Changes for delta motor?? - Use of "space vector modulation" ,"phase Voltage calc32" and "ACI Motor" blocks

Altair Forum User

Submitted by murthyakella on Fri, 06/15/2012 - 14:28 

Hi,

I have a small question using 'space vector modulation', 'phase Voltage calc32' and 'ACI Motor' blocks etc with delta (or triangle) connected motors.

Are these block designed for star connected motors alone? Or can they be used for delta motors too?

If they can be used for delta motors too, then can these blocks be used directly or should we add some extra blocks to transform from star to delta ?

Also, in ACI motor block, can one use delta parameters or should one use equivalent star paramters?

The reason for this question is because: mag(spaceVector_delta) = sqrt(3)* mag(spaceVector_star)and phase(spaceVector_delta) = 30° + phase(spaceVector_star)
Example: For IGBT switching sequence 001 (i.e. branch A and B = Bottom IGBT ON and branch C = Top IGBT ON),
For delta winding: Phase voltages (Ua, Ub, Uc) = (0, -Udc, +Udc ) ; mag(spaceVector) = (2/sqrt(3)) * Udc and phase(spaceVector) = 270°
For star winding: Phase voltages (Ua, Ub, Uc) = (-1/3 Udc, -1/3 Udc, +2/3 Udc ) ; mag(spaceVector) = (2/3) * Udc and phase(spaceVector) = 240°

Regards, Murthy

Altair Forum User

Submitted by Anders89 on Sat, 06/16/2012 - 07:36.

 

Excellent question. Yes the blocks can be used for both motors. Transforms like Park/Clarke are not changed. The 'space vector modulation' block is just an inverse Clarke with a 3rd harmonic, so no change there. The big differences are in

the motor force constant Kf

• Delta: Kf = sqrt(3)/2*LB
• Wye: Kf = 3/2*LB

and BEMF:

• Delta: Kbmf = LB
• WYE: Kbmf = sqrt(3)LB

This would affect the AC Induction motor models. The ACI block is constructed using TI code. We checked and there is no mention of whether it is modeled with Wye or Delta.