Energy Feedback Control of Light-Load Voltage Regulation for <i>LLC</i> Resonant Converter

Fang, Zhijian; Wang, Junhua; Liu, Rong; Xiao, Liangle; Zhang, Junkun; Hu, Guozhen; Liu, Qisheng

doi:10.1109/tpel.2018.2858854

Cited by 26 publications

(4 citation statements)

References 26 publications

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“…To regulate the output voltage and improve the efficiency of resonant converters under light-load conditions, many control methods have been proposed [14][15][16][17][18][19][20][21][22]. Burst control [14,[18][19][20][21][22] is an effective way to adjust the voltage gain and raise the light-load efficiency by switching the converter between on and off state. The performance of hysteresis burst control for LLC converter greatly depends on the select of hysteresis band [19].…”

Section: Introductionmentioning

confidence: 99%

“…However, the switching patterns are still quite complicated. [22] adopts an energy feedback control using synchronous rectifiers (SRs) during the off time of burst control. The SR bridges are controlled ahead of the primary bridges, delivering the energy from load to source and reducing the output voltage, but the phase-shift of SRs should be optimized to balance the voltage regulation capacity and efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Zhu

Zhuo

Zhao

et al. 2020

IEEE Trans. Power Electron.

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The CLLC resonant converters are drawing more and more attention for their superiority in soft switching, wide output range and symmetrically bidirectional operation. However, CLLC converter still suffers the problems of unsatisfactory voltage regulation and low efficiency under lightload conditions. Therefore, this paper proposes an optimization for extended phase-shift (EPS) control in full-bridge CLLC resonant converter to improve the light-load efficiency. In order to study the relations between phase-shifts of EPS control and converter efficiency, a detailed circuit model is first established to solve the voltage gain, time-domain expressions of main circuit variables and root mean square (RMS) values of resonant currents. Then, a comprehensive loss evaluation is conducted by calculating and analyzing the main power losses, including conduction loss, switching loss and core losses of magnetic components. Besides, zero voltage switching (ZVS) conditions of primary and rectifier switches are derived to define the range of soft switching. Finally, based on these analyses, the optimal combination of phase-shifts for EPS control is determined to achieve the maximum conversion efficiency of full-bridge CLLC converter at light-load conditions. The validity of the proposed optimized EPS control is verified on a 18~25V/400V, 200W GaN based CLLC resonant converter prototype.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Zhu

Zhuo

Zhao

et al. 2020

IEEE Trans. Power Electron.

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“…Kim et al [20] proposed a synchronous rectifier (SR) control method to improve the light-load efficiency, but the SR turn-off time should be limited within half of the switching period. In [21], the energy feedback control method is proposed by controlling the SR bridges ahead of the inverter bridges to regulate output power at the expense of compromising power efficiency.…”

Section: Introductionmentioning

confidence: 99%

Hybrid mode‐hopping modulation for LLC resonant converter achieving high efficiency and linear behaviour

Fang

Huang

Jing

et al. 2020

IET Power Electronics

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Frequency modulation (FM) has been widely used in the inductor-inductor-capacitor (LLC) resonant converter due to excellent soft switching features. However, low power efficiency in light load conditions and complex control due to the nonlinear converter behaviour are common concerns for the FM method. In this study, a hybrid mode-hopping modulation method is proposed for the LLC resonant converter to address these challenges. The LLC resonant converter operates at any two of three power-efficient operating modes for a different amount of time within a single modulation period. By determining the mode hopping time and combining different mode-hopping modulations, the LLC resonant converter can achieve a wide range of output power and maintain high efficiency at the same time. Besides, since the switching frequencies are fixed, the relationships between the duty cycle and the output power are linear, which can significantly simplify the control design. Compared with the existing modulation methods, the proposed hybrid mode-hopping modulation makes the LLC resonant converter behaves linear, simplifies the control design, achieves wide operation range and ensures high efficiency even in light load condition.

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“…[26], but also the reverse recovery of the subsequent stages of the diodes. It can also evaluate the light-load operating condition with effects beyond the diode junction capacitances, whereas past studies consider only the effect of diode junction capacitances [27][28][29]. Besides DH phenomenon, it can also evaluate the EMI generated by SiC and Si diodes in the voltage doubler and the BiCWVM quantitatively.…”

mentioning

confidence: 99%

Mitigation of Deane and Hamill phenomenon in gallium nitride high‐voltage power supply for electric propulsion system application

Dong,

Li,

Yin

et al. 2023

High Voltage

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The step‐up resonant converters are widely adopted to provide high voltage in kV‐level for electric propulsion system due to their high efficiency, low mass, modularisation, and high‐power density. The bipolar Cockcroft‐Walton voltage multiplier (BiCWVM) is a major circuit that steps up the voltage in the resonant converter. However, the diode non‐linearity in BiCWVM can introduce self‐sustained quasi‐periodic oscillations in the voltage and current waveforms, which is commonly known as the Deane and Hamill (DH) phenomenon. The oscillation can lead to higher magnetic loss and control failure, and it is more likely to present in the gallium nitride‐based converter due to the high‐frequency operation. The authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be implemented. To facilitate the investigation, the circuit before the BiCWVM in the converter is derived and modelled as a voltage source vm and a series inductor Lsy. Also, the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise‐linear (PWL) model, with the simplified circuit and PWL model, the relationship between voltage and current under different operating conditions can be determined with ease. The relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH phenomenon. Finally, a hybrid‐/full‐silicon carbide (SiC) design is proposed to mitigate the DH phenomenon, which is verified experimentally for a 300‐kHz, 5‐W, 20‐V/1.5‐kV GaN‐based step‐up resonant converter.

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Energy Feedback Control of Light-Load Voltage Regulation for LLC Resonant Converter

Cited by 26 publications

References 26 publications

Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Hybrid mode‐hopping modulation for LLC resonant converter achieving high efficiency and linear behaviour

Mitigation of Deane and Hamill phenomenon in gallium nitride high‐voltage power supply for electric propulsion system application

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