Overcurrent Detection Circuit With Time-Varying Threshold Control

The patent applies dynamics by making the detection threshold variable rather than fixed. The threshold is dynamically adjusted based on the operating period: during the transient period, a first threshold is used that allows normal current fluctuations, while in the steady state period, a second threshold provides high sensitivity for short-circuit detection. This temporal dynamic adjustment resolves the contradiction between avoiding false alarms and detecting actual faults.

The patent segments the operating period into distinct phases: a transient period immediately after switching element activation, and a steady state period thereafter. Each segment has its own detection threshold characteristics. This segmentation allows the system to apply different detection criteria appropriate to each operational phase, preventing erroneous detection during transient normal current while maintaining high sensitivity during steady-state abnormal conditions.

The patent implements a dynamic thresholding mechanism that adapts the detection threshold based on the operational phase. Rather than using a single fixed threshold, the system transitions between a first threshold during the transient period and a second threshold during the steady state period. This dynamic approach maintains detection accuracy across different operating conditions without requiring overly complex circuitry.

The patent employs periodic action by establishing a clear temporal sequence: a transient period followed by a steady state period. The detection threshold is periodically adjusted according to which phase is active. This time-based periodic structure allows simple implementation through sequential logic while achieving high detection accuracy appropriate for each operational phase.