Parallel Semiconductor Switch Control With Short-Circuit Isolation
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Solution Overview
Problem
High-power semiconductor switch circuits connected in parallel face challenges in preventing short circuits, which can lead to fires or undesired torque in electric machines, especially when a defective switch causes a short circuit that couples through the gate driver supply, preventing the establishment of an active short circuit and potentially damaging the power electronics.
Innovation Solution
A circuit arrangement with switch-on and switch-off terminals connected in parallel to semiconductor switches, incorporating a switch disconnector and detection/control arrangement to identify and respond to short circuits by opening the disconnector, thereby decoupling the defective switch and preventing crosstalk, while using diodes to latch control terminals and resistors to manage current flow and filter out regular operation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If semiconductor switches are connected in parallel to increase current-carrying capacity, then the power handling capability is improved, but the risk of short circuit propagation and system failure increases
Solution Approach 1:
The patent divides the control system into separate control circuits for each semiconductor switch, with individual control terminals that can be independently controlled. This segmentation allows the control system to isolate and manage faults in individual switches without affecting the entire parallel system, thereby maintaining reliability while preserving current-carrying capacity.
Solution Approach 2:
The patent introduces an intermediary control circuit between the power supply and the semiconductor switches that can detect short circuits and isolate defective switches. This intermediary layer prevents direct short circuit propagation to the power supply while maintaining control over intact switches, resolving the contradiction between power handling and short circuit risk.
2Reliability
If a defective semiconductor switch causes a short circuit, then the immediate switch failure occurs, but the short circuit can couple through the gate driver supply and prevent safe state establishment
Solution Approach 1:
The patent extracts the defective semiconductor switch from the parallel system by opening its associated switch disconnector when a short circuit is detected. This removal isolates the harmful short circuit effect from the gate driver supply and prevents it from coupling to other switches, allowing the system to establish a safe state with the remaining intact switches.
Solution Approach 2:
The patent converts the harmful short circuit condition into a beneficial isolation mechanism. By detecting the short circuit and automatically opening the switch disconnector, the system uses the fault condition itself to trigger the isolation of the defective switch, preventing further harm while maintaining system operation through intact switches.
3Reliability
If switch disconnectors are provided for each control terminal to enable individual isolation, then the ability to prevent short circuit propagation is improved, but the device complexity increases
Solution Approach 1:
The patent designs the control circuit to perform multiple functions: normal switch control, short circuit detection, and automatic isolation. This multi-functional approach allows the same control infrastructure to handle both routine operation and fault management, reducing the need for separate dedicated components and thereby limiting the increase in device complexity while maintaining high isolation capability.
Data Source
AI summary
The invention relates to a circuit arrangement (200) for controlling a plurality of semiconductor switches connected in parallel, having an activation connection (213) and a deactivation connection (214), and having a plurality of control connections (220), each provided for connection to a control connection (123) of one of the plurality of semiconductor switches, wherein the activation connection (213) and the deactivation connection (214) are each connected to each of the plurality of control connections (220), and wherein a circuit breaker (230) is provided between the activation connection (213) and at least one of the control connections (220), furthermore having at least one detection and control arrangement which is designed to detect a current flow in the at least one of the control connections (220) and, if a short-circuit is detected on the basis of the current flow, to control the circuit breaker (230) to open.