US3919610A
Expired / Lapsed
US
⏱️ 0.0 years remaining
AC motor speed control
Assignee: Unitron Inc USA
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Filing: 1974-11-13
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Granted: 1975-11-11
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Expires: 1994-11-13
Abstract
Abstract A system for generating drive signals for a three-phased motor is disclosed. The system includes an integrator driving a threshold circuit which together operate as a voltage control oscillator providing a triangular output waveform. Timing circuitry provides AC coupled signals to an input of the integrator to vary time intervals within the triangular output waveform. Additional circuitry is disclosed which adds the triangular output waveform to timing signals to provide a composite waveform. A comparator circuit is disclosed which compares the composite waveform with a DC reference speed determining signal which is also applied to the integrator. The output of the comparator circuit is combined with timing signals to provide drive signals for the three-phased induction motor.
Inventors
- 👤 Jimmie D Gillett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:23
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/047
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
176 words
In a device for supplying drive voltages, having a fundamental frequency controlled by a speed determining signal, to a multi-phase motor: means responsive to said speed determining signal for providing a time base signal having a first predetermined number of transitions for each cycle of said fundamental frequency, thereby providing a second predetermined number of time intervals within each of said cycles of said fundamental frequency; means responsive to said time base signal for generating a composite waveform in which the amplitude of said composite waveform in a first of said second predetermined number of time intervals varies between a first value and a second value and in a second of said second predetermined number of time intervals between a third value and a fourth value; and means responsive to said speed determining signal and said composite waveform for generating said drive voltage; the improvement comprising: means for controlling the duration of said first of said second predetermined number of time intervals to be different than said second of said second predetermined number of time intervals.
Claim 2
Dependent Claim
176 words
In a device for supplying drive voltages, having a fundamental frequency controlled by a speed determining signal, to a multi-phase motor: means responsive to said speed determining signal for providing a time base signal having a first predetermined number of transitions for each cycle of said fundamental frequency, thereby providing a second predetermined number of time intervals within each of said cycles of said fundamental frequency; means responsive to said time base signal for generating a composite waveform in which the amplitude of said composite waveform in a first of said second predetermined number of time intervals varies between a first value and a second value and in a second of said second predetermined number of time intervals between a third value and a fourth value; and means responsive to said speed determining signal and said composite waveform for generating said drive voltage; the improvement comprising: means for controlling the duration of said first of said second predetermined number of time intervals to be different than said second of said second predetermined number of time intervals.
Claim 3
Dependent Claim
88 words
In the device defined in claim 1 in which said means for controlling the duration of said first of said second predetermined number of time intervals controls the duration of said first of said second predetermined number of time intervals so that the ratio of the difference between said first and second values to said first value is an integer multiple of the ratio of said duration of said first of said second predetermined number of time intervals to the duration of 1/6 cycle of said fundamental frequency.
Claim 4
Dependent Claim
13 words
In the device as defined in claim 2 in which said integer is
Claim 5
Dependent Claim
19 words
In the device as defined in claim 2 in which said second value is equal to said third value.
Claim 6
Dependent Claim
70 words
In the device as defined in claim 4 in which the amplitude of said composite waveform in a third of said second predetermined number of time intervals varies between said third value and said fourth value and the time duration of the sum of said second and third of said second predetermined number of time intervals equals the duration of said first of said second predetermined number of time intervals.
Claim 7
Dependent Claim
29 words
In the device as defined in claim 5 in which the difference between said first and second values is equal to the difference between said third and fourth values.
Claim 8
Dependent Claim
15 words
In the device as defined in claim 6 in which said whole number is 1.
Claim 9
Dependent Claim
66 words
In the device as defined in claim 1 in which said means for providing a time base signal is a control signal responsive oscillator circuit and said means for controlling the duration of said first of said second predetermined number of time intervals includes means for AC coupling a control signal to said oscillator circuit during said first of said seconD predetermined number of time intervals.
Claim 10
Dependent Claim
21 words
In the device as defined in claim 8 in which said oscillator circuit provides a triangular waveform having a fixed amplitude.
Claim 11
Dependent Claim
21 words
In the device as defined in claim 9 in which said oscillator circuit includes an integrator and a level sensing circuit.
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) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |