Short-Circuit Detection Circuit Using Parallel Sampling Branches
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Solution Overview
Problem
Existing short-circuit protection systems for power electronic components, such as MOSFETs and IGBTs, are ineffective in quickly detecting and rectifying short-circuits due to the influence of inductance, leading to potential damage or system failures.
Innovation Solution
A short-circuit protection apparatus comprising parallel detection branches with sampling resistors and capacitors, which compare voltage differences to quickly identify short-circuits and control the target circuit to prevent damage, while filtering spike voltages to improve accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional short-circuit protection using operational amplifier and series resistor is used, then the circuit can detect short-circuit conditions, but the protection response is delayed due to inductance affecting current increase
Solution Approach 1:
The protection circuit is segmented into two independent detection branches: one detecting voltage changes across the power source terminals, and another detecting current changes through sampling resistors. This segmentation allows the circuit to detect short-circuit conditions through voltage change rate rather than waiting for current to build up against inductance, achieving fast protection without being constrained by inductive effects
Solution Approach 2:
Sampling resistors are introduced as intermediary elements in parallel with the power source terminals. These resistors convert the difficult-to-detect fast voltage changes into measurable voltage signals that can be compared by the controller, enabling rapid short-circuit detection without being affected by the inductance in the main circuit path
2Adaptability or versatility
If inductance is present in the circuit to enable power conversion, then the circuit can perform power conversion functions, but the short-circuit detection accuracy is reduced due to inductance affecting current increase
Solution Approach 1:
The circuit uses sampling resistors as intermediary measurement elements that are placed in parallel with the inductive power conversion circuit. These resistors provide a direct path for detecting voltage changes without being affected by the inductance, thereby maintaining measurement precision while preserving the power conversion capability of the main circuit
Solution Approach 2:
Instead of detecting short-circuit conditions solely through the current dimension (which is affected by inductance), the invention adds a voltage change rate detection dimension. By monitoring how quickly voltage changes across the terminals, the system can accurately detect short-circuits independent of the inductive effects in the power conversion path
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables timely and effective protection of the target circuit from short-circuits, reducing the risk of damage and enhancing system reliability by quickly differentiating voltage changes from current increases, even in the presence of inductance.
Implementation Method 1
The first detection branch includes a first sampling resistor and a first sampling capacitor that is connected in parallel to the first sampling resistor
Data Source
AI summary
A short-circuit protection apparatus includes a first detection branch, a second detection branch, and a controller. The first detection branch includes a first sampling resistor and a first sampling capacitor that is connected in parallel to the first sampling resistor. A difference between an absolute value of a second sampling voltage and an absolute value of a first sampling voltage is a first difference. The controller obtains a comparison result between an absolute value of a first sampling voltage at two terminals of the first sampling resistor and an absolute value of a second sampling voltage at two terminals of the second sampling resistor, and if a difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference and the second difference is less than the first difference, controls the target circuit to stop working.