US3863121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Means for controlling the output condition of an induction motor
Assignee: Magnetek Inc
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Filing: 1973-03-02
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Granted: 1975-01-28
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Expires: 1993-03-02
Abstract
Abstract A motor control for controlling the output torque condition of an induction motor includes a first signal means for generating a torque command signal. A second signal means is coupled to the motor for providing a signal indicative of the rotor frequency of the motor. A stator winding energization means is coupled to both of the signal means for establishing a slip frequency in the motor in accordance with the torque command signal. A power supply means is coupled to the first signal means for regulating the magnitude of the stator current as predetermined functions of the torque command signal. The phase displacement of the stator current may ne altered as a predetermined function of the torque command signal. By making the torque command signal proportional to speed error, the speed control of induction motors may also be obtained.
Inventors
- 👤 Charles E Rettig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:18
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P25/00; H02P25/02; H02P25/08; H02P25/092; H02P25/0925; H02P27/048; H02P3/00; H02P3/06; H02P3/065; H02P2207/00; H02P2207/01; H02P27/047
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
350 words
A motor control interposible between an electrical energy source and the stator winding of an induction motor having a flux producing exciting current and a stator current displaceable with respect thereto for controlling the torque developed by the motor, said control comprising: first signal means for generating a torque command signal indicative of the desired motor output torque condition independently of the existing torque condition of the motor; second signal means coupled to the motor for providing a signal indicative of the rotor frequency of the motor rotor; stator winding energization means connectable to the stator winding of the motor for energizing the stator winding with a cyclical stator current, said stator winding energization means including signal responsive stator current frequency establishing means, said frequency establishing means being coupled to said first and second signal means for providing a frequency characteristic to the stator current sufficient to establish the slip frequency of the motor proportional to the torque command signal said stator winding energization means further including a phase displacement establishing means for effecting a phase displacement of the stator current with respect to the exciting current; a second function generator interposed between said first signal means and said phase displacement establishment means and responsive to said torque command signal for providing a control signal to said phase displacement establishment means having a predetermined function with respect to said torque command signal for establishing the phase displacement of the stator current with respect to the exciting current by amounts tending to maintain desired flux levels in the motor; power supply means connectable to the electrical energy source and coupled to said stator winding energization means for providing an adjustable current to the stator winding energization means, said power supply means including a current regulation stabilizing inductor regulating the output current of said power supply means to a substantially desired magnitude; and stator current magnitude establishing means coupled to said first signal means and to said power supply means and responsive to said torque command signal for establishing the magnitude of the stator current as a predetermined function of said signal.
Claim 2
Dependent Claim
350 words
A motor control interposible between an electrical energy source and the stator winding of an induction motor having a flux producing exciting current and a stator current displaceable with respect thereto for controlling the torque developed by the motor, said control comprising: first signal means for generating a torque command signal indicative of the desired motor output torque condition independently of the existing torque condition of the motor; second signal means coupled to the motor for providing a signal indicative of the rotor frequency of the motor rotor; stator winding energization means connectable to the stator winding of the motor for energizing the stator winding with a cyclical stator current, said stator winding energization means including signal responsive stator current frequency establishing means, said frequency establishing means being coupled to said first and second signal means for providing a frequency characteristic to the stator current sufficient to establish the slip frequency of the motor proportional to the torque command signal said stator winding energization means further including a phase displacement establishing means for effecting a phase displacement of the stator current with respect to the exciting current; a second function generator interposed between said first signal means and said phase displacement establishment means and responsive to said torque command signal for providing a control signal to said phase displacement establishment means having a predetermined function with respect to said torque command signal for establishing the phase displacement of the stator current with respect to the exciting current by amounts tending to maintain desired flux levels in the motor; power supply means connectable to the electrical energy source and coupled to said stator winding energization means for providing an adjustable current to the stator winding energization means, said power supply means including a current regulation stabilizing inductor regulating the output current of said power supply means to a substantially desired magnitude; and stator current magnitude establishing means coupled to said first signal means and to said power supply means and responsive to said torque command signal for establishing the magnitude of the stator current as a predetermined function of said signal.
Claim 3
Dependent Claim
44 words
The motor control according to claim 1 wherein said stator current magnitude establishing means is further defined as means for establishing the stator current as a predetermined function of the torque command signal to magnitudes tending to maintain desired flux levels in the motor.
Claim 4
Dependent Claim
83 words
The motor control according to claim 2 wherein the power supply means is further defined as responsive to an input signal for adjusting the magnitude of the stator current in accordance therewith and wherein said stator current magnitude establishing means includes a first function generator interposed between said first signal means and said power supply means and responsive to said torque command signal for providing an input signal to said power supply means which is a predetermined function of the torque command signal.
Claim 5
Dependent Claim
39 words
The motor control according to claim 1 further defined as a speed control for the motor and wherein said first signal means is further defined as including means for providing a speed error signal as the torque command signal.
Claim 6
Dependent Claim
72 words
The motor control according to claim 4 wherein said first signal means includes means for providing a sIgnal indicative of a desired speed of the motor, means generating a signal indicative of the actual speed of the motor, and summing junction means receiving said desired speed signal and said actual speed signal for providing a torque command signal representative of the difference between said desired speed signal and said actual speed signal.
Claim 7
Dependent Claim
30 words
The motor control according to claim 5 including limiting means for coordinately limiting the magnitude of the stator current and the slip frequency of the motor under excessive torque conditions.
Claim 8
Dependent Claim
48 words
The motor control according to claim 5 including signal limiting means coupled to said summing junction means for limiting the magnitude of said torque command signal for coordinately limiting the magnitude of the stator current and the slip frequency of the motor under excessive torque command signal conditions.
Claim 9
Dependent Claim
39 words
The motor control according to claim 1 further defined as a speed control for the motor and wherein said first signal means is further defined as including means for providing a speed error signal as the torque command signal.
Claim 10
Dependent Claim
72 words
The motor control according to claim 8 wherein said first signal means includes means for providing a signal indicative of a desired speed of the motor, means generating a signal indicative of the actual speed of the motor, and summing junction means receiving said desired speed signal and said actual speed signal for providing a torque command signal representative of the difference between said desired speed signal and said actual speed signal.
Claim 11
Dependent Claim
33 words
The motor control according to claim 9 including limiting means for coordinately limiting the magnitude and phase displacement of the stator current and the slip frequency of the motor under excessive torque conditions.
Claim 12
Dependent Claim
50 words
The motor control according to claim 10 including signal means coupled to said summing junction means for limiting the magnitude of said torque command signal for coordinately limiting the magnitude and phase displacement of the stator current and the slip frequency of the motor under excessive torque command signal conditions.
Claim 13
Dependent Claim
33 words
The motor control according to claim 1 wherein said power supply means provides an adjustable unidirectional current to the stator winding energization means and wherein said stator winding energization means includes an inverter.
Claim 14
Dependent Claim
22 words
The motor control according to claim 12 wherein said inverter is further defined as being of the capacitor commutated, diode isolated type.
Claim 15
Dependent Claim
35 words
The motor control according to claim 12 having a plurality of inverters connectable to the stator winding of the motor and coupled to said power supply means for energizing the stator winding with cyclical current.
Claim 16
Dependent Claim
118 words
The motor control according to claim 12 for controlling the torque developed by the motor in both the motoring and regenerative modes of operation, the change from operation in the motoring mode to operation in the regenerative mode being accompanied by the reversal of the voltage polarity in the power supply means, and wherein said power supply means is so constructed as to provide a regulatable unidirectional current to said inverter regardless of the polarity of the voltage impressed on said power supply means, whereby said power supply means may supply adjustable current to the motor from the electrical energy source during motoring operation and supply energization from the motor to the electrical energy source during regenerative operation.
Claim 17
Dependent Claim
49 words
The motor control according to claim 12 connectable to an electrical energy source of the alternating current voltage type, wherein said power supply means includes thyristor means having conductive and a non conductive states for providing the adjustable unidirectional current by rectifying half cycles of the alternating current voltage.
Claim 18
Dependent Claim
47 words
The motor control according to claim 12 wherein the electrical energy source is a direct current voltage source and wherein said power supply means includes adjustable direct current voltage means Connectable to the direct current source for providing the adjustable unidirectional current of the power supply means.
Claim 19
Dependent Claim
123 words
The motor control means according to claim 17 for controlling the torque developed by the motor in the motoring and regenerative modes of operation, the change from operation in the motoring mode to operation in the regenerative mode being accompanied by a reversal of the voltage polarity in the power supply means, wherein said adjustable direct current voltage means is so constructed as to provide the adjustable unidirectional current to said inverter regardless of the polarity of the voltage impressed on said adjustable direct current voltage means, whereby said adjustable direct current voltage means may supply adjustable current from the direct current source to the motor during motoring operation and supply energization from the motor to the direct current source during regenerative operation.
Claim 20
Dependent Claim
31 words
The motor control according to claim 1 wherein said power supply means provides an adjustable unidirectional current to the frequency control means and wherein said frequency control means includes an inverter.
Claim 21
Dependent Claim
22 words
The motor control according to claim 19 wherein said inverter is further defined as being of the capacitor commutated, diode isolated type.
Claim 22
Dependent Claim
35 words
The motor control according to claim 19 having a plurality of inverters connectable to the stator winding of the motor and coupled to said power supply means for energizing the stator winding with cyclical current.
Claim 23
Dependent Claim
31 words
The motor control according to claim 1 wherein said power supply means includes current regulating circuitry for regulating the output current of the power supply means to substantially a desired magnitude.
Claim 24
Dependent Claim
30 words
The motor control according to claim 20 wherein said power supply means includes a current regulation stabilizing inductor interposed between said power supply means and said stator winding energization means.
Claim 25
Dependent Claim
118 words
The motor control according to claim 19 for controlling the torque developed by the motor in both the motoring and regenerative modes of operation, the change from operation in the motoring mode to operation in the regenerative mode being accompanied by the reversal of the voltage polarity in the power supply means, and wherein said power supply means is so constructed as to provide an adjustable unidirectional current to said inverter regardless of the polarity of the voltage impressed on said power supply means, whereby said power supply means may supply adjustable current to the motor from the electrical energy source during motoring operation and supply energization from the motor to the electrical energy source during regenerative operation.
Claim 26
Dependent Claim
50 words
The motor control according to claim 19 connectable to an electrical energy source of the alternating current voltage type, wherein said power supply means includes a thyristor means having a conductive and non conductive states for providing the adjustable unidirectional current by rectifying half cycles of the alternating current voltage.
Claim 27
Dependent Claim
47 words
The motor control according to claim 19 wherein the electrical energy source is a direct current voltage source and wherein said power supply means includes adjustable direct current voltage means connectable to the direct current source for providing the adjustable unidirectional current of the power supply means.
Claim 28
Dependent Claim
122 words
The motor control means according to claim 26 for controlling the torque developed by the motor in the motoring and regenerative modes of operation, the change from operation in the motoring modes operation in the regenerative mode being accompanied by a reversal of the voltage polarity in the power supply means, wherein said adjustable direct current voltage means is so constructed as to provide the adjustable unidirectional current to said inverter regardless of the polarity of the voltage impressed on said adjustable direct current voltage means, whereby said adjustable direct current voltage means may supply adjustable current from the direct cUrrent source to the motor during motoring operation and supply energization from the motor to the direct current source during regenerative operation.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |