| 摘要 |
A brushless permanent magnet motor has a rotor constructed of spaced ferromagnetic backirons and a circumferential array of alternating polarity magnetic poles that drive magnetic flux back and forth across an armature air gap between the backirons. A stator includes an air core armature in the air gap with three-phase windings. An inverter includes a pulse-modulated semiconductor H-bridge that switches and regulates power to the three-phase windings to drive the rotor. Harmonic losses in the motor caused by ripple currents generated by the higher pulse switching frequency in electronic variable speed drives, due to the inherently lower inductance of air core motors, are substantially reduced by adding serial inductance between the motor and drive. The H-bridge is serially electrically connected to the three-phase armature windings through three inductors that employ a low cost powder core. Each of the inductors provides an inductance that is greater than twice the value of the leg inductance of the three-phase windings.
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