Benjamin Eichinger

Case Studies of Acoustic Noise Emission From Inverter-Fed Asynchronous Machines

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 todays variable speed drives, which are supplied with nonsinusoidal voltages, the issue of noise reduction has become more complex. This is because the influence of additional factors, compared to machines supplied with sinusoidal voltage, must be considered over a wide speed range. The key to optimizing the machines acoustic behavior is the thorough knowledge of the influence of the different noise sources and the excitation mechanisms over the complete speed range. Apart from the theoretical analysis and the simulation, an experimental investigation is necessary to obtain a better understanding of the previously mentioned factors and to minimize the machines acoustic noise. This paper presents some characteristic case studies of acoustic noise emission in asynchronous machines supplied from voltage source inverters in order to examine the influence of diverse factors on the total noise level.

Sound optimization of a converter‐fed drive system using an acoustic camera in combination with modal analysis

Purpose – Modern variable‐speed drive systems using frequency converters generate additional audible noise as a result of the voltages that are no longer sinusoidal. Using suitable measures, the purpose of this paper is to find an optimum for minimum noise radiation in the complete drive system.Design/methodology/approach – The main areas to concentrate on to achieve an optimum are the source of excitation itself – the frequency converter, as well as the actual source of the noise, the motor. Optimization measures are drawn‐up using soundscaping with subsequent modal analysis of the actual state. The effectiveness of any changes made can be estimated using simulation techniques. This approach is confirmed by subsequently implementing the selected measures and verifying them by performing the appropriate measurements.Findings – The paper takes care of the increasingly important field of converter‐fed drive systems and their special acoustical challenge. It shows a practical way to reduce audible noise comb...

Influence of the number of pole pairs on the audible noise of inverter-fed induction motors: Radial force waves and mechanical resonances

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 for a certain motor speed (and also modulation index). The radiated noise of induction motors with the same shaft height but different number of pole pairs has been measured in the laboratory and significant differences have been identified. A theoretical analysis of the excitation forces and calculations with the help of finite element analysis was performed in order to investigate the reasons for these differences.

Case studies of acoustic noise emission from inverter-fed asynchronous machines

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 todays 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 factors, compared to machines supplied with sinusoidal voltage, must be considered over a wide speed range. The key to optimizing the machines acoustic behavior is the thorough knowledge of the influence of the different noise sources and the excitation mechanisms over the complete speed range. Apart from the theoretical analysis and the simulation, an experimental investigation is necessary to obtain a better understanding of the previously mentioned factors and to minimize the machines acoustic noise. This paper presents some characteristic case studies of acoustic noise emission in asynchronous machines supplied from voltage source inverters in order to examine the influence of diverse factors on the total noise level.