Summary ATV71 1 Bertrand Guarinos STIEATV71 M3 motor control V2 Flux vector control basics The control of an asynchronous motor is made more difficult by the fact that the electrical parameters (current, voltage, flux) are alternating. Furthermore, flux and torque are dependant upon current. The principal of flux vector control consists in transforming the machine equations in such a fashion so as to:: –use variables as though the are continuous and no longer alternating, –simplify the equations in order to decouple the flux and torque variables. Flux  r = K 1 Id Torque C = K 2  s Iq Flux is proportional to the Id component of current. If the flux is constant, the torque is proportional to the Iq component of current.

Summary ATV71 2 Bertrand Guarinos STIEATV71 M3 motor control V2 Flux vector control basics Vector control allows the controller to separate the torque producing current and the flux producing current This is analogous to a DC motor with separate excitation. Flux is maintained constant and set at a point to obtain constant torque over the entire speed range. DC Motor I inductive I induced ss rr Id Flux Torque rr ss Iq Asynchronous Motor The vector control has a speed estimation function that allows the full time correction of torque and flux. Thus the performance is much better, for low speed torque, dynamic response, and speed precision compared to a scalar volts/Hertz law.

Summary ATV71 3 Bertrand Guarinos STIEATV71 M3 motor control V2 Flux vector control basics  Comparison of U/F and Vector control Flux Vector Control U/F Law Automatic Compensation (Rs and slip) Manual Compensation (U0 voltage at origin) C/Cn FrS % 200 % C/Cn F hz