AMR Current Sensor Using Sloped Substrate and Magnetic Field Sensing
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Solution Overview
Problem
Existing electric current sensors face challenges in achieving high accuracy, low power consumption, and small volume, especially in portable devices, due to high current consumption and heat generation issues with traditional shunt resistor methods.
Innovation Solution
An electric current sensor utilizing anisotropic magnetoresistors (AMR) units connected in a Wheatstone bridge configuration, with magnetization direction setting devices, to sense magnetic fields induced by electric currents without direct contact, thereby providing high sensitivity and accuracy while minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt resistor is used to measure electric current, then the electric current can be estimated by measuring voltage difference, but the resistor has small resistance causing high current consumption and heat generation
Solution Approach 1:
The patent replaces the electrical measurement system (shunt resistor) with a magnetic field-based sensing system using AMR units. The AMR units detect the magnetic field generated by current flow through conductive wires without direct electrical contact, substituting electrical resistance-based measurement with magnetoresistive sensing, thereby eliminating the power consumption and heat generation issues of shunt resistors
Solution Approach 2:
The patent introduces magnetic field as an intermediary between the current-carrying conductors and the sensing elements. The AMR units sense the magnetic field components generated by the current flow through the conductive wires, using the magnetic field as a non-contact mediator to transfer information about the current without requiring direct electrical connection or power dissipation
2Measurement precision
If a shunt resistor is used to measure electric current, then the voltage difference can be measured, but high electric current generates heat causing other problems
Solution Approach 1:
The patent replaces the thermal-electrical measurement system (shunt resistor converting current to voltage through resistance) with a magnetic field-based system. The AMR units convert magnetic field components into resistance changes, eliminating the Joule heating effect inherent in resistive measurement methods while maintaining measurement capability
Solution Approach 2:
The patent uses magnetic field as an intermediary that does not generate heat during the sensing process. Unlike the shunt resistor where current flow through resistance generates heat (I²R losses), the magnetic field sensing method uses the magnetic field generated by the current as the measurement medium, which does not dissipate energy as heat
3Measurement precision
If traditional current sensing methods are used, then current measurement is achieved, but the device volume is not minimized for portable applications
Solution Approach 1:
The patent utilizes the magnetic field dimension (spatial distribution of magnetic field components in three dimensions) to enable current sensing. By measuring magnetic field components in multiple directions using AMR units with different magnetization orientations, the system extracts current information from the magnetic field vector without requiring large physical dimensions, achieving compact sensor design
Solution Approach 2:
The patent changes the sensing parameter from direct electrical measurement (voltage across resistor) to magnetic field measurement (magnetic field components). This parameter change enables the use of highly sensitive AMR units that can detect very small magnetic field changes, allowing for miniaturized sensor design while maintaining measurement precision
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 enables high sensitivity and accuracy in electric current sensing with low power consumption, suitable for small and portable devices, by leveraging the magnetic field-induced resistance variations in AMR units, which are not in direct contact with the electric current.
Implementation Method 1
a first anisotropic magnetoresistor (AMR) unit, a second AMR unit... The first AMR unit is disposed on the first sloped surface, and the second AMR unit is disposed on the second sloped surface
Implementation Method 2
a first magnetization direction setting device, and a second magnetization direction setting device... The first magnetization direction setting device is configured to set a magnetization direction of the first AMR unit, and the second magnetization direction setting device is configured to set a magnetization direction of the second AMR unit
Implementation Method 3
When an electric current flows through the at least one conductive wire, a magnetic field component generated by the electric current on the first sloped surface in a third direction is opposite to a magnetic field component generated by the electric current on the second sloped surface in the third direction
Data Source
AI summary
An electric current sensor includes a substrate, a first sloped surface, a second sloped surface, at least one conductive wire, a first anisotropic magnetoresistor (AMR) unit, a second AMR unit, a first magnetization direction setting device, and a second magnetization direction setting device. The first sloped surface and the second sloped surface are disposed on the substrate and arranged in a first direction. The at least one conductive wire extends along a second direction and is disposed beside the substrate. The first AMR unit is disposed on the first sloped surface. The second AMR unit is disposed on the second sloped surface. The first magnetization direction setting device and the second magnetization direction setting device are configured to set magnetization directions of the AMR units.