Analysis of theory and methodology used in determination of electric motor drive system losses and efficiency
Kärkkäinen, Hannu (2021-04-23)
Väitöskirja
23.04.2021
Lappeenranta-Lahti University of Technology LUT
Acta Universitatis Lappeenrantaensis
School of Energy Systems
School of Energy Systems, Sähkötekniikka
Kaikki oikeudet pidätetään.
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In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of Lappeenranta-Lahti University of Technology LUT's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_ standards/publications/rights/rights_ link.html to learn how to obtain a License from RightsLink.
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-335-648-1
https://urn.fi/URN:ISBN:978-952-335-648-1
Tiivistelmä
This research is divided into two main parts: loss determination of motors, converters, and motor drive systems and determination of measurement uncertainty. With its accurate measurements and data analysis, the work provides significant findings. For example, it is now clear that converter-caused additional losses in a motor depend on the load and excitation frequency.
The measurement uncertainty related to converter-fed machines and pulse-widthmodulated power is a controversial topic. It has been shown that in the practical measurement uncertainty analysis of converters and electric machines, the PWM supply can be analyzed using fundamental wave values, and they can be treated in the uncertainty analysis similar to the analysis of a typical sinusoidal supply.
To the author’s knowledge, there has not been a procedure to thoroughly analyze the measurement uncertainty of electric motors and drives. A method to determine the overall measurement uncertainty for direct-on-line and converter-fed motor drive systems is developed starting from measurement instrument datasheets and resulting in the total expanded measurement uncertainty. The main uncertainty contributors are demonstrated, and it is shown that it is important to identify all uncertainty sources, as a single high uncertainty contributor can have a significantly deteriorating effect on the overall measurement uncertainty.
So far, there has not been general guidance available on how the data should be collected from the measurement instruments in the case of electric motor and converter efficiency determination. The number of samples and measurement time needed to achieve an acceptable level of measurement uncertainty are demonstrated in this work.
Although the international standards are generally well prepared and widely studied, the methods for loss and efficiency determination have room for improvement. The results published in the papers of this study show that there are grounds for criticism of some of the present standard methods.
The open and balance type calorimeter used in this study has been considered one of the most accurate types of calorimetric systems. However, the method consists of two separate tests, and the impact of changes in air properties between the tests has not been clear. In this work, it is shown that humidity and barometric pressure measurements are, after all, not essential for an open and balance type calorimeter. A comprehensive procedure to establish a measurement system has been set up to make compliance measurements possible in general.
The measurement uncertainty related to converter-fed machines and pulse-widthmodulated power is a controversial topic. It has been shown that in the practical measurement uncertainty analysis of converters and electric machines, the PWM supply can be analyzed using fundamental wave values, and they can be treated in the uncertainty analysis similar to the analysis of a typical sinusoidal supply.
To the author’s knowledge, there has not been a procedure to thoroughly analyze the measurement uncertainty of electric motors and drives. A method to determine the overall measurement uncertainty for direct-on-line and converter-fed motor drive systems is developed starting from measurement instrument datasheets and resulting in the total expanded measurement uncertainty. The main uncertainty contributors are demonstrated, and it is shown that it is important to identify all uncertainty sources, as a single high uncertainty contributor can have a significantly deteriorating effect on the overall measurement uncertainty.
So far, there has not been general guidance available on how the data should be collected from the measurement instruments in the case of electric motor and converter efficiency determination. The number of samples and measurement time needed to achieve an acceptable level of measurement uncertainty are demonstrated in this work.
Although the international standards are generally well prepared and widely studied, the methods for loss and efficiency determination have room for improvement. The results published in the papers of this study show that there are grounds for criticism of some of the present standard methods.
The open and balance type calorimeter used in this study has been considered one of the most accurate types of calorimetric systems. However, the method consists of two separate tests, and the impact of changes in air properties between the tests has not been clear. In this work, it is shown that humidity and barometric pressure measurements are, after all, not essential for an open and balance type calorimeter. A comprehensive procedure to establish a measurement system has been set up to make compliance measurements possible in general.
Kokoelmat
- Väitöskirjat [1070]