1 Assume we are dealing with transformed variables from

actual stationary 3 phase variables of machine viz synchronous or Induction motor to rotating ref frame ie d q and 0 sequence.

2. In the case of SM the rotating ref franme can be fixed to the daxis .Recall this d axis carries the field which is already excited via slip rings or pm so we dont need vd to excite a rotating field , we need only vq to produce the orthogonal torque component of flux.

3. In case of IM it is alittle more complex as the rotor carries no

current say at synch speed , the rotating flux has to be developed by both vd and vq (depending on ref frame fixed to stator flux or rotor flux both id and iq will have to be manipulated). In other words for an intuitive idea consider approx

a simple single phase IM circuit with just xm and r2/s . The stator current will consist of im and ir . ir is determined by both wsynch and slip at a particular mech wr . If we wish to simulate this as a dc motor in the rotating ref frame then we neeed to manipulate both vd and vq .

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