FOC

FOC is an acronym used in several domains to denote different concepts, and its meaning is determined by context. Common interpretations include field-oriented control in electric motor drive systems, fiber optic cable in communications, and free of charge in transactional language.

Field-oriented control: Field-oriented Control (also known as vector control) is a method for controlling AC motors that aims to decouple torque and flux, enabling performance similar to DC motors. By transforming three-phase currents into a rotating dq reference frame aligned with the rotor flux, the control system can independently regulate torque-producing and magnetizing components. Practical implementations rely on rotor position or speed estimation, Clarke and Park transforms, and pulse-width modulation to drive the motor windings. Applications include servo drives, robotics, and electric vehicles, particularly with permanent magnet synchronous motors and some induction motors. Benefits include improved dynamic response, higher efficiency, and smooth torque control, though the technique adds complexity and sensitivity to sensor noise and model accuracy.

Fiber optic cable: In telecommunications and data networks, a fiber optic cable (FOC) transmits data as light through glass or plastic fibers. Light signals travel in the core, with the surrounding cladding guiding the light by total internal reflection. Common types are single-mode fibers for long-haul links and multi-mode fibers for shorter runs. FOC offers high bandwidth, low attenuation, and immunity to electromagnetic interference, making it central to backbone networks, data centers, and fiber-to-the-home deployments. Cables are composed of the fiber, protective coatings, strength members, and jackets.

Free of charge: In business and invoicing, FOC is sometimes used to denote free of charge, indicating that goods or services are supplied at no cost.