Half-Bridge Sensor Circuit Redundancy for Functional Safety
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Solution Overview
Problem
Current sensor technologies in the automotive industry face challenges in achieving high automotive safety integrity levels (ASIL) due to inadequate failure-in-time (FIT) rates, diagnostic coverage, and single point faults in position sensors like angle sensors, which require improved functional safety.
Innovation Solution
A sensor circuit with a plurality of half-bridge sensor circuits, including a sensor output value determination circuit, an error determination circuit, and a control circuit that selects between half-bridge sensor signals to ensure redundancy and replace faulty sensors, thereby improving safety and reducing costs by avoiding full-bridge sensor replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple half-bridge sensor circuits are implemented with redundancy, then functional safety and reliability are improved, but device complexity increases
Solution Approach 1:
The sensor circuit is divided into multiple independent half-bridge sensor circuits (first half-bridge sensor circuit and second half-bridge sensor circuit), each capable of providing sensor signals. This segmentation allows redundancy without requiring a complete full-bridge sensor, reducing the complexity increase while maintaining reliability improvements.
Solution Approach 2:
Instead of implementing complete redundant full-bridge sensor circuits, the patent uses partial redundancy with half-bridge circuits. The error determination circuit performs partial error detection by comparing signals from multiple half-bridge circuits, providing sufficient safety improvement without the full complexity of complete circuit redundancy.
2Ease of manufacture
If half-bridge sensor circuits are used instead of full-bridge sensors, then cost is reduced, but measurement precision may be affected
Solution Approach 1:
Multiple half-bridge sensor circuits are combined to achieve the functional equivalence and precision of full-bridge sensors. The sensor output value determination circuit processes signals from multiple half-bridge circuits and determines the final sensor output value, thereby achieving accurate measurement while using cost-effective half-bridge structures.
Solution Approach 2:
The error determination circuit continuously monitors the sensor signals from multiple half-bridge circuits and generates error signals. This feedback mechanism allows real-time detection of signal deviations and enables the system to maintain measurement precision by identifying and compensating for errors in individual half-bridge circuits.
3Reliability
If error determination circuit is added to detect faulty sensors, then diagnostic coverage is improved, but device complexity increases
Solution Approach 1:
The half-bridge sensor circuits perform self-diagnosis by comparing their own sensor signals with each other. The error determination circuit evaluates whether deviations between signals from different half-bridge circuits exceed threshold values, enabling the system to self-detect faults without requiring external diagnostic equipment or complex additional circuitry.
Solution Approach 2:
The error determination circuit provides feedback about the health status of individual half-bridge sensor circuits by generating error signals when deviations are detected. This feedback enables the control circuit to respond appropriately by selecting functional circuits or triggering safety protocols, improving diagnostic coverage with minimal additional complexity.
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 solution enhances safety and reliability by enabling the detection and replacement of faulty half-bridge sensor circuits within the sensor circuit, improving the overall functional safety and reducing costs associated with replacing full-bridge sensors.
Implementation Method 1
The sensor device includes a plurality of half-bridge sensor circuits, each including a pair of magnetoresistive structures
Data Source
AI summary
A method for forming a sensor circuit. The method includes forming a plurality of magnetoresistive structures having a first predefined reference magnetization direction in a first common area of a common semiconductor substrate; forming a plurality of magnetoresistive structures having a second predefined reference magnetization direction in a second common area of the common semiconductor substrate; and forming electrically conductive structures electrically coupling the magnetoresistive structures having the first predefined reference magnetization direction to the magnetoresistive structures having the second predefined reference magnetization direction to form a plurality of half-bridge sensor circuits, wherein each half-bridge sensor circuit comprises a magnetoresistive structure having the first predefined reference magnetization direction electrically coupled to a second magnetoresistive structure having the second predefined reference magnetization direction.