Electric Motor Speed Signal Correction Using Half-Period Averaging
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Solution Overview
Problem
Existing methods for generating speed signals in electric motors are hindered by signal disturbances, such as noise components and angle errors, which prevent precise regulation, especially in applications requiring high accuracy.
Innovation Solution
A method that uses a commutation sensor to ascertain an angle signal, which is then converted into a raw speed signal and corrected by averaging samples spaced half a period apart to eliminate disturbance waviness, leaving only the noise component, which can be further filtered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a commutation sensor is used to ascertain an angle signal for speed determination, then the speed signal can be obtained, but the angle signal contains disturbance components (noise and angle error) that prevent precise regulation
Solution Approach 1:
The patent extracts and removes the disturbance waviness from the speed signal by identifying and eliminating the periodic error components. The method separates the useful speed information from the harmful disturbance waviness caused by angle errors, extracting only the noise component which can be further filtered, thereby achieving a clean speed signal suitable for precise regulation.
Solution Approach 2:
The patent utilizes the periodic nature of the angle error to correct it. Since the angle error repeats periodically with the rotor rotation, the method uses this periodicity to identify and remove the disturbance waviness from the speed signal. By averaging samples spaced half a period apart, the periodic disturbance is eliminated while preserving the actual speed information.
2Measurement precision
If conventional correction methods using previously ascertained correction values are used, then some error correction is achieved, but the correction is insufficient for high-precision applications
Solution Approach 1:
The patent transitions from static correction values to dynamic correction. Instead of using fixed previously ascertained correction values, the method continuously adapts the correction by using the current speed signal and averaging samples spaced half a period apart. This dynamic approach allows the correction to respond to changing operating conditions, achieving higher precision for high-precision applications.
Solution Approach 2:
The patent implements feedback by using the speed signal itself to determine the correction. The method averages samples spaced half a period apart based on the current speed information, creating a feedback loop that continuously refines the speed signal. This feedback mechanism ensures that the correction is based on actual operating conditions rather than pre-stored values, improving both precision and reliability.
3Measurement precision
If the angle error is corrected by averaging multiple samples, then the disturbance waviness is reduced, but the complexity of the correction process increases
Solution Approach 1:
The patent applies partial action by using only two samples spaced half a period apart, rather than averaging multiple samples. This minimal averaging approach is sufficient to eliminate the periodic disturbance waviness while keeping the correction process simple. The method uses exactly the minimum number of samples needed to remove the disturbance, avoiding unnecessary complexity while achieving the desired precision.
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
This approach provides a highly accurate speed signal by completely removing disturbance waviness, allowing for precise motor regulation and continuous operation without requiring a full period of the disturbance signal.
Implementation Method 1
A commutation sensor based on a magnetic rotary encoder may be used as the signal generator
Data Source
AI summary
A method for the improved speed determination of electric motors while taking into account angle errors of an angular position sensor is provided. A commutation sensor based on a magnetic rotary encoder, the angle signal of which has an angle-dependent and thus periodic angle error, is used. By differentiation, this defective angle signal is converted into a raw speed signal, which has two disturbance components. One disturbance component results from the angle error and is the disturbance waviness, which is periodic similar to the angle error. The second disturbance component is formed by a noise component superposing the raw speed signal. In order to correct the defective raw speed signal, half of the period duration of the raw speed signal must be ascertained. If this half of the period duration is ascertained two samples of the raw speed signal lying exactly one half of the period duration of the raw speed signal apart from each other are averaged. A speed signal having no disturbance waviness but rather only the noise component results from these method steps.