A Two-Stage Buck–Boost Integrated <i>LLC</i> Converter With Extended ZVS Range and Reduced Conduction Loss for High-Frequency and High-Efficiency Applications

Liu, Qi; Qian, Qinsong; Ren, Bowen; Xu, Shengyou; Sun, Weifeng; Yang, Lanlan

doi:10.1109/jestpe.2019.2956240

Cited by 40 publications

(18 citation statements)

References 19 publications

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“…It is a two-stage topology, the second stage is an LLC resonant converter, while the first stage is a buck-boost stage. The peculiarity of this topology is the integration of the two power switches 978-1-6654-3613-7/21/$31.00 ©2021 IEEE S bH and S bL of the buck-boost stage as primary switches of the half-bridge LLC topology [7]- [10].…”

Section: A Topology Descriptionmentioning

confidence: 99%

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A Two-Stage Isolated Resonant DC-DC Converter for Wide Voltage Range Operation

Zanatta

Caldognetto

Spiazzi

et al. 2021

2021 IEEE International Conference on Environment and Electrical Engineering and 2021 IEEE Industrial and Commercial Power Syst

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This paper proposes a high-efficiency two-stage isolated dc-dc converter for applications with wide variations of output voltages. It employs a first, pre-regulation stage and a second stage based on an LLC converter, integrated with the first. The second stage is always operated at resonance, ensuring maximum efficiency. The first pre-regulation stage is in charge of i) achieving the desired overall conversion ratio and of ii) always achieving soft-switching operation of all the switches, even in presence of wide output voltage variations. This allows to tackle the typical challenge of keeping conversion loss low even with input or output port voltages that may vary in a wide range. In this paper, the considered conversion structure is shown considering a preliminary experimental prototype that interfaces a 750-V dc-link with an output bus of nominal voltage in the range 250 V to 500 V, which is common in electric vehicle battery-charging applications. The considered preliminary prototype is rated 5 kW and achieves a peak efficiency of 97.5% at 3 kW output power.

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Section: A Topology Descriptionmentioning

confidence: 99%

“…with ∆t k = 0 for k > N . Equation (7) allows to determine the initial value I 0 , once the output current is known.…”

Section: Inductor Current Derivationmentioning

confidence: 99%

A Two-Stage Isolated Resonant DC-DC Converter for Wide Voltage Range Operation

Zanatta

Caldognetto

Spiazzi

et al. 2021

2021 IEEE International Conference on Environment and Electrical Engineering and 2021 IEEE Industrial and Commercial Power Syst

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show abstract

“…For Continuous Conduction operational Mode (CCM), I L,min needs to be greater than zero. Therefore, for obtaining the boundary between CCM and Discontinuous Conduction Mode (DCM), inductor current can be determined from (20):…”

Section: Current Ripples For the Inductorsmentioning

confidence: 99%

“…By increasing the switching frequency, the number of the intersection time intervals will be increased and gives more switching power losses. For that, different soft switching techniques like the zero voltage (ZVS) and zero current switching (ZCS), and zero voltage (ZVT) and zero current transition (ZCT) are presented [20]- [23]. Although these techniques help the switches and diodes to work under fewer power losses, normally the design of these snubber structures is difficult and the switching frequency of the converter is extremely high.…”

Section: Introductionmentioning

confidence: 99%

A Novel and High-Gain Switched-Capacitor and Switched-Inductor-Based DC/DC Boost Converter With Low Input Current Ripple and Mitigated Voltage Stresses

et al. 2022

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High voltage gain DC-DC boost converters are widely used in grid-connected applications through integration with the Renewable Energy Sources (RESs). Photovoltaic (PV) arrays or Fuel Cells (FCs) generate a limited value of the DC voltages and then for high power and high voltage applications, at the first stage, these voltages should be increased. This study presents a high gain, single-switched, and efficient DC-DC boost converter using the switched-capacitor and switched-inductor cells. These blocks easily can enhance the voltage and present an input current with the least values of the ripples. This will be done through replacing the location of the input inductors and by applying a switched-inductor block. Magnetizing in parallel and demagnetizing in series for the inductors present the smaller input current stresses. A single switch is used for the proposed boost converter that directly decreases the complexity of the control circuit for obtaining a fixed DC voltage at the output side for flexible input voltages or loads. More voltages will be presented by the used switched-capacitor cell simply by adding several diodes and capacitors. A deep and detailed mathematical analysis will be presented for continuous (CCM) and discontinuous conduction modes (DCM) and a 200 W laboratory-scaled prototype is presented. The results of the hardware tests confirm the correctness of the theoretical analysis and simulation results.INDEX TERMS DC-DC boost converter, switched-capacitor, switched-inductor, continuous conduction mode (CCM), discontinuous conduction mode (DCM).

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“…2. Its peculiarity is the integration of the two power switches S bH and S bL of the buck-boost stage as primary switches of the half-bridge LLC [17], [19]- [21]. In order to exploit the high performance of the LLC stage working as dc-transformer (DCX) [15], the right-leg (S bH and S bL ) duty cycle is fixed at 50%.…”

Section: A Converter Description and Operationmentioning

confidence: 99%

Analysis and Performance Evaluation of a Two-Stage Resonant Converter for Wide Voltage Range Operation

Zanatta

Caldognetto

Spiazzi

et al. 2022

2022 IEEE Applied Power Electronics Conference and Exposition (APEC)

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This paper proposes a two-stage isolated dc-dc converter for electric vehicle charging applications, where high efficiency over a wide range of battery voltages is required. It employs a first pre-regulation stage and a second half-bridge LLC stage, integrated with the first. The second stage is always operated at resonance, ensuring very high efficiency. The first pre-regulation stage is responsible for the desired input-to-output voltage conversion ratio and the zero-voltage switching operation of all the switches. This allows low conversion losses even with voltages that may vary over a wide range. The conversion structure is shown considering a first experimental prototype that interfaces a 750-V dc-link with an output bus with nominal voltage range 250V-500V. The implemented module is rated 5 kW and achieves a peak efficiency of 98.0% at 3 kW output power.

show abstract

A Two-Stage Buck–Boost Integrated LLC Converter With Extended ZVS Range and Reduced Conduction Loss for High-Frequency and High-Efficiency Applications

Cited by 40 publications

References 19 publications

A Two-Stage Isolated Resonant DC-DC Converter for Wide Voltage Range Operation

A Two-Stage Isolated Resonant DC-DC Converter for Wide Voltage Range Operation

A Novel and High-Gain Switched-Capacitor and Switched-Inductor-Based DC/DC Boost Converter With Low Input Current Ripple and Mitigated Voltage Stresses

Analysis and Performance Evaluation of a Two-Stage Resonant Converter for Wide Voltage Range Operation

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