Current-Measuring Unit with Bus Bar Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current-measuring units for vehicles with electric motors face challenges in reliably detecting high battery currents while maintaining a simple and cost-effective configuration.
Innovation Solution
A current-measuring unit comprising a printed circuit board, two bus bars with shunt contact surfaces, measuring strip conductors, and a shunt resistor connected via soldering, allowing for efficient heat dissipation and four-conductor measurement, avoiding interference and thermal overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-power shunt resistors are used to measure high battery currents, then reliable detection is achieved, but device complexity and cost increase
Solution Approach 1:
The current measurement function is segmented into multiple components: the shunt resistor for voltage measurement, the bus bars for current conduction, and the printed circuit board for signal processing. This segmentation allows each component to be optimized independently, enabling the use of lower-power shunt resistors while maintaining measurement reliability through the four-conductor configuration.
Solution Approach 2:
The bus bars serve multiple functions: they conduct the high battery current and simultaneously serve as part of the measurement circuit by providing stable reference potentials to the shunt resistor. This multi-functionality eliminates the need for separate high-power current conductors and measurement elements, reducing overall device complexity.
2Reliability
If high-power shunt resistors are used to handle high currents, then thermal overload is prevented, but manufacturing cost increases
Solution Approach 1:
The patent converts the potentially harmful thermal effect into a beneficial measurement mechanism. By using the four-conductor configuration with low-power shunt resistors, the heat generation is minimized while the bus bars efficiently conduct the high current. The measurement is performed through voltage drop across the shunt resistor rather than direct current measurement, allowing the use of cost-effective low-power components.
Solution Approach 2:
The shunt resistor acts as an intermediary element that converts the high current into a measurable voltage signal. Instead of directly measuring the high current with expensive high-power resistors, the system uses the shunt resistor to create a proportional voltage that can be measured by standard electronics, thereby reducing the power handling requirements and cost of the measurement components.
3Temperature
If bus bars are directly connected to the printed circuit board, then heat dissipation is improved, but manufacturing precision requirements increase
Solution Approach 1:
The shunt resistor is nested within the structure formed by the bus bars and printed circuit board. The bus bars are positioned to provide both mechanical support and thermal pathways, while the shunt resistor is mounted in the space between them. This nested arrangement allows efficient heat dissipation through multiple pathways (bus bars to PCB, shunt resistor to PCB) while maintaining compact dimensions and reducing alignment tolerances through the interlocking structure.
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 reliable detection of high battery currents with efficient heat dissipation, preventing thermal overload and allowing the use of low-power SMD shunt resistors, thus maintaining a cost-effective and stable configuration.
Implementation Method 1
reliably dissipate the power loss generated, in general, in the form of heat via the bus bars in such a shunt resistor
Implementation Method 2
a shunt resistor with a first contact area connected by soldering to the first bus bar and to the first measuring strip conductor and with a second contact area connected by soldering to the second bus bar
Data Source
AI summary
A current-measuring unit, especially for measuring a battery current in a vehicle, includes a printed circuit board (12) and a first bus bar (16) leading to and fixed at the printed circuit board that provides at least one first shunt contact surface (30). A second bus bar (18) leading to and fixed at the printed circuit board provides at least one second shunt contact surface (42). A first measuring strip conductor (44) is associated with the first bus bar at the printed circuit board. A second measuring strip conductor (46) is associated with the second bus bar at the printed circuit board. A shunt resistor (48) has a first contact area (50) connected by soldering to the first bus bar and to the first measuring strip conductor and has a second contact area (52) connected by soldering to the second bus bar and to the second measuring strip conductor.