Three phase full converter drive

The circuit diagram of one three phase full converter in the armature circuit and 1 phase full converter in the field circuit, is as shown in figure.

Three phase full converter dc drive

For converter 1 in the armature circuit, the average output voltage from given by, 

                                V₀ =  V_t =  3V_ml/2∏  * Cos  ɖ  for 0<  ɖ <  ∏

For converter 2 in the field circuit,

                                    V_f =  3V_ml/2∏  * Cos ɖ₁  for 0< ɖ₁  <  ∏