Power Converter Current Limit Control Using Semiconductor Temperature
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Solution Overview
Problem
Existing power electronic converters operate under conservative current limits to prevent overheating, leading to inefficient utilization of converter capabilities and potential underutilization in certain operating conditions.
Innovation Solution
A method for operating power electronic converters that dynamically adjusts current limits based on the actual and historical temperatures of semiconductor devices, allowing for increased current ratings when operating conditions permit and reducing current limits when temperatures rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conservative current limits are applied to prevent overheating, then semiconductor safety is ensured, but converter efficiency and capability utilization deteriorate
Solution Approach 1:
The patent implements dynamic current limit adjustment by continuously monitoring semiconductor temperature and adapting the current limit accordingly. When temperature is below a threshold, higher current limits are permitted; when temperature exceeds the threshold, current limits are reduced. This dynamic approach replaces static conservative limits with adaptive limits that optimize both safety and efficiency.
Solution Approach 2:
The system employs feedback control by monitoring semiconductor temperature in real-time and using this information to adjust the current limit. The temperature measurement feeds back to the control system, which then modifies the current limit to maintain safe operating conditions while maximizing converter capability utilization.
2Device complexity
If fixed current limits are used for all operating conditions, then semiconductor protection is simplified, but converter capability underutilization occurs in favorable conditions
Solution Approach 1:
The patent transitions from static fixed current limits to dynamic adaptive current limits that change based on operating conditions. The system monitors temperature and adjusts the current limit accordingly, allowing higher utilization when conditions permit while maintaining protection when temperatures rise.
Solution Approach 2:
The system changes the current limit parameter based on temperature conditions. When semiconductor temperature is below a threshold, a higher current limit is applied; when temperature exceeds the threshold, a lower current limit is applied. This parameter adaptation enables the system to optimize converter capability utilization across different operating conditions.
3Productivity
If higher current ratings are permitted, then converter efficiency improves, but semiconductor overheating risk increases
Solution Approach 1:
The system uses temperature feedback to control the current limit. Temperature sensors monitor semiconductor temperature and feed this information to the control system, which adjusts the current limit to prevent overheating while allowing higher currents when safe. This closed-loop control balances efficiency improvement with temperature management.
Solution Approach 2:
The system takes preliminary protective action by monitoring temperature and reducing the current limit before overheating occurs. When temperature approaches the threshold, the system proactively lowers the current limit to prevent excessive temperature rise, rather than waiting for overheating to occur.
Data Source
AI summary
A method for operating a power electronic converter comprising at least one power semiconductor device is provided. The method comprises the determination of the at least one current limit, by carrying out a first operation if the temperature of the at least one semiconductor device is above an upper temperature threshold in order to decrease the current limit, and by carrying out a second operation if the temperature of the at least one semiconductor device is below a lower temperature threshold in order to increase the current limit.