Offshore Wind Converter Thermal Warning via Junction Temperature Prediction
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Solution Overview
Problem
Conventional methods for calculating junction temperature in power devices of offshore wind power converters are limited to steady-state conditions and suffer from a lag effect, leading to inefficient thermal protection and reduced utilization of the power device's physical limits.
Innovation Solution
A thermal protection and warning method based on junction temperature prediction using a Cauer thermal resistance-capacitance network model, which calculates power consumption and heat flux variations to predict the junction temperature trajectory and trigger protective measures before reaching a warning temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the conventional calculation method (TJ=TH+P·Rth) is used to determine junction temperature, then the calculation is simple and straightforward, but the method only provides steady-state temperature and suffers from lag effect during transient processes, leading to insufficient protection timing
Solution Approach 1:
The patent applies preliminary action by predicting the junction temperature trajectory in advance using a thermal network model before the actual temperature reaches critical levels. The method calculates future temperature states based on current power loss and thermal parameters, enabling proactive protection measures to be taken before thermal damage occurs, rather than reacting after the fact.
Solution Approach 2:
The patent transitions from static steady-state calculation to dynamic transient analysis by implementing a thermal network model that captures time-varying thermal behavior. The model uses differential equations to describe heat transfer processes dynamically, allowing the system to adapt to changing power loss conditions and provide accurate temperature prediction during transient operations.
2Reliability
If a sufficient margin is reserved in the junction temperature protection threshold setting, then the power device is protected in advance, but the physical limit of the power device cannot be fully utilized, resulting in increased system costs and reduced working efficiency
Solution Approach 1:
The patent implements feedback by continuously monitoring actual power loss, case temperature, and calculated junction temperature, then comparing the predicted temperature trajectory against the protection threshold. Based on this feedback, the system dynamically adjusts protection actions, allowing operation closer to the true thermal limits when conditions permit while maintaining safety margins when risks are detected, thereby optimizing both reliability and efficiency.
Solution Approach 2:
The patent changes the parameter approach from using a fixed conservative temperature threshold to using a dynamic predicted temperature trajectory. By calculating future temperature states based on real-time power loss and thermal model parameters, the system adapts the effective protection threshold to actual operating conditions, enabling maximum utilization of device capabilities without compromising safety.
3Device complexity
If the conventional method is used, then the protection mechanism is simple to implement, but it cannot accurately predict the actual junction temperature variation trajectory during transient processes
Solution Approach 1:
The patent introduces a thermal network model as an intermediary between measurable quantities (power loss, case temperature) and the unmeasurable junction temperature. This thermal model acts as a mediator that translates easily measured electrical and thermal parameters into accurate predictions of internal junction temperature, bridging the gap between simple measurements and precise temperature assessment without requiring direct junction temperature sensors.
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 effectively protects the power device by predicting and managing junction temperature variations, ensuring safe operation within a defined temperature range while maximizing the utilization of the power device's physical limits, thereby enhancing stability and efficiency.
Implementation Method 1
the equation TJ=TH+P·Rth is used to obtain the junction temperature, considering the power consumption, measured case temperature, and the packaging thermal resistance
Implementation Method 2
a Cauer thermal resistance-capacitance network model, which calculates power consumption and heat flux variations to predict the junction temperature trajectory
Data Source
AI summary
The present invention discloses a thermal protection and warning method and system based on junction temperature prediction for a power device of an offshore wind power converter. The method includes: calculating a thermal resistance and a thermal capacitance corresponding to each layer inside the power device, and establishing a corresponding Cauer thermal network model; calculating power consumption at n future moments according to state variables at the n future moments corresponding to a minimized cost function, that is, calculating a variation trajectory of a heat flux parameter; calculating a variation trajectory of a junction temperature of the power device according to the Cauer thermal network model and the variation trajectory of the heat flux parameter; and comparing the calculated variation trajectory of the junction temperature with a warning temperature, and determining a current operating state of the power device.