Asymmetrical Amplifier Circuit for Sensor Fault Detection in Power Steering
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Solution Overview
Problem
Existing sensor systems in electric power steering apparatuses face challenges in detecting short-circuit faults between signal lines, which can lead to inaccurate torque detection and motor control, affecting the reliability and performance of the system.
Innovation Solution
A sensor fault detection circuit is implemented using a first and second amplifier circuit with asymmetrical characteristics, amplifying different sensor signals and detecting abnormalities based on the difference between these signals, allowing for the detection of short-circuit faults between signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sensors are used with multiplexing technology to improve reliability and detect faults, then sensor reliability is improved, but the ability to detect short-circuit faults between signal lines deteriorates
Solution Approach 1:
The patent applies asymmetry by configuring the first and second amplifier circuits with different gain values. The first amplifier circuit has a first gain value while the second amplifier circuit has a second gain value that is different from the first. This asymmetric configuration creates distinct output characteristics that enable the detection of short-circuit faults between signal lines, resolving the contradiction between using multiplexing for reliability and maintaining fault detectability
2Ease of manufacture
If amplifier circuits with identical characteristics are used, then circuit design is simplified, but fault detection capability deteriorates
Solution Approach 1:
The patent deliberately introduces asymmetry between the first and second amplifier circuits by setting different gain values. This asymmetric design sacrifices some design simplicity but enables precise detection of short-circuit faults by creating distinguishable output signals that reflect the actual sensor states rather than identical masked signals
Data Source
AI summary
A sensor fault detection circuit includes: a first amplifier circuit that includes a first pair of elements operating reversely to each other, and amplifies a first sensor signal input from a first voltage amplifier; a second amplifier circuit that includes a second pair of elements operating reversely to each other, and amplifies a second sensor signal input from the second voltage amplifier; and a fault diagnosis unit that detects abnormality of a first voltage signal or a second voltage signal based on the first voltage signal output from the first amplifier circuit and the second voltage signal output from the second amplifier circuit. Characteristics of the first pair of elements are asymmetrical to each other, and characteristics of the second pair of elements are asymmetrical to each other in a same relationship with a relationship of the asymmetry between the characteristics of the first pair of elements.