A Modular Multilevel Resonant DC–DC Converter

Shao, Shuai; Li, Yucen; Sheng, Jiajing; Li, Chushan; Li, Wuhua; Zhang, Junming; He, Xiangning

doi:10.1109/tpel.2019.2962032

Cited by 46 publications

(22 citation statements)

References 23 publications

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“…Metalized film capacitors rated at 1100 V are practical here because the required capacitance is relatively small considering there is no low-frequency current flow. Voltage balancing among these series capacitors can be realized with parallel balancing resistors [40], [41]. This solution may not scale well to high voltage applications (>100 kV) and the reliability would be a problem.…”

Section: Low Step-ratio Rmmcmentioning

confidence: 99%

Resonant Modular Multilevel DC–DC Converters for Both High and Low Step-Ratio Connections in MVDC Distribution Systems

Xiang

Qiao

et al. 2021

IEEE Trans. Power Electron.

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DC transformers based on power electronics are key items of equipment for medium voltage dc (MVDC) distribution systems. Both high and low step-ratio dc-dc conversions are required to interface dc links at different voltages to form an integrated dc distribution system. The transformer-coupled resonant modular multilevel dc-dc converter (RMMC) is wellsuited to high step-ratio connection between a MVDC network and a low voltage dc (LVDC) network but it is not suitable in low stepratio conversion for linking two MVDC networks with similar but not identical voltages. This paper presents a circuit evolution of the high step-ratio transformer-coupled RMMC into its low step-ratio transformer-less RMMC counterpart. These two RMMCs share the same structure and the same resonant process within the resonant SM stack (RSS) giving rise to the same operational advantages. Also, the circuit design experience can be readily transferred from one to the other. From these two base RMMC circuits, a family of RMMCs with further configurations is elaborated that provide a wider variety of connection options for MVDC distribution systems. In this circuit family, each high step-ratio transformer-coupled RMMC has a low step-ratio transformer-less RMMC counterpart and one can be transformed into the other via the circuit evolution process presented. The theoretical analysis for both high and low stepratio RMMCs has been verified through full-scale simulations of medium voltage examples and further verified through downscaled experiments on laboratory prototypes.

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Section: Low Step-ratio Rmmcmentioning

confidence: 99%

Resonant Modular Multilevel DC–DC Converters for Both High and Low Step-Ratio Connections in MVDC Distribution Systems

Xiang

Qiao

et al. 2021

IEEE Trans. Power Electron.

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“…In [10], a modular multilevel based LLC resonant converter has been proposed which is capable of operating the converters over a narrow frequency range for a wide range…”

Section: Introductionmentioning

confidence: 99%

A Single Phase, Single Stage AC-DC Multilevel LLC Resonant Converter With Power Factor Correction

Peter

Mathew

2021

IEEE Access

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Single stage LLC resonant converters with inherent power factor correction are getting popularity in AC-DC converters due to its reduced size and weight. However, single stage topologies are usually less efficient in regulating the dc bus capacitor voltage pertaining to line and load transients. This paper proposes a multi-level flying capacitor based single stage AC-DC LLC topology to address the issue of voltage balancing of dc-bus capacitor and to reduce the voltage stress of the switching devices. The proposed three-level inverter topology guarantees zero voltage switching, less circulating currents, reduced switching stress and losses. The converter uses bridgeless rectification scheme for better efficiency and the power factor is made nearly unity by operating the source-side inductor in discontinuous current conduction. Variable switching frequency control is used to regulate the output voltage of the converter and pulse width modulation is used to control the dc-bus voltage. This dual control scheme is very effective to keep the dc-bus voltage nearly constant over a wide range of line and load variations. The proposed topology and control scheme have been validated by hardware results on a 250W resistive load.

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“…Therefore, another modular multilevel resonant DC-DC converter has been reported in the literature that achieves lower current stresses. 29 Recently, an arm interchange concept-based two-stage modular DC-DC converter is presented in the literature. 30 This converter consists of a half-bridge single-phase HBSM-based MMC with additional SMs followed by an H-bridge FBSMs-based MMC.…”

Section: Introductionmentioning

confidence: 99%

A hybrid two‐stage modular DC–DC converter with zero‐voltage switching

Nazih

Hossam-Eldin

Elserougi

2021

Circuit Theory & Apps

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Conventional modular multilevel converters (MMCs) are widely used in high power applications due to their various astonishing advantages; however, they fail to achieve balanced capacitor voltage in DC operation. In this paper, a hybrid two-stage modular DC-DC converter is proposed to solve the issue of unbalanced capacitor voltages. The proposed converter consists of a singlephase half-bridge MMC with half-bridge submodules followed by a medium voltage valves-based H-bridge rectifier. The proposed converter is used in medium-voltage applications such as feeding a DC-load or interconnection between two DC grids of different voltage levels. The proposed configuration achieves successful DC-DC conversion with a low number of switches, a high conversion ratio with bidirectional power flow, low current stresses, soft switching across the second stage, and low switching losses. The operational concept and the control algorithm have been illustrated in detail. Finally, the effectiveness of the proposed DC-DC converter is evaluated based on simulation studies of MATLAB SIMULINK and a scaled-down laboratory experimental test rig.

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A Modular Multilevel Resonant DC–DC Converter

Cited by 46 publications

References 23 publications

Resonant Modular Multilevel DC–DC Converters for Both High and Low Step-Ratio Connections in MVDC Distribution Systems

Resonant Modular Multilevel DC–DC Converters for Both High and Low Step-Ratio Connections in MVDC Distribution Systems

A Single Phase, Single Stage AC-DC Multilevel LLC Resonant Converter With Power Factor Correction

A hybrid two‐stage modular DC–DC converter with zero‐voltage switching

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