Switch Short-Circuit Detection Circuit With dv/dt Noise Margin

The patent applies preliminary action by discharging the capacitor at the beginning of each switching cycle (when the switch is turned off) before any potential noise interference can occur. The connection unit is configured to connect the capacitor to ground during the off-state, proactively removing any accumulated charge that could be misinterpreted as a fault condition. This preliminary discharge ensures that subsequent voltage measurements during the on-state are not contaminated by residual charge, thereby increasing noise margin while maintaining the simplicity of desaturation-based detection.

The patent introduces an intermediary element - the capacitor with controlled discharge - between the voltage measurement point and the ground. This capacitor acts as a noise filter that smooths out voltage fluctuations during switching transitions. By controlling the capacitor's discharge timing through the connection unit, the circuit effectively isolates the detection mechanism from high-frequency dv/dt noise while preserving the ability to detect actual short-circuit conditions, thus enabling high-speed switching without malfunction.

The patent implements continuous feedback monitoring of the capacitor voltage during the switch on-state. The voltage measurement unit continuously monitors the capacitor voltage, and when it exceeds the reference voltage threshold, the control unit immediately activates the protection mechanism to turn off the switch. This feedback loop enables rapid overcurrent detection without requiring complex detection circuits, as the capacitor's charging rate directly reflects the current magnitude through the known resistance value, providing both simplicity and speed.