Open-Circuit Detection in Multilevel Converter Bridge Arms
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Solution Overview
Problem
Multilevel converters experience increased complexity and reliability issues due to open-circuit malfunctions in power semiconductor switches, leading to potential device and system damage without effective detection mechanisms.
Innovation Solution
A converter circuit with a capacitor module, bridge arms, a voltage measuring module, and an open-circuit detection module that transmits testing impulse signals to determine the operational states of bridge arms by measuring voltage differences and comparing them to reference values, identifying potential open-circuit conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the level number of multilevel converter increases to provide high voltage and high power convenience, then the application capability is improved, but the number of switches doubles and circuit structure becomes more complex, leading to increased malfunction probability and reduced system reliability
Solution Approach 1:
The patent implements preliminary detection actions by continuously monitoring the converter circuit for open-circuit conditions before they can cause damage. The detection mechanism proactively identifies switch failures early in the malfunction process, allowing for preventive measures to be taken before the fault propagates and causes system-wide damage, thus maintaining reliability despite increased complexity.
Solution Approach 2:
The patent establishes a feedback mechanism where the detection module continuously monitors bridge arm voltages and provides real-time information about switch status to the control system. This feedback loop enables the system to respond to malfunctions dynamically, adjusting operation to maintain reliability even as the number of switches and circuit complexity increase with higher converter levels.
2Power
If the number of power semiconductor switches increases with higher converter levels, then the power handling capability is improved, but the probability of open-circuit malfunction increases
Solution Approach 1:
The patent segments the monitoring function by dedicating specific detection circuits to monitor each bridge arm's voltage independently. This segmentation allows the system to identify which specific switch has failed without being overwhelmed by the increased number of switches, enabling targeted response to individual failures rather than system-wide shutdown, thus managing the increased malfunction probability inherent in higher-power converters with more switches.
3Device complexity
If no effective detection mechanism is implemented, then the device complexity is reduced, but the converter circuit can easily be damaged during operations, resulting in production stoppage or serious accidents
Solution Approach 1:
The patent introduces a voltage measuring module as an intermediary component that safely interfaces with the high-voltage bridge arms to extract diagnostic information without directly interfering with the power circuit operation. This intermediary measurement approach enables detection functionality with minimal added complexity, as it uses non-intrusive voltage sensing rather than requiring direct interaction with the power switches, thus maintaining operational safety without significantly increasing device complexity.
Data Source
AI summary
A converter circuit is provided. The converter circuit includes a capacitor module, bridge arms, a voltage measuring module and an open-circuit detection module. Each bridge arm is connected to the capacitor module in parallel and includes an upper arm and a lower bridge arm connected at a middle point. The voltage measuring module measures voltage differences between each two bridge arms. The open-circuit detection module transmits test impulse signals to the bridge arms to activate at least one upper-conducted bridge arm and at least one lower-conducted bridge arm. The open-circuit detection module retrieves the voltage differences of each pair of the upper-conducted and lower-conducted bridge arms to make comparison with a reference value to determine an operation state thereof, and makes comparison of the operation state determined according to the different groups of test impulse signals to determine whether the upper and the lower bridge arms are actually open circuit.