The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Johann W. Kolar - One of the best experts on this subject based on the ideXlab platform.

  • wide input voltage range 3 kw dc dc converter with hybrid llc boundary Discontinuous Mode control
    Applied Power Electronics Conference, 2020
    Co-Authors: Gustavo C Knabben, Johann W. Kolar, J Scahfer, Grayson Zulauf, Matthias Kasper, Gerald Deboy
    Abstract:

    Growing applications such as electric vehicles, data centers, and industrial robotics require power-dense and efficient converters systems to provide high output currents at low output voltages of generally 12 V. Today’s converters achieve high efficiencies at a specific input voltage, but drastically lose efficiency once the input voltage deviates from its nominal value. A large voltage swing, however, is a common situation in the aforementioned applications, as the respective input voltages, in worst-case, can easily drop by 50 %, whereby full functionality still needs to be maintained. In this work, we demonstrate a wide-input-voltage-range 400 V to 12 V, 3 kW dc-dc converter with a novel control method and transformer design. The employed boundary/Discontinuous Mode control scheme reduces circulating currents over conventional LLC techniques, and the "snake-core" matrix transformer achieves ideal parallel-connected secondary voltage balance. The converter achieves 350 W/in3 power density while operating from 300 V to 430 V input voltage and from 10 % to full load. An advanced design for a data center power supply application additionally utilizes the magnetizing inductance for boost operation in order to optimize the operating conditions of the converter system and to increase the overall efficiency. A performance comparison is finally explored for comparing the advanced design with the current hardware demonstrator and with conventional LLC converters.

  • Wide-Input-Voltage-Range 3 kW DC-DC Converter with Hybrid LLC & Boundary / Discontinuous Mode Control
    2020 IEEE Applied Power Electronics Conference and Exposition (APEC), 2020
    Co-Authors: Gustavo C Knabben, Johann W. Kolar, J Scahfer, Grayson Zulauf, Matthias Kasper, Gerald Deboy
    Abstract:

    Growing applications such as electric vehicles, data centers, and industrial robotics require power-dense and efficient converters systems to provide high output currents at low output voltages of generally 12 V. Today’s converters achieve high efficiencies at a specific input voltage, but drastically lose efficiency once the input voltage deviates from its nominal value. A large voltage swing, however, is a common situation in the aforementioned applications, as the respective input voltages, in worst-case, can easily drop by 50 %, whereby full functionality still needs to be maintained. In this work, we demonstrate a wide-input-voltage-range 400 V to 12 V, 3 kW dc-dc converter with a novel control method and transformer design. The employed boundary/Discontinuous Mode control scheme reduces circulating currents over conventional LLC techniques, and the "snake-core" matrix transformer achieves ideal parallel-connected secondary voltage balance. The converter achieves 350 W/in3 power density while operating from 300 V to 430 V input voltage and from 10 % to full load. An advanced design for a data center power supply application additionally utilizes the magnetizing inductance for boost operation in order to optimize the operating conditions of the converter system and to increase the overall efficiency. A performance comparison is finally explored for comparing the advanced design with the current hardware demonstrator and with conventional LLC converters.

  • Space vector-based analytical analysis of the input current distortion of a three-phase Discontinuous-Mode boost rectifier system
    IEEE Transactions on Power Electronics, 1995
    Co-Authors: Johann W. Kolar, H. Ertl, F.c. Zach
    Abstract:

    In this paper the low frequency harmonic distortion of the mains current of a three-phase single-switch Discontinuous-Mode boost-rectifier is calculated. The system analysis is based on application of space vector calculus and on substitution of Discontinuous time shapes within a pulse period by quasicontinuous time shapes. The quasicontinuous time shapes are defined by averaging over the pulse period. The dependency of the shape of the input currents on the voltage transformation ratio is given for various control methods in analytical form. The results of the theoretical analysis are verified by digital simulation and by measurements on a laboratory Model. A good consistency of the results has been found. >

  • a novel three phase single switch Discontinuous Mode ac dc buck boost converter with high quality input current waveforms and isolated output
    IEEE Transactions on Power Electronics, 1994
    Co-Authors: Johann W. Kolar, H. Ertl, F.c. Zach
    Abstract:

    In this paper, a new three-phase single-switch AC-DC flyback converter system is presented. The system operates in the Discontinuous Mode. The simple structure of its power and control circuit, low mains current distortion, and resistive fundamental behavior, as well as the high-frequency isolation of the controlled output voltage, have to be pointed out. Besides the analysis of the stationary operating behavior, the dependencies of the peak values, average values, and rms values of the device currents, and of the maximum blocking voltages across the power electronic devices on the circuit parameters, are given as analytic approximations. The theoretical analysis is verified by digital simulation. >

Gerald Deboy - One of the best experts on this subject based on the ideXlab platform.

  • wide input voltage range 3 kw dc dc converter with hybrid llc boundary Discontinuous Mode control
    Applied Power Electronics Conference, 2020
    Co-Authors: Gustavo C Knabben, Johann W. Kolar, J Scahfer, Grayson Zulauf, Matthias Kasper, Gerald Deboy
    Abstract:

    Growing applications such as electric vehicles, data centers, and industrial robotics require power-dense and efficient converters systems to provide high output currents at low output voltages of generally 12 V. Today’s converters achieve high efficiencies at a specific input voltage, but drastically lose efficiency once the input voltage deviates from its nominal value. A large voltage swing, however, is a common situation in the aforementioned applications, as the respective input voltages, in worst-case, can easily drop by 50 %, whereby full functionality still needs to be maintained. In this work, we demonstrate a wide-input-voltage-range 400 V to 12 V, 3 kW dc-dc converter with a novel control method and transformer design. The employed boundary/Discontinuous Mode control scheme reduces circulating currents over conventional LLC techniques, and the "snake-core" matrix transformer achieves ideal parallel-connected secondary voltage balance. The converter achieves 350 W/in3 power density while operating from 300 V to 430 V input voltage and from 10 % to full load. An advanced design for a data center power supply application additionally utilizes the magnetizing inductance for boost operation in order to optimize the operating conditions of the converter system and to increase the overall efficiency. A performance comparison is finally explored for comparing the advanced design with the current hardware demonstrator and with conventional LLC converters.

  • Wide-Input-Voltage-Range 3 kW DC-DC Converter with Hybrid LLC & Boundary / Discontinuous Mode Control
    2020 IEEE Applied Power Electronics Conference and Exposition (APEC), 2020
    Co-Authors: Gustavo C Knabben, Johann W. Kolar, J Scahfer, Grayson Zulauf, Matthias Kasper, Gerald Deboy
    Abstract:

    Growing applications such as electric vehicles, data centers, and industrial robotics require power-dense and efficient converters systems to provide high output currents at low output voltages of generally 12 V. Today’s converters achieve high efficiencies at a specific input voltage, but drastically lose efficiency once the input voltage deviates from its nominal value. A large voltage swing, however, is a common situation in the aforementioned applications, as the respective input voltages, in worst-case, can easily drop by 50 %, whereby full functionality still needs to be maintained. In this work, we demonstrate a wide-input-voltage-range 400 V to 12 V, 3 kW dc-dc converter with a novel control method and transformer design. The employed boundary/Discontinuous Mode control scheme reduces circulating currents over conventional LLC techniques, and the "snake-core" matrix transformer achieves ideal parallel-connected secondary voltage balance. The converter achieves 350 W/in3 power density while operating from 300 V to 430 V input voltage and from 10 % to full load. An advanced design for a data center power supply application additionally utilizes the magnetizing inductance for boost operation in order to optimize the operating conditions of the converter system and to increase the overall efficiency. A performance comparison is finally explored for comparing the advanced design with the current hardware demonstrator and with conventional LLC converters.

M.h.l. Chow - One of the best experts on this subject based on the ideXlab platform.

  • New single-stage PFC regulator using the Sheppard-Taylor topology
    IEEE Transactions on Power Electronics, 1998
    Co-Authors: M.h.l. Chow
    Abstract:

    This paper describes a new usage of the DC/DC converter developed by D.I. Sheppard and B.E. Taylor in 1983 for achieving high power factor and output regulation. This converter may be viewed as a cascade of a modified boost stage and a buck stage, with the two stages sharing the same active switch. Two possible operation regimes are described. In the first regime, the converter's input part, which is a modified boost converter, operates in Discontinuous Mode, and the output part, which is a buck converter, operates in continuous Mode. In this regime, high power factor is naturally achieved, and the output voltage is regulated by duty-cycle modulation via a simple output feedback. In the second regime, the input part operates in continuous Mode, and the output part operates in Discontinuous Mode, with duty-cycle modulation maintaining a high power factor and frequency modulation regulating the output. Some comparisons between the Sheppard-Taylor converter and conventional boost and buck cascade are given in the paper.

  • Single stage high power factor converter using the Sheppard-Taylor topology
    PESC Record. 27th Annual IEEE Power Electronics Specialists Conference, 1996
    Co-Authors: M.h.l. Chow
    Abstract:

    This paper describes a new usage of the DC/DC converter developed by D.I. Sheppard and B.E. Taylor in 1983, for achieving high power factor and output regulation. This converter may be viewed as a cascade of a modified boost stage and a buck stage, with the two stages sharing the same active switch. Two possible operation regimes are described. In the first regime, the converter's input part, which is a modified boost converter, operates in Discontinuous Mode, and the output part, which is a buck converter, operates in continuous Mode. In this regime, high power factor is naturally achieved and the output voltage is regulated by duty cycle modulation via a simple output feedback. In the second regime, the input part operates in continuous Mode and the output part operates in Discontinuous Mode, with duty cycle modulation maintaining a high power factor and frequency modulation regulating the output. Compared to the usual boost-buck cascade operating in the first regime, the proposed converter has a wider operating range. When operating in the second regime, the modified boost stage has the ability of producing a harmonic free input current, unlike the standard boost PFC whose current always suffers a cusp distortion.

  • Small-signal analysis of single-stage cascaded boost-and-buck PFC converters
    PESC 98 Record. 29th Annual IEEE Power Electronics Specialists Conference (Cat. No.98CH36196), 1
    Co-Authors: V.s. Murah, Chi K Tse, M.h.l. Chow
    Abstract:

    Single-stage power-factor-correction (PFC) regulators based on the cascade combination of a Discontinuous-Mode boost converter and a buck converter have been proposed recently. Much of the work on this type of single-stage regulators has been performed around a number of topologically equivalent configurations, e.g., BIBRED, SSIPP and decoupled Cuk converter. Circuit operation and steady-state design have been the main focus of study. This paper gives a detailed analysis of the dynamical response of this type of converter, and explains how the relative sizes of the storage and output capacitors affect the dynamics. Complete sets of small-signal transfer functions are derived for all common operating Modes. In particular, the authors have shown that when the boost part operates in Discontinuous Mode and the buck part in continuous Mode, the duty-ratio-to-output transfer function can be reduced to a simple second-order function when the storage capacitor is sufficiently large. Such order reduction (pole-zero cancellation) is important for achieving fast response. Also, the power converter has a high output impedance, in contrast to the normal continuous-Mode buck stage. Moreover, when both the boost and buck parts operate in Discontinuous Mode, the system can achieve fast response for most practical situations regardless of the occurrence of pole-zero cancellation.

Gustavo C Knabben - One of the best experts on this subject based on the ideXlab platform.

  • wide input voltage range 3 kw dc dc converter with hybrid llc boundary Discontinuous Mode control
    Applied Power Electronics Conference, 2020
    Co-Authors: Gustavo C Knabben, Johann W. Kolar, J Scahfer, Grayson Zulauf, Matthias Kasper, Gerald Deboy
    Abstract:

    Growing applications such as electric vehicles, data centers, and industrial robotics require power-dense and efficient converters systems to provide high output currents at low output voltages of generally 12 V. Today’s converters achieve high efficiencies at a specific input voltage, but drastically lose efficiency once the input voltage deviates from its nominal value. A large voltage swing, however, is a common situation in the aforementioned applications, as the respective input voltages, in worst-case, can easily drop by 50 %, whereby full functionality still needs to be maintained. In this work, we demonstrate a wide-input-voltage-range 400 V to 12 V, 3 kW dc-dc converter with a novel control method and transformer design. The employed boundary/Discontinuous Mode control scheme reduces circulating currents over conventional LLC techniques, and the "snake-core" matrix transformer achieves ideal parallel-connected secondary voltage balance. The converter achieves 350 W/in3 power density while operating from 300 V to 430 V input voltage and from 10 % to full load. An advanced design for a data center power supply application additionally utilizes the magnetizing inductance for boost operation in order to optimize the operating conditions of the converter system and to increase the overall efficiency. A performance comparison is finally explored for comparing the advanced design with the current hardware demonstrator and with conventional LLC converters.

  • Wide-Input-Voltage-Range 3 kW DC-DC Converter with Hybrid LLC & Boundary / Discontinuous Mode Control
    2020 IEEE Applied Power Electronics Conference and Exposition (APEC), 2020
    Co-Authors: Gustavo C Knabben, Johann W. Kolar, J Scahfer, Grayson Zulauf, Matthias Kasper, Gerald Deboy
    Abstract:

    Growing applications such as electric vehicles, data centers, and industrial robotics require power-dense and efficient converters systems to provide high output currents at low output voltages of generally 12 V. Today’s converters achieve high efficiencies at a specific input voltage, but drastically lose efficiency once the input voltage deviates from its nominal value. A large voltage swing, however, is a common situation in the aforementioned applications, as the respective input voltages, in worst-case, can easily drop by 50 %, whereby full functionality still needs to be maintained. In this work, we demonstrate a wide-input-voltage-range 400 V to 12 V, 3 kW dc-dc converter with a novel control method and transformer design. The employed boundary/Discontinuous Mode control scheme reduces circulating currents over conventional LLC techniques, and the "snake-core" matrix transformer achieves ideal parallel-connected secondary voltage balance. The converter achieves 350 W/in3 power density while operating from 300 V to 430 V input voltage and from 10 % to full load. An advanced design for a data center power supply application additionally utilizes the magnetizing inductance for boost operation in order to optimize the operating conditions of the converter system and to increase the overall efficiency. A performance comparison is finally explored for comparing the advanced design with the current hardware demonstrator and with conventional LLC converters.

F.c. Zach - One of the best experts on this subject based on the ideXlab platform.

  • Space vector-based analytical analysis of the input current distortion of a three-phase Discontinuous-Mode boost rectifier system
    IEEE Transactions on Power Electronics, 1995
    Co-Authors: Johann W. Kolar, H. Ertl, F.c. Zach
    Abstract:

    In this paper the low frequency harmonic distortion of the mains current of a three-phase single-switch Discontinuous-Mode boost-rectifier is calculated. The system analysis is based on application of space vector calculus and on substitution of Discontinuous time shapes within a pulse period by quasicontinuous time shapes. The quasicontinuous time shapes are defined by averaging over the pulse period. The dependency of the shape of the input currents on the voltage transformation ratio is given for various control methods in analytical form. The results of the theoretical analysis are verified by digital simulation and by measurements on a laboratory Model. A good consistency of the results has been found. >

  • a novel three phase single switch Discontinuous Mode ac dc buck boost converter with high quality input current waveforms and isolated output
    IEEE Transactions on Power Electronics, 1994
    Co-Authors: Johann W. Kolar, H. Ertl, F.c. Zach
    Abstract:

    In this paper, a new three-phase single-switch AC-DC flyback converter system is presented. The system operates in the Discontinuous Mode. The simple structure of its power and control circuit, low mains current distortion, and resistive fundamental behavior, as well as the high-frequency isolation of the controlled output voltage, have to be pointed out. Besides the analysis of the stationary operating behavior, the dependencies of the peak values, average values, and rms values of the device currents, and of the maximum blocking voltages across the power electronic devices on the circuit parameters, are given as analytic approximations. The theoretical analysis is verified by digital simulation. >