Variable speed induction motor
OwnerLouis W. Parkerinventor
Life of this patent
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Abstract
A polyphase motor of the wound rotor type has the rotor of a polyphase generator, smaller in size than said motor, mounted on the motor shaft. Polyphase voltages produced across the generator rotor are coupled to the input of an amplifier having an output power commensurate with the size of the motor and the amplifier output is connected to the windings of the motor rotor to supply the current to the motor rotor windings. The frequency of the voltage fed to the motor rotor is inversely proportional to the motor speed, and a frequency sensitive filter is provided to adjust the output of the amplifier thereby to control the motor speed and to maintain said speed at a selected predetermined value regardless of the motor load.
Claims22
A motor system comprising a polyphase induction motor having a first wound stator and a first wound rotor mounted on a rotatable shaft for rotation adjacent said first stator, a polyphase generator having the same number of poles as said motor, said generator comprising a second wound stator and a second wound rotor mounted for rotation adjacent said second stator, the horsepower rating of said generator being less than that of said motor, means mechanically coupling said second rotor to said rotatable shaft to cause rotation of said first rotor to rotate said second rotor at the same rotational speed, a polyphase power source connected in parallel to both of said wound stators for energizing said stators in phase with one another with sinewave shaped voltages of like magnitude, a polyphase linear amplifier, rectifier power supply means disposed between said polyphase power source and said amplifier for energizing said amplifier with substantially D.C. power, said amplifier having its inputs connected to the windings of said second rotor, the outputs of said linear amplifier being connected to the windings of said first rotor whereby the polyphase sinewave shaped output voltages generated across the windings of said second rotor are amplified by said linear amplifier and supplied as amplified sinewave shaped voltages respectively to the windings of said first rotor to control the current flow in the windings of said first rotor.
A motor system comprising a polyphase induction motor having a wound stator and a wound rotor mounted for rotation adjacent said stator, a first polyphase power source connected to said stator windings for energizing said stator to produce a rotating magnetic field adjacent said rotor, a second polyphase power source comprising a dynamoelectric machine connected to said motor for rotation therewith and operative to supply sinewave shaped polyphase output voltages having the same phase as but a smaller amplitude than the sinewave shaped polyphase voltages which are induced in said motor rotor windings by said rotating magnetic field, a linear polyphase amplifier coupled to said machine for amplifying the polyphase output voltages of said dynamoelectric machine, means for connecting said amplified polyphase voltages to the windings of said induction motor wound rotor respectively, and means for selectively producing a phase difference between the amplified sinewave shaped polyphase voltages which are connected from said amplifier to said rotor windings and the sinewave shaped polyphase voltages which are induced in said rotor windings by said rotating field to produce a torque between the rotor and stator of said motor.
A variable speed motor system comprising a polyphase induction motor having a first wound stator and a first wound rotor mounted on a rotatable shaft for rotation adjacent said first stator, a polyphase generator having the same number of poles as said motor, said generator comprising a second wound stator and a second wound rotor mounted for rotation adjacent said second stator, the horsepower rating of said generator being less than that of said motor, means mechanically coupling said generator rotor to said rotatable shaft to cause rotation of said motor rotor to rotate said generator rotor at the same rotational speed, a polyphase power source connected in parallel to both of said wound stators for energizing said stators in phase with one another with sinewave-shaped voltages of like magnitude, polyphase linear amplifier means having its inputs connected to the windings of said generator rotor and its outputs connected to the windings of said motor rotor whereby the sinewave-shaped output voltages generated across the windings of said generator rotor are amplified by said amplifier means and supplied to the windings of said motor rotor to control the current flow in the windings of said motor rotor, frequency sensitive means coupled to the output of said generator rotor for monitoring the frequency of the voltages which are supplied to the inputs of said amplifier means, and means responsive to the output of said frequency sensitive means for controlling the magnitude of voltages at the output of said amplifier means thereby to regulate the rotational speed of said induction motor.
Dependencies are inferred from the claim text.