DESAT Overcurrent Circuit Tuning for Ringing-Resistant Detection
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Solution Overview
Problem
Existing DESAT protection circuits in inverter circuits face challenges in accurately detecting overcurrents without erroneous detection due to ringing, and the adjustment process is labor-intensive and time-consuming, with potential delays in protection activation.
Innovation Solution
An electronic circuitry with a comparison circuit, blanking filter, and noise removal filter is employed to detect overcurrents by adjusting parameters such as threshold voltage, blanking time, and noise removal time to prevent erroneous detection and ensure timely protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blanking time is increased to prevent erroneous detection due to ringing, then the reliability of overcurrent detection is improved, but the response time for detecting actual short circuits is delayed
Solution Approach 1:
The patent implements dynamic adjustment of the blanking time parameter based on operating conditions. The control circuit modifies the blanking time duration according to the detected voltage waveform characteristics and operating state, allowing the system to extend blanking time when ringing is present while maintaining shorter blanking times during normal operation, thus resolving the contradiction between preventing erroneous detection and ensuring rapid protection activation
Solution Approach 2:
The patent changes the blanking time parameter dynamically based on detected conditions. By monitoring the voltage waveform and identifying ringing characteristics, the system adjusts the blanking time parameter in real-time, transitioning between different parameter states to optimize both detection accuracy and response time under different operating conditions
2Adaptability or versatility
If external resistors and capacitors are replaced to adjust circuit configuration for different power devices, then the adaptability of the DESAT protection circuit is improved, but the complexity of evaluation and adjustment process increases
Solution Approach 1:
The patent implements self-service through automatic parameter adjustment and evaluation. The control circuit automatically tests the DESAT protection function by generating test signals, measuring voltage waveforms, and adjusting parameters without requiring manual intervention or physical component replacement, thereby maintaining adaptability while significantly reducing adjustment complexity
Solution Approach 2:
The patent replaces the mechanical process of physically replacing external resistors and capacitors with an electronic parameter adjustment system. The control circuit electronically modifies circuit parameters through software control, substituting the mechanical adjustment method with an automated electronic system that achieves the same adaptability without the associated complexity
3Reliability
If the threshold voltage is increased to avoid false detection during ringing, then the reliability of overcurrent detection is improved, but the sensitivity to detect actual overcurrent conditions is reduced
Solution Approach 1:
The patent implements dynamic adjustment of the threshold voltage parameter based on the detected voltage waveform characteristics. The control circuit monitors the waveform and automatically modifies the threshold voltage level according to the operating state, allowing higher thresholds during ringing conditions while maintaining lower thresholds for sensitive detection during normal operation, thus resolving the contradiction between preventing false detection and maintaining detection sensitivity
Data Source
AI summary
An electronic circuitry includes: a comparison circuit to detect a first voltage at a first node relating to a first end of a semiconductor switching element and output a first signal in response to the first voltage larger than a predetermined voltage or equal to; a first filter including a first switch between the first node and a second end of the element, the first filter turning on the first switch for a first time based on a control signal indicating conduction of the element; and a second filter to, in response to the first signal output for at least a second time, generate a second signal indicating an overcurrent of the element, wherein the electronic circuitry changes at least one of: a first waveform related to driving of the semiconductor switching element based on the control signal; the second time; the first time; or the predetermined voltage.