Motor/generator

Two rotors (3,4) and one stator (2) are arranged coaxially. The stator (2) comprises a coil unit (6) which produces, by the supply of a first alternating current, the same number of rotating magnetic fields as the number of magnetic poles of said first rotor (3), and, by the supply of a second alternating current, the same number of rotating magnetic fields as the number of magnetic poles of said second rotor (4). A composite current of said first and second alternating currents is supplied to said coil unit (6), and a circuit (15) is provided for compensating torque fluctuation due to non-uniformity of the magnetic field accompanying the relative rotation of the two said rotors (3, 4).

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What is claimed is:

1. A motor/generator comprising:

a first rotor comprising plural magnetic poles and supported free to rotate,

a second rotor comprising plural magnetic poles and supported free to rotate coaxially with said first rotor,

a stator fixed co-axially with said first rotor,

a coil unit comprising plural coils disposed at equal angular intervals on said stator, wherein said coil unit forms plural rotating magnetic fields of equal number to the number of magnetic poles of said first rotor according to a firstalternating current and forms plural rotating magnetic fields of equal number to the number of magnetic poles of said second rotor according to a second alternating current,

an electrical circuit for supplying a composite electrical current comprising said first alternating current and said second alternating current to said coil unit, and

a circuit for compensating a torque fluctuation produced in either of said two rotors due to the non-uniformity of the magnetic field accompanying the relative rotation of said first rotor and second rotor.

2. A motor/generator as defined in claim 1, wherein said compensating circuit is configured to compensate said torque fluctuation by adding an amplitude modulation to an alternating current forming said composite current which produces thetorque fluctuation.

3. A motor/generator as defined in claim 1, wherein said rotor which suffers the torque fluctuation comprises an extra coil for generating a magnetic force according to supply of a direct current, and said compensating circuit is furtherconfigured to compensate said torque fluctuation by periodically varying the voltage of said direct current.

4. A motor/generator as defined in claim 1, wherein the number of magnetic poles of said first rotor is set to any number other than twice the number of magnetic poles of said second rotor.