Asynchronous Motor Synchronous Speed Detection From Acoustic Signals
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Solution Overview
Problem
Existing methods for determining the synchronous speed of speed-controlled asynchronous machines are challenging, especially when electrical measured variables are not accessible, and the synchronous speed is unknown, making it difficult to determine the operating point accurately.
Innovation Solution
A method that uses mechanical measurement variables, such as noise information, to determine the synchronous speed by analyzing the frequency spectrum and selecting specific frequency ranges based on the clock frequency and its multiples, allowing for the determination of peak values that indicate the synchronous speed without relying on electrical measurements or control parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical measured variables are used to determine synchronous speed, then measurement precision is improved, but device complexity and accessibility requirements worsen
Solution Approach 1:
The patent replaces electrical measurement systems with acoustic measurement systems. Instead of using electrical sensors and control parameters to determine synchronous speed, the invention uses microphones to capture acoustic emissions from the motor, processes these signals through frequency analysis, and identifies synchronous speed from acoustic frequency peaks. This substitution eliminates the need for direct electrical measurement access while maintaining measurement capability.
Solution Approach 2:
The patent introduces acoustic signals as an intermediary medium to indirectly determine synchronous speed. Rather than directly measuring electrical parameters, the system captures acoustic emissions from the motor, uses these acoustic signals as intermediaries to infer rotational frequency and synchronous speed through spectral analysis. This intermediary approach allows measurement without direct electrical access.
2Measurement precision
If control parameters are required for synchronous speed determination, then measurement precision is improved, but ease of operation worsens
Solution Approach 1:
The patent enables the measurement system to determine synchronous speed autonomously without requiring external control parameters. The system captures acoustic emissions, performs frequency analysis, and automatically identifies synchronous speed from the acoustic spectrum. This self-service capability eliminates the need for operators to provide control parameters, improving ease of operation while maintaining measurement accuracy.
3Ease of operation
If acoustic emissions are analyzed instead of electrical measurements, then ease of operation is improved, but measurement precision may worsen
Solution Approach 1:
The patent performs preliminary frequency analysis and spectrum processing on the captured acoustic emissions before identifying synchronous speed. By pre-processing the acoustic signals through Fourier transforms and frequency spectrum analysis, the system prepares the data in advance to facilitate accurate peak identification. This preliminary action ensures that despite using acoustic rather than electrical measurements, the precision requirement is met through thorough signal processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the determination of synchronous speed and operating point of speed-controlled asynchronous machines without direct access to electrical measurements, improving accuracy and reducing complexity, and allowing for the characterization of the operating point using mechanical variables like sound pressure or vibration.
Implementation Method 1
initiating and/or carrying out the acquisition of at least one (in particular mechanical) measured variable in the electric machine and/or the driven machine, preferably to obtain acquisition information specific to a rotational sound of the electric machine and/or the driven machine and/or to the synchronous speed, in particular in the form of noise information
Implementation Method 2
carrying out a signal analysis, in particular frequency analysis, of the acquisition information to obtain a spectrum, in particular frequency spectrum, of the acquisition information
Data Source
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AI summary
The invention relates to a method for determining a synchronous speed (n0) of an electric machine (2), in particular a speed-controlled asynchronous machine (2), in a work machine (1) driven by the electric machine (2), wherein a control device (3) is provided for controlling the speed of the electric machine (2), wherein the following steps are carried out: - initiating a detection (101) of at least one mechanical measurement variable in the electric machine (2) and/or the driven work machine (1) to obtain detection information (200) specific to a rotation-induced sound of the electric machine (2) and/or the driven work machine (1), - carrying out a frequency analysis (102) of the detection information (200) to obtain a frequency spectrum (210) of the detection information (200), - carrying out a selection (103) of at least one frequency range (220) in the frequency spectrum (210) on the basis of a clock frequency (fT) of the control device (3), - carrying out an identification (104) of at least one peak value (230) in the frequency range (220) to determine at least one frequency (f1, f2) specific to the synchronous speed (n0), - carrying out the determination (105) of the synchronous speed (n0) by means of the at least one determined frequency (f1, f2).