FOC Induction Motor Control - Rotor Flux Angle
Start with a flux angle of 0. As there is no current in the machine at the beginning, this is correct. Then you can do the Park Transformation and calculate Id and Iq. With these you can calculate the flux angle for your next iteration. 
Texas Instruments described it under 3.9.1 here:
https://www.google.com/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=4&amp;ved=2ahUKEwiZuuCU_YfdAhUi_SoKHTN0CewQFjADegQIBxAC&amp;url=https%3A%2F%2Fwww.researchgate.net%2Fprofile%2FSai_Sudheer_Reddy_Bonthu%2Fpost%2FWhat_are_the_methods_to_implement_PARK_transformation_on_C2000_DSP_micro_controller%2Fattachment%2F59d64d7079197b80779a7006%2FAS%253A488146115796992%25401493394511043%2Fdownload%2FFOC.pdf&amp;usg=AOvVaw2TEZzD_6dVsD1KEAMmm-IQ