MATLAB: When modeling a Permanent Magnet Synchronous Machine in SimPowerSystems, how can I calculate Ld(H) and Lq(H) from one L

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I want to model a motor with the following parameters:
R between phase-phase [Ohm] = Ra = Rb = Rc
L between phase-phase [H] = La = Lb = Lc
Kt torque constant [Nm/A]
Ke back induced voltage [V/s]
How can I recalculate the one L value (La=Lb=Lc) into the values Ld(H) and Lq(H)?

Best Answer

The set of "preset parameters" for the Permanent Magnet Synchronous Machine (PMSM) was generated under the assumption that we are using round-rotor machines (as opposed to salient-pole), hence the simplification Ls = Ld = Lq holds. For sinusoidal distribution machines, this is generally the case.
If the datasheet provides an inductance bridge measurement across two
phases(lines), Ls = Lph-ph / 2.
Otherwise (salient-pole PMSM), Ld and Lq values, which are necessarily different, would be obtained from computations using the minimum and maximum values of phase-to-phase inductance, assuming the manufacturer supplies these two values. This tends to be rare.
The actual computation is more involved and information on this can be found in texts such as
:
"Analysis of Electric Machinery" by P.C.Krause, for more details.
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