# FOC Induction Motor Control - Rotor Flux Angle

In Field oriented control of induction motor it's necessary to do:

1. Clark Transformation
2. Park Transformation

According to the note (page 3): http://ww1.microchip.com/downloads/en/AppNotes/ACIM%20Vector%20Control%2000908a.pdf To calculate Park trans. (flux and torque stator current components /Id, Iq/) rotor flux angle is needed - it's described at page 4 how to calculate it.

My misunderstanding is how to do it if at these equations (EQ 1: Magnetizing current, EQ 2: flux speed) there is a necessity to have Id, Iq current which we haven't (as I mentioned to calculate it rotor flux is needed)?

What are the steps to do it exactly?

• Not clear what is the question but: You get Id and Iq through Clarke->Park transformation. The flux can be estimated with use of estimator. – Marko Buršič Sep 3 '17 at 18:24
• Thanks for reply. My question was how to calculate rotor flux angle which is needed to calc. Clarke->Park transformation. – Fasset Sep 3 '17 at 18:27
• You get it from the encoder. Actually you need to know the slip frequency, which is $\omega_S - \omega_R$ – Marko Buršič Sep 3 '17 at 19:28
• To be more precise I'm trying to write my own soft to FOC. – Fasset Sep 3 '17 at 19:54
• Too complicated, good luck. – Marko Buršič Sep 3 '17 at 19:57