Annette Muetze

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22 HE EFFECTS OF PARASITIC BEARING currents in variable-speed drive systems caused by fast-switching insulated gate bipolar transistor (IGBT) inverters have been reported during the past several years [1]–[24]. In the past, research has focused on physical explanations of the bearing currents for a given drive system at a particular power level. The results(More)
The occurrence of high-frequency discharge bearing currents (also called "electric discharge machining (EDM) currents") that can occur in machines of inverter-based drive systems depends strongly on the value of the capacitive voltage divider "bearing voltage ratio" (BVR) of the machine. This paper presents a straightforward approach to calculate the(More)
While the cause-and-effect chains of inverter-induced bearing currents have been well understood today, not much is known about the damage mechanism inside the bearings. Research has suggested that the bearing degradation is approximately proportional to the frequency of occurrence of the bearing currents. For bearing currents that occur statistically(More)
An eddy-current model can describe the high frequency circulating bearing current that may occur in machines of inverter-based drive systems. The parameters of an equivalent circuit are derived from the model. The ratio between bearing current and common mode current amplitudes for different machines is calculated. The theoretical maximum ratio is about(More)
Ocean energy conversion has been of interest for many years. Recent developments such as concern over global warming have renewed interest in the topic. This paper gives a systematic and comprehensive overview of wave energy converters (WEC) as opposed to ocean current energy converters. The point absorber and oscillating water column WEC devices are(More)
In this article, the term "electric bicycle" is used to describe "electric-motor-powered bicycles," including both fully and partially motor-powered bicycles. Here, the electric bicycle market would benefit from further research both on the battery and on the drive technology and their use with electric bicycles. In the United States, electric bicycles are(More)
Inverter-induced high-frequency bearing currents are a parasitic effect that can occur in variable-speed drive systems. While the physical cause-and-effect chains are understood, little has been known on appropriate quantitative assessment of the phenomena. This paper discusses reliable techniques for the measurement of different parameters of importance(More)
Electric motor powered bicycles (short: "electric bicycles") have been making their way into the U.S. market for about two decades. Such electric bicycles can be used for a large variety of purposes. This paper gives a systematic, comprehensive, theoretically and experimentally based characterization of electric bicycles, and reports on the different(More)
The high-frequency (HF) circulating bearing current that may occur in the machines of the inverter-based drive systems can be reduced or even completely suppressed by the use of the electrically insulated bearings or the insulated inner bearing seats. This paper proposes a method to calculate the influence of the thickness of the insulating coat on the(More)
The influence of different parameters of a variablespeed drive system on the phenomena of inverter-induced bearing currents has been studied under exactly the same conditions on inverter-operated alternating current motors from 1 to 500 kW. Detailed modeling may not always be applicable with practical applications in the field, where many parameters might(More)