US3569805A
Expired / Lapsed
US
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Synchronizing circuit
Assignee: Reliance Electric Co
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Filing: 1968-08-28
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Granted: 1971-03-09
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Expires: 1988-08-28
Abstract
Abstract A synchronizing circuit for use especially with a pulse width modulated inverter wherein a carrier establishes the pulsed conduction periods of the inverter in accordance with a reference voltage at a lower frequency which determines the fundamental frequency at which the inverter output voltage is supplied. This voltage may be supplied to an AC motor which runs at a speed corresponding to this fundamental frequency. The inverter may energize the motor at variable frequencies for variable speed hence the reference frequency is variable and the carrier frequency may not be an integral multiple thereof. Accordingly the present circuit shows a means to synchronize the reference with the carrier twice each cycle of the reference voltage. A shortened carrier period is provided so that this shortened carrier period plus a plurality of normal carrier periods equals a synchronizing interval; namely, one-half of the reference voltage cycle. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.
Inventors
- 👤 Peter W Hammond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:30
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/28
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
135 words
A synchronizing circuit for two different frequencies, means establishing a carrier frequency signal, means establishing a reference voltage of lower frequency, said reference voltage having a synchronizing interval proportional to the period thereof, there being a plurality of cycles of the carrier frequency in one synchronizing interval and the carrieR frequency being other than an integral multiple of the reference voltage frequency, means for synchronizing the carrier and reference voltages once each synchronizing interval including, first means establishing said carrier signal as a train of repetitive cycles and each having a normal carrier period, second means establishing a corrected carrier period of a time interval different from the normal carrier period by a feedback from the phase of a previous carrier period to supply a correction to the frequency of a subsequent corrected carrier period.
Claim 2
Dependent Claim
135 words
A synchronizing circuit for two different frequencies, means establishing a carrier frequency signal, means establishing a reference voltage of lower frequency, said reference voltage having a synchronizing interval proportional to the period thereof, there being a plurality of cycles of the carrier frequency in one synchronizing interval and the carrieR frequency being other than an integral multiple of the reference voltage frequency, means for synchronizing the carrier and reference voltages once each synchronizing interval including, first means establishing said carrier signal as a train of repetitive cycles and each having a normal carrier period, second means establishing a corrected carrier period of a time interval different from the normal carrier period by a feedback from the phase of a previous carrier period to supply a correction to the frequency of a subsequent corrected carrier period.
Claim 3
Dependent Claim
52 words
A synchronizing circuit as set forth in claim 1 wherein said synchronizing circuit is for an inverter to operate an alternating current motor at a varying speed by applying thereto a voltage at a variable frequency proportional to said reference frequency, and said reference frequency being variable to vary the motor speed.
Claim 4
Dependent Claim
30 words
A synchronizing circuit as set forth in claim 2 wherein said motor has a substantially constant speed relative to the frequency applied thereto and variable with the variable reference frequency.
Claim 5
Dependent Claim
16 words
A synchronizing circuit as set forth in claim 1 wherein the exponent is greater than unity.
Claim 6
Dependent Claim
30 words
A synchronizing circuit as set forth in claim 1 wherein said difference between the normal and corrected carrier periods is proportional to the square of the duration of the correction.
Claim 7
Dependent Claim
22 words
A synchronizing circuit as set forth in claim 1 wherein said exponent is established by a means to integrate the frequency signal.
Claim 8
Dependent Claim
33 words
A synchronizing circuit as set forth in claim 1 wherein the corrected carrier period is established by subtracting a term from the normal carrier period proportional to an exponential function of the error.
Claim 9
Dependent Claim
21 words
A synchronizing circuit as set forth in claim 7 wherein the exponential function is proportional to the square of the error.
Claim 10
Dependent Claim
27 words
A synchronizing circuit as set forth in claim 1 wherein the synchronizing interval is proportional to one-half the period of the reference voltage and symmetry is preserved.
Claim 11
Dependent Claim
29 words
A synchronizing circuit as set forth in claim 1 wherein the carrier frequency is other than an integral multiple of the reference voltage frequency for many different reference frequencies.
Claim 12
Dependent Claim
32 words
A synchronizing circuit as set forth in claim 1 wherein said carrier signal is established as a train of repetitive triangular wave cycles at the carrier frequency during the normal carrier periods.
Claim 13
Dependent Claim
22 words
A synchronizing circuit as set forth in claim 1 wherein there is a plurality of corrected carrier periods in each synchronizing interval.
Claim 14
Dependent Claim
33 words
A synchronizing circuit as set forth in claim 1 wherein the corrected carrier period differs from the normal carrier period by algebraically adding a term thereto proportional to the square of the error.
Claim 15
Dependent Claim
25 words
A synchronizing circuit as set forth in claim 1 including means to start the synchronizing interval at each time the reference voltage goes to zero.
Claim 16
Dependent Claim
79 words
A synchronizing circuit as set forth in claim 1 wherein said means establishing said carrier frequency signal includes: a linear voltage with time unit to establish during the normal carrier periods a constant DC voltage and to establish during the corrected carrier periods a voltage increasing at a given rate; and a voltage to frequency converter to establish a repetitive train of triangular wave cycles whose frequency is proportional to the voltage from the linear voltage with time unit.
Claim 17
Dependent Claim
15 words
A synchronizing circuit as set forth in claim 15 wherein said converter includes an integrator.
Claim 18
Dependent Claim
23 words
A synchronizing circuit as set forth in claim 1, wherein said second means includes a means to vary the carrier voltage with time.
Claim 19
Dependent Claim
24 words
A synchronizing circuit as set forth in claim 1, wherein said second means includes a means to vary the carrier voltage exponentially with time.
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) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |