Patent US3577057A successfully refreshed from Google Patents.
US3577057A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for controlling the speed of a motor utilizing pulse width modulation
Assignee: Boeing North American Inc
•
Filing: 1969-09-26
•
Granted: 1971-05-04
•
Expires: 1989-09-26
Abstract
Abstract An input voltage is summed with a voltage picked off from a polyphase motor for driving a voltage-controlled oscillator. The frequency of the output signal from the oscillator is dependent on the magnitude of the summed voltage. The pulse width is modified within a predetermined range as a function of the frequency and is converted into three phase signals which are summed and applied to the stator windings of a motor. The signal across the windings has an optimum voltage and frequency ratio which is varied when the speed of the motor is changed.
Inventors
- 👤 George A Dyer
- 👤 Emil Kohler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:08
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/045; H02P27/047
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
127 words
A system for controlling the speed of a polyphase motor, said system comprising: means for generating a voltage representing the difference between a command speed for said motor and the actual speed of said motor, voltage-controlled oscillator means responsive to said voltage for generating a signal having a frequency as a function of said voltage, means for generating polyphase signals from said signals, means for modifying the pulse width of said polyphase signals as a function of the pulse width of said signal, said pulse widths being modifiable over a range of widths with the maximum limit being fixed by the maximum speed of said motor, polyphase bridge means for providing a drive signal to said motor under the control of said modified pulse width polyphase signals.
Claim 2
Independent Claim
127 words
A system for controlling the speed of a polyphase motor, said system comprising: means for generating a voltage representing the difference between a command speed for said motor and the actual speed of said motor, voltage-controlled oscillator means responsive to said voltage for generating a signal having a frequency as a function of said voltage, means for generating polyphase signals from said signals, means for modifying the pulse width of said polyphase signals as a function of the pulse width of said signal, said pulse widths being modifiable over a range of widths with the maximum limit being fixed by the maximum speed of said motor, polyphase bridge means for providing a drive signal to said motor under the control of said modified pulse width polyphase signals.
Claim 3
Dependent Claim
18 words
The combination recited in claim 1 wherein said means for generating polyphase signals comprises a three-phase signal generator.
Claim 4
Dependent Claim
48 words
The combination recited in claim 2 wherein said means for modifying comprises a pulse width modulator for decreasing the width of said three phase signals from a maximum width representing the maximum speed of said motor to a minimum width representing the lowest operating speed of said motor.
Claim 5
Dependent Claim
42 words
The combination recited in claim 1 wherein said system further includes an oscillator responsive to said signal for generating a signal having a frequency six times that of the operating frequency of the motor for turning said bridge network off every 60*.
Claim 6
Dependent Claim
44 words
The combination recited in claim 1 wherein said polyphase bridge means includes a constant DC power pulse, and wherein the leading and trailing edges of the modified pulse width signals turn said bridge means on-and-off for varying the average power across the bridge means.
Claim 7
Dependent Claim
16 words
The combination recited in claim 1 wherein said bridge means has a variable DC power source.
Claim 8
Dependent Claim
63 words
The combination recited in claim 1 wherein said system further includes means for generating a signal to turn said bridge network off every 60 electrical degrees, and means responsive to said signal for enabling a capacitor to be charged after a short delay, means responsive to the capacitor voltage and said pulse width modified polyphase signals for supplying drive voltages to said motor.
Claim 9
Dependent Claim
33 words
The system recited in claim 7 further comprising a relatively high frequency signal generator means for providing an input to said bridge means to provide sharp turn on pulses for said bridge means.
References Cited (Backward Citations)
US3436635A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-03 | 1974-11-02 | 1975-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-03 | 1978-11-02 | 1979-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-03 | 1982-11-02 | 1983-05-04 | $7700.00 | Window Closed / Lapsed |