U-Shaped Bus Bar Current Sensor for MR Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional current sensors face issues with degraded linearity of detected resistance values due to the properties of magnetoresistive elements and their arrangement relative to the current passage.
Innovation Solution
A current sensor design featuring a U-shaped bus bar with symmetrical bent portions and strategically positioned magnetoresistive effect elements, forming a bridge circuit with specific magnetization directions to enhance linearity, and housed in a semiconductor package for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistive effect elements are arranged relative to the current passage, then current detection is enabled, but linearity of detected resistance values degrades
Solution Approach 1:
The current sensor divides the detection function into four separate magnetoresistive effect elements arranged in a bridge circuit configuration. Each element detects the magnetic field at different positions around the bus bar, allowing the system to compensate for non-linearities by combining the readings through the bridge circuit, thereby improving overall linearity and measurement accuracy.
Solution Approach 2:
The bus bar is designed with symmetrical bent portions that create asymmetrical magnetic field distributions around the current passage. The magnetoresistive elements are positioned to exploit this asymmetry, with their magnetization directions specifically oriented to cancel out non-linear effects. The bridge circuit is configured with unequal arm lengths to optimize the linearity compensation.
2Measurement precision
If magnetoresistive effect elements are positioned to detect current, then current detection capability is achieved, but linearity errors increase
Solution Approach 1:
The patent combines four magnetoresistive effect elements into a single bridge circuit configuration, merging their individual detection functions into a unified measurement system. The bridge circuit integrates the outputs of all four elements, allowing them to work together to compensate for non-linearities while maintaining a relatively simple overall structure. This merging approach improves linearity without proportionally increasing device 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 design achieves good linearity of output values with respect to input current, reducing linearity errors and enhancing measurement accuracy.
Implementation Method 1
a current sensor is known that is interposed in the current passage to detect the current value of the current. The current sensor may include a current passage, which may be bent in a U-shape, for example, and detects an induced magnetic field generated by the current flowing through the current passage by using a magnetoresistive effect element
Implementation Method 2
an application portion configured to apply a bias magnetic field to the free layer of each of the first to fourth detection elements
Data Source
AI summary
A current sensor includes: a bus bar; magnetoresistive effect elements (MR elements) that are disposed in pairs over a corresponding one of bent portions of the bus bar that are symmetrical; and an application portion that applies a bias magnetic field to each MR element, and when the MR elements form a bridge circuit, magnetization directions of fixed layers of the two MR elements are perpendicular to the center line of the bus bar and opposite to each other, and magnetization directions of the fixed layers are perpendicular to the center line and opposite to each other, and in a state in which the bus bar is not energized and the bias magnetic field is applied, magnetization directions of the free layers are parallel to the center line and in the same direction, and magnetization directions of the free layers of the other two MR elements are opposite.