Current Sensor Malfunction Detection via Addition Difference Correlation
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Solution Overview
Problem
Current non-contact current sensors face challenges in accurately determining malfunctions due to the influence of external magnetic fields, which can mask malfunction signals, leading to improper determination in safety-critical applications like motor drive technologies for electric and hybrid cars.
Innovation Solution
A current sensor system comprising two current sensor units with similar sensitivity, a computation unit to calculate addition and difference values, and a determination processing unit that uses correlation analysis between these values to accurately detect malfunctions, reducing the impact of external magnetic fields by identifying correlations between addition and difference values over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If malfunction determination is performed using the sum of output values from two sensors, then malfunction detection capability is improved, but the determination accuracy deteriorates under the influence of adscititious magnetic fields
Solution Approach 1:
The patent divides the malfunction determination process into two independent evaluation dimensions: sum of output values and difference of output values. By segmenting the determination criteria, the system can evaluate different aspects of sensor performance separately, allowing the sum to detect malfunctions while the difference filters out common-mode magnetic field interference.
Solution Approach 2:
The difference value between the two sensor outputs acts as an intermediary that mediates the effect of adscititious magnetic fields. Since both sensors are equally influenced by external magnetic fields, the difference value cancels out this common interference, providing a clean reference for accurate malfunction determination.
2Difficulty of detecting and measuring
If the sum of output values is used for malfunction determination, then malfunction detection is enabled, but external magnetic field interference masks malfunction signals
Solution Approach 1:
The patent converts the harmful effect of adscititious magnetic fields into a beneficial feature by using the difference value. Since external magnetic fields affect both sensors equally, their difference automatically eliminates this interference, transforming what was previously a masking factor into a filtering mechanism that enhances malfunction detection accuracy.
Solution Approach 2:
The system changes the evaluation parameter from a single sum value to a combination of sum and difference values. This parameter transformation allows the system to maintain sensitivity to malfunction signals in the sum while using the difference parameter to reject magnetic field interference, effectively separating signal from noise.
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 high-accuracy malfunction detection even under the influence of external magnetic fields, allowing for prompt and reliable determination with minimal storage capacity requirements, improving safety in vehicle-mounted devices.
Implementation Method 1
current sensor units configured to output signals in response to an induction field generated by a target current to be measured which flows through a current wire
Data Source
AI summary
There is provided a current sensor capable of performing malfunction determination with high accuracy even under the influence of an adscititious magnetic field. A current sensor includes first and second current sensor units, a computation unit, a storage unit, and a determination processing unit. The first current sensor unit measures a target current. The first and second current sensor units have almost the same sensitivity. The computation unit calculates and outputs an addition value and a difference value of outputs of the first and second current sensor units. In the storage unit, the addition and difference values output from the computation unit are stored. The determination processing unit determines whether a malfunction has occurred by using the addition and difference values stored in the storage unit. The determination processing unit determines that a malfunction has occurred, in a case where there is a correlation between the addition and difference values.