Predicting the torque of a switched reluctance machine from its finite element field solution

The discretization errors that affect the accuracy of the calculated torque of a switched reluctance machine (SRM) from its finite-element solution are examined. A significant improvement in the accuracy of the computed flux density and torque fan be obtained with a reasonably fine mesh in the air gap by selecting properly shaped and uniform triangular elements. The computed torque/angle characteristic will be smooth and accurate when the proper mesh model is preserved as the rotor is rotated. A reasonably accurate value of the torque can be obtained from three different methods: the global virtual work method, the Maxwell stress-tensor method, and the Coulomb virtual work method. The computed torque/angle characteristics of a 4 kW SRM are generated from the three methods. The computed characteristics are checked against the measured torque/angle characteristics.>