The Experts below are selected from a list of 17685 Experts worldwide ranked by ideXlab platform
F C Lee - One of the best experts on this subject based on the ideXlab platform.
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a novel winding coupled Buck Converter for high frequency high step down dc dc conversion
IEEE Transactions on Power Electronics, 2005Co-Authors: Kaiwei Yao, Yang Qiu, F C LeeAbstract:This paper analyzes the fundamental limitations of the Buck Converter for high-frequency, high-step-down dc-dc conversion. Further modification with additional coupled windings in the Buck Converter yields a novel topology, which significantly improves the efficiency without compromising the transient response. An integrated magnetic structure is proposed for these windings so that the same magnetic cores used in the Buck Converter can be used here as well. Furthermore, it is easy to implement a lossless clamp circuit to limit the device voltage stress and to recover inductor leakage energy. This new topology is applied for a 12V-to-1.5V/25A voltage regulator module (VRM) design. At a switching frequency of 2MHz, over 80% full-load efficiency is achieved, which is 8% higher than that of the conventional Buck Converter.
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tapped inductor Buck Converter for high step down dc dc conversion
IEEE Transactions on Power Electronics, 2005Co-Authors: Kaiwei Yao, F C LeeAbstract:The narrow duty cycle in the Buck Converter limits its application for high-step-down dc-dc conversion. With a simple structure, the tapped-inductor Buck Converter shows promise for extending the duty cycle. However, the leakage inductance causes a huge turn-off voltage spike across the top switch. Also, the gate drive for the top switch is not simple due to its floating source connection. This paper solves all these problems by modifying the tapped-inductor structure. A simple lossless clamp circuit can effectively clamp the switch turn-off voltage spike and totally recover the leakage energy. Experimental results for 12V-to-1.5V and 48V-to-6V dc-dc conversions show significant improvements in efficiency.
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multiphase coupled Buck Converter a novel high efficient 12 v voltage regulator module
IEEE Transactions on Power Electronics, 2003Co-Authors: Jia Wei, F C LeeAbstract:The most popular VRM topology-multiphase Buck Converter operates at a very small duty cycle due to a high input voltage and a low output voltage. The performance of the multiphase Buck Converter suffers from the very small duty cycle. Alternative topologies with an extended duty cycle are explored in order to improve the efficiency without compromising the transient response. A novel topology named multiphase coupled-Buck Converter is proposed, which enables the use of a large duty cycle with recovered leakage energy and clamped MOSFET voltage. The input filter is further integrated in the proposed circuit to reduce the number of components. A 12 V-to-1.5 V/50 A VRM prototype demonstrates that the multiphase coupled Buck Converter can have a much better efficiency than the multiphase Buck Converter with the same transient response.
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the active clamp couple Buck Converter a novel high efficiency voltage regulator modules
Applied Power Electronics Conference, 2001Co-Authors: Jia Wei, F C LeeAbstract:As the power demand for microprocessors increases steadily, the VRMs are required to work with a higher input voltage. The widely used synchronous Buck Converter will NOT work properly and efficiently for this higher input voltage because of an extremely small duty-ratio, This paper proposes a novel active-clamp couple-Buck Converter to solve the extremely small duty-ratio problem, Other benefits of the proposed circuit include recovery leakage energy, clamped device voltage and reduced input filter. The proposed circuit was demonstrated on a 4-phase VRM, which delivers power from a 12 V input to a 1.5 V/50 A microprocessor load. Experiments show that the proposed circuit would significantly improve the VRM efficiency.
Jin Sha - One of the best experts on this subject based on the ideXlab platform.
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a peak capacitor current pulse train controlled Buck Converter with fast transient response and a wide load range
IEEE Transactions on Industrial Electronics, 2016Co-Authors: Jin Sha, Yiming Chen, B W WilliamsAbstract:It is known that the ripple-based control of a switching dc–dc Converter benefits from a faster transient response than a conventional pulse width modulation (PWM) control switching dc–dc Converter. However, ripple-based control switching dc–dc Converters may suffer from fast-scale oscillation. In order to achieve fast transient response and ensure the stable operation of a switching dc–dc Converter over a wide load range, based on a conventional pulse train (PT) control technique, a peak capacitor current PT (PCC-PT) control technique is proposed in this paper. With a Buck Converter as an example, the operating modes, steady-state performance, and transient respond performance of a PCC-PT controlled Buck Converter are presented and assessed. To eliminate fast-scale oscillation, circuit and control parameter design considerations are given. An accurate discrete iteration model of a PCC-PT controlled Buck Converter is established, based on which the effects of circuit parameters on the stability of the Converter operating in a discontinuous current mode (DCM), mixed DCM-continuous conduction mode (CCM), and CCM are studied. Simulation and experimental results are presented to verify the analysis results.
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effects of circuit parameters on dynamics of current mode pulse train controlled Buck Converter
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Jin Sha, Bocheng Bao, Tiesheng YanAbstract:Current-mode pulse train (CMPT) control technique, a novel discrete control technique for switching dc-dc Converters, has completely different dynamics from the traditional pulsewidth modulation control technique. In this paper, a 1-D normal form of discrete-time map of CMPT-controlled Buck Converter operating in discontinuous conduction mode (DCM) is established, upon which the effects of the circuit parameters on the dynamics and the border collision bifurcation behaviors of CMPT-controlled DCM Buck Converter are observed and analyzed. According to discrete iterative maps of period-1, period-2, and period-3, the fixed point analyses of the corresponding periodicities are studied, and the mechanism of border collision bifurcation is revealed. Simultaneously, the parameter conditions of different periodicities are formulated, which are helpful to better understand the behaviors and to analyze the CMPT-controlled Buck Converter.
Jih-sheng Lai - One of the best experts on this subject based on the ideXlab platform.
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a mhz zero voltage switching zvs tapped inductor Buck Converter for wide input high step down low power applications
IEEE International Future Energy Electronics Conference and ECCE Asia, 2017Co-Authors: Chih-shen Yeh, Xiaonan Zhao, Jih-sheng LaiAbstract:In this paper, a tapped-inductor (TI) Buck Converter using planar coupled inductor is presented for low power applications. The duty cycle of TI Buck is much wider compared with traditional Buck Converter under same voltage conversion ratio conditions. Therefore, it is suitable for high step-down applications. With synchronous conduction mode (SCM), TI Buck Converter obtains zero voltage switching (ZVS) of both switches and thus be able to operate at high switching frequency. Besides, compared with other three-switch Buck-type topologies, its simplicity in circuit topology leads to less gate driver and other auxiliary power loss, which is beneficial for low power applications. In this paper, Converter operating principle and design for a compact coupled inductor are presented. Finally, experimental results of a 15-W prototype are given. Under switching frequency of 2 MHz, the peak efficiency of power stage reaches to 89 % with magnetic component size less than 150 mm3.
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An investigation on zero-voltage-switching condition in synchronous-conduction-mode Buck Converter
2017 IEEE Energy Conversion Congress and Exposition (ECCE), 2017Co-Authors: Chih-shen Yeh, Xiaonan Zhao, Jih-sheng LaiAbstract:A Buck Converter operated in synchronous — conduction-mode (SCM) can obtain zero-voltage-switching (ZVS) of both switches without any auxiliary components, which is beneficial for high-switching frequency operation. To obtain ZVS of high-side switch, Buck Converter requires adequate dead-time duration and reverse inductor current. Through the law of conservation of energy, minimum reverse inductor current required for ZVS can be calculated accurately by a modified method. On top of the modified method, a ZVS model based on resonance is proposed in this paper. The proposed method also leads to accurate ZVS condition but with more information within the transition. The principle and application of the proposed resonant model are interpreted by a comparative example. Moreover, simulation waveforms and hardware testing results of a 1 MHz/30 W SCM Buck Converter prototype are presented for verification.
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derivation of boost Buck Converter based high efficiency robust pv inverter
Energy Conversion Congress and Exposition, 2010Co-Authors: Zheng Zhao, Jih-sheng Lai, Qiaoliang Chen, Younghoon ChoAbstract:A single-phase grid connected transformerless PV inverter for residential application is presented. The inverter is derived from a boost cascaded with Buck Converter along with a line frequency unfolding circuit. High efficiency can be achieved because the Converter allows the use of power MOSFET and ultra fast reverse recovery diode, which also features a robust structure because the phase-leg does not have shoot-through issue. By interleaving multiple phases, the ripple can be reduced, and thus the inductor size can also be reduced. This paper begins with theoretical analysis and modeling of this boost-Buck Converter based inverter to define the operation limit and to design the closed-loop controller. A two-phase interleaved inverter is then designed accordingly. Finally, the simulation and experiment results are shown to verify the concept.
Dragan Maksimovic - One of the best experts on this subject based on the ideXlab platform.
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interleaved zero current transition Buck Converter
IEEE Transactions on Industry Applications, 2007Co-Authors: Milan Zarko Ilic, Dragan MaksimovicAbstract:This paper introduces interleaved zero-current-transition (ZCT) Converters where two sets of switches are operating out-of-phase and share the load power equally. Turn-on transitions at zero current and a significant reduction of the losses associated with diode reverse recovery are accomplished through addition of two small inductors. This paper describes a 30-kW (300 V/100 A) interleaved ZCT Buck Converter operating at 32-kHz effective switching frequency. Losses and efficiency of the experimental prototype compare favorably against the standard and interleaved hard-switched Buck Converters. Constant frequency operation with low switching losses and low output current ripple is very well suited for the realization of dc power supplies in plasma processes.
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three level Buck Converter for envelope tracking applications
IEEE Transactions on Power Electronics, 2006Co-Authors: Vahid Yousefzadeh, Eduard Alarcon, Dragan MaksimovicAbstract:This letter proposes a three-level Buck Converter for tracking applications such as envelope-tracking in radio frequency power amplifiers (RFPAs). It is shown that the three-level Buck Converter can offer advantages in terms of switching ripples, losses, bandwidth, or the size of magnetic components compared to a standard Buck or a two-phase Buck Converter. Experimental results illustrate improved efficiency and ripple rejection in an RFPA envelope-tracking application representative for low-power battery-operated systems.
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interleaved zero current transition Buck Converter
Applied Power Electronics Conference, 2005Co-Authors: Milan Zarko Ilic, Dragan MaksimovicAbstract:This paper introduces interleaved zero current transition (ZCT) Converters where two sets of switches are operating out of phase and share the load power equally. Turn-on transitions at zero current and a significant reduction of the losses associated with diode reverse recovery are accomplished through addition of two small inductors. The paper describes a 30 kW (300 V, 100 A) interleaved ZCT Buck Converter operating at 32 kHz switching frequency. Losses and efficiency of the experimental prototype compare favorably against the standard hard-switched Buck Converter, and against previously proposed ZCT approaches.
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three level Buck Converter for envelope tracking in rf power amplifiers
Applied Power Electronics Conference, 2005Co-Authors: Vahid Yousefzadeh, Eduard Alarcon, Dragan MaksimovicAbstract:This paper proposes a three-level Buck Converter for efficient wide-bandwidth envelope tracking in RF power amplifiers (RFPA). The focus is on low-power battery-operated systems, and the goal is to enable practical implementation of the envelope elimination and restoration (EER) technique, which theoretically allows realization of a highly linear, highly efficient RFPA for non-constant envelope modulations. In terms of ripple, switching frequency and bandwidth tradeoffs, it is shown that the three-level Buck Converter is similar to the two-phase configuration, while employing a single inductor in the power stage. Additionally, a digital control technique for regulation of the flying capacitor voltage is proposed to ensure signal tracking fidelity. Experimental results show the improved performance of a three-level Buck Converter prototype as regards efficiency and ripple rejection for the illustrative case of tracking the envelope of a two-tone test signal
Kaiwei Yao - One of the best experts on this subject based on the ideXlab platform.
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a novel winding coupled Buck Converter for high frequency high step down dc dc conversion
IEEE Transactions on Power Electronics, 2005Co-Authors: Kaiwei Yao, Yang Qiu, F C LeeAbstract:This paper analyzes the fundamental limitations of the Buck Converter for high-frequency, high-step-down dc-dc conversion. Further modification with additional coupled windings in the Buck Converter yields a novel topology, which significantly improves the efficiency without compromising the transient response. An integrated magnetic structure is proposed for these windings so that the same magnetic cores used in the Buck Converter can be used here as well. Furthermore, it is easy to implement a lossless clamp circuit to limit the device voltage stress and to recover inductor leakage energy. This new topology is applied for a 12V-to-1.5V/25A voltage regulator module (VRM) design. At a switching frequency of 2MHz, over 80% full-load efficiency is achieved, which is 8% higher than that of the conventional Buck Converter.
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tapped inductor Buck Converter for high step down dc dc conversion
IEEE Transactions on Power Electronics, 2005Co-Authors: Kaiwei Yao, F C LeeAbstract:The narrow duty cycle in the Buck Converter limits its application for high-step-down dc-dc conversion. With a simple structure, the tapped-inductor Buck Converter shows promise for extending the duty cycle. However, the leakage inductance causes a huge turn-off voltage spike across the top switch. Also, the gate drive for the top switch is not simple due to its floating source connection. This paper solves all these problems by modifying the tapped-inductor structure. A simple lossless clamp circuit can effectively clamp the switch turn-off voltage spike and totally recover the leakage energy. Experimental results for 12V-to-1.5V and 48V-to-6V dc-dc conversions show significant improvements in efficiency.
