Field-Oriented Control (FOC)
Field-oriented control (FOC), also called vector control, is a motor-control method that represents multiphase current on axes rotating with the motor's magnetic field so torque-producing and flux-changing components can be regulated separately.
What the controller does
The controller transforms measured phase currents into direct-axis and quadrature-axis components, compares them with current targets, and transforms the resulting voltage commands back into phase commands for the inverter. It needs an accurate rotor-field angle from a position sensor or estimator.
FOC is a control method, not a motor type, and it is not automatically sensorless. The useful meaning of each current component also depends on the motor: induction, surface-magnet, interior-magnet, and electrically excited machines require different models and targets.
For the complete control chain, current maps, and operating regions, see Motor Control and Efficiency Maps.