Compact Current Measurement Device with Magnetic Shielding
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Solution Overview
Problem
Existing current measurement devices face challenges in accurately measuring currents in a non-contact manner, especially when affected by external magnetic fields, and often require significant space for installation.
Innovation Solution
A compact current measurement device that includes a first sensor to detect direct current and low-frequency alternating current magnetic fields, a hollow magnetic shielding member with a cutout for the measurement target conductor, a fixing mechanism to maintain a predetermined distance between the sensor and the conductor, and calculators to compute the current based on the sensor's detection results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic core with windings is provided around the measurement target conductor to measure current, then current measurement capability is achieved, but the device size becomes large and installation space is increased
Solution Approach 1:
The patent extracts the measurement function from a traditional magnetic core structure and implements it using a compact sensor head with magnetic sensors arranged around a measurement target conductor. The sensor head measures the magnetic field generated by the conductor without requiring a large magnetic core, thereby achieving accurate current measurement in a compact form factor.
Solution Approach 2:
The patent employs a nested structure where the measurement target conductor is inserted through a hollow cylindrical member, and magnetic sensors are arranged around it. This nested configuration allows the sensors to be positioned close to the conductor for accurate measurement while maintaining a compact overall device structure that can be installed in limited spaces.
2Measurement precision
If magnetic sensors are disposed at different distances from the measurement target conductor to calculate distance and current, then current measurement capability is achieved, but the device structure becomes complex and installation space is increased
Solution Approach 1:
The patent positions magnetic sensors at specific locations around the measurement target conductor within the sensor head. By optimizing the local arrangement of sensors at predetermined distances, the system achieves accurate current measurement without requiring complex structures with sensors at multiple varying distances, thus simplifying the overall device design.
3Ease of operation
If measurement is performed in a non-contact manner, then measurement simplicity and efficiency are improved, but measurement accuracy deteriorates due to external magnetic field interference
Solution Approach 1:
The patent converts the challenge of external magnetic field interference into a benefit by using magnetic shielding members that selectively block external magnetic fields while allowing the measurement of the magnetic field generated by the measurement target conductor. This enables accurate non-contact current measurement by eliminating the harmful effect of external magnetic fields.
Solution Approach 2:
The patent introduces magnetic shielding members as intermediaries between the magnetic sensors and the external environment. These shielding members filter out external magnetic field interference while permitting the passage of the magnetic field signal from the measurement target conductor, thereby enabling accurate non-contact measurement.
4Volume of stationary object
If a compact device structure is implemented, then installation in limited spaces is enabled, but measurement accuracy may deteriorate due to reduced sensor-to-conductor distance control
Solution Approach 1:
The patent incorporates a fixing mechanism that preliminarily positions the measurement target conductor at a predetermined distance from the magnetic sensors within the sensor head. This preliminary positioning ensures consistent and accurate measurement conditions are established before the actual current measurement takes place, maintaining measurement precision in the compact device structure.
Solution Approach 2:
The patent optimizes the parameters of the sensor head design, including the arrangement and positioning of magnetic sensors relative to the measurement target conductor. By carefully adjusting these parameters within the compact structure, the system achieves accurate current measurement while maintaining a small device size suitable for installation in limited spaces.
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
Enables accurate non-contact measurement of currents flowing through a measurement target conductor with high precision, while being compact enough for installation in limited spaces.
Implementation Method 1
a first sensor (SE1) configured to detect a direct current magnetic field and a low-frequency alternating current magnetic field generated by the current flowing through the measurement target conductor
Implementation Method 2
a hollow magnetic shielding member (12) that comprises a cutout portion (CP2) into which the measurement target conductor is inserted and in which the first sensor is accommodated
Implementation Method 3
a fixing mechanism (13) configured to fix the measurement target conductor such that a distance between a center of the measurement target conductor inserted into the cutout portion of the magnetic shielding member and the first sensor is a predetermined reference distance (r)
Implementation Method 4
a first calculator (21) configured to calculate a current flowing through the measurement target conductor based on a detection result of the first sensor
Data Source
AI summary
A current measurement device (1 to 3) includes a first sensor (SE1) configured to detect a direct current magnetic field and a low-frequency alternating current magnetic field generated by a current (I) flowing through a measurement target conductor (MC), a hollow magnetic shielding member (12) that includes a cutout portion (CP2) into which the measurement target conductor is inserted and in which the first sensor is accommodated, a fixing mechanism (13) configured to fix the measurement target conductor such that a distance between a center of the measurement target conductor inserted into the cutout portion of the magnetic shielding member and the first sensor is a predetermined reference distance (r), and a first calculator (21) configured to calculate a current flowing through the measurement target conductor based on a detection result of the first sensor.