Hans-Peter Nee

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This paper discusses the impact of modulation on stability issues of the Modular Multilevel Converter (M2C). The main idea is to describe the operation of this converter system mathematically, and suggest a control method that offers stable operation in the whole operation range. A possible approach is to as­sume a continuous model, where all the(More)
Previous results concerning instability of the dc link in inverter drives fed from a dc grid or via a rectifier are extended. It is shown that rectifier–inverter drives equipped with small (film) dc-link capacitors may need active stabilization. The impact of limited bandwidth and switching frequency in the inverter–motor current control loop is considered,(More)
Modular multilevel converters (M2C) are increasingly used in high voltage direct current (HVDC) systems. The efficiency of M2Cs is highly related to the modulation method which determines the switching frequency and capacitor voltage ripple in the converter station. A new approach to modulation of M2C is presented in this paper. Tolerance-band methods are(More)
Modular multilevel converters are shown to have a great potential in the area of medium-voltage drives. Low-distortion output quantities combined with low average switching frequencies for the semiconductor devices create an ideal combination for very high-efficiency drives. However, the large number of devices and capacitors that have to conduct the(More)
In this paper, a comparison of the energy storage requirements is performed for the modular multilevel converter (MMC) with half-bridge and full-bridge submodules as well as for the alternate arm converter (AAC). Concerning the AAC, the operational mode with overlap period is taken into account and an analytical relation between the overlap angle and the(More)
Modular multilevel converters require that the controller is designed so that the submodule capacitor voltages are equalized and stable, independent of the loading conditions. Assuming that the individual capacitor-voltage sharing is managed effectively, an open-loop strategy has been designed to ensure that the total amount of energy stored inside the(More)
The modular multilevel converter is a promising topology for high-voltage high-power applications. By the series-connection of submodules it can generate high-quality voltage waveforms with low harmonic distortion at low switching frequencies. The submodules are low-voltage converters with capacitive energy storages. These capacitive energy storages are a(More)
Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are distinct developmental disorders caused by absence of paternal or maternal contributions of the chromosome region 15q11-q13, resulting from deletions, uniparental disomy (UPD), or rare imprinting mutations. Molecular cytogenetic diagnosis is currently performed using a combination of fluorescence in(More)