Performance prediction in saturated variable reluctance and hybrid motors

Two methods of predicting the torque/rotor angular position characteristics of switched reluctance motors (SRMs), and both PM hybrid and variable reluctance (VR) stepping motors have been presented and compared. Known flux-linkage data forms the basis for the methods. Although experimental flux-linkage characteristics were used in this comparison, to concentrate attention on the methods, calculated characteristics have also been used with success. The static torque of the SRM or the stepping motor can be found by using any of the prediction methods with accuracy better than 5%. SRM running torque, produced by an idealised 50/50 square wave of current, can be predicted by using any of the methods with accuracy typically better than 2%. Reductions in the number of the flux-linkage data points can reduced CPU time if the polynomial fitting method is used. Both methods are capable of predicting these characteristics with good accuracy for each motor type. The purely numerical method is in addition very economical in terms of computation time. These features extend to the dynamic behaviour of the motor, both in steady state running and for true transients. The numerical method is recommended.<
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