Rotation Angle Detection Device Abnormal Signal Identification
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Solution Overview
Problem
Conventional rotation angle detection devices cannot specify which output signal is abnormal and fail to detect the rotation angle if one of the cosine or sine signals is lost, limiting their ability to operate persistently in the presence of partial failures.
Innovation Solution
A rotation angle detection device comprising multiple bridge circuits and a control unit that acquires and processes output signals from half bridges to determine abnormal signals and calculate the rotation angle, even in the presence of partial failures, by using at least four output signals and calculating abnormality based on predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional abnormality determination methods are used, then abnormality can be detected, but the specific abnormal signal cannot be specified and rotation angle detection fails when one signal is lost
Solution Approach 1:
The system uses the relationship between multiple output signals (sinθ, -sinθ, cosθ, -cosθ) as feedback to determine abnormality. By calculating expected values based on signal relationships and comparing with actual values, the system identifies which specific signal is abnormal while maintaining detection capability.
Solution Approach 2:
The invention transitions from single-signal abnormality detection to multi-dimensional signal relationship analysis. By utilizing the interrelationships between four output signals and performing calculations across multiple dimensions (signal combinations), the system can identify specific abnormal signals and maintain rotation angle detection even when one signal is lost.
2Productivity
If simple abnormality detection is implemented, then detection speed is maintained, but the system cannot continue operation after partial failure
Solution Approach 1:
The system performs preliminary calculations of expected signal relationships and abnormality determinations in advance. By pre-establishing the mathematical relationships between signals and preparing abnormality determination algorithms, the system can quickly identify failures and switch to backup signals without interrupting rotation angle detection, ensuring continuous operation.
Solution Approach 2:
The system dynamically changes operational parameters based on detected abnormalities. When a signal abnormality is detected, the system switches to using remaining normal signals for rotation angle calculation, changing the operational mode from using all four signals to using a reduced set, thereby maintaining continuous operation.
3Reliability
If multiple bridge circuits are used, then signal redundancy is provided, but determining which specific signal is abnormal becomes complex
Solution Approach 1:
The abnormality determination process is segmented into distinct calculation steps: calculating expected values based on signal relationships, comparing with actual values, determining abnormality, and identifying the specific abnormal signal. This segmentation simplifies the complex determination process into manageable stages that can be systematically executed.
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 the detection of rotation angles persistently and specifies abnormal signals, allowing for continued operation of electric power steering systems even when partial failures occur, thereby preventing erroneous detection and maintaining steering assist functionality.
Implementation Method 1
Each of the half bridges includes a sensor element varying an impedance thereof in response to rotating magnetic field generated by rotation of a reference part
Data Source
AI summary
Bridge circuits have half bridges formed of sensor elements, which vary respective impedances in accordance with a rotating magnetic field generated by a rotary object. A control unit acquires output signals produced from intermediate points of the half bridges, and calculates a rotation angle of the rotary object based on the output signals. The control unit determines that the output signal is abnormal, if a calculation value of the output signal calculated based on at least four output signals is outside a predetermined range. The control unit thus determines which one of the output signals has become abnormal due to failure or the like.