Current-Sensing Resistor Interference Reduction via Merged Lead Routing
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Solution Overview
Problem
Existing current measuring resistors suffer from thermal and mechanical coupling with the measuring circuit, leading to unsatisfactory sensitivity to interference radiation due to a large conductor loop area between voltage taps and the circuit board.
Innovation Solution
The design incorporates flexible printed circuit board measuring lines that are connected to the resistor over part of their length, forming a small conductor loop area by routing inwardly to a connection point and then outwardly in a common cable harness, with voltage taps arranged directly on the edge between connection parts and the resistance element to minimize interference sensitivity and thermal coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring leads are routed outwards in opposite directions to the current flow direction on opposite sides of the circuit board, then the voltage drop can be measured, but the conductor loop area becomes large leading to high interference sensitivity
Solution Approach 1:
The patent transitions from routing measuring leads in opposite directions on opposite sides of the circuit board (2D plane routing) to routing both leads in the same direction on the same side of the circuit board (changing the routing dimension and configuration). This dimensional change in lead arrangement reduces the enclosed conductor loop area, thereby reducing interference sensitivity while maintaining measurement capability
Solution Approach 2:
The patent merges the routing paths of the two measuring leads by directing them in the same direction along the same side of the circuit board, rather than separating them in opposite directions. This merging of lead paths minimizes the conductor loop area enclosed by the leads, reducing the antenna effect and interference sensitivity
2Device complexity
If the measuring circuit is mounted directly on the current-sensing resistor, then the assembly is compact, but mechanical and thermal coupling between the resistor and measuring circuit occurs
Solution Approach 1:
The patent segments the measuring circuit from the current-sensing resistor by mounting the measuring circuit on a separate circuit board rather than directly on the resistor. This spatial segmentation prevents direct thermal and mechanical coupling between the two components, allowing independent thermal management and reducing measurement errors caused by heat transfer
Solution Approach 2:
The patent introduces a circuit board as an intermediary component between the current-sensing resistor and the measuring circuit. This intermediary provides electrical connection while maintaining thermal and mechanical separation, acting as a buffer that prevents direct coupling between the heat-generating resistor and the sensitive measuring circuit
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 significantly reduces the area of the conductor loop, making the resistor less sensitive to interference radiation and improving measurement accuracy by minimizing thermal and mechanical coupling.
Implementation Method 1
the voltage drop across the low-resistance resistive element, according to Ohm's law, provides a measure of the electric current
Data Source
Figure 1
Figure 1A
Figure 2~3
AI summary
The invention relates to a resistor (1), in particular a current-sensing resistor for measuring an electric current, with two terminals (2, 3) for introducing and removing the electric current (I), a low-resistance resistive element (4) electrically arranged between the terminals (2, 3) so that the electric current (I) flows through the resistive element (4), and with two voltage taps (5, 6) for measuring the voltage drop across the resistive element (4) and two measuring leads (7, 8) for connecting the voltage taps (5, 6) to a measuring circuit. It is proposed that the two measuring leads (7, 8) are each initially routed inwards from the outer voltage taps (5, 6) to a connection point (10), and that the two measuring leads (7, 8) are routed outwards from the connection point (10) in a common cable (11). This reduces the sensitivity to interference radiation.