Quasi-Two-Level Converter for overvoltage mitigation in medium voltage drives

Bertoldi, Federico; Pathmanathan, Mehanathan; Kanchan, R.S.; Spiliotis, Konstantinos; Driesen, Johan

doi:10.23919/ipec.2018.8507745

Cited by 9 publications

(6 citation statements)

References 16 publications

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“…7 forî b /i o = 1.5. After that, the branch inductance L b , the module capacitance C mod , and the maximum achievable duty cycle δ max can be determined according to (18), (19), and (23), respectively. This optimum design case is referred to as Case A in Table 2, which shows the design results.…”

Section: B Impact Of Stray Inductancesmentioning

confidence: 99%

“…The particular value for the design scenario is difficult to determine and it can be estimated by an FEM simulation of planned converter construction. When L b,min is substituted into (19), the restriction for the ζ and product can be expressed:…”

Section: B Impact Of Stray Inductancesmentioning

confidence: 99%

“…Hence, more research needs to be done until these approaches can be considered a more attractive alternative. In [19], [20], Bertoldi et al study an application of dv/dt filters and active canceling of the reflected waves for the quasi-two-level PWM-operated MMCs in scenarios, when very long machine cables are applied and only very low overvoltages are acceptable for the machine.…”

Section: Introductionmentioning

confidence: 99%

“…1) approaches that do not control internal (leg) currents of the converter nor the capacitor energies [8]- [10], [15], [16], [19], [20], 2) approaches that control both the leg currents and the capacitor energies [1]- [3], [12], [13], and…”

Section: Introductionmentioning

confidence: 99%

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Designing a Passively Damped Quasi-Two-Level-Operated Modular Multilevel Converter for Drive Applications

Kucka¹,

Mertens²

2020

IEEE Access

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This paper concentrates on the simplest quasi-two-level PWM operation mode for modular multilevel converters, where the internal currents within the converter are not controlled. The model of the converter is derived and the properties of the inherent resonance circuit within the converter are discussed. The paper proposes an optimized design approach for the converter parameters and shows several challenges in the practical design. The main problem of the studied converter operation mode is the dependency of the converter behavior on many parasitic parameters that can significantly vary in the converter production. Moreover, the paper shows that when the converter losses are low, the optimized converter inductances are below the values expected for realistic converter construction. Consequently, the module capacitances have to be significantly increased or the converter internal currents reach exceedingly high values. Furthermore, a comparison is drawn to the quasi-two-level PWM operation mode in which the leg currents and branch energies are controlled, showing several crucial disadvantages of the studied passively damped operation mode. The utilized models and the basic concepts are validated experimentally on a downscaled converter prototype.INDEX TERMS Modular multilevel converter, passive damping, quasi-two-level.

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Section: B Impact Of Stray Inductancesmentioning

confidence: 99%

Section: B Impact Of Stray Inductancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Designing a Passively Damped Quasi-Two-Level-Operated Modular Multilevel Converter for Drive Applications

Kucka¹,

Mertens²

2020

IEEE Access

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“…To fulfill the requirements of efficiency, grid code and output voltage spectrum, the carrier frequency can be optimized as compared to a twolevel converter. The output voltage spectrum of the Quasi-Two-Level modulation has a higher harmonic content than a conventional n-level modulation as presented in [13]. The losses and stress of all components (converter and output-filter) has to be considered for each application.…”

Section: Quasi Two-level-operationmentioning

confidence: 99%

Quasi-Two-Level Flying-Capacitor-Converter for Medium Voltage Grid Applications

Mersche

Bernet

Hiller

2019

2019 IEEE Energy Conversion Congress and Exposition (ECCE)

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Medium voltage converters are becoming more relevant in future grid applications. Especially more wind and PV generation systems will be have to added and integrated into the grid in order to achieve the required reduction in CO2 emissions. High power generation units will be integrated into the grid at medium voltage level. Furthermore meshed MV grids will require interties based on MV converter technology. Today's standard medium voltage converters are either based on the MMC technology or us 3L/5L approaches operated at low switching frequencies and containing bulky filters. Both concepts still lead to relatively high costs and low efficiencies which are major reasons for the slow spread of power converters in medium voltage grid applications.. Future grid applications demand less distortion, higher reliability and lower costs for converter systems at each voltage level. The Quasi-Two-Level operation of the flying capacitor multilevel converter with silicone-carbide (SiC) based semiconductors is a method for achieving these requirements for medium voltage converters. This paper presents a new concept for minimizing capacitance and balancing the capacitors with fast switching semiconductors. Moreover, a novel approach for limiting the overvoltage stress caused by the Quasi-Two-Level modulation of a flying capacitor converter is presented.

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