Extended Harmonics Based Phase Tracking for Synchronous Rectification in CLLC Converters

Sankar, Arun; Mallik, Ayan; Khaligh, Alireza

doi:10.1109/tie.2018.2874348

Cited by 65 publications

(17 citation statements)

References 23 publications

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“…As can be seen, first harmonic value of sin kφ /k 3 would be at least ×10 times larger than the other harmonic total if φ > 25°. Thus, the active power could be regarded to be contributed by only the first harmonic component in this case, which is expressed by P active ≃ P 1 , if φ > 25° (25) Combining (12), the relationship between frequency and phase shift can be simply formulated as (26) which highly simplifies the computation without significant loss of generality.…”

Section: Proposed Dual-control Modulation and Systematic Optimisationmentioning

confidence: 99%

“…Alternatively, the switching timing of the secondary switches can be estimated using different approximation methods [22,[25][26][27]. First harmonic approximation (FHA) method has been a simple solution to model the converter, where only the first-order harmonic component of the voltage and the current is analysed [8,22].…”

Section: Introductionmentioning

confidence: 99%

“…However, there is no commercially available SR chip that works at the vehicle HV battery voltage level (200–450 V). Although analogue circuits could be utilised to detect zero‐crossings of the voltage, phase synchronisation errors are usually inevitable due to the limited sampling frequency and the turn‐on delays (to tolerate the voltage oscillation during switching) [25].…”

Section: Introductionmentioning

confidence: 99%

“…This method is refined by the extended harmonic approximation (EHA) [25, 27], where higher harmonics are also included in the model to improve the estimation accuracy. Nevertheless, the model established in [25] relies on the assumption that the load equivalent resistance is identical at different harmonic orders, which oversimplifies the problem and its accuracy relies much on the selection of converter parameters. A more generalised model was proposed in [27], but it is only shown for fixed‐frequency control and its accuracy is not validated by either simulation or experiments.…”

Section: Introductionmentioning

confidence: 99%

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Modelling and optimisation of a dual‐control MHz‐level CLLC converter with minimised power losses in battery charging applications

Zhang

Khaligh

2020

IET Power Electronics

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In this study, a novel ' f − φ' dual-control modulation is proposed for the MHz-level CLLC converters in battery charging applications. Phase shift between the primary and secondary switches is utilised as an additional control variable to effectively reduce the power losses, especially in light-and medium-load conditions. Compared to other state of the art, a more generalised theoretical model is developed to characterise the converter with higher accuracy based on extended harmonic approximation. Furthermore, a numerical algorithm is utilised to thoroughly examine the converter performance under various operating conditions and systematically search for the optimised design parameters under the proposed modulation scheme. The modelling and optimisation are verified by simulation on a 3.3 kW onboard charger design for electric vehicles, which shows an estimated efficiency enhancement between 1 and 4%. Finally, a laboratory prototype has been developed using gallium nitride semiconductor devices, at the resonant frequency of 1 MHz. The converter measured efficiencies are 96.4, 96.2 and 94% for the selected heavy, medium-and light-load conditions, respectively. This system would allow insights into the practical implementation and evaluation of utilising wide bandgap semiconductors to achieve both high power density and enhanced efficiency for emerging power electronic systems.

show abstract

Section: Proposed Dual-control Modulation and Systematic Optimisationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modelling and optimisation of a dual‐control MHz‐level CLLC converter with minimised power losses in battery charging applications

Zhang

Khaligh

2020

IET Power Electronics

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“…To address this problem, some observation-based control strategies are proposed [30], [31]. In [30] the harmonics approximation modeling approach is presented, and the pulse width locked loop is used in [31]. However, these methods are to track and adjust the resonant frequency.…”

Section: Introductionmentioning

confidence: 99%

PWM Modulation and Control Strategy for LLC-DCX Converter to Achieve Bidirectional Power Flow in Facing With Resonant Parameters Variation

Yang

et al. 2019

IEEE Access

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The LLC resonant converter can be used as a dc-dc transformer (DCX) to provide isolation and fixed voltage transfer ratio. For applications requiring bidirectional power transmission, this paper proposes a PWM modulation and control strategy to achieve naturally bidirectional power flow for LLC-DCX, even in the case when the resonant parameters vary. Without the loss of generality, the proposed modulation can achieve ZVS of one side switches and ZCS of other side switches. Meanwhile, the additional benefits are that the PWM logic exchanging of the primary full bridge and the secondary full bridge is avoided and the auxiliary SR circuit is not needed. This simplifies the control and makes the converter to achieve naturally bidirectional power flow. Meanwhile, according to the analysis, it can also provide a fixed voltage conversion ratio independent of switching frequency if properly designed. Furthermore, to accurately locate the zerocrossing instant of the current when resonant parameters vary, the optimal duty cycle tracking based on the perturbation and observation method (P&O) is adopted. The characteristics and design considerations of the proposed modulation and control are also presented in detail in this paper. Finally, the experimental results are given to verify the effectiveness and advantages of the proposed solution. INDEX TERMS Bidirectional power flow, DCX, fixed voltage gain, LLC converter, optimal duty cycle tracking.

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Design of Three-Phase Staggered LLC Resonant Converter with Flexible Transition Control for Wide Voltage Gain

Feng

Wang

et al. 2022

J. Electr. Eng. Technol.

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Extended Harmonics Based Phase Tracking for Synchronous Rectification in CLLC Converters

Cited by 65 publications

References 23 publications

Modelling and optimisation of a dual‐control MHz‐level CLLC converter with minimised power losses in battery charging applications

Modelling and optimisation of a dual‐control MHz‐level CLLC converter with minimised power losses in battery charging applications

PWM Modulation and Control Strategy for LLC-DCX Converter to Achieve Bidirectional Power Flow in Facing With Resonant Parameters Variation

Design of Three-Phase Staggered LLC Resonant Converter with Flexible Transition Control for Wide Voltage Gain

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