A Complete Step-by-Step Optimal Design for <i>LLC</i> Resonant Converter

Wei, Yuqi; Luo, Quanming; Wang, Zhiqing; Mantooth, H. Alan

doi:10.1109/tpel.2020.3015094

Cited by 75 publications

(24 citation statements)

References 31 publications

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“…In contrast to the method in refs. [7] and [19], the proposed method accounts for the charges flowing through the input voltage source during the dead time. As previously mentioned, the voltage v C r2 (t ) remains constant in t ∈ (t 0 , t 1 ); therefore,…”

Section: 2mentioning

confidence: 99%

An improved time‐domain analytical method for LLC resonant converters and dead time designs for zero‐voltage switching

Jiao

Guo

Wang

et al. 2023

IET Power Electronics

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In this paper, an improved time‐domain analytical method for LLC resonant converters is proposed. Unlike traditional time‐domain analytical methods, the resonant current in the dead time is derived by considering the equivalent capacitances of the switching devices and the transformer. The equivalent output capacitance of the primary‐side switch is calculated by using a two‐segment fitting approach. The equivalent capacitance of the transformer is calculated by using the six‐capacitor model. The current increment method is used to calculate the initial value of the magnetizing current and to determine the numerical calculation conditions for the proposed time‐domain expressions. Finally, the dead time ranges for zero‐voltage switching of the converter are derived based on the improved time‐domain method. Experiments were carried out with a 10 kW LLC resonant converter. The lower limit of the dead time calculated with the proposed method is closer to the experimental results than the values of two conventional methods.

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Section: 2mentioning

confidence: 99%

An improved time‐domain analytical method for LLC resonant converters and dead time designs for zero‐voltage switching

Jiao

Guo

Wang

et al. 2023

IET Power Electronics

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“…Furthermore, Refs. [8,20] show an optimal design methodology under the worst operation condition (minimum input voltage with maximum output power or maximum input voltage with minimum output power). Some constraints are included to obtain the suitable design area, such as operation mode, voltage stress for resonant capacitor, ZVS operation for primary switches, and resonant tank root-mean-square current.…”

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%

“…There are many topologies of isolated converters, such as Dual Active Bridge (DAB) converters [5] and Series Resonant Converters (SRC) [6], but they suffer from soft switching property loss at high input voltage and with a light load. DC-DC LLC resonant converters [7][8][9][10] are commonly selected for applications that demand a high power density, such as the EV charger.…”

Section: Introduction 1overviewmentioning

confidence: 99%

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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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“…Additionally, some other works for designing the LLC converter have been proposed in recent years. In Wei et al, 17 step‐by‐step optimal design methodology with converter analysis in time domain has been proposed; in Deng et al 18 for PHEV application, an LLC converter has been designed based on the worst‐case conditions for primary‐side ZVS operation with FHA method and constant maximum power (CMP) charging profile, and Authors in an earlier study, 19 a two‐step approach was proposed to solve the optimal design problem. In the first step, possible designs that have required peak gain are found and in the second step loss analysis is used to find the optimal design.…”

Section: Introductionmentioning

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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A Complete Step-by-Step Optimal Design for LLC Resonant Converter

Cited by 75 publications

References 31 publications

An improved time‐domain analytical method for LLC resonant converters and dead time designs for zero‐voltage switching

An improved time‐domain analytical method for LLC resonant converters and dead time designs for zero‐voltage switching

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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