoming more prominent, leading to significant modeling errors if not considered. For resonant converters this especially becomes a problem at high frequencies. This paper presents a reduced model for a class-DE series resonant converter based on generalized averaging that incorporates the relevant parasitics and uses multiple harmonics to obtain an accurate linear model. Comparison between the proposed model, prior art, and a prototype converter running at 1 MHz is conducted, and a PI-controller is designed based on each model and tested. The results show that the parasitics have a significant impact on the DC-gain and dynamics of the converter, and that the proposed model improves on the prior art by reducing the DC-gain error by more than 7 dB, and the error in the low frequency pole from 168 % to 16.9 %. Furthermore, the PI-controller designed on the prior art was found to have more than 40 times larger overshoot in the control signal when measured compared to the model prediction, while the controller based on the proposed model showed correct performance when simulated and measured.

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A Current Sharing Method Utilizing Single Balancing Transformer for a Multiphase LLC Resonant Converter With Integrated Magnetics

Cited by 62 publications

References 25 publications

Decoupled PI Controllers Based on Pulse-Frequency Modulation for Current Sharing in Multi-Phase LLC Resonant Converters

Decoupled PI Controllers Based on Pulse-Frequency Modulation for Current Sharing in Multi-Phase LLC Resonant Converters

Three-Phase Interleaved LLC Asymmetric Resonant Converter With Capacitive Current Balancing and Reduced Switch Voltage Stress

An Improved Linear Model for High-Frequency Class-DE Resonant Converter Using the Generalized Averaging Modeling Technique

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