One-Piece Busbar Geometry for Precise High-Current Measurement

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Solution Overview

Problem

Existing current measurement technologies face challenges in achieving precise and cost-effective measurement of high currents due to phase errors, material transitions, and interference from external magnetic fields, particularly in AC current measurements.

Innovation Solution

A busbar design with a current shadow geometry and integrated temperature compensation, featuring a resistor section with current-free measuring contacts and optimized lead routing to minimize interference and ensure accurate voltage measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional current measuring device (clamp meter, current transformer, or shunt) is used, then current measurement is achieved, but the device is bulky, expensive, and/or requires disassembling electrical equipment

Engineering Contradiction:
Improvedevice size and installation complexityVSAvoidcurrent measurement capability
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The busbar serves dual functions: it acts as both the current-carrying conductor and the measurement sensor. The measuring element is integrated directly into the busbar structure, allowing the same component to perform both power transmission and current sensing without requiring separate measurement devices

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The measurement function is merged with the power conductor by embedding the measuring element (such as a strain gauge or piezoelectric sensor) directly into the busbar structure. This integration eliminates the need for separate clamp meters, current transformers, or shunts, thereby reducing device complexity while maintaining measurement capability

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If a measuring element is integrated into the busbar, then device size is reduced and installation is simplified, but the busbar structure becomes more complex

Engineering Contradiction:
Improveinstallation easeVSAvoidbusbar structure complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The busbar is divided into distinct functional segments: current-carrying sections and measurement sections. The measuring element is integrated into specific locations where it can sense current without interfering with the overall busbar assembly, allowing for modular manufacturing and installation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The measuring element is integrated only at specific locations on the busbar where current measurement is required, rather than throughout the entire structure. This localized integration minimizes the impact on overall busbar design while providing necessary measurement functionality

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

The design achieves high measurement accuracy and cost-effectiveness by minimizing phase errors and material transitions, allowing precise current measurement across a wide range of frequencies and temperatures.

Implementation Method 1

the measuring element (13) is adapted to detect current flowing through the busbar (10) by means of a physical quantity, in particular temperature, force or voltage

Methodology Applied
Scientific EffectTemperature measurement:

Implementation Method 2

the measuring element (13) is adapted to detect current flowing through the busbar (10) by means of a physical quantity, in particular temperature, force or voltage

Methodology Applied
Scientific EffectForce measurement:

Implementation Method 3

the measuring element (13) is adapted to detect current flowing through the busbar (10) by means of a physical quantity, in particular temperature, force or voltage

Methodology Applied
Scientific EffectVoltage measurement:

Data Source

PatentEP4359805B1Busbar for measuring a direct and/or alternating current
Publication Date: 2026.04.15 SMA SOLAR TECH AG
  • EP4359805B1 patent drawingFigure 1a~1c
  • EP4359805B1 patent drawingFigure 2a~2b
  • EP4359805B1 patent drawingFigure 3a~3b

AI summary

A busbar (11, 14) for measuring a direct and/or alternating current, in particular with current intensities of greater than 100 amperes, has connection regions (11a) and at least one resistance region (11b) which is arranged between the connection regions (11a) and has two measuring contacts (12) arranged in the resistance region (11b), wherein the busbar (11, 14) has a geometry in which the regions of the measuring contacts (12) are substantially deenergized during operation of the busbar (11, 14), wherein the busbar (11, 14) is formed in one piece. An apparatus (10) for determining current and having such a busbar (11, 14) and a power converter having such an apparatus are also disclosed.