Power Tool Capacitor Precharge Circuit to Prevent Terminal Sparking

The patent applies preliminary action by pre-charging the capacitor through a current limiting element before the main power connection is fully established. The control module activates the current limiting element in advance to charge the capacitor with limited current, preventing large inrush current and electric sparks when the battery pack is connected to the tool body.

The patent introduces a current limiting element as an intermediary between the battery pack and the capacitor. This intermediary component controls the charging current flow, allowing the capacitor to charge at an acceptable speed while preventing excessive current that would damage the connection terminals. The switching element further mediates by controlling when the current limiting element is active versus when the capacitor is directly connected.

The patent applies dynamics by making the circuit configuration changeable through a switching element. The system dynamically transitions between two states: initially using the current limiting element for protected charging, then switching to a direct connection state for faster charging once the capacitor is sufficiently charged. This dynamic reconfiguration optimizes both terminal protection and charging efficiency.

The switching element serves multiple functions simultaneously: it controls the transition between charging and discharging modes, manages the activation of the current limiting element, and coordinates the overall power flow management. By making this single component multi-functional, the patent achieves precise current control without proportionally increasing device complexity.