Magneto-resistive Current Sensor Bus Bar Module Thermal Management
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Solution Overview
Problem
Current sensor-equipped bus bar modules using Hall elements face issues with temperature rise due to heat transmission from magnetic flux concentrating cores and bus bars, leading to reduced operating life and accuracy in current measurement, especially when affected by neighboring magnetic fields.
Innovation Solution
The use of magneto-resistive elements without a magnetic flux concentrating core, positioned adjacent to bus bars and shielded by plates to prevent heat transfer and magnetic interference, allowing for accurate current measurement while minimizing temperature increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Hall element is used as the current sensor with a magnetic flux concentrating core, then the sensitivity to magnetic field is improved, but the temperature of the Hall element increases due to heat transmission from the magnetic flux concentrating core and bus bars
Solution Approach 1:
The patent removes the magnetic flux concentrating core from the system and uses a magneto-resistive element that inherently provides sufficient sensitivity without it. This extraction eliminates the source of eddy current heating and heat transmission to the sensor, resolving the temperature problem while maintaining measurement capability
Solution Approach 2:
The patent introduces a non-magnetic spacer between the bus bar and the magneto-resistive element. This intermediary prevents direct thermal contact and magnetic field interference while allowing the sensor to detect the magnetic field generated by the bus bar current, thus protecting the sensor from heat without compromising measurement accuracy
2Measurement precision
If the Hall element is disposed in contact with the bus bar to achieve compactness and high sensitivity, then the measurement capability is improved, but the resistive heat from the bus bar is transmitted to the Hall element causing temperature rise
Solution Approach 1:
The non-magnetic spacer acts as a thermal barrier between the bus bar and the magneto-resistive element. It allows magnetic field penetration for accurate current measurement while blocking direct thermal conduction, thus preventing heat transmission to the sensor without compromising measurement capability
Solution Approach 2:
By removing the magnetic flux concentrating core and using the inherent sensitivity of the magneto-resistive element, the system can maintain accurate measurement without requiring direct contact with the bus bar, thereby eliminating the heat transmission pathway
3Temperature
If a magneto-resistive element is used as the current sensor to eliminate the magnetic flux concentrating core, then the temperature rise is prevented, but the sensor is readily affected by magnetic fields from neighboring bus bars making accurate measurement difficult
Solution Approach 1:
The non-magnetic spacer serves as a magnetic field barrier that isolates the magneto-resistive element from magnetic fields generated by neighboring bus bars. This intermediary allows the sensor to detect only the magnetic field from the target bus bar while blocking interfering fields, thus maintaining measurement accuracy
Solution Approach 2:
The spacer creates a localized magnetic shielding effect around the sensor, differentiating the magnetic field environment in different regions. The area around the sensor is protected from external magnetic interference while still allowing detection of the primary bus bar field, achieving both temperature control and 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
This configuration extends the operating life of current sensors by preventing heat transfer from bus bars and magnetic flux concentrating cores, while maintaining high sensitivity to accurately measure current values by shielding magnetic fields from neighboring bus bars.
Implementation Method 1
measures the value of current in a bus bar by detecting a strength of the magnetic field which is generated around the bus bar by the flow of the current in the bus bar
Implementation Method 2
the current sensor includes a magneto-resistive element
Implementation Method 3
a shield plate which shields magnetic fields generated around the bus bars
Implementation Method 4
A Hall element may be used as the current sensor, for example. When a current flows through a bus bar, a magnetic field is generated around the bus bar. The strength of the magnetic field is ensured to be detected by means of the Hall element, and used for calculating the value of the current
Implementation Method 5
When AC current flows in a bus bar, an AC magnetic field is generated around the bus bar. As a result, eddy currents may be generated in the magnetic flux concentrating core by the AC magnetic field, so that heating may occur
Implementation Method 6
if the Hall element is disposed in contact with the bus bar, resistive heat generated from the bus bar can readily be transmitted to the Hall element
Data Source
AI summary
A bus bar module equipped with current sensors is provided. The module includes a plurality of bus bars, a current sensor, and shield plates. The current sensor is formed of a magneto-resistive element. The plurality of bus bars are arrayed along a width direction (X direction) of the bus bars that is at right angles to both the thickness direction (Z direction) and the extension direction (Y direction) of the bus bars. The current sensor is arranged being spaced apart from the bus bars, while being adjacent to the bus bars in the Z direction. The bus bars and the current sensor are covered from both sides in the Z direction, by the shield plates.