Flux vector control basics ATV 71 The control

Flux vector control basics ATV 71 • 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. Bertrand Guarinos STIE ATV 71 M 3 motor control V 2 Summary 1

Flux vector control basics • • • ATV 71 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. Asynchronous Motor DC Motor r r s s Id Flux I inductive Torque I induced Iq • • 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. Bertrand Guarinos STIE ATV 71 M 3 motor control V 2 Summary 2

Flux vector control basics ATV 71 Ø Comparison of U/F and Vector control Flux Vector Control U/F Law Automatic Compensation (Rs and slip) Manual Compensation (U 0 voltage at origin) C/Cn 200 % 100% F hz 1 3 Bertrand Guarinos STIE Fr. S F hz 5 10 ATV 71 M 3 motor control V 2 Fr. S Summary 3