Power Converter Short-Circuit Detection Using Switch Voltage Signals
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Solution Overview
Problem
Medium-voltage power converters face challenges in detecting short-circuits effectively, particularly in systems with numerous semiconductor switches, where existing methods are complex, costly, or difficult to implement due to high sensor usage and data handling issues, leading to potential catastrophic failures.
Innovation Solution
A method for detecting short-circuits in power converters that involves measuring switch voltages and determining inductance voltage to calculate current, allowing for early detection before device desaturation, using existing measurements and circuits to maintain reliability and reduce complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional sensors and measurement components are added to detect short-circuits, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The converter uses its own existing voltage measurements and circuits to detect short-circuits, without requiring external sensors or additional measurement components. The control device leverages the voltage signals already present in the converter to determine fault conditions, making the system self-diagnostic.
Solution Approach 2:
The existing voltage measurement circuits in the converter are made to serve dual purposes: both normal operation monitoring and short-circuit detection. The same voltage signals used for control are also used for fault detection, eliminating the need for dedicated detection hardware.
2Power
If more semiconductor switches are added to increase power rating, then converter capacity is improved, but reliability decreases due to increased fault probability
Solution Approach 1:
The control device continuously monitors voltage signals from the semiconductor switches and provides feedback to detect abnormal conditions. When a short-circuit is detected through voltage signal analysis, the system can immediately respond by switching off affected components, preventing cascading failures and maintaining overall system reliability despite having multiple switches.
3Loss of time
If fast short-circuit detection is implemented, then fault response time is improved, but measurement precision requirements increase
Solution Approach 1:
The system detects short-circuits by monitoring changes in voltage signal characteristics rather than requiring absolute precision measurements. The control device identifies fault conditions through patterns and deviations in voltage signals during switching operations, allowing fast detection without demanding ultra-precise measurement equipment.
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 fast and reliable fault containment by initiating turn-off sequences at lower fault current levels, reducing thermal stress and preventing cascading failures in medium-voltage drive systems.
Implementation Method 1
an inductance (36)... determining an inductance voltage over the inductance (36) depending on the measured switch voltage and a DC voltage
Data Source
Figure 1~2
Figure 3
AI summary
A method for detecting a short-circuit (18) in a power converter (20) is provided. The power converter (20) comprises a first DC terminal (22), a second DC terminal (24), an AC terminal (26), a first semiconductor switch (S 1) electrically coupled to the first DC terminal (22) and the AC terminal (26), a second semiconductor switch (S2) electrically coupled to the second DC terminal (24) and the AC terminal (26), and an inductance. The method comprises: sending a turn-on signal (ON) to the first semiconductor switch (S 1) for turning on the first semiconductor switch (S 1) and a turn-off signal (OFF) to the second semiconductor switch (S2) for turning off the second semiconductor switch (S2); receiving a voltage signal which is representative for a switch voltage (vS1, vS2) measured over the first semiconductor switch (S 1) and the second semiconductor switch (S2); determining an inductance voltage (VL) over the inductance depending on the measured switch voltage (vS1, vS2) and a DC voltage (VDC) between the first and second DC terminals (24); determining a current (isc) flowing through the semiconductor switches (S 1, S2) depending on the determined inductance voltage (VL); and determining that the short-circuit (18) is present depending on a predetermined current threshold.