Power Converter Arm Current Limiting Based on Thermal Integration
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Solution Overview
Problem
Modern high-voltage DC transmission power converters face inefficiencies and complexity in determining semiconductor internal temperature and losses, leading to suboptimal operation during steady-state and dynamic processes, with existing methods providing insufficient accuracy and requiring additional switching modules for fault events.
Innovation Solution
A method that calculates temperature values and setpoint current limitation values for power converter arms, integrating these values over time to form an integral value, which triggers protective measures when exceeding a threshold, allowing for more efficient operation during dynamic processes and fault events without the need for additional switching modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional switching modules are installed to ensure sufficient reserve for dynamic fault events, then the reliability and fault management capability of the power converter is improved, but the device complexity and hardware cost increase
Solution Approach 1:
The patent changes the parameter of current limitation from a fixed value to a dynamically adjustable value based on semiconductor temperature. By continuously monitoring temperature and adapting the current limitation value accordingly, the system can safely operate without additional switching modules while maintaining reliability during fault events.
2Reliability
If the setpoint current limitation value is preset to prevent overloading, then the protection capability is improved, but the productivity and efficiency during dynamic processes deteriorate
Solution Approach 1:
The patent makes the current limitation value dynamic by continuously adapting it to the actual semiconductor temperature. During steady-state operation, the limitation prevents overloading, but during dynamic processes and fault events, the limitation can be temporarily increased when temperature conditions permit, thereby maintaining both protection and productivity.
Solution Approach 2:
The system implements feedback by continuously monitoring semiconductor temperature and using this information to adjust the current limitation value. This closed-loop control allows the system to respond to actual thermal conditions, enabling efficient operation during dynamic processes while maintaining protection capabilities.
3Measurement precision
If semiconductor internal temperature is determined using measurement technology, then the temperature accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent implements self-service by having the power converter determine its own semiconductor internal temperature through a state model that uses readily available operational parameters. This eliminates the need for complex external measurement technology while providing sufficient temperature information for control purposes.
Solution Approach 2:
The patent replaces physical measurement technology with a computational model approach. Instead of using sensors and measurement hardware to determine temperature, the system uses a state model that calculates temperature based on electrical parameters, thereby substituting mechanical/physical measurement systems with computational methods.
Data Source
AI summary
A method operates a power converter having power converter arms, which are switchable between in each case an AC voltage side and a DC voltage side or connectable to phase lines of an AC voltage power supply system. Each power converter arm has a series circuit of switching modules each having a plurality of semiconductor switches and an energy store, in which at least one temperature value for the power converter is determined. A setpoint current limitation value is determined taking into consideration the temperature value, and a setpoint current value is determined taking into consideration the setpoint current limitation value. The temperature value, the arm setpoint current value, the arm actual current value and/or the arm setpoint current limitation value is time-integrated to form an arm integral value. When the arm integral value reaches or exceeds a predetermined arm integral threshold value, a protective measure is performed.