Analysis of three-level converters with voltage balancing capability in bipolar DC distribution networks

Broeck, Giel Van den; Breucker, Sven De; Beerten, Jef; Zwysen, Jeroen; Vecchia, Mauricio Dalla; Driesen, Johan

doi:10.1109/icdcm.2017.8001052

Cited by 15 publications

(5 citation statements)

References 26 publications

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“…The three state-variables describing the converter dynamics are the capacitor voltages v p and v n and the inductor current i L , which are governed by (16)- (18). In this section, lower-case symbols are used for time-varying signals, while capitals were used previously to indicate steady-state variables…”

Section: Converter Dynamicsmentioning

confidence: 99%

“…To facilitate the subsequent analysis of the FB‐TLC in unbalanced conditions, the steady‐state equations will be expressed in balanced and unbalanced components [18, 34]. The balanced components (voltages, currents and duty cycles) are denoted by the subscript ‘b’ and the unbalanced components are denoted by the subscript ‘u’.…”

Section: Unbalanced Operating Areamentioning

confidence: 99%

“…The price to pay to benefit from aforementioned advantages, is the need for power electronic blocks named voltage balancers that can equalise the pole-to-neutral voltages [14][15][16][17][18]. The most straightforward solution is a resistive voltage divider, which is not preferred as it presents a trade-off between high quiescent losses and tolerable voltage unbalance [19].…”

Section: Introductionmentioning

confidence: 99%

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Operation of the full‐bridge three‐level DC–DC converter in unbalanced bipolar DC microgrids

Broeck

Beerten

Vecchia

et al. 2019

IET Power Electronics

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As compared to two-wire, unipolar DC microgrids (DCμGs), bipolar DCμGs apply a positive, neutral and negative conductor to increase the power transfer capability while retaining two voltage levels for supplying low-and high-power devices at an appropriate voltage. However, connecting devices between the positive or negative pole and the neutral conductor will result in unbalanced currents causing voltage to unbalance. Therefore, power electronic converters with voltage balancing capability are essential. Instead of installing dedicated voltage balancing converters, this study proposes to apply three-level DC-DC converters. These converters can interface battery storage with bipolar DCμGs and balance the pole-to-neutral voltages at the same time. However, high levels of unbalanced currents drive three-level DC-DC converters towards their theoretical unbalanced operating limits. To derive these, a method is presented which decomposes the governing equations in balanced and unbalanced components. Although the method is generally applicable to the three-level converters, the full-bridge threelevel converter serves as a comprehensive example. The method enables to derive the unbalanced operating area of threelevel DC-DC converters and to appropriately size the filter inductor. Furthermore, a novel modulation strategy is introduced in order to lower the inductor current ripple in unbalanced conditions, supported by experimental results.

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Section: Converter Dynamicsmentioning

confidence: 99%

Section: Unbalanced Operating Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Operation of the full‐bridge three‐level DC–DC converter in unbalanced bipolar DC microgrids

Broeck

Beerten

Vecchia

et al. 2019

IET Power Electronics

Self Cite

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“…The decomposition into balanced and unbalanced components of voltages and currents in bipolar DCµG [27,28] enables to define a voltage unbalance factor V U F in (1) as the ratio between the unbalanced and balanced voltage at a certain node in the network.…”

Section: Voltage Imbalancementioning

confidence: 99%

A critical review of power quality standards and definitions applied to DC microgrids

2018

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As compared to AC microgrids, DC microgrids reduce the hardware complexity of converter-dominated power distribution in the presence of a high number of renewable energy sources, energy storage systems and energy efficient loads. Another frequently highlighted advantage is their resiliency and tolerance against AC grid disturbances resulting in improved overall power quality. However, with respect to power quality, the question arises whether existing international power quality standards and metrics remain applicable in DC microgrids or require adjustments. Therefore, this paper critically revises the definitions and power quality indicators specified in IEC 61000 and IEEE Std1159. The resulting review is essential to unambiguously define the responsibilities of the microgrid operators, customers and device manufacturers. Apart from that, causes and consequences of power quality issues in DC microgrids are discussed.

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“…Discussions among the voltage levels that are implemented in these systems are extensively presented in the literature [11], for instance, with a voltage between 350 and 400 V for distribution in unipolar or bipolar [6,12,13] DC configurations to supply high power equipments. The 48 V level is [14,15] normally adopted as an intermediate bus stage to supply the low voltage/low power loads aforementioned.…”

Section: Introductionmentioning

confidence: 99%

Novel Step-Down DC–DC Converters Based on the Inductor–Diode and Inductor–Capacitor–Diode Structures in a Two-Stage Buck Converter

et al. 2019

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This paper explores and presents the application of the Inductor–Diode and Inductor-Capacitor-Diode structures in a DC–DC step-down configuration for systems that require voltage adjustments. DC micro/picogrids are becoming more popular nowadays and the study of power electronics converters to supply the load demand in different voltage levels is required. Multiple strategies to step-down voltages are proposed based on different approaches, e.g., high-frequency transformer and voltage multiplier/divider cells. The key question that motivates the research is the investigation of the aforementioned Inductor–Diode and Inductor–Capacitor–Diode, current multiplier/divider cells, in a step-down application. The two-stage buck converter is used as a study case to achieve the output voltage required. To extend the intermediate voltage level flexibility in the two-stage buck converter, a second switch was implemented replacing a diode, which gives an extra degree-of-freedom for the topology. Based on this modification, three regions of operation are theoretically defined, depending on the operational duty cycles δ2 and δ1 of switches S2 and S1. The intermediate and output voltage levels are defined based on the choice of the region of operation and are mapped herein, summarizing the possible voltage levels achieved by each configuration. The paper presents the theoretical analysis, simulation, implementation and experimental validation of a converter with the following specifications; 48 V/12 V input-to-output voltage, different intermediate voltage levels, 100 W power rating, and switching frequency of 300 kHz. Comparisons between mathematical, simulation, and experimental results are made with the objective of validating the statements herein introduced.

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Analysis of three-level converters with voltage balancing capability in bipolar DC distribution networks

Cited by 15 publications

References 26 publications

Operation of the full‐bridge three‐level DC–DC converter in unbalanced bipolar DC microgrids

Operation of the full‐bridge three‐level DC–DC converter in unbalanced bipolar DC microgrids

A critical review of power quality standards and definitions applied to DC microgrids

Novel Step-Down DC–DC Converters Based on the Inductor–Diode and Inductor–Capacitor–Diode Structures in a Two-Stage Buck Converter

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