This enhancement has been incorporated in Release 2010a (R2010a).
For previous product releases, the ability to use a DC permanent magnet motor block directly from a library is not available in SimPowerSystems.
To work around this issue:
You can use and modify the DC machine block to model a DC motor with permanent magnets. You can copy a DC Machine block (DC motor) in a new model, and then break the link to the library.
Note that the motor has two sets of electrical terminals: the armature (A+ A-) and the field armature (F+ F-). For the case of a permanent magnet DC motor, the field armature does not exist. Look under the mask of the block, note the Rf Lf and the iF current measurement block. In a permanent magnet model, the magnets provide a constant 'if' current to the model. Remove the F+ and F- terminals and all the blocks between them, then use a Constant block to feed the mechanical input 'if'. The constant value depends on the type of magnet used in the DC motor. The knowledge about the constant value and the type of magnet used will have to be obtained from the manufacturer sheet of the machine.
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