Two simple flux observers for induction motors

✍ Scribed by Ph. Martin; P. Rouchon

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 68 KB
• Volume: 14
• Category: Article
• ISSN: 0890-6327
• DOI: 10.1002/(sici)1099-1115(200003/05)14:2/3<171::aid-acs583>3.0.co;2-0

✦ Synopsis

The induction motor has very good qualities*reliability, ruggedness, relatively low cost, etc., for industrial applications. The reason for this is that there is no mechanical commutation: the rotor consists simply of closed windings in which currents are induced by a rotating magnetic "eld set up by the stator, hence creating a torque. But the control of the induction motor is not so easy, mainly because of the three following points: the model is rather non-linear, some variables (in particular, the magnetic #uxes, or equivalently, the rotor currents) cannot easily be measured, and some parameters (rotor resistance, load torque, inertia) vary a lot in operation. This has motivated a growing literature in the control community.

We propose here two simple #ux observers assuming that the rotor velocity and the stator currents are measured: the "rst observer makes use of a natural &&passivity'' property (in fact, it requires only velocity measurements); the second observer [1] relies on a &&reparametrization of time'' and can be rendered as fast as desired.

It is worth mentioning that all the computations are straightforward mainly because they are carried out using the complex variable notation (time-varying phasor) model of the induction motor.