| 摘要 |
A multi-speed permanent magnet D.C. electric motor system 10 includes at least one permanent magnet DC electric motor 11 configured to operate at at least one speed. A current limiting device R 1 is constructed and arranged to lower electrical input power to the motor 11 so that a speed of the motor is reduced, when the motor is powered together with the current limiting device, as compared to a speed of the motor powered absent the current limiting device. Switching structure K 1 , K 2 , K 3 is associated with the current limiting device to selectively operate the motor at at least three discrete speeds, even though the motor is configured for at least one-speed operation.
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