The principal objective of this work was to establish the feasibility of the axial flux permanent magnet ac disc motor with load-commutated inverter as a candidate for an electric passenger vehicle drive system component.
Three motors were built in the course of the project. The first, known as the proof-of-principal (POP) motor, was built to demonstrate the electromagnetic concepts and establish design data. It was built with rare earth magnets and a dc motor type random winding. The second motor, known as the Functional Model A [FM(A)] motor, was built for full performance and high speed (11,000 rpm). Alnico 8E magnets were used to stimulate manganese-aluminum. A three-layer air gap winding was used in the stator. This motor did not perform as predicted due primarily to demagnetization of the magnets and, secondarily, to imbalance in the windings. The third motor, known as Functional Model B [FM(B)], corrected these problems by use of rare earth magnets and a novel, single-layer chain winding. The motor performed well and in excess of contract requirements electromagnetically, thermally, and mechanically. A peak efficiency of 93% was measured at cycling power when the motor was being driven by the inverter. Several modifications were proposed to raise the efficiency to 95%.