Rotating Field Sensor Angle Detection Circuit Failure Handling
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Solution Overview
Problem
Existing rotating field sensors fail to accurately determine the angle of a rotating magnetic field when one of the detection circuits fails, especially in cases where the failure is subtle, such as a short-circuit or anisotropy in magnetoresistive films, leading to incorrect angle detection values.
Innovation Solution
A rotating field sensor with N detection circuits, where each circuit generates an output signal responsive to the rotating magnetic field, and a computing unit that defines multiple detection circuit groups to calculate and determine the angle value, even if one circuit fails, by identifying normal and abnormal groups based on angle value ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple detection circuits are used to improve reliability, then the system can detect failures, but the complexity of the system increases
Solution Approach 1:
The system divides the detection function into multiple independent detection circuits (first, second, third, and fourth detection circuits), each capable of independently detecting the rotating magnetic field. This segmentation allows the system to maintain reliability by having redundant circuits while managing complexity through modular design.
Solution Approach 2:
The system changes the operational parameters by selectively activating different detection circuits based on their operational status. When a failure is detected in one circuit, the system switches to using another circuit, thereby adapting the system's behavior to maintain reliability without requiring complete system redesign.
2Ease of operation
If simple failure detection methods are used, then the system is easy to operate, but subtle failures such as short-circuits or anisotropy cannot be detected
Solution Approach 1:
The system implements a feedback mechanism where the angle detection values from multiple detection circuits are continuously compared. When the angle detection values from different circuits diverge beyond a threshold, the system identifies this as a failure condition and switches to using only the reliable circuit. This feedback loop enables detection of subtle failures while maintaining ease of operation through automated decision-making.
Solution Approach 2:
The system uses a composite approach by combining multiple detection circuits with different characteristics (some oriented in different directions) to create a more robust detection system. This composite structure allows the system to detect subtle failures that would be invisible to a single circuit, improving measurement precision without significantly complicating operation.
3Measurement precision
If angle detection value is determined using arithmetic operation with output signals, then measurement precision is improved, but the system cannot handle failures in detection circuits
Solution Approach 1:
The system dynamically adjusts its angle detection method based on the operational status of detection circuits. When all circuits are functioning, the system uses arithmetic operations on signals from multiple circuits to improve precision. When a failure is detected, the system dynamically switches to using only the reliable circuit, thereby maintaining both precision and reliability under different operating conditions.
Solution Approach 2:
The system extracts and isolates the failure-affected detection circuit from the angle detection calculation process. When a failure is detected in one circuit, the system separates that circuit's output from the arithmetic operations and relies solely on the outputs from healthy circuits, thereby preventing the failure from degrading measurement precision while maintaining reliability.
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 accurate angle detection even if one detection circuit fails, by distinguishing normal from abnormal groups and correcting the angle value based on the output from functional circuits, thus ensuring reliable operation.
Implementation Method 1
A known magnetic detection element for use in a bridge circuit is a magnetoresistive (MR) element that is formed by serially connecting a plurality of MR films each of which exhibits a magnetoresistive effect
Data Source
AI summary
A rotating field sensor includes four detection circuits and a computing unit. In the computing unit, defined are four first detection circuit groups each consisting of three detection circuits. Further, defined in each first detection circuit group are three second detection circuit groups each consisting of two detection circuits. The computing unit calculates an angle value for each of all the second detection circuit groups on the basis of the output signals of the two detection circuits, extracts one or more normal first detection circuit groups each of which is such one that all three angle values corresponding to the three second detection circuit groups fall within an angle range of a predetermined breadth, and determines an angle detection value on the basis of at least one of all angle values corresponding to all second detection circuit groups belonging to the one or more normal first detection circuit groups.