Bus Bar Sensor Assembly for Thermal-Stable Current Detection
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Solution Overview
Problem
Existing sensor units in motor systems face challenges in maintaining accurate current detection due to thermal expansion and contraction of insulating members, which can alter the relative positional relationship between current sensors and bus bars, leading to fluctuations in magnetic field transmission and decreased current detection accuracy.
Innovation Solution
A sensor unit design featuring a plurality of bus bars connected to switch modules and embedded in an insulating resin case, with magnetic-electric conversion units positioned to face the embedded bus bars and detect currents by sensing the magnetic field generated. The design includes a support body with higher rigidity than the resin case to maintain stability and prevent warping due to thermal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin case is used to connect bus bars, then ease of manufacture and insulation are improved, but rigidity and stability under thermal changes deteriorate
Solution Approach 1:
The patent employs a composite structure combining a resin case with a support body having higher rigidity. The resin case provides insulation and ease of manufacture, while the support body (made of metal or high-rigidity material) reinforces the structure to maintain stability under thermal expansion and contraction. This composite approach allows the sensor unit to benefit from both the manufacturing advantages of resin and the structural stability of rigid materials.
2Ease of manufacture
If a resin case is used to connect bus bars, then ease of manufacture and insulation are improved, but stability under thermal changes deteriorates
Solution Approach 1:
The patent employs a composite structure combining a resin case with a support body having higher rigidity. The resin case provides insulation and ease of manufacture, while the support body (made of metal or high-rigidity material) reinforces the structure to maintain stability under thermal expansion and contraction. This composite approach allows the sensor unit to benefit from both the manufacturing advantages of resin and the structural stability of rigid materials.
3Ease of operation
If the relative positional relationship between sensors and bus bars changes due to thermal expansion, then ease of operation is improved (flexibility), but measurement precision deteriorates
Solution Approach 1:
The support body is designed to preemptively counteract the effects of thermal expansion and contraction on the resin case. By providing a rigid framework that maintains the relative positions of bus bars and magnetic-electric conversion units, the support body prevents the positional changes that would otherwise occur due to thermal effects, thereby preserving measurement precision while allowing the resin case to provide its insulating and manufacturing advantages.
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 proposed sensor unit effectively suppresses decreases in current detection accuracy by maintaining the stability of the relative positional relationships between the magnetic-electric conversion units and the bus bars, even under thermal variations, thereby ensuring consistent and accurate current measurement.
Implementation Method 1
detect currents flowing through the bus bars by detecting a magnetic field generated by flow of current flowing through one of the bus bars
Data Source
AI summary
A sensor unit includes a first connection bus bar to a seventh connection bus bar connected to switch modules. The sensor unit includes a base integrally molding the first connection bus bar to the seventh connection bus bar. The sensor unit includes a plurality of magnetic-electric conversion units which detects current of the first connection bus bar to the seventh connection bus bar, respectively. The sensor unit includes a nut box connected to the base. The base and the nut box extends in the x-direction. A plurality of pillars, which are separated each other in the x-direction, are formed on the base. The nut box is fixed to the plurality of pillars by fixing bolts.