Inverter Temperature History Calculation for Semiconductor Life Prediction
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Solution Overview
Problem
Existing power conversion devices face challenges in accurately calculating the life of power semiconductor devices due to high computational loads and inaccuracies in heat production calculations, especially when distinguishing between powering and regenerating states.
Innovation Solution
A power conversion device that includes a motor control unit for calculating gate signals, a temperature history calculator for estimating losses, and a damage calculator to determine the life of power semiconductor devices based on temperature history data, allowing for precise life prediction and prevention of failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simultaneous calculation of temperature change estimation, thermal stress conversion, and life estimation is performed, then comprehensive life prediction is achieved, but computational load increases and calculation accuracy decreases
Solution Approach 1:
The patent divides the life prediction process into three separate calculation units: a temperature change estimation unit, a thermal stress calculation unit, and a life estimation unit. Each unit performs its specific function independently, which reduces the computational load on any single processing element while maintaining comprehensive life prediction capability through the sequential operation of all units.
2Ease of manufacture
If heat production is calculated as a function of output current only, then calculation is simplified, but accuracy decreases because effective current differs between powering and regenerating states
Solution Approach 1:
The patent applies different heat production calculation methods based on the operating state. For powering states, heat production is calculated using output current. For regenerating states, a different calculation method is used that accounts for the distinct electrical characteristics. This localized approach ensures high accuracy for each specific operating condition while maintaining reasonable calculation complexity.
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
Enables high-accuracy life calculation of power semiconductor devices, reducing the risk of unexpected failures by providing clear life specifications and enabling proactive maintenance.
Implementation Method 1
When a current flows through the power semiconductor device or interrupted, the power semiconductor device produces heat, and a temperature difference (hereinafter, referred to as ΔT) occurs between a junction and a fin
Implementation Method 2
Since a material having a different thermal expansion coefficient is generally used in the junction (the wire bonding or the junction to the copper foil pattern) of the power semiconductor device, a thermal stress is exerted to the junction, in accordance with the fluctuation of ΔT
Data Source
AI summary
Provided are a power conversion device and a remote monitoring system capable of calculating the life of a power semiconductor device with high accuracy. In order to achieve the above purpose, a power conversion device, which controls the flow or interruption of a current with an inverter having a power semiconductor device and performs desired power conversion, comprises: a motor control unit which calculates a gate signal on the basis of a current value, a speed command, and a carrier frequency detected by a current sensor and controls the inverter; a temperature history calculator which estimates the loss of the power semiconductor device and calculates a temperature history; a temperature history storage device which stores the calculation result of the temperature history; and a damage calculator which calculates damage to the power semiconductor device from the temperature history read from the temperature history storage device.