Magnetic Balance Current Sensor Substrate Integration
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Solution Overview
Problem
Current magnetic-balance-system current sensors face challenges in miniaturization and sensitivity, particularly when handling large currents in electric vehicles, as they require larger magnetic cores to prevent magnetic saturation, leading to increased sensor size and a need for higher accuracy.
Innovation Solution
A magnetic-balance-system current sensor is designed with a magnetoresistive element, a feedback coil, and a magnetic-field detecting bridge circuit formed on the same substrate, utilizing a spiral feedback coil and magnetic cores disposed above and below it, which generates a cancelling magnetic field to effectively measure large currents with enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of magnetic cores is increased to prevent magnetic saturation when large currents flow, then magnetic saturation is prevented, but the size of current sensors is increased
Solution Approach 1:
The patent combines multiple functional elements (feedback coil, magnetic cores, magnetoresistive element, and bridge circuit) onto a single substrate, integrating them into a compact configuration. This merging allows the sensor to maintain high reliability for large current measurement while significantly reducing the overall sensor volume by eliminating separate mounting and interconnections.
Solution Approach 2:
The patent transitions from a traditional three-dimensional assembly of magnetic cores and coils to a planar two-dimensional integration on a substrate. By arranging the feedback coil, magnetic cores, and magnetoresistive element in a flat configuration, the sensor achieves compact size while maintaining the necessary magnetic field interaction for accurate large current measurement.
2Reliability
If the size of magnetic cores is increased to prevent magnetic saturation, then magnetic saturation is prevented, but the sensitivity of the current sensor is reduced
Solution Approach 1:
The patent employs magnetoresistive elements with high sensitivity to detect magnetic fields locally at the substrate level. By concentrating the detection function in these high-sensitivity elements positioned close to the magnetic cores, the system achieves both saturation prevention through adequate core size and high measurement precision through localized sensitive detection.
Solution Approach 2:
The integration of the magnetoresistive element directly on the substrate in close proximity to the magnetic cores enhances the magnetic coupling efficiency. This merging of detection and magnetic field generation functions in a compact configuration maintains high sensitivity even when magnetic cores are sized appropriately for saturation prevention.
3Reliability
If traditional current sensor structures are used, then magnetic saturation can be prevented with adequate core size, but the sensor cannot be miniaturized
Solution Approach 1:
The patent merges the feedback coil, magnetic cores, magnetoresistive element, and bridge circuit onto a single substrate, creating an integrated compact sensor. This consolidation maintains the magnetic balance function for saturation prevention while reducing the sensor to a minimal footprint suitable for modern electric vehicle applications.
Solution Approach 2:
The patent replaces traditional mechanical/wire-based connections with printed circuit board traces and integrated substrate mounting. This substitution enables compact routing of electrical connections between the feedback coil, magnetoresistive element, and bridge circuit, facilitating miniaturization while maintaining functional reliability.
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 allows for the miniaturization of the current sensor while maintaining high sensitivity, enabling accurate measurement of large currents by increasing the magnitude of the cancelling magnetic field and utilizing a magnetoresistive element for improved detection.
Implementation Method 1
A resistance value of the magnetoresistive element is changed by application of an induction magnetic field generated by a measurement target current
Implementation Method 2
The feedback coil is disposed in the vicinity of the magnetoresistive element, and configured to generate a cancelling magnetic field
Data Source
AI summary
A magnetic-balance-system current sensor includes: a magnetoresistive element, a resistance value of the magnetoresistive element being changed by applying an induction magnetic field generated by a measurement target current; magnetic cores disposed near the magnetoresistive element; a feedback coil disposed near the magnetoresistive element and configured to generate a cancelling magnetic field that cancels out the induction magnetic field; and a magnetic-field detecting bridge circuit having two outputs. The measurement target current is measured on the basis of a current flowing through the feedback coil when the induction magnetic field and the induction magnetic field and the cancelling magnetic field cancel each other out. The feedback coil, the magnetic cores, and the magnetic-field detecting bridge circuit are formed on a same substrate. The feedback coil is of a spiral type, and the magnetic cores are provided above and below the feedback coil.