Silicon Photovoltaic Cell Scanning Eddy Current Thermography Detection

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Solution Overview

Problem

Existing silicon photovoltaic cell defect detection methods are inefficient, with low manual detection speed, high error rates, and limited detection capacity, failing to accurately classify defects such as cracks and scratches in a non-destructive and scalable manner.

Innovation Solution

A dynamic scanning eddy current thermography platform using a thermal imager and inductive heating module, combined with convolutional neural networks, to classify defects in real-time, enabling fast and accurate detection and sorting of silicon photovoltaic cells with defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual detection method is used, then detection flexibility is maintained, but detection speed is low and error rate is high

Engineering Contradiction:
Improvedetection speedVSAvoiddetection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces manual mechanical detection with an automated eddy current thermography system. The system uses an electromagnetic induction coil to generate eddy currents in the photovoltaic cell, a thermal imager to capture temperature distribution, and a computer to analyze thermal images and classify defects automatically, eliminating manual intervention and achieving both high speed and high accuracy

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces thermal imaging as an intermediary measurement method. Instead of direct visual inspection, the system uses thermal radiation detection to indirectly observe defects through temperature distribution patterns, enabling non-contact, high-speed, and accurate defect detection

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If static eddy current thermography detection is used, then equipment complexity is reduced, but detection speed is low

Engineering Contradiction:
Improvedetection speedVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent transitions from static to dynamic eddy current thermography detection. The system continuously moves the electromagnetic induction coil along the photovoltaic cell surface while the thermal imager continuously captures thermal images, enabling real-time dynamic detection at high speed

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements continuous detection by maintaining uninterrupted eddy current heating and thermal imaging throughout the scanning process. The electromagnetic induction coil continuously generates eddy currents while the thermal imager continuously records temperature fields, ensuring no detection gaps and maximizing detection speed

Inventive Principle:
Principle #20Continuity of useful action

3Manufacturing precision

If conventional heating method is used, then equipment complexity is reduced, but heating uniformity is poor leading to poor defect detection effect

Engineering Contradiction:
Improvedefect detection qualityVSAvoidheating system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses electromagnetic induction heating instead of conventional contact heating. By adjusting electromagnetic field parameters (frequency, amplitude) and coil positioning, the system achieves uniform heating across the photovoltaic cell surface, creating optimal thermal contrast for defect detection

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The electromagnetic induction heating operates through periodic alternating current in the induction coil, creating cyclic eddy currents that generate uniform heat distribution in the photovoltaic cell material, improving thermal field homogeneity for better defect detection

Inventive Principle:
Principle #19Periodic action

4Measurement precision

If small-scale detection is performed, then detection quality is maintained, but detection throughput is limited

Engineering Contradiction:
Improvedetection accuracyVSAvoiddetection throughput
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent creates a universal detection system that maintains high detection accuracy while handling large numbers of photovoltaic cells. The automated system with standardized procedures and algorithms can process cells of various sizes and defect types without sacrificing quality, enabling both high throughput and high accuracy

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

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 solution enhances detection speed, reduces error rates, and enables large-scale defect classification, transforming manual detection into automated infrared machine vision, improving the efficiency and reliability of silicon photovoltaic cell manufacturing processes.

Implementation Method 1

an inductive sensing heating module that inductively heats a silicon photovoltaic cell through electromagnetic induction

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

scanning eddy current thermography detection platform

Methodology Applied
Scientific EffectEddy current heating: Eddy Currents

Implementation Method 3

a thermal imager disposed above the silicon photovoltaic cell on the main displacement platform to capture surface thermal radiation information of the plurality of silicon photovoltaic cells in real time

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS11218112B2Silicon photovoltaic cell scanning eddy current thermography detection platform and defect classification method
Publication Date: 2022.01.04 WUHAN UNIV
  • US11218112B2 patent drawing
  • US11218112B2 patent drawing
  • US11218112B2 patent drawing

AI summary

The disclosure provides a silicon photovoltaic cell scanning eddy current thermography detection platform and a defect classification method. The technical solution adopted by the disclosure is: firstly, fixing the position of the electromagnetic inductive coil and the thermal imager, and using the main conveyor belt to carry the silicon photovoltaic cell to move forward on the production line to form a scanning eddy current heating of the silicon photovoltaic cell. Secondly, the defect temperature information is obtained through the thermal imager in terms of thermal image sequences. Thirdly, the feature extraction algorithms are used to extract the silicon photovoltaic cell defect features. Finally, the image classification algorithms are used to classify the silicon photovoltaic cell defects, and the sorting conveyor belts are used to realize the automatic sorting of silicon photovoltaic cells with different types of defects on the production line.