New Hybrid Control Technique to Improve Light Load Efficiency While Meeting the Hold-up Time Requirement for Two-Stage Server Power

Lai, Yen-Shin; Su, Zih-Jie; Chen, Wen-Shyue

doi:10.1109/tpel.2013.2283747

Cited by 48 publications

(18 citation statements)

References 31 publications

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“…And they are derived by (9), (13), (16), and (19) for proposed method. The transformer losses are calculated by (24) and (32) for conventional method, (22) and (24) for proposed method. The calculation of inductor losses is based upon (21) and (24).…”

Section: Resultsmentioning

confidence: 99%

“…In [21]- [22], light load condition can be reduced by dynamically adjust the DC-link voltage to reduce the switching losses of both PFC and PSFB converter. However, further reduction of PSFB converter losses under light load condition by changing the switching control technique is not considered in [21]- [22]. In [36], a three-level ac/dc single-stage converter with phase-shift pulse width modulation is proposed to improve efficiency.…”

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confidence: 99%

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New Integrated Control Technique for Two-Stage Server Power to Improve Efficiency Under the Light-Load Condition

Lai

2015

IEEE Trans. Ind. Electron.

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A new control technique for two-stage server power is proposed in this paper. The propose technique will significantly reduce power consumption under light load condition. The basic idea of the proposed control technique is to control both DC-link voltage of PFC stage and switching method of full-bridge stage. Under light load condition, the output voltage of PFC stage is no more fixed and adjusted dynamically to significantly reduce the switching losses. Moreover, under light load condition the fullbridge stage is with PWM and burst mode control to reduce the circulating current losses. The former approach will reduce the switching losses due to the reduction of voltage across the power devices. The later one will dramatically reduce the circulating current losses caused by phase-shift control method since phaseshift switching control is replaced by PWM switching control. Moreover, due to the reduction of DC-link voltage, the switching losses for PWM and burst mode control can be further reduced as compared to those for fixed DC-link voltage.Experimental results of a 480 W server power are presented. It is shown that the efficiency of two-stage power converter can be improved up to 8% and 3.9% under light load and 10% load conditions for input voltage = 110 V, respectively. For 220 V input voltage the efficiency improvement using proposed method is 6.4% and 4.2% under light load and 10% load conditions, respectively.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

New Integrated Control Technique for Two-Stage Server Power to Improve Efficiency Under the Light-Load Condition

Lai

2015

IEEE Trans. Ind. Electron.

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“…2 LLC resonant converters have many advantages that include zero-voltage-switching (ZVS) capability from zero to full load range, low turn-off current of primary-side switches, and zero-current switching for synchronous rectifier (SR) devices. [3][4][5][6][7][8][9][10] It results in lower efficiency by larger circulating current. Generally, LLC resonant converter operates around resonant frequency for achieving high efficiency since the impedance of the resonant tank is nearly zero.…”

Section: Introductionmentioning

confidence: 99%

“…However, in order to obtain high voltage gain for holdup time requirement, the practical magnetizing inductance of transformer is designed lower than the magnetizing inductance of transformer for ZVS. [3][4][5][6][7][8][9][10] It results in lower efficiency by larger circulating current. The performance of the converter will be downgraded for meeting holdup time requirement.…”

Section: Introductionmentioning

confidence: 99%

LLC resonant converter utilizing a step‐gap transformer structure for holdup time improvement

Lin

Lee

Yueh

2018

Circuit Theory & Apps

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This letter presents a current-controlled variable magnetizing inductance of transformer for further improving the holdup time on half-bridge LLC converter. When the input voltage is failed, the magnetizing inductance of transformer can be decreased sharply; therefore, the LLC converter holdup time can be improved without adding additional auxiliary circuit. The mathematic model between magnetizing inductance and step-gap structure of transformer is proposed, and the benefit effects using this step-gap structure of transformer have been verified in this letter. Finally, a 180-W, LLC converter utilizing step-gap structure of transformer has been achieved, and detailed analysis and design of the proposed step-gap structure are described.

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“…OLD-UP time is a special requirement for the distributed power systems and server power supplies which require continuous output voltage regulation for certain time after input ac line dropout [1]. During the hold-up time, i.e.…”

Section: Introductionmentioning

confidence: 99%

A Secondary-Side Phase-Shift-Controlled <italic>LLC</italic> Resonant Converter With Reduced Conduction Loss at Normal Operation for Hold-Up Time Compensation Application

Gao

et al. 2015

IEEE Trans. Power Electron.

134

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A novel secondary-side phase-shift-controlled (SS-PSC) LLC resonant converter is proposed for applications requiring hold-up time operation such as distributed power systems and server power supplies. High efficiency at the normal input voltage is achieved because the proposed SS-PSC LLC converter always operates at the series-resonant frequency of the resonant tank. What's more, the magnetizing inductor of the proposed converter doesn't need to be reduced to provide desired voltage boost ratio for the hold-up time operation, which results in reduced conduction losses and improved efficiency. Sufficient voltage boost ratio for the hold-up time operation is provided by using secondary-side phase-shift control strategy. In comparison with the conventional variable-frequency-controlled LLC resonant converter, the main advantages are that the circulating current caused by the magnetizing inductor is effectively suppressed and the efficiency of normal operation is significantly improved. The operation principles, output characteristics and design considerations of the proposed converter are presented in detail. Experimental results are given to verify the effectiveness and the advantages of the proposed solutions.

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New Hybrid Control Technique to Improve Light Load Efficiency While Meeting the Hold-up Time Requirement for Two-Stage Server Power

Cited by 48 publications

References 31 publications

New Integrated Control Technique for Two-Stage Server Power to Improve Efficiency Under the Light-Load Condition

New Integrated Control Technique for Two-Stage Server Power to Improve Efficiency Under the Light-Load Condition

LLC resonant converter utilizing a step‐gap transformer structure for holdup time improvement

A Secondary-Side Phase-Shift-Controlled <italic>LLC</italic> Resonant Converter With Reduced Conduction Loss at Normal Operation for Hold-Up Time Compensation Application

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