Design and experimental verification of a direct-drive interior PM synchronous machine using a saturable lumped-parameter model

This paper presents the design and experimental verification of a 6 kW interior permanent magnet (IPM) synchronous machine intended for an automotive direct-drive starter/alternator application. The machine was designed using a saturable lumped-parameter magnetic circuit model in combination with a Monte Carlo optimization process that minimized the machine-plus-converter cost. An experimental IPM machine has been constructed based on the resulting design specifications. Laboratory tests have confirmed the accuracy of the analytical models for predicting the q-axis inductance L/sub q/ (including saturation effects) and the torque production characteristics, but discrepancies between the predicted and measured d-axis inductance L/sub d/ were revealed. The impact of these differences on machine performance is discussed, as well as potential adjustments in the IPM analytical model to improve the performance of future machines.