Corrected Rotational Speed Signal for Electric Motor Interference
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Solution Overview
Problem
Existing methods for determining the rotational speed of electric motors are prone to interference, leading to inaccurate regulation, particularly in applications requiring precise speed control.
Innovation Solution
A method that uses a commutation sensor with a magnetic wheel transducer to determine a periodic rotational angle signal, which is then converted into a digital raw rotational speed signal. This signal is corrected by averaging sampled values and accounting for discretization errors, resulting in a corrected rotational speed signal that minimizes interference ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a commutation sensor with magnetic wheel transducer is used to determine rotational angle signal, then the rotational speed can be determined, but interference components and rotational angle errors occur in the signal
Solution Approach 1:
The patent identifies that the interference ripple has a periodic structure with predictable half-period characteristics. By intentionally sampling at intervals of half the ripple period and averaging these samples, the method converts the harmful periodic interference into a predictable pattern that can be systematically eliminated through selective sampling and averaging, transforming the harmful periodic signal into a beneficial correction opportunity.
Solution Approach 2:
The method changes the sampling parameter by introducing a sampling interval specifically set to half the period of the interference ripple. This parameter change allows the sampling points to be strategically positioned to capture the periodic interference pattern, enabling subsequent averaging to eliminate the ripple while preserving the true rotational speed information.
2Measurement precision
If rotational angle signal is converted to digital raw rotational speed signal, then speed information is obtained, but discretization errors are introduced
Solution Approach 1:
The patent implements a feedback mechanism where the determined half-period of the interference ripple is used to guide the sampling process. The sampling interval is dynamically set based on the detected ripple characteristics, creating a closed-loop system that continuously adapts to the interference pattern and optimizes the sampling strategy to minimize discretization errors while maximizing interference cancellation.
3Measurement precision
If correction value is determined by averaging sampled values with half-period spacing, then interference ripple is reduced, but additional processing time is required
Solution Approach 1:
The method performs preliminary determination of the interference ripple's half-period characteristics from the raw signal before executing the averaging correction process. This preliminary analysis enables the subsequent sampling and averaging to be optimized and executed efficiently, reducing the overall processing time by avoiding iterative or trial-and-error correction approaches.
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
The method provides a precise and stable corrected rotational speed signal, enabling effective regulation of electric motors by accounting for system-specific errors and discretization errors, thus improving the accuracy of rotational speed control.
Implementation Method 1
A commutation sensor on the basis of a magnetic wheel transducer may be used as a signal transmitter for the rotational angle signal
Data Source
AI summary
A method of determining a corrected rotational speed signal for an electric motor, comprising determining a periodic rotational angle signal that has a periodic rotational angle error that is dependent on the rotational angle, determining a half period duration of an interference ripple of a raw rotational speed signal, averaging of at least one pair of sampled values of the raw rotational speed signal, converting a rotational angle signal to a digital raw rotational speed signal that includes an interference ripple, determining an average value in response to at least one pair of sampled values of the raw rotational speed signal, forming a correction value dependent on a sampling period duration and on a frequency of the interference ripple of the raw rotational speed signal for consideration of a discretization error, and forming the corrected rotational speed signal from a difference between the average value and the correction value.