For the purpose of comparison, the system stability is
also studied by assuming that the PM brushless drive is
represented by an ideal Constant Power Load (CPL), and the
resulting variation of the dominant pair of eigenvalues is
shown in Fig. 9. In this case, the system experiences
instability when the load torque reaches 5Nm as opposed to
~7.8Nm in Fig. 8 when the drive dynamics are fully
accounted for. Thus the constant power load assumption
leads to a lower stability margin and