Motor Speed Sensor Monitoring via Common Reference Conversion
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Solution Overview
Problem
Conventional methods for monitoring the failsafe operation of sensors used to determine the rotational speed of an electric motor face challenges due to the sensors operating in different reference systems, making it difficult to compare and detect faults effectively.
Innovation Solution
A method that transforms the input information from two different sensors into an abstracted and identical value system by forming products of current count values and maximum count values from each sensor, allowing for direct comparison and fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two sensors operating in different reference systems are used for rotational speed monitoring, then measurement coverage and redundancy are improved, but the complexity of comparing and detecting faults between sensors increases
Solution Approach 1:
The patent transforms the output signals from different sensor reference systems into a common reference system by applying transformation parameters (such as gear ratios, pulse frequencies, or scaling factors). This allows sensors with different characteristics (e.g., incremental encoders with 100 strokes/rotation vs. Hall sensors with 6 segments/rotation) to be compared directly, resolving the contradiction between using diverse sensors for reliability and the complexity of comparing them.
2Measurement precision
If a mathematical model of the motor is used to monitor rotational speed, then fault detection capability is improved, but the computational complexity and programming effort increase
Solution Approach 1:
The patent introduces an intermediary transformation layer that converts sensor outputs into a common reference system before comparison. This intermediary step simplifies the monitoring algorithm by eliminating the need for complex mathematical models, as the transformed signals can be directly compared using simple equality checks or threshold evaluations, thereby reducing computational complexity while maintaining fault detection precision.
3Adaptability or versatility
If sensors with different resolutions and reference systems are integrated, then system versatility is improved, but the difficulty of synchronizing and comparing sensor outputs increases
Solution Approach 1:
The patent applies parameter transformation to normalize the outputs of sensors with different resolutions and reference systems. By multiplying sensor outputs by appropriate transformation parameters (e.g., converting Hall sensor segments to equivalent encoder pulses), the system achieves direct comparability of sensor signals, resolving the synchronization and comparison difficulties while maintaining the versatility of using diverse sensor types.
Data Source
AI summary
A system and method for redundantly monitoring faultless functioning of first and second rotational speed sensors on an electric motor, where the rotational speed is to precisely determine and monitor a rotor position, where a first product is formed from a first current count of the first output signal of the first sensor and a maximum count of the second output signal, a second product is formed from a second current count of the second output signal of the second sensor and a maximum count of the first output signal, the two products are cyclically checked for equality and, in when the check is negative, an error message is generated, where the method provides the position of both sensors in a common values system and the positions can be directly compared with one another such that precise determination and monitoring of the rotor position becomes possible.