Contactor Coil Control Using Inrush-Hold Current Switching

The coil control is segmented into two distinct phases: inrush phase and hold phase. During the inrush phase, a larger current flows through the coil to ensure reliable pull-in of the movable contact. Once the contact is engaged, the system transitions to the hold phase where a smaller current is sufficient to maintain the engaged state. This segmentation allows the system to use high current only when necessary for reliability, rather than continuously, thereby reducing overall energy consumption and preventing coil heating.

The control system dynamically adjusts the coil current based on the operational phase. During the inrush phase, the full switching capacity is utilized to quickly engage the contactor. Once engaged, the system transitions to the hold phase where the current is reduced and maintained at a lower level. This dynamic control prevents frequent and unnecessary state switching, reducing mechanical stress and wear on the contacts, thereby extending contact life while maintaining relatively simple control architecture.

The patent extracts and eliminates the complex flyback circuit from the coil control system. Instead of using a flyback topology with its associated complexity, the invention employs a simplified control approach using multiple switches (high side and low side controls) that can directly regulate coil current. This extraction of the flyback circuit maintains effective current control during both inrush and hold phases while significantly reducing device complexity and cost.

The control circuit is designed with multi-functionality to perform both inrush current delivery and holding current regulation using the same switch network. The high side and low side controls work together to first deliver high current for pull-in, then seamlessly transition to providing lower holding current without requiring a separate buck circuit. This universal approach achieves energy-efficient holding while avoiding the design complexity and extended validation associated with dedicated buck circuits.