Parallel Switch Drive Circuit With Dynamic Overcurrent Thresholds
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Solution Overview
Problem
Existing drive circuits for switches connected in parallel face challenges in accurately determining overcurrent and overheating states due to varying current and temperature thresholds based on the driving state of each switch, leading to potential erroneous determinations.
Innovation Solution
A drive circuit with a determining unit and a setting unit that adjusts thresholds dynamically based on the driving state, setting a higher target threshold for the switching completion switch during specific on-driving periods to prevent erroneous overcurrent or overheating determinations while promptly detecting such states when they occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed threshold is used to determine overcurrent or overheating states, then the determination process is simple, but erroneous determinations occur due to varying driving states of switches
Solution Approach 1:
The patent applies dynamics by making the threshold value changeable based on the driving state of the switches. The threshold is set to a first value during the on-driving period of only the switching completion switch and to a second value (lower than the first) during the on-driving period of all parallel switches. This dynamic adjustment prevents erroneous overcurrent determinations while maintaining accurate detection capability.
Solution Approach 2:
The patent changes the threshold parameter according to the driving state. By setting different threshold values (first threshold during partial on-driving, second threshold during full on-driving) based on which switches are active, the system accurately determines overcurrent states without false positives, resolving the contradiction between reliability and complexity.
2Reliability
If a high threshold is set to prevent erroneous determination during switching completion, then false alarms are reduced, but actual overcurrent states may not be detected promptly
Solution Approach 1:
The patent uses dynamics to adjust the threshold based on the operational context. During the on-driving period of only the switching completion switch, a first threshold is applied to prevent false alarms. During the on-driving period of all parallel switches, a second threshold (lower than the first) is applied to enable prompt detection of actual overcurrent states. This dynamic switching of thresholds resolves both concerns.
Solution Approach 2:
The threshold parameter is changed based on the driving state: a higher first threshold during switching completion prevents false alarms, while a lower second threshold during full operation enables timely detection. This parameter change strategy simultaneously achieves both objectives of reducing erroneous determination and maintaining prompt detection capability.
3Loss of time
If a low threshold is set to detect overcurrent promptly during full on-driving, then detection speed increases, but erroneous determination occurs during switching completion period
Solution Approach 1:
The patent applies dynamics by switching between different threshold values based on the driving state. During the on-driving period of only the switching completion switch, a first threshold is used to prevent erroneous determination. During the on-driving period of all parallel switches, a second threshold (lower than the first) is used to achieve prompt detection. This dynamic approach resolves the contradiction between detection speed and accuracy.
Solution Approach 2:
The threshold parameter is adjusted according to the operational phase: a higher first threshold during switching completion prevents false positives, while a lower second threshold during full operation enables fast detection. This parameter change strategy simultaneously achieves both high detection speed and high determination accuracy.
Data Source
AI summary
A drive circuit drives a plurality of switches and sets a target threshold as a threshold compared to a physical quantity correlated with current flowing to a switching completion switch driven to complete switching from one of first and second states to the other. In the first state, a flow of current to at least one of the switches is allowed. In the second state, a flow of current to all of the switches is blocked. The drive circuit sets the target threshold to a first target threshold during at least a part of a first on-driving period in which only a switching completion switch is being on-driven and sets the target threshold to a second target threshold during at least a part of a second on-driving period in which all of the plurality of switches are being on-driven. The first target threshold is greater than the second target threshold.