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The knowledge of the system behavior of modern drive trains is essential for more and more integrated drive systems with variable-speed operation. While state-of-the-art inverters have a lot of advantages, there are also some downsides. Parasitic currents driven by the common-mode voltage of voltage source inverters can damage the machine elements of the drive train. Three different types of these...
The knowledge of the inherent common-mode voltage of voltage source inverters and its impact on the mechanical drive train elements is an important issue. With the help of model-based calculations it is possible to identify critical operating points. In addition to the influence of the converter, different operating conditions such as speed and temperature have a main influence on the resulting discharge...
Voltage source inverters in electrical drive systems are the main sources of possible mechanical degeneration inside the anti-friction bearings of downstream drive train components. In order to find the right countermeasures to avoid these parasitic effects, knowledge of the switching conditions of the converter and the subsequent effects are an important issue. This paper focuses on the converter's...
This paper examines the influence of the motor pole pair number on the audible noise of electric motors for inverter operation. The number of pole pairs affects different parameters related to electromagnetic noise generation: the mode shape of the related force waves, the motor eigenfrequencies, the speed range where flux weakening is activated, as well as the frequencies of the radial force waves...
A new Standard that defines, for the first time, efficiency classes for converters and electric drive systems will take effect in 2014. This paper focuses on the drive system, which is referred to as Power Drive System (PDS) in the Standard. The paper also addresses the procedure for determining the drive system efficiency classes, referred to as IES classes, as well as the possible loss determination...
As shown in [6], the issue of current flowing through a motor bearing is a system-related topic. Different aspects have to be taken into account to identify countermeasures to avoid or dampen the current flow. Up until now, it is not possible to define clear limits where the changes in the bearing raceways lead to the so called corrugation and with this to a possible bearing failure. This paper shows...
The possibility to calculate motor bearing currents from motor geometry and the mechanisms that lead to these currents are known today [1], [2]. The precise mechanical and electrical procedures which lead to the well known corrugated patterns, a “mountain/valley” structure in the bearing raceway, which reduces the bearing lifetime, are still unknown. But, this paper will present research results that...
Bearing currents in converter-fed three-phase motors are significantly dependent on the lubricant film condition. As a consequence, the lubricant film thickness and the resulting capacitance are important input quantities for a simulation model aiming at predicting bearing currents and harmful electric discharges, which was presented in corresponding work. In addition to speed, load and temperature,...
This paper deals with the early detection and monitoring of possible bearing damage of variable-speed, converter-fed electric motors. After a brief description about the issue of bearing currents in converter-fed drives, the main subject will be outlined with the focus on practical experience. A measurement systemology is used for this purpose, where the electrical measurement of bearing current events...
The basic interrelationships that are required to investigate the cross-system subject of “bearing currents in converter operation”, are discussed in this paper. In order to obtain an integrated overview of the situation, it is decisive that the main points of the investigation are not discussed individually, but must be considered from an overall point of view. Results from the parameter test area...
Motor bearings in industrial converter-fed three-phase motors are mostly equipped with grease-lubricated roller bearings. It is known that under certain operating conditions bearing currents flow that can damage the bearings. When estimating the danger of damaging bearing currents it is important to look at the thickness and the capacitance of the lubricant film as well as the electrical parameters...
The mechanisms that lead to bearing currents have been known for several years. Empirical results have been collected for a few combinations comprising converter, motor and motor feeder cable. Although there are a series of remedial measures, the basic parameters which favor subsequent bearing damage, especially corrugation, have still not been adequately clarified. After a brief introduction into...
The basic inter-relationships, which are required to investigate the cross-system subject of “bearing currents in converter operation”, are discussed in this paper. In order to obtain an integrated overview of the situation, it is decisive that the main points of investigation that are discussed are combined and viewed holistically. Results from the parameter test area and their link with the overall...
The issue of noise emission from electric drives is becoming increasingly important. Motor manufacturers have to comply with certain standards in order to assure the high competitiveness of their products. At the same time, with today's variable speed drives, which are supplied with non-sinusoidal voltages, the issue of noise reduction has become more complex. This is because the influence of additional...
The SINAMICS GM150 IGBT, a new 3-level-neutral-point-clamped (3L-NPC) Voltage-Source- Converter (VSC) with series-connected 6.5 kV-IGBTs for industrial Medium Voltage Drives is presented. It covers the output voltage range from 6 kV up to 7.2 kV without the need for a step-up output transformer. The SINAMICS GM150 IGBT is based on the proven basic design of its predecessor SIMOVERT MV while the output...
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