Electronic Circuit Breaker Current Limiting Without MOSFET Oversizing
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Solution Overview
Problem
Current electronic circuit breakers face challenges in quickly responding to faults like short circuits, leading to current peaks and instability in the control loop, which can cause damage and increase costs due to the need for oversized MOSFETs and expensive components.
Innovation Solution
An electronic circuit breaker design featuring a first semiconductor switch and a control device that includes a current sensor and control units for current limitation and switching off, allowing for rapid response to faults by actively limiting and blocking the load current, thereby reducing current peaks and eliminating the need for oversized MOSFETs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the response speed of the current limiting circuit is improved, then the reaction time to faults is reduced, but the stability of the control loop deteriorates and signal oscillation occurs
Solution Approach 1:
The patent segments the fault response into two distinct phases: an immediate switching-off phase for rapid fault containment, followed by a controlled current limitation phase. This segmentation allows the system to achieve fast response without causing control loop oscillation, as each phase has its own optimized control strategy.
Solution Approach 2:
The patent implements preliminary action by switching off the MOSFET immediately upon fault detection, before the current limiting circuit can cause oscillation. This preliminary switch-off action contains the fault instantly, and then the current limiting circuit is activated in a controlled manner, preventing the stability issues that would occur with direct speed optimization.
2Loss of time
If a current limiting circuit with sufficient response time is used, then fault response is adequate, but current peaks occur that require oversized MOSFETs
Solution Approach 1:
The patent applies preliminary action by switching off the MOSFET immediately upon fault detection, before current peaks can develop. This preliminary switch-off action prevents the formation of harmful current peaks, allowing the use of properly sized MOSFETs without requiring oversized components for peak current handling.
Solution Approach 2:
The patent extracts the harmful current peaks from the system by implementing immediate switch-off upon fault detection. This removes the need for oversized MOSFETs designed to handle these peaks, allowing the use of appropriately sized components that match the normal operating requirements.
3Reliability
If oversized MOSFETs are used to handle current peaks, then fault protection is ensured, but costs increase
Solution Approach 1:
The patent implements preliminary switch-off action immediately upon fault detection, preventing current peaks from occurring in the first place. This eliminates the need for oversized MOSFETs, allowing the use of cost-effective, properly sized components while maintaining reliable fault protection through the immediate switch-off mechanism.
Solution Approach 2:
The patent employs a strategy where the MOSFET is designed to be switched off immediately upon fault detection, effectively using it as a short-lived protective element during normal operation. This allows the use of more economical, properly sized MOSFETs rather than expensive oversized components designed for rare peak conditions.
Data Source
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AI summary
The invention relates to an electronic circuit breaker (2) comprising a first semiconductor switch (Q3) which is switched into a current path (3) between a voltage input (4) and a load output (6) and comprising a controller (10) which is connected to the control input (8) of the first semiconductor switch (Q3). The first semiconductor switch (Q3) is actuated depending on an actual value (Iactual) of the load current (Iload), said actual value being supplied to the controller (10), and the controller (10) is designed to limit the current of the first semiconductor switch (Q3) and disconnect same. The invention additionally relates to a method for operating same.