Synchronous motor equivalent
circuit
A synchronous motor has the same
equivalent circuit as synchronous
generator, except that the direction of
power flow (and the direction of IA) is
reversed. Per-phase circuit is shown:
A change in direction of IA changes the Kirchhoff’s voltage law equation:
A S A A A V E jX I RI φ = + +
A S A A A E V jX I RI φ = − −
Therefore, the internal generated voltage is
We observe that this is exactly the same equation as the equation for the generator,
except that the sign on the current terms is reversed.