Current Sensor Magnetic Field Cancellation
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Solution Overview
Problem
Current sensors using magnetic sensors like GMR elements face challenges in suppressing the influence of induction magnetic fields from adjacent currents, leading to reduced measurement accuracy, especially when the sensitivity in directions perpendicular to the main sensitivity axis is significant.
Innovation Solution
The use of two magnetic sensors with sub-sensitivity axes oriented in specific directions relative to each other and the induction magnetic fields, allowing for the cancellation of induction magnetic field influences through arithmetic operations such as subtraction or addition, to reduce the impact on current measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is used to detect current in a non-contact manner, then current measurement capability is improved, but measurement accuracy is reduced due to induction magnetic fields from adjacent currents
Solution Approach 1:
The current sensor is divided into multiple magnetic sensors (first and second magnetic sensors) with different sensitivity axis orientations. Each sensor detects magnetic fields from different directions, allowing the system to separate the desired current signal from interfering induction magnetic fields through directional segmentation.
Solution Approach 2:
The patent introduces directional dimensionality by orienting magnetic sensors along different axes (main sensitivity axis and sub-sensitivity axis). This multi-dimensional detection approach enables the system to distinguish between magnetic fields originating from the target current versus adjacent currents based on their different spatial orientations.
2Object-affected harmful factors
If the sub-sensitivity axis direction is aligned with the induction magnetic field from adjacent current, then the influence of adjacent current is maximized, but this provides an opportunity for cancellation through differential measurement
Solution Approach 1:
The patent deliberately orients the sub-sensitivity axes of the magnetic sensors to align with the expected direction of induction magnetic fields from adjacent currents. This preliminary positioning allows the system to detect these interfering fields and cancel them out through differential arithmetic operations before they can significantly degrade measurement accuracy.
Solution Approach 2:
The patent converts the harmful effect of adjacent current induction magnetic fields into a useful signal by deliberately detecting them with specifically oriented sensors. The interference signal is then subtracted from the total measurement, transforming what would be pure noise into a correctable component that improves overall measurement accuracy.
3Measurement precision
If multiple magnetic sensors with different orientations are used, then the ability to cancel induction magnetic field influence is improved, but device complexity increases
Solution Approach 1:
Each magnetic sensor is assigned a specific local function based on its orientation: the main sensitivity axis detects the primary current signal while the sub-sensitivity axis detects induction magnetic fields from adjacent currents. This localized functional differentiation allows the system to process complex multi-directional magnetic field information through relatively simple arithmetic operations.
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
This configuration effectively suppresses the reduction in current measurement accuracy by minimizing the influence of induction magnetic fields from adjacent currents, enhancing the overall measurement precision and allowing for potential miniaturization of the current sensor system.
Implementation Method 1
first magnetic sensor and a second magnetic sensor that are disposed around a current line through which a current to be measured flows and detect an induction magnetic field from a current flowing through the current line
Implementation Method 2
As a magnetic sensor used for the above-mentioned current sensor, a giant magneto resistance (GMR) element, a Hall element, or the like is used
Implementation Method 3
As a magnetic sensor used for the above-mentioned current sensor, a giant magneto resistance (GMR) element, a Hall element, or the like is used
Data Source
AI summary
A first magnetic sensor and a second magnetic sensor are disposed so that the main sensitivity axis direction of the first magnetic sensor is oriented in the direction of an induction magnetic field from a current flowing through a current line, the main sensitivity axis direction of the second magnetic sensor is oriented in a direction opposite to the direction of an induction magnetic field from the current flowing therethrough, the individual main sensitivity axis directions of the first and second magnetic sensors are oriented in a same direction, and the individual sub-sensitivity axis directions of the first and second magnetic sensors are oriented in the same directions as or directions opposite to the directions of the sub-sensitivity axis components of the induction magnetic fields to which the first and second magnetic sensors are individually subjected from a current flowing through an adjacent current line adjacent to the current line.