Dynamic Overcurrent Detection Voltage Adjustment for Switching Elements
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Solution Overview
Problem
Conventional overcurrent determining apparatuses for switching elements are unable to detect overcurrents promptly, leading to increased integral current flow and potential damage, as they rely on fixed determination voltages that do not account for temperature variations, resulting in longer determination periods and potential erroneous readings.
Innovation Solution
The overcurrent determining apparatus dynamically adjusts the determination voltage based on the temperature of the switching element, setting a lower voltage at higher temperatures to reduce determination periods and prevent false positives, thereby enabling earlier detection of overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed determination voltage is used for overcurrent detection, then the detection threshold remains constant, but the determination period increases and false positives occur at different temperatures
Solution Approach 1:
The patent applies dynamics by making the determination voltage variable rather than fixed. The determination voltage is dynamically adjusted based on the temperature of the switching element, allowing the detection threshold to adapt to changing thermal conditions. This resolves the contradiction by enabling accurate detection across temperature ranges while reducing determination time at higher temperatures where Miller voltage decreases.
Solution Approach 2:
The patent changes the voltage parameter based on temperature conditions. By establishing a relationship between temperature and determination voltage, the system adjusts the voltage threshold to match the Miller voltage characteristics at different temperatures. This parameter change enables earlier overcurrent detection at high temperatures without causing false positives, thereby reducing the determination period while maintaining reliability.
2Reliability
If the determination voltage is set higher to avoid false positives, then detection reliability improves, but overcurrent detection is delayed
Solution Approach 1:
The determination voltage is made dynamic and temperature-dependent. At higher temperatures where Miller voltage is lower, the determination voltage is reduced accordingly, enabling faster detection without false positives. At lower temperatures, the determination voltage is higher to prevent false positives. This dynamic adjustment resolves the contradiction between detection speed and reliability.
Solution Approach 2:
The patent applies different determination voltage values for different temperature conditions. Instead of using a single universal threshold, the system implements local optimization by tailoring the voltage threshold to the specific thermal state of the switching element. This allows optimal detection performance in each temperature regime, achieving both speed and reliability.
3Measurement precision
If the determination period is extended to ensure accurate detection, then measurement precision improves, but the response time to overcurrent events increases
Solution Approach 1:
The patent changes the determination voltage parameter based on temperature to optimize the detection process. By aligning the determination voltage with the Miller voltage at different temperatures, the system achieves accurate detection with shorter determination periods. This parameter adaptation allows precise overcurrent detection without extending the response time.
Data Source
AI summary
In an overcurrent determining apparatus, a temperature obtainer obtains a temperature parameter indicative of a temperature of a switching element as a temperature measurement value. A determination voltage has a first voltage value when the temperature measurement value is a first temperature. A setter sets the determination voltage to a second voltage value upon determining that the temperature measurement value is a second temperature higher than the first temperature. The second voltage value is lower than the first voltage value and higher than a value of a Miller voltage of the switching element at the second temperature.