US3585489A
Expired / Lapsed
US
⏱️ 0.0 years remaining
A low-frequency ac reference generator with inherently balanced controllable output voltage
Assignee: Westinghouse Electric Corp
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Filing: 1969-06-20
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Granted: 1971-06-15
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Expires: 1989-06-20
Abstract
Abstract The invention comprises a low-power variable frequency AC generator with inherently controllable output voltage means and inherent phase reversal capabilities. The AC generator includes switching circuits which are controlled by the output pulses of an adjustable frequency pulse generator to establish the period within which each phase of a polyphase voltage source is in conduction. Additional control circuitry is provided to subdivide the period allotted for each phase conduction into a conduction and nonconduction subperiods to thereby control the amplitude of the output voltage waveform. The adjustable frequency pulse generator is controlled by a DC voltage and the frequency of the output pulses is proportional to this voltage.
Inventors
- 👤 Brian R Pelly
- 👤 Laszlo Gyugyi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:14
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/02; H02M5/04; H02M5/22; H02M5/25; H02M5/27; H02M5/271
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
193 words
A polyphase, variable frequency, sinusoidal waveform generator for producing low-power, balanced, reference waveforms comprising, a plurality of switching element sets, each set including mulTiple switching elements, an alternating-current input voltage source of at least one phase, each phase of said input voltage operatively connected to at least one of the switching elements in each of said switching element sets, an adjustable frequency pulse generator means having an input and an output terminal, said input terminal connected to a voltage excitation source, first circuit means responsive to the output of said adjustable frequency pulse generator and connected to said switching element sets for actuating combinations of said switching elements, the period of actuation of said switching element combinations determined by the output pulses of said pulse generator, the actuation of said switches generating a sinusoidal reference waveform, second circuit means associated with said first circuit means to determine periods of conduction of said actuated switches within said actuation period, the amplitude of the reference waveform being a function of the duration of the conduction periods of said switching elements, said adjustable frequency pulse generator providing for selective phase sequence reversal of the reference waveform.
Claim 2
Dependent Claim
193 words
A polyphase, variable frequency, sinusoidal waveform generator for producing low-power, balanced, reference waveforms comprising, a plurality of switching element sets, each set including mulTiple switching elements, an alternating-current input voltage source of at least one phase, each phase of said input voltage operatively connected to at least one of the switching elements in each of said switching element sets, an adjustable frequency pulse generator means having an input and an output terminal, said input terminal connected to a voltage excitation source, first circuit means responsive to the output of said adjustable frequency pulse generator and connected to said switching element sets for actuating combinations of said switching elements, the period of actuation of said switching element combinations determined by the output pulses of said pulse generator, the actuation of said switches generating a sinusoidal reference waveform, second circuit means associated with said first circuit means to determine periods of conduction of said actuated switches within said actuation period, the amplitude of the reference waveform being a function of the duration of the conduction periods of said switching elements, said adjustable frequency pulse generator providing for selective phase sequence reversal of the reference waveform.
Claim 3
Dependent Claim
59 words
A combination of claim 1 including filter means associated with said switching element sets to filter the harmonic content of the reference waveform generated during the conduction periods to provide for an undistorted sinusoidal reference waveform, said harmonic content being a function of the frequency of the input voltage waveform and the frequency of the generated reference voltage waveform.
Claim 4
Dependent Claim
53 words
The combination as claimed in claim 1 wherein the displacement of the pulses generated by said second circuit means relative to the pulses generated by said adjustable frequency pulse generator is adjustable to provide control of the conduction periods of said switching elements and consequently control of the amplitude of the reference waveform.
Claim 5
Dependent Claim
81 words
The combination as claimed in claim 1 wherein said second circuit means includes an adjustable time delay circuit having an input and an output terminal, said input terminal connected to the output terminal of said adjustable frequency pulse generator, said time delay circuit being responsive to the output pulses of said adjustable frequency pulse generator and generating output pulses at a selected delay time interval, said pulse generator pulses initiating the switch actuation period, said delay pulses determining said conduction periods.
Claim 6
Dependent Claim
75 words
The combination as claimed in claim 1 wherein said first circuit means includes a multistage counter circuit having an input terminal and a plurality of output terminals, each output terminal corresponding to a stage of said counter circuit, said input terminal connected to the output of said adjustable frequency pulse generator, the output pulses of said adjustable frequency pulse generator incrementing the stages of said counters, the output of said counter actuating said switch elements.
Claim 7
Dependent Claim
35 words
The combination as claimed in claim 1 including circuit means for maintaining the limits of the conduction periods of said switching element combinations within the limits of the actuating period of said switching element combination.
Claim 8
Dependent Claim
42 words
The combination as claimed in claim 1 including logic means for actuating to a closed condition switching elements corresponding to the same input phase during the portion of the actuation period not occupied by conduction periods, all other switching elements remaining opened.
Claim 9
Dependent Claim
21 words
The combination as claimed in claim 1 including isolating circuit means interposed between said first circuit means and said switching elements.
Claim 10
Dependent Claim
28 words
The combination as claimed in claim 1 wherein the frequency of the reference waveform is a function of the output pulse rate of said adjustable frequency pulse generator.
Claim 11
Dependent Claim
28 words
The combination as claimed in claim 1 wherein the phase reversal capability of the adjustable frequency pulse generator is a function of the polarity of the excitation voltage.
Claim 12
Dependent Claim
53 words
The combination as claimed in claim 1 wherein the relationship of output waveform frequency to pulse generator frequency and input voltage source frequency is represented as where fo is output waveform frequency, f1 is input voltage source frequency, fp is pulse generator frequency and n is the number of phases of input voltage.
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) | 1974-06-14 | 1974-12-14 | 1975-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-14 | 1978-12-14 | 1979-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-14 | 1982-12-14 | 1983-06-15 | $7700.00 | Window Closed / Lapsed |