Quarter-Turn Transformer Design and Optimization for High Power Density 1-MHz <i>LLC</i> Resonant Converter

Liu, Yuchen; Chen, Kai-De; Chen, Chen; Syu, Yong-Long; Lin, Gong−Ru; Kim, Katherine A.; Chiu, Huang‐Jen

doi:10.1109/tie.2019.2902821

Cited by 46 publications

(18 citation statements)

References 21 publications

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“…The B pk,op for design set-A that was calculated to be 0.1583 T using OPFDM, becomes 0.1574 T using OPFDM-SR (21). However, this change is little and upon calculation of A prod , the value changes from 0.7738 to 0.7791 cm 4 . This change is too little to affect the choice of the core, thereby limiting the overall impact of high-frequency effect on the choice of model.…”

Section: Impact Of High Frequencymentioning

confidence: 97%

“…LLC resonant converters with zero-voltage switching are the most widely used and preferred converters in isolated DC-DC conversion stage of switching power supplies (SPSs). These stateof-the-art converters in comparison to other resonant converters (such as dual-active bridge) have, the smallest number of active switching devices, high performance, soft-switching, a wide range of voltage-gain, and capability to operate at high switching frequencies [1][2][3][4]. In these converters, litz-wire-based highfrequency gapped transformer (HFGT) plays an important role in isolation and voltage conversion, as well as providing proper magnetising inductance for efficient operation.…”

Section: Introductionmentioning

confidence: 99%

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Optimal peak flux density model (OPFDM) for non‐iterative design of high‐frequency gapped transformer (HFGT) in LLC resonant converters

Ahmed

Wang

2020

IET Power Electronics

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In LLC resonant converters, litz-wire high-frequency gapped transformer (HFGT) is one of the most critical components, responsible for efficient operation. However, it is also a major contributor to overall weight and volume. Therefore, designers perform multi-objective optimisation for minimising its losses and size, which is itself complex and cumbersome. This usually requires many iterations because the losses vary non-linearly with the decrease in size. The selection of initial-setup parameter (ISP) values, plays a vital role in overall performance improvement of the optimisation. The closer the ISPs to optimal values, the smaller are the iterations required for convergence. Therefore, this study proposes an optimal peak flux density model (OPFDM), considering the voltage excitation waveform, duty cycle, core material parameters, and the response of litzwire to high-frequency. The aim is to obtain an optimised HFGT design through a non-iterative approach by directly estimating optimal values of ISPs through OPFDM. The designed HFGT results in minimised losses and size, while keeping the thermal constraints within limits. Moreover, the impact of frequency and duty cycle on OPFDM is also presented. The proposed model is implemented to design HFGT for 380 VDC/12 VDC LLC converter. Comparison-based analytical, finite-elements method and experimental results validate the model.

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Section: Impact Of High Frequencymentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Optimal peak flux density model (OPFDM) for non‐iterative design of high‐frequency gapped transformer (HFGT) in LLC resonant converters

Ahmed

Wang

2020

IET Power Electronics

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“…Refs. [21][22][23] highlight an optimized transformer design for LLC converter to reduce core volume and conduction losses in the transformer windings for high power density. In addition to that, it provides the necessary isolation and required voltage-conversion and magnetizing inductance for efficient converter operation.…”

Section: State Of the Artmentioning

confidence: 99%

“…However, the proposed optimization strategies in the literature are mostly intended to minimize the cost and weight of the DC-DC LLC converter and guarantee soft-switching property in one operation mode, i.e., G2V mode [11,12,20,[24][25][26]. Moreover, the LLC converter is designed based on a reduced battery voltage (12-48 V) [8,[20][21][22][23][24][25][26] and converter power (20-1000 W) [8,12,[20][21][22][23][24][25][26]. For our best knowledge, no optimization algorithm, which takes into consideration the DC-DC LLC converter behavior in the two operation modes G2V and V2X for a bidirectional charger application, is presented to minimize the cost and increase the soft-switching range for a wide variation of the battery voltage and power.…”

Section: State Of the Artmentioning

confidence: 99%

LLC DC-DC Converter Performances Improvement for Bidirectional Electric Vehicle Charger Application

Attar

Hamida

Ghanes

et al. 2021

WEVJ

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Electric Vehicle (EV) bidirectional charger technology is growing in importance. It defines the fact of returning the electricity stored in the batteries of EV to Grid (V2G), to Home (V2H), to Load (V2L), or in one word V2X mode. The EV onboard charger is divided into two parts: AC-DC and DC-DC converters. The isolated bidirectional DC-DC LLC resonant converter is used to improve the charger efficiency within both battery power and voltage ranges. It is controlled by varying the switching frequency based on a small signal modeling approach using the gain transfer function inversion method. The dimensions of the DC-DC LLC converter directly affect the charger cost. Moreover, they cause an important control frequency saturation zone, especially in V2X mode, where the switching frequency is out of the feasibility zone. The new challenge in this paper is to design an optimization strategy to minimize the LLC converter cost and improve the control frequency feasibility zone, for a wide variation of battery voltage and converter power, in the charging (G2V) and discharging (V2X) modes simultaneously. For our best knowledge, this optimization problem, in the case of a bidirectional (G2V and V2X) charger, is not yet considered in the literature. An optimal design that considers the control stability equations in the optimization algorithm is elaborated. The obtained results show a significant converter cost decrease and important expansion of control frequency feasibility zones. A comparative study between initial and optimized values, in G2V and V2X modes, is generated according to the converter efficiency.

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“…There are some references that investigate how to design an HF-transformer to reduce losses. [25][26][27][28] In Liu et al 25 a so-called quarter-turn planar transformer structure was proposed and implemented in an LLC resonant converter for server power supply applications. With proposed design which is examined by FEM analysis, transformer secondaryside winding loss and core loss have been reduced by reducing the minimum numbers of turns on the primary and secondary sides also core size.…”

mentioning

confidence: 99%

A new detailed loss model and design approach for LLC resonant converter with phase shift control to overall optimization of converter loss at whole battery charging process

Saadati

Ghayebloo

2022

Circuit Theory & Apps

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This paper proposes a new loss modeling and design method for phase shift controlled resonant LLC converter with optimization applied to minimize the overall loss during the whole battery charging process. In this work, the loss model has been formulated more accurately for phase shift controlled LLC converter. One of the contributions in accurate loss modeling is all switching modes of power switches have been investigated in detail in the aspect of zero voltage switching (ZVS) and ZCS occurrence and their related dynamic loss are updated in loss calculation during the whole charging process. In addition, to optimize the copper and core losses of high‐frequency transformer and resonant inductor, a design trend is included in optimization process to calculate the best physical dimensions and winding parameters of magnetic components. A genetic algorithm has been employed for the optimization during the charging process. In this work, the first harmonic approximation (FHA) model was developed and solved by nonlinear Newton–Raphson method in any operating point along one complete charging process. The target of optimization was designing a wall mounted type level 2 battery charger (7.4 kw/32A) for charging a battery pack with specs according to the Nissan Leaf 2011 electric vehicle. For verification of the proposed method, simulation results are provided and also experimental results for a low‐scale prototype are proposed. In this study, the average efficiency along the overall charging process obtained up to 95% in simulation and 84% in experiments.

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Quarter-Turn Transformer Design and Optimization for High Power Density 1-MHz LLC Resonant Converter

Cited by 46 publications

References 21 publications

Optimal peak flux density model (OPFDM) for non‐iterative design of high‐frequency gapped transformer (HFGT) in LLC resonant converters

Optimal peak flux density model (OPFDM) for non‐iterative design of high‐frequency gapped transformer (HFGT) in LLC resonant converters

LLC DC-DC Converter Performances Improvement for Bidirectional Electric Vehicle Charger Application

A new detailed loss model and design approach for LLC resonant converter with phase shift control to overall optimization of converter loss at whole battery charging process

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