Overcurrent Detection Circuit for Paralleled Switches
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Solution Overview
Problem
Existing overcurrent detection circuits for parallely-connected switches, such as IGBTs, face challenges in accurately determining overcurrent due to current imbalances between switches, leading to erroneous determinations and reduced reliability.
Innovation Solution
An overcurrent detection circuit that calculates a determination parameter based on sense voltages from respective sense detectors, which is less affected by current imbalances, allowing for a lower overcurrent threshold setting and preventing reduction in switch reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a predetermined overcurrent threshold is set for detecting overcurrent in parallely-connected switches, then overcurrent can be detected, but current imbalances between switches cause erroneous determinations and reduced reliability
Solution Approach 1:
The patent segments the overcurrent detection by introducing individual sense detectors for each switch to measure sense voltages, and then processes these segmented measurements through calculation to determine overall overcurrent status. This segmentation allows accurate detection while accounting for current imbalances between individual switches.
Solution Approach 2:
The patent changes the detection parameter from direct current measurement to sense voltage measurement, and further transforms it by calculating a determination parameter based on multiple sense voltages. This parameter transformation enables the system to distinguish between normal current imbalances and actual overcurrent conditions, improving both detection accuracy and reliability.
2Measurement precision
If a lower overcurrent threshold is set to enable earlier detection, then detection sensitivity improves, but switch reliability may be reduced due to erroneous determinations from current imbalances
Solution Approach 1:
The patent implements a feedback mechanism where sense voltages from individual switches are continuously monitored and fed into a calculation process that determines the determination parameter. This feedback loop allows the system to adapt to current imbalances and maintain reliable operation even with lower threshold settings for earlier detection.
Solution Approach 2:
The patent creates a composite detection approach by combining multiple sense voltage measurements from different switches and processing them together through a calculation algorithm. This composite method filters out individual variations and current imbalances, enabling sensitive detection without compromising reliability.
3Measurement precision
If individual sense detectors are used for each switch to measure sense voltages, then detection capability improves, but device complexity increases
Solution Approach 1:
The patent applies universality by using identical sense detector circuits for each switch, allowing the same detection mechanism to serve multiple switches. The sense detectors are standardized and can be replicated, which improves measurement accuracy while controlling complexity through design standardization.
Solution Approach 2:
The patent merges the individual sense voltage measurements into a single determination parameter through calculation. By combining multiple measurements into one integrated assessment, the system achieves high measurement precision without proportionally increasing the complexity of the overall detection circuit.
Data Source
AI summary
In an overcurrent detection circuit for switches parallely connected to each other, sense detectors are respectively provided for the switches. Each of the sense detectors detects a sense voltage of the corresponding one of the switches. The sense voltage of each of the switches is based on a sense current associated with a current flowing through the corresponding one of the switches. A parameter calculator calculates, based on the sense voltages calculated by the respective sense detectors, a determination parameter that is less subject to imbalance between currents flowing through the respective switches. A determiner determines whether a value of the determination parameter is higher than an overcurrent threshold, and determines that there is an overcurrent flowing through at least one of the switches upon determining that the value of the determination parameter is higher than the overcurrent threshold.