Differential Hall Current Sensor for Large EV Conductors
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Solution Overview
Problem
Existing current sensors for measuring large electric currents in conductors are either physically large and difficult to install, or require bulky magnetic shields to mitigate background magnetic field interference.
Innovation Solution
A current sensor design featuring a flexible carrier with first and second hall effect sensors mounted on opposing faces of the conductor, and a differential amplifier to combine their signals and compensate for background magnetic fields, allowing for accurate current measurement without the need for magnetic flux concentrators or apertures in the conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ferrite ring flux concentrator is used to measure current, then measurement accuracy is improved, but the device becomes physically large and difficult to install
Solution Approach 1:
The sensor is divided into two separate measurement locations around the conductor, with individual hall sensors at each location. The measurements from both locations are combined through differential processing to achieve accurate current measurement without requiring a large ferrite ring structure.
Solution Approach 2:
The measurement function is extracted from a single centralized location to multiple distributed locations around the conductor. This eliminates the need for a flux concentrator ring while maintaining measurement capability through spatial distribution of sensors.
2Measurement precision
If a ferrite ring flux concentrator is used, then measurement accuracy is improved, but installation difficulty increases
Solution Approach 1:
The sensor system is segmented into two independent measurement points that can be installed separately around the conductor. This modular approach allows for easier installation compared to a single large ferrite ring structure, as the segmented components can be adapted to different conductor sizes and geometries.
Solution Approach 2:
The sensor configuration allows for flexible positioning around the conductor, adapting to different installation scenarios. The two-point measurement approach provides dynamic adaptability to various conductor arrangements, making installation easier than with a fixed ferrite ring structure.
3Device complexity
If a hall effect sensor is used without magnetic shielding, then device complexity is reduced, but sensitivity to background magnetic fields increases
Solution Approach 1:
The background magnetic field interference, which is harmful to measurement accuracy, is converted into a beneficial factor through differential measurement. By measuring at two opposite locations and subtracting the readings, the common-mode background field is rejected while the differential current signal is enhanced.
Solution Approach 2:
The measurement approach uses asymmetric positioning of two hall sensors at opposite locations around the conductor, creating a differential measurement configuration. This asymmetric arrangement allows the system to reject symmetric background fields while detecting the asymmetric current-generated magnetic field.
4Object-affected harmful factors
If an IMC-Hall current sensor with magnetic shield is used, then background field sensitivity is reduced, but device volume increases
Solution Approach 1:
The magnetic shielding function is extracted and replaced by a differential measurement configuration. Instead of using physical magnetic shields to block background fields, the system extracts the background field component through mathematical subtraction of measurements taken at opposite locations, eliminating the need for bulky shield structures.
Solution Approach 2:
The mechanical magnetic shielding approach is replaced by an electronic/differential measurement system. Rather than physically blocking magnetic fields with shield materials, the system uses signal processing and differential measurement to reject background field interference, substituting a simpler non-mechanical solution.
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 precise measurement of electric current in conductors with large cross-sectional areas, improving installation ease and reducing sensitivity to background magnetic fields, thus enhancing the accuracy and reliability of current measurement in various applications, including electric vehicles.
Implementation Method 1
separate first and second hall effect sensors or hall sensor packages or components mounted on the carrier at the opposing faces or points of or around the conductor, each hall sensor being arranged to output a signal representative of a magnetic field at the respective sensor
Data Source
AI summary
There is described an electrically powered vehicle comprising: an electrical conductor arranged to carry motive electric current for powering movement of the vehicle; and a current sensor arranged to measure the motive electric current in the electrical conductor, the current sensor comprising: a carrier extending around the conductor so as to be in confrontation with opposing faces of the electrical conductor; first and second hall sensor packages mounted on the carrier at the opposing faces of the conductor, each hall sensor package being arranged to output a signal representative of a magnetic field at the package; a differential amplifier mounted on the carrier to receive the signals from the first and second hall sensor packages and to combine the signals to provide at least one amplifier output representing the motive electrical current. The carrier may comprise a flexible PCB. There is also described a method of measuring electric current.