Electric Current Sensor With Thermal Isolation and Magnetic Shielding
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Solution Overview
Problem
Current sensors face issues with increased temperature due to heat generated by busbars, leading to reduced measurement accuracy and product life, and there is a need for miniaturization without compromising performance.
Innovation Solution
A current sensor design with a magnetic detection unit separated from the busbar by a spacer portion, featuring a magnetic shield and a substrate with protruding portions for heat dissipation, and additional shields to reduce noise and protect components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the busbar current increases to meet high power demands, then the motor capacity and continuous driving capability improve, but the heat generated by the busbar increases proportionally to the square of the current, causing temperature rise in electronic components
Solution Approach 1:
The magnetic detection unit is extracted from the immediate vicinity of the busbar and mounted on a separate substrate positioned at a distance. This spatial separation removes the heat-generating component from the heat-sensitive component's environment, allowing high current operation without excessive temperature rise in the detection unit.
Solution Approach 2:
A non-magnetic spacer portion is introduced as an intermediary element between the busbar and the substrate holding the magnetic detection unit. This spacer maintains the necessary separation distance while providing mechanical support and structural stability, enabling effective heat isolation without compromising the magnetic field detection path.
2Volume of moving object
If the magnetic detection unit is placed close to the busbar for compact design, then the sensor size is reduced, but the temperature in the storage space increases beyond the heat-resistant temperature of the magnetic detection unit
Solution Approach 1:
Instead of reducing separation distance in the horizontal plane, the solution utilizes the vertical dimension by mounting the substrate with the magnetic detection unit above the busbar at a controlled height. This vertical arrangement maintains compact overall footprint while achieving effective thermal separation through the air gap and spacer structure.
3Temperature
If a heat radiating uneven portion is added to the casing to prevent temperature rise, then the measurement accuracy is maintained, but the size of the product and manufacturing cost increase
Solution Approach 1:
The heat dissipation function is extracted from the casing structure and transferred to the substrate that naturally protrudes from the casing. This protruding substrate acts as a heat sink and radiation surface without requiring additional heat radiating features molded into the casing, simplifying the overall structure while maintaining thermal management effectiveness.
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 design effectively dissipates heat, reduces temperature rise, and maintains measurement accuracy while minimizing sensor size and risk of damage, suitable for large currents.
Implementation Method 1
a magnetic detection unit configured to detect a magnetic field generated when the current to be measured flows through the busbar
Implementation Method 2
The substrate can dissipate the heat generated from the busbar due to the current to be measured from its protruding portion to the outside
Implementation Method 3
a first magnetic shield configured to reduce disturbance magnetic field noise applied to the magnetic detection unit
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A current sensor 1 according to the present invention includes a busbar 11 through which a current to be measured flows, a magnetic detection unit 12 capable of detecting a magnetic field generated when the current to be measured flows through the busbar 11, a casing 13 that holds the busbar 11, a first magnetic shield 14A capable of reducing disturbance magnetic field noise applied to the magnetic detection unit 12, a substrate 15 having the magnetic detection unit 12 on an X1 side surface of the substrate 15 in the X-axis direction, where the busbar 11, the magnetic detection unit 12, the substrate 15, and the first magnetic shield 14A are disposed in this order from the X1 side, and a spacer portion 16 between the casing 13 and the substrate 15 to separate the busbar 11 from the magnetic detection unit 12 in the X-axis direction. The substrate 15 has a protruding portion 151 protruding from the position where it is held by the spacer portion 16 in at least one of protruding directions that are the Y-axis direction and the Z-axis direction and, thus, an electronic component, such as the magnetic detection unit, is prevented from having a high temperature caused by heat generated by the busbar. The current sensor 1 is suitable for measuring a large amount of current.