Flexible Rogowski Sensor for Narrow Clearance Current Measurement
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Solution Overview
Problem
Conventional Rogowski-type current sensors face challenges with rigid printed wiring boards causing measurement errors due to thickness deviations and damage from repeated measurements, especially when clearance is narrow, and flexible sensors are prone to magnetic flux interference.
Innovation Solution
A Rogowski-type current sensor with a belt-shaped flexible wiring board that can be bent to surround measurement targets, featuring a Rogowski coil with a specific coil pitch and deviation relationship to reduce magnetic flux interference and improve noise resistance, allowing accurate current measurement even in tight spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid printed wiring board is used for the Rogowski coil support, then manufacturing precision is improved, but flexibility and ease of mounting in narrow clearances deteriorates
Solution Approach 1:
The patent applies this principle by replacing the rigid printed wiring board with a flexible printed wiring board (FPWB). The FPWB maintains manufacturing precision through controlled thickness (0.05-0.2mm) while providing the necessary flexibility to bend and mount in narrow clearances around current paths. The flexible board can be deformed to surround the measurement target and then fixed in position, combining precision with adaptability.
2Reliability
If a thick hollow flexible member is used to protect the Rogowski coil, then reliability is improved, but ease of mounting in narrow clearances deteriorates
Solution Approach 1:
The patent replaces the thick hollow flexible member with a thin flexible printed wiring board that provides sufficient mechanical support and protection for the Rogowski coil while being thin enough to insert into narrow clearances. The FPWB's flexibility allows it to be inserted, bent around the current path, and fixed without requiring excessive clearance space.
Solution Approach 2:
The patent substitutes the mechanical hollow flexible member structure with an integrated flexible printed wiring board that combines structural support, coil mounting, and electrical connection functions. This integration eliminates the need for separate protective housings while maintaining reliability and improving ease of installation.
3Adaptability or versatility
If repeated measurements are performed with conventional flexible sensors, then adaptability is improved, but reliability deteriorates due to member damage
Solution Approach 1:
The flexible printed wiring board provides a durable yet flexible substrate that can be repeatedly bent and deformed without damage. The rigid conductive patterns on the flexible board maintain their electrical integrity through repeated bending cycles, enabling reliable repeated measurements while maintaining adaptability.
Solution Approach 2:
The flexible printed wiring board combines flexible substrate material with rigid conductive trace materials to create a composite structure that exhibits both flexibility for repeated deformation and structural integrity for durability. This composite construction allows the sensor to withstand repeated measurement cycles.
4Manufacturing precision
If the Rogowski coil is formed with conventional winding methods, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical winding process with a printing process for forming the Rogowski coil. Conductive patterns are printed directly onto the flexible printed wiring board to create the coil structure, eliminating the need for manual or automated winding operations. This maintains coil pitch consistency through controlled printing while significantly reducing manufacturing complexity.
Solution Approach 2:
The patent changes the manufacturing method from mechanical winding to printing, altering the fundamental process parameter. The coil is formed by depositing conductive material in precise patterns rather than winding wire, which simplifies the process while maintaining or improving pitch consistency through digital pattern control.
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 flexible design enables easy mounting and accurate current measurement in narrow clearances, reducing measurement errors and sensor damage, while the coil configuration minimizes magnetic flux interference for improved noise resistance.
Implementation Method 1
The Rogowski-type current sensor detects a current in a manner that a measuring portion, in which a Rogowski coil is formed, bends in an annular shape to surround a wiring as a measurement target
Data Source
AI summary
Provided are a Rogowski-type current sensor capable of being flexibly deformed and easily mounted even when a clearance is narrow, an inverter, and a method of mounting a Rogowski-type current sensor. A main body of a Rogowski-type current sensor is formed from a belt-shaped flexible wiring board. The main body includes a measuring portion in which a Rogowski coil is formed in a length direction by a conductive pattern. When measuring a current flowing through a wiring of a measurement target, the main body is mounted such that it is bent in an annular shape to surround the wiring of the measurement target, and front surfaces (first main surfaces) are overlaid with each other so as to surround the wiring of the measurement target.