Small signal analysis of the resonant LLC converter

Stähl, Jutta; Hieke, Tobias; Oeder, Christian; Duerbaum, Thomas

doi:10.1109/ecce-asia.2013.6579069

Cited by 15 publications

(6 citation statements)

References 11 publications

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“…The above (18) can be further simplified as: (19) The investigation regarding the cross frequency on (19) has been revealed that the factor δ (R L , f n ) is much smaller than the value of the variable o / k f in the practical application, then the cross frequency can be simplified further as: (20) Equation (20) shows that the cross frequency for the open control to output is firmly related to the operation frequency no matter whatever the output load is, which can be verified from the results shown in Fig. 11, where the cross frequency is proved not to be affected by the output load directly.…”

Section: Whilementioning

confidence: 99%

“…To work out the model of LLC converter, lots of researches [17]− [20] based on the extended describing function or other similar averaged modeling concept [21] have been employed and the results are proved to be accurate to predict the beat frequency dynamics. However, the models are still hard to meet the practical engineering design due to its lack of analytical transfer functions for the physical insight extraction and most precise modes are only based on the simulation in which the physical insight is hard to yield.…”

Section: Introductionmentioning

confidence: 99%

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Investigation on the Small Signal Characteristic Based on the LLC Hybrid Hysteretic Charge Control

Yang¹,

McDonald²,

Li³

2019

CPSS TPEA

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In this paper, an analytical small-signal model applied for hybrid hysteretic charge (HHC) control has been proposed and analyzed with the advantages over direct frequency control (DFC). Based on the approach of extended describing function method and average concept, for the first time, the systematical analytical open loop transfer functions from control to output, input to output, output impedance and the closed transfer functions of the overall loop, audio susceptibility and output impedance are proposed and verified through simulation. Additionally, some important physical insights have been extracted, analyzed and verified. Finally, the experiments on a design example of 12 VDC&12 A output power are conducted and verified. It shows that the calculations match well with the results from both the simulation and experiment, which reveals the proposed analytical transfer functions are very useful for the practical power design to achieve good prediction result. Index Terms-Analytical small signal model, hybrid hysteretic charge (HHC), hybrid hysteretic charge control, LLC, UCC25630.

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Section: Whilementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation on the Small Signal Characteristic Based on the LLC Hybrid Hysteretic Charge Control

Yang¹,

McDonald²,

Li³

2019

CPSS TPEA

View full text Add to dashboard Cite

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“…But the weak spot with this approach is the inaccuracy of the model for lower frequencies. To tackle the inaccuracy issue of this strategy, a new approach called Virtual Network Analyzer (VNA) is presented by [7]. The accuracy of this method, however, is relatively high, it suffers from a long simulation time.…”

Section: Introductionmentioning

confidence: 99%

“…The accuracy of this method, however, is relatively high, it suffers from a long simulation time. Compared to VNA, sampled-data modeling suggested by [7] is another approach that is fast; although the accuracy of the obtained model deteriorates for higher frequencies. Moreover, extreme numerical and analytical efforts would be needed for converters with more operating modes.…”

Section: Introductionmentioning

confidence: 99%

Validation of a Discrete-Time-Domain Model of a High-Power Medium-Voltage Resonant Converter*

Mahdizadeh Shalmaei,

Soltani,

Hajizadeh

2023

2023 IEEE Conference on Control Technology and Applications (CCTA)

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The widespread deployment of LLC resonant converters in DC technologies has attached a profound significance to the modeling and controlling of such power converters. Compared to the conventional DC-DC converters that could be modeled through small-signal analysis, the Modeling of the LLC resonant converters is complicated. This complexity comes from the way that the electrical energy in a resonant tank is processed, which leads to high non-linearity. Therefore, small-signal analysis is traditionally performed via empirical approaches or iterative simulation methods at around the resonant frequency. But, the weak spot associated with these methods is that they provide superficial and limited insight into the system's dynamic. Moreover, the accuracy of the model is adversely affected as far as the switching frequency deviates from the resonant frequency. This inaccuracy issue becomes serious when the converter operates in sub-resonant mode as this mode is preferred for medium voltage applications. This article, therefore, presents a discrete-time domain approach through which the model of a medium-voltage LLC resonant is derived. Then, the dynamic and static behaviors of the plant are briefly investigated. Finally, a meaningful comparison between the simulation and experimental results obtained from a scaled prototype is provided to validate the modeling approach.

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“…One of the main drawbacks of this approach is the low model accuracy for lower frequencies. The Virtual Network Analyzer (VNA) approach presented by [7] measures the transfer function of a device under test. The accuracy of this method is high, but the simulation time is quite long as repetition of the procedure for various switching frequencies is necessary.…”

Section: Introductionmentioning

confidence: 99%

Discrete-Time Domain Modeling of a High-Power Medium-Voltage Resonant Converter

Mahdizadeh,

Soltani,

Hajizadeh

2023

2023 25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe)

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LLC resonant converters are widely used in diverse industrial applications, due in part to their high efficiency and high power density. In spite of their numerous advantages, these converters are still considered the most challenging converters from a modeling and control perspective. Several factors contribute to this complexity, including the nonlinear behavior and different operating modes. Therefore, a high-power medium-voltage resonant converter is modeled in this manuscript, and its dynamic behavior is investigated. The nonlinear model simulation performed by MATLAB/Simulink and the electrical circuit simulation performed by PLECS are then compared to verify the accuracy of the obtained model.

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Small signal analysis of the resonant LLC converter

Cited by 15 publications

References 11 publications

Investigation on the Small Signal Characteristic Based on the LLC Hybrid Hysteretic Charge Control

Investigation on the Small Signal Characteristic Based on the LLC Hybrid Hysteretic Charge Control

Validation of a Discrete-Time-Domain Model of a High-Power Medium-Voltage Resonant Converter*

Discrete-Time Domain Modeling of a High-Power Medium-Voltage Resonant Converter

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