VR Transient Improvement at High Slew Rate Load—Active Transient Voltage Compensator

Wang, Xiangcheng; Batarseh, Issa; Chickamenahalli, S.A.; Standford, Edward

doi:10.1109/tpel.2007.900601

Cited by 26 publications

(6 citation statements)

References 9 publications

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“…Examples include additional circuits consisting of a smaller converter [24]- [31], transformers [32]- [34], an LC/RC network [35]- [38], or a pair of linearly controlled active clamps [39], [40]. The auxiliary circuit is activated during transients, to help inject or remove the charge from the output capacitor, drastically minimizing its energy storage requirements.…”

Section: Introductionmentioning

confidence: 99%

Mixed-Signal-Controlled Flyback-Transformer-Based Buck Converter With Improved Dynamic Performance and Transient Energy Recycling

Wang

Prodić

2013

IEEE Trans. Power Electron.

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This paper introduces a practical modification of the buck converter and a complementary controller that are well suited for point of load applications with highly dynamic loads. The presented flyback-transformer-based buck (FTBB) converter has faster transient response than the conventional buck, allowing for a reduction in the output capacitance without penalty in the size of the magnetic core. During heavy-to-light load transients, the FTBB converter also recycles excess energy stored in the magnetic component, providing a useful energy savings mechanism. In this modification, the conventional buck inductor is replaced with the primary winding of the flyback transformer, an extra switch, and a set of small auxiliary switches on the secondary side. During heavy-tolight load transients, the inductor current is steered away from the output capacitor to the input port, achieving both energy recycling and savings due to reduced voltage overshoots. The light-to-heavy transient response is improved by reducing the equivalent inductance of the primary transformer winding to its leakage value. A mixed-signal current-programmed mode controller regulates operation of the converter. The controller provides minimum output voltage deviation and ensures seamless transitions between different operating modes. The performance of the FTBB converter is verified with a 6-to-1-V, 3-W, 390-kHz experimental prototype. In comparison with an equivalent buck converter, the experimental system has about three times smaller maximum output voltage deviation, allowing for the same output capacitor reduction and, for frequently changing loads, about 7% decrease in power losses.Index Terms-DC-DC power converters, digital control, energy efficiency, flyback transformers, switched-mode power supply, transient response.

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Section: Introductionmentioning

confidence: 99%

Mixed-Signal-Controlled Flyback-Transformer-Based Buck Converter With Improved Dynamic Performance and Transient Energy Recycling

Wang

Prodić

2013

IEEE Trans. Power Electron.

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“…Increasing the switching frequency to reduce the size of the inductor increases switching loss, and therefore has an upper limit. Attempts to increase the response of buck converters through topology modifications have been made to mitigate the inherent flaws of the topology [1], [2]. However, they come at the expense of increased cost, complexity, and size.…”

Section: Introductionmentioning

confidence: 99%

“…1, the load current is i av and the per (switching) cycle average of rectified resonant current is i o . The equivalent ac resistance is a function of the pulse-density duty cycle, and defined by (1N is the transformer turns ratio.The transfer function is given by(2), with the variables in Schematic of SRC under VF-PDM control…”

mentioning

confidence: 99%

Digital control of resonant converters at ultra high frequency

Tschirhart

Jain

2010

Intelec 2010

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Voltage regulators (VRs) powering microprocessors face stringent requirements on size; response; and efficiency. Current-type resonant converters, like the series resonant converter are particularly well-suited for these applications as they are able to achieve efficient high frequency operation, and have a capacitive output filter. However, despite their merits, they are often overlooked because of size and performance issues associated with their control. In this paper, variable frequency pulse density modulation (VF-PDM) control of the series resonant converter (SRC) is presented to enable resonant converter benefits to be realized in VR applications. It achieves efficient multi-megahertz switching frequency, ultra-fast transient response with minimal filter capacitance, and is inherently stable. It will be shown that with proper converter design, these benefits can be achieved with a simple, low clock rate digital controller.

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“…In order to address the large overshoots typical of voltage regulator module (VRM) applications, numerous auxiliary circuits have been proposed for the Buck converter [4]- [10].…”

Section: Introductionmentioning

confidence: 99%

“…In [4]- [5], a transformer is connected across the impedance of the output trace of a Buck converter in order to inject/absorb excess load current to improve the dynamic performance.…”

Section: Introductionmentioning

confidence: 99%

Controlled Auxiliary Circuit with Measured Response for Reduction of Output Voltage Overshoot in Buck Converters

Meyer

Zhang

Liu

2009

2009 Twenty-Fourth Annual IEEE Applied Power Electronics Conference and Exposition

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In order to adhere to voltage regulation criteria, capacitor selection of a Buck converter must be based on the worst possible scenario. It is well known that, for a low duty cycle Buck converter, the output voltage deviation of a Buck converter undergoing an unloading transient will be significantly larger than that of a corresponding loading transient of equal magnitude. Therefore, in this paper, an auxiliary circuit and corresponding control method is presented to reduce the output voltage overshoot of a Buck converter undergoing an unloading transient. The proposed auxiliary circuit diverts a constant controlled current from the output of the converter to the input of the converter thereby significantly reducing the output voltage overshoot. In addition, the proposed auxiliary controller estimates the magnitude of the unloading transient and sets the auxiliary current to an appropriate level based on a pre-defined set of criteria. This allows for greater design flexibility and increases the auxiliary circuit efficiency for unloading transients of lesser magnitude. As demonstrated through simulation and experimental results, the proposed converter successfully estimates the unloading transient magnitude and diverts a proportional amount of current from the converter output.I.

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VR Transient Improvement at High Slew Rate Load—Active Transient Voltage Compensator

Cited by 26 publications

References 9 publications

Mixed-Signal-Controlled Flyback-Transformer-Based Buck Converter With Improved Dynamic Performance and Transient Energy Recycling

Mixed-Signal-Controlled Flyback-Transformer-Based Buck Converter With Improved Dynamic Performance and Transient Energy Recycling

Digital control of resonant converters at ultra high frequency

Controlled Auxiliary Circuit with Measured Response for Reduction of Output Voltage Overshoot in Buck Converters

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