AMR Current Sensor Using Magnetic Field Substitution
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Solution Overview
Problem
Existing electric current sensors face challenges in achieving high accuracy and low power consumption, particularly in small or portable devices, due to high power consumption and heat generation issues associated with shunt resistors.
Innovation Solution
The electric current sensor employs anisotropic magnetoresistor (AMR) units connected in a Wheatstone bridge configuration to sense the magnetic field generated by the electric current, allowing for high sensitivity and accuracy without direct contact with the current, thus reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt resistor is used to measure electric current by measuring voltage difference, then the electric current can be estimated, but the resistor consumes high power and generates heat
Solution Approach 1:
The patent replaces the electrical measurement system (shunt resistor) with a magnetic field sensing system using AMR units. Instead of measuring voltage drop through a resistor, the invention detects the magnetic field generated by the current-carrying conductor through anisotropic magnetoresistive sensors, thereby eliminating the need for high-power resistive elements while maintaining measurement capability
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the current-carrying conductor and the measurement system. The magnetic field serves as a mediator that transfers information about the current to the AMR sensors without requiring direct electrical contact or high-power components, thus reducing power consumption while enabling accurate current measurement
2Measurement precision
If a shunt resistor is used to measure electric current, then the current can be sensed, but high electric current generates heat causing other problems
Solution Approach 1:
The patent substitutes the thermal-based measurement approach (voltage drop across resistor) with a magnetic field-based detection approach using AMR units. This replacement eliminates the heat generation inherent in resistive measurements while preserving the ability to sense current through the magnetic field produced by the conductor
Solution Approach 2:
The patent converts the harmful effect of high current (which generates both useful magnetic field and harmful heat) into a beneficial measurement mechanism. By utilizing the magnetic field generated by the current-carrying conductor as the measurement signal for the AMR sensors, the invention transforms what is otherwise a source of heat and energy loss into a useful sensing mechanism that eliminates the need for high-power resistors
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 solution provides high sensitivity and accuracy in electric current sensing with low power consumption, making it suitable for small or portable devices by leveraging the magnetic field to derive current measurements.
Implementation Method 1
a first anisotropic magnetoresistor (AMR) unit, a second AMR unit, a third AMR unit, and a fourth AMR unit... When an electric current flows through the conductive wire, due to a magnetic field generated by the electric current, a resistance variation of the first AMR unit is opposite to a resistance variation of the second AMR unit
Data Source
AI summary
An electric current sensor includes a substrate, a conductive wire, a first anisotropic magnetoresistor (AMR) unit, a second AMR unit, a third AMR unit, a fourth AMR unit, a first magnetization direction setting device, and a second magnetization direction setting device. The conductive wire has a first conductive segment and a second conductive segment respectively disposed below a first end and a second end opposite to the first end of the substrate. The first AMR unit and the second AMR unit are disposed above the first end of the substrate. The third AMR unit and the fourth AMR unit are disposed above the second end of the substrate. The first magnetization direction setting device and the second magnetization direction setting device are configured to set magnetization directions of the AMR units.