IGBT Junction Temperature Correction via Aging Database
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Solution Overview
Problem
The reliability of photovoltaic inverters is compromised due to the aging of insulated gate bipolar transistors (IGBTs), which causes junction temperature fluctuations, leading to thermal stress and potential device failure, as existing models fail to accurately account for the aging process.
Innovation Solution
A method and system for online correction of IGBT junction temperatures in photovoltaic inverters, involving the construction of an electrothermal coupling model, voltage sampling circuits, and an aging database to calibrate aging coefficients, ensuring accurate junction temperature data and real-time monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electrothermal coupling model is constructed based on factory technical manual, then the model can be established quickly, but the model becomes inaccurate due to IGBT aging during operation
Solution Approach 1:
The patent applies preliminary action by constructing an aging database before actual operation using accelerated aging tests. The database stores the relationship between collector-emitter voltage and junction temperature at different aging stages, enabling the model to adapt to aging IGBTs without real-time recalibration during operation
Solution Approach 2:
The patent changes parameters by using collector-emitter on-state voltage drop as an aging indicator parameter. By monitoring voltage changes over time, the system determines the IGBT aging stage and selects corresponding parameters from the pre-constructed aging database to correct junction temperature calculations
2Reliability
If junction temperature is monitored without considering aging, then the monitoring system is simple, but the reliability assessment becomes inaccurate
Solution Approach 1:
The patent replaces complex physical measurement mechanisms with electrical parameter monitoring. Instead of using complex thermal measurement devices, it substitutes with simple voltage drop measurements across the IGBT, which can be obtained through standard electrical testing
Solution Approach 2:
The patent creates a virtual copy of the aging process through the aging database, which stores temperature-voltage relationships at different aging stages. This allows the system to assess reliability based on electrical parameters without physically measuring temperature at each aging stage
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 approach improves the accuracy of reliability assessments by accounting for the aging process, ensuring the authenticity of junction temperature data and enhancing the online monitoring capabilities of IGBTs in photovoltaic inverters.
Implementation Method 1
an electrothermal coupling model of an IGBT model is constructed based on a photovoltaic inverter topology, the IGBT model, a light radiation intensity, and an ambient temperature
Implementation Method 2
An IGBT collector-emitter on-state voltage drop Vce_on is used as an aging parameter and a voltage sampling circuit is designed according to working characteristics of the IGBT to collect the IGBT collector-emitter on-state voltage drop
Data Source
AI summary
The invention discloses a method and a system for correction of the junction temperatures of an IGBT module in a photovoltaic inverter. The method includes: constructing an electrothermal coupling model of an IGBT model based on a photovoltaic inverter topology, a light radiation intensity, and an ambient temperature; selecting an IGBT collector-emitter on-state voltage drop as an aging parameter and designing an on-state voltage drop sampling circuit to ensure measurement accuracy; constructing an aging database for IGBT modules in different aging stages based on large current and small current injection methods; comparing a junction temperature value output by the electrothermal coupling model with the calibrated junction temperature value and calibrating an aging process coefficient of an electrothermal coupling model correction formula; comparing an IGBT aging monitoring value with the aging threshold to determine the aging process and selecting a corresponding aging process coefficient to ensure accuracy of junction temperature data.