Sensorless field-oriented control
Replacing the sensors entirely in an FOC motor controller reduces the cost and increases the reliability of an AC induction motor, but also increases the complexity and cost of the controller. To replace the sensor, the information on the rotor speed is extracted from the voltages and currents in the stator windings via the motor terminals. This is then fed back into the current control of the motor.
The dynamic performance and steady-state speed can be determined accurately at low speeds using the parasitic effects. Profiling tools can be used to determine the performance of particular system designs to build a model that can be used for sensorless motor control.
FOC can be used across AC induction motors and brushless (BLDC) motors to improve the control and accuracy of the motors for a wide range of applications from pumps and fans to conveyors, particularly in industrial automation where long-term reliability is essential.