Field-Oriented Control is a powerful control strategy to control torque of three-phase AC machines and stepper motors with high accuracy and bandwidth. It can be implemented in either hardware or software.
The control structure is based on two simple mathematical transformations - called Clarke and Park - of the actual phase currents. The resulting coordinate system has only two dimensions. The first axis is in-phase with the motor's current flux. The second axis is orthogonal to the flux and proportional to the motor’s torque. With field-oriented control, two PI current controllers can be used to control both components of the motor current vector separately. The transformations are based on the actual rotor angle, which has to be acquired by position sensors like hall sensors or encoders.
Field-Oriented Control, also called Vector Control or Rotor-Oriented Control for synchronous motors, was developed during the 1970s for induction machines and subsequently adapted for synchronous motors.
The actual phase currents are transformed from stator-fixed to field synchronous coordinate systems. This type of coordinate system has two dimensions. The first axis is in phase with the flux (d-axis). Current in this axis influences machine flux, which is provided by permanent rotor magnets or induction. The second axis is orthogonal to the flux (q-axis). Current in the q-axis is proportional to motor torque.
Field-Oriented Control builds the inner control loop of a full cascade servo controller as built in the TMC4670 or motionCookie.
TMCC160 motionCookie™ is an integrated microsystem with a powerful 3-Phase Servo Gate driver for up to 24V and 1A gate current with complete servocontroller software stack in a small 12mm x 17mm Package. The integrated gate-driver powers a wide range of N-channel Power switches for 24V PMSM and BLDC motors.
With a field oriented current control with space vector PWM: velocity control loop, and position control loop and ramp controllers, the software builds a complete servo controller stack. TMCC160 uses ABN incremental (quadrature) encoders or Hall signals for position feedback.
MotionCookie microsystems are designed to minimize time-to-market and total cost of ownership.