Laminated Bus Bar Layout for Lightweight Current Sensing

Solution Overview

Problem

Current sensors face challenges in achieving weight reduction and cost reduction while maintaining high sensing precision and frequency characteristics, particularly in applications like electric cars and hybrid vehicles.

Innovation Solution

The bus bar is formed from a laminate material composed of two different metal materials, where the first metal material has a higher density and lower electrical resistivity than the second, with the magnetic detection unit facing the surface of the bus bar formed from the first material, allowing for heat generation suppression and weight reduction while maintaining high frequency characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a bus bar is made from a single superior electrical conductor (copper or aluminum), then the electrical conductivity is high, but the weight and cost increase

Engineering Contradiction:

Improveheat generationVSAvoidbus bar weight

Core Design Contradiction:

Loss of energyVSWeight of moving object

Solution Approach 1:

The bus bar is constructed by laminating multiple metal materials with different properties (such as copper and aluminum). This composite structure allows the bus bar to achieve a balance between electrical conductivity (low heat generation) and weight reduction, as each layer contributes its advantageous properties to the overall structure.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different portions of the bus bar cross-section are made from different metal materials based on their local functional requirements. The high-conductivity material is positioned where current density is highest, while lighter materials are used in regions where weight reduction is prioritized, optimizing both electrical performance and weight characteristics.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If a bus bar is made from a single superior electrical conductor, then the electrical conductivity is high, but the cost increases

Engineering Contradiction:

Improveheat generationVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The bus bar is constructed by laminating multiple metal materials with different properties (such as copper and aluminum). This composite structure allows the bus bar to achieve a balance between electrical conductivity (low heat generation) and weight reduction, as each layer contributes its advantageous properties to the overall structure.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different portions of the bus bar cross-section are made from different metal materials based on their local functional requirements. The high-conductivity material is positioned where current density is highest, while lighter materials are used in regions where weight reduction is prioritized, optimizing both electrical performance and weight characteristics.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If the magnetic detection unit faces the surface formed from the first metal material (higher density, lower resistivity), then heat generation is suppressed, but the weight increases compared to using only the second material

Engineering Contradiction:

Improveheat generationVSAvoidbus bar weight

Core Design Contradiction:

Loss of energyVSWeight of moving object

Solution Approach 1:

The bus bar is constructed by laminating multiple metal materials with different properties (such as copper and aluminum). This composite structure allows the bus bar to achieve a balance between electrical conductivity (low heat generation) and weight reduction, as each layer contributes its advantageous properties to the overall structure.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different portions of the bus bar cross-section are made from different metal materials based on their local functional requirements. The high-conductivity material is positioned where current density is highest, while lighter materials are used in regions where weight reduction is prioritized, optimizing both electrical performance and weight characteristics.

Inventive Principle:

Principle #3Local quality

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 structure achieves a balance between reducing heat generation and weight of the bus bar, enhancing sensing precision and frequency characteristics, particularly in multi-phase current sensors.

Implementation Method 1

a magnetic detection unit placed so as to face the bus bar, the magnetic detection unit sensing a magnetic field generated around the bus bar

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Data Source

PatentEP4657081A1Electric current sensor

Publication Date: 2025.12.03 ALPS ALPINE CO LTD

Figure 1A~1B
Figure 2~3
Figure 4~5

AI summary

A current sensor 10, which has a bus bar effective in achieving a low cost and weight reduction, according to the present invention has a bus bar 1 in which a current under measurement flows as well as a magnetic detection unit 2 placed so as to face the bus bar 1, the magnetic detection unit 2 sensing a magnetic field generated around the bus bar 1. The bus bar 1 is formed from a laminate material in which a first metal material 3 and a second metal material 4, which are different types of metal materials, are laminated. The density of the first metal material 3 is larger than that of the second metal material 4. The electrical resistivity of the first metal material 3 is smaller than that of the second metal material 4. The magnetic detection unit 2 is placed so as to face a surface 3S of the bus bar 1, the surface 3S being formed from the first metal material 3.