Adaptive Inverter Shutdown Sequence for Fault Protection
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Solution Overview
Problem
Existing electrical circuits with power converters, such as three-level converters, face challenges in safely switching off switching devices during faults without causing further damage or unbalanced short-circuit currents.
Innovation Solution
A method that evaluates fault information to determine a target state and sequence for transitioning switching devices, using measured signals like voltages, currents, and temperatures to adapt the shutdown process flexibly and minimize damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed shutdown procedure is used (switching off all IGBTs immediately or in predetermined sequence), then the shutdown is simple and fast, but it may cause further component damage or unbalanced short-circuit currents
Solution Approach 1:
The shutdown procedure transitions from a static, fixed sequence to a dynamic, adaptive process. The control device continuously monitors circuit state (currents, voltages, temperatures) and adjusts the shutdown sequence in real-time based on actual conditions. This allows the system to optimize component safety while managing complexity through intelligent control algorithms.
Solution Approach 2:
The system implements feedback control by measuring actual circuit parameters during shutdown and using this information to adjust the shutdown sequence. Sensors monitor currents, voltages, and temperatures, feeding this data back to the control device which then modifies the switching sequence to prevent damage and balance short-circuit currents, resolving the contradiction between safety and complexity.
2Speed
If all IGBTs are switched off immediately upon fault detection, then the shutdown is fast and simple, but it may cause overvoltage or unbalanced short-circuit currents that damage components
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing multiple shutdown sequences for different fault conditions. When a fault is detected, the control device quickly selects and executes the appropriate pre-planned sequence, achieving fast shutdown while avoiding harmful effects. This eliminates the need for real-time complex calculations during the actual shutdown event.
Solution Approach 2:
The system changes operational parameters dynamically during shutdown by adjusting switching times, sequences, and states based on real-time measurements of currents, voltages, and temperatures. This allows the shutdown to proceed quickly while adapting parameters to prevent overvoltage and unbalanced currents, resolving the contradiction between speed and safety.
3Ease of operation
If a predetermined shutdown sequence is used independent of fault type, then the control is simple, but it cannot optimize protection for different fault conditions
Solution Approach 1:
The system changes control parameters based on fault type by identifying the specific fault condition and selecting appropriate shutdown parameters from stored sequences. This maintains operational simplicity through automated parameter selection while achieving fault-specific optimization, as the control device automatically adjusts the shutdown sequence based on the detected fault type without requiring complex real-time decision-making.
Data Source
Figure 1
AI summary
The method involves detecting fault of an electrical circuit (10), and measuring signals within the circuit. A target condition is determined in event of fault depending on the measured signals, where the circuit for control of the fault is transferred in the target condition. A sequence is determined depending on the measured signals, and switching devices e.g. insulated gate bipolar transistors (121-124), of an inverter e.g. three point neutral point clamped (NPC) inverter (11), are transferred into a target switching condition corresponding to the target condition with the sequence.