Accurate Rotational Speed Measurement for Determining the Mechanical Power and Efficiency of Electrical Machines

In this paper, the efficiency of a 2.75 MW nacelle drivetrain on a test bench was determined traceably at various load points. For this purpose, so-called transfer standards for mechanical and electrical power measurement were additionally installed and integrated into the nacelle drivetrain. As torque measurement contributes greatly to the overall uncertainty, the static torque calibration was expanded to include additional influences present under rotation. An overall system efficiency of 89% was measured in the high torque and high speed range. The relative expanded measurement uncertainty for efficiency determination was between 0.30% and 0.72% over the entire operating range. Both the efficiency and the relative expanded measurement uncertainty were calculated for each operating point.

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“…With the torque and speed ripples ratio being smaller than 1% and 90°shifted, the assumption in Eq. 6 is valid [6].…”

Section: Ripples In Raw Torque and Rotational Speed Signalsmentioning

confidence: 98%

“…In practice, the applicability of Eq. 6 is related to the torque quality and should be examined according to the method proposed in [6].…”

Section: Mechanical Power Measurementmentioning

confidence: 99%

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Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Song

Weidinger

Zweiffel

et al. 2023

Forsch Ingenieurwes

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“…The power output of the motor, which is the prime object of these tests, is derived from torque and angular speed, the latter of which can be estimated based on the angular displacement of the motor shaft. This estimation allows for the use of cost-effective alternatives such as encoders [8], as the limitations posed by low-resolution encoders can be mitigated to an extent by choosing an appropriate angular speed calculation or estimation algorithm. The estimation itself can be performed in several ways depending upon the accuracy and bandwidth needed for the particular application, processing capabilities of the microcontroller or programmable logic controller used for implementation, and considerations around system cost and complexity, which often involve significant trade-offs [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Impact of Angular Speed Calculation Methods from Encoder Measurements on the Test Uncertainty of Electric Motor Efficiency

Machado,

Thaler,

Pacheco

et al. 2024

Metrology

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The imperative need to advance the development of more efficient electric motors requires the meticulous measurement of small increments while minimizing the associated uncertainty in dynamometer tests. One of the key variables in such tests is the angular speed, which is typically obtained based on encoder measurements. This paper proposes a systematic measurement uncertainty assessment method based on the Guide to the Expression of Uncertainty for the two most widely used methods for angular speed measurement, namely, the frequency and period methods. In addition, the impact of the angular speed calculation method on the efficiency test uncertainty is assessed using an automatic test rig for electric motors. Our experimental results consider both steady-state and dynamic analyses. The results show that the period measurement method provides measurements with lower uncertainty for the encoders typically used in such test rigs, about 30 times less than the uncertainty determined for the frequency measurement method. Based on these results, the choice of a proper method can drastically decrease the angular speed uncertainty, and consequently the motor efficiency uncertainty, without increasing instrumentation cost.

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Accurate Rotational Speed Measurement for Determining the Mechanical Power and Efficiency of Electrical Machines

Cited by 2 publications

References 8 publications

Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Impact of Angular Speed Calculation Methods from Encoder Measurements on the Test Uncertainty of Electric Motor Efficiency

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Accurate Rotational Speed Measurement for Determining the Mechanical Power and Efficiency of Electrical Machines

Cited by 2 publications

References 8 publications

Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Impact of Angular Speed Calculation Methods from Encoder Measurements on the Test Uncertainty of Electric Motor Efficiency

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Product

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Traceable efficiency determination of a 2.75 MW nacelle on a test bench

Traceable efficiency determination of a 2.75 MW nacelle on a test bench