US3611086A
Expired / Lapsed
US
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Integral carrier ratio inverter
Assignee: Reliance Electric Co
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Filing: 1970-01-14
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Granted: 1971-10-05
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Expires: 1990-01-14
Abstract
Abstract A pulse width modulated inverter is described wherein an integral ratio carrier is used, the carrier frequency dictating the on and off periods of thyristors in the inverter system and the modulation frequency on the carrier is the fundamental output frequency of the inverter determining the speed at which a motor connected to the inverter will run. A control signal having a variable maximum amplitude establishes a variable and high clock frequency which varies directly with the control signal. A frequency divider divides this clock frequency into a plurality of output signals each being a predetermined multiple or ratio of the modulation frequency. A carrier range switch means is a selecting means connected to different outputs of the frequency divider to be responsive to different outputs of the frequency divider to be responsive to different frequency ratios and to pass a selected signal to carrier generator means. The carrier generator output is applied to an integrator to develop an inverter thyristor gating signal. This controls the conduction periods of the thyristors to establish the modulation frequency output of the inverter. Synchronizing means is provided to establish changing from one frequency ratio to another at a time when the output of the carrier generator integrator is at zero and at a time when the frequency divider outputs are zero, thereby to minimize current surges in the output of the inverter.
Inventors
- 👤 Boris Mokrytzki
- 👤 Dennis L Szymanski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:08
CPC Classifications
H; H02; H02P; H02P29/00; H02P29/02; H02P29/032; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/525; H02M7/527; H02P29/50
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
91 words
An integral ratio carrier pulSe width modulated inverter system, comprising in combination; a variable control signal, ratio generating means generating a plurality of output signals at frequencies having an integral ratio with respect to the inverter output or modulation frequency, carrier generator means having an output of variable frequency, means dependent on said carrier generator means output to develop an inverter gating signal; and means selecting one of said different output signals of said ratio generating means in accordance with said control signal and applying same to said carrier generator means.
Claim 2
Dependent Claim
91 words
An integral ratio carrier pulSe width modulated inverter system, comprising in combination; a variable control signal, ratio generating means generating a plurality of output signals at frequencies having an integral ratio with respect to the inverter output or modulation frequency, carrier generator means having an output of variable frequency, means dependent on said carrier generator means output to develop an inverter gating signal; and means selecting one of said different output signals of said ratio generating means in accordance with said control signal and applying same to said carrier generator means.
Claim 3
Dependent Claim
19 words
An inverter system as set forth in claim 1, wherein said control signal has a variable maximum DC amplitude.
Claim 4
Dependent Claim
48 words
An inverter system as set forth in claim 2, wherein said control signal includes a linear volts with time unit having a linear rate of voltage amplitude increase to a limit value, said limit value being the variable maximum amplitude and establishing the selection of the frequency ratio.
Claim 5
Dependent Claim
21 words
An inverter system as set forth in claim 3, including a volts-to-frequency converter connected to said linear volts with time unit.
Claim 6
Dependent Claim
30 words
An inverter system as set forth in claim 1, wherein said selecting means includes a plurality of gating means each individually gated by different maximum amplitudes of said control signal.
Claim 7
Dependent Claim
53 words
An inverter system as set forth in claim 5, including a plurality of latch gates latched in a first logic condition, a plurality of bias signals, and comparator means in said selecting means comparing said control signal with the respective bias signal to actuate the respective latch gate to a second logic condition.
Claim 8
Dependent Claim
38 words
An inverter system as set forth in claim 6, including switching logic means in said selecting means to prevent skipping of frequency ratios in moving from increasing to decreasing ratios and in moving from decreasing to increasing ratios.
Claim 9
Dependent Claim
34 words
An inverter system as set forth in claim 1, including a motor energized by the output of said inverter system for operation at a speed determined by the fundamental output frequency of the inverter.
Claim 10
Dependent Claim
58 words
An inverter system as set forth in claim 1, wherein said ratio generating means includes a variable frequency clock generating a clock frequency of a predetermined integral multiple of the modulation frequency, and frequency divider means connected to said clock generating a plurality of output signals at frequencies having an integral ratio with respect to the modulation frequency.
Claim 11
Dependent Claim
36 words
An inverter system as set forth in claim 9, wherein said frequency divider means includes first and second series of flip-flops scaling down the frequency applied thereto by ratios of 1:2 in a sequence of steps.
Claim 12
Dependent Claim
75 words
An inverter system as set forth in claim 9, wherein said frequency divider means includes first and second series of flip-flops scaling down the frequency applied thereto by ratios of 1:2 in a sequence of steps, said first series scaling down said clock frequency by a ratio of 1:2, and said second series scaling down said clock frequency by a ratio of 1:3 on the first sequential step and then ratios of 1: 2 thereafter.
Claim 13
Dependent Claim
44 words
An inverter system as set forth in claim 1, including ring counter means connected to the output of said ratio generating means to develop a control signal of a three-phase, six-step wave form for basic control of the switching devices in the inverter system.
Claim 14
Dependent Claim
97 words
An inverter system as set forth in claim 2, including an integrator in said carrier generator means having a square wave input and generating an isosceles triangular wave output of variable frequency the maximum amplitude of which varies inversely with frequency, means generating a DC reference voltage, constant volts per Hertz means to change the relative value of said carrier generator means output and said reference voltage to maintain a substantially constant volts per Hertz, and comParator means to develop an inverter gating signal upon said output of said carrier generator means exceeding said DC reference voltage.
Claim 15
Dependent Claim
46 words
An inverter system as set forth in claim 1, including synchronizing means to establish changing from one frequency ratio to another at a time when the output of said carrier generator means is at zero to minimize current surges in the output of said inverter system.
Claim 16
Dependent Claim
42 words
An inverter system as set forth in claim 14, including latch gates in said selecting means, and said synchronizing means establishing a change from one frequency ratio to another at a time when all of said latch gates have a zero output.
Claim 17
Dependent Claim
53 words
An inverter system as set forth in claim 15, including ring counter means connected to the output of said ratio generating means, and said synchronizing means having an input from said ring counter means at a frequency equal to said modulation frequency and having a narrow synchronizing pulse output at said modulation frequency.
Claim 18
Dependent Claim
100 words
An inverter having switching devices, means to establish a control signal, a first path from said control signal means including means to establish a modulation frequency to control the switching rate of the switching devices in the inverter for the fundamental output frequency of the inverter, a second path from said control signal means including means to establish at least two different carrier frequencies each an integral multiple of the modulation frequency, and means to dynamically change from one carrier frequency to the other in accordance with a change in said control signal while retaining said modulation frequency substantially constant.
Claim 19
Dependent Claim
100 words
An inverter having switching devices, means to establish a control signal, a first path from said control signal means including means to establish a modulation frequency to control the switching rate of the switching devices in the inverter for the fundamental output frequency of the inverter, a second path from said control signal means including means to establish at least two different carrier frequencies each an integral multiple of the modulation frequency, and means to dynamically change from one carrier frequency to the other in accordance with a change in said control signal while retaining said modulation frequency substantially constant.
Claim 20
Dependent Claim
34 words
An inverter as set forth in claim 17, including means to change the relative amplitudes of the carrier and modulation frequencies to control the effective output voltage at said modulation frequency of the inverter.
Claim 21
Dependent Claim
22 words
An inverter as set forth in claim 17, including synchronization means to relatively synchronize said modulation frequency and said two carrier frequencies.
Claim 22
Dependent Claim
88 words
A pulse width modulated inverter having power switching devices, an output modulation frequency determining means, means to provide a carrier and a modulation frequency, means to compare said carrier and modulation voltages, means to control said power switching devices in accordance with said comparison means, means to change the relative amplitude of carrier frequency to modulation frequency thereby changing pulse width in output waveforms and thus controlling output voltage, and means to change said carrier to modulation frequency ratio while the inverter is supplying power to a load.
Claim 23
Dependent Claim
88 words
A pulse width modulated inverter having power switching devices, an output modulation frequency determining means, means to provide a carrier and a modulation frequency, means to compare said carrier and modulation voltages, means to control said power switching devices in accordance with said comparison means, means to change the relative amplitude of carrier frequency to modulation frequency thereby changing pulse width in output waveforms and thus controlling output voltage, and means to change said carrier to modulation frequency ratio while the inverter is supplying power to a load.
Claim 24
Dependent Claim
38 words
An inverter as set forth in claim 20, including means to change the relative amplitude of the carrier and modulation frequencies to provide substantially equal output voltage at the modulation frequency before and after the carrier frequency change.
Claim 25
Dependent Claim
18 words
An inverter as set forth in claim 20, including control means to synchronize said carrier and modulation frequencies.
Claim 26
Dependent Claim
29 words
An inverter as set forth in claim 22, wherein said synchronization means synchronizes said carrier and modulation frequencies at a neutral point of one phase of the output voltage.
Claim 27
Dependent Claim
19 words
An inverter as set forth in claim 20, wherein the input power voltage to the inverter is fixed voltage.
Claim 28
Dependent Claim
102 words
In a polyphase inverter having switching devices for a polyphase output to a load and a direct current input voltage, polyphase pattern generating means to generate a conduction pattern for the switching devices at a modulation frequency, a carrier frequency generator capable of developing a carrier frequency signal, said carrier frequency being synchronized with the zero crossover point of one of the outputs of the pattern generating means, said carrier frequency being an integral multiple of the modulation frequency, said carrier frequency being changeable to other multiples of the modulation frequency, and means to dyNamically change from one carrier ratio to another.
Claim 29
Dependent Claim
102 words
In a polyphase inverter having switching devices for a polyphase output to a load and a direct current input voltage, polyphase pattern generating means to generate a conduction pattern for the switching devices at a modulation frequency, a carrier frequency generator capable of developing a carrier frequency signal, said carrier frequency being synchronized with the zero crossover point of one of the outputs of the pattern generating means, said carrier frequency being an integral multiple of the modulation frequency, said carrier frequency being changeable to other multiples of the modulation frequency, and means to dyNamically change from one carrier ratio to another.
Claim 30
Dependent Claim
23 words
An inverter as set forth in claim 25, including synchronizing means to synchronize the carrier and modulation frequencies at a zero crossover point.
Claim 31
Dependent Claim
30 words
An inverter as set forth in claim 26, including means to maintain synchronization between the carrier and modulation frequencies by making the carrier ratio change at the zero crossover point.
Claim 32
Dependent Claim
33 words
An inverter as set forth in claim 25, including means to change the relative magnitude of the carrier and modulation frequency outputs thereby controlling the switching devices in each phase of the inverter.
Claim 33
Dependent Claim
48 words
An inverter as set forth in claim 25, including means to adjust the relative amplitude of the modulation and carrier frequencies at the time of carrier ratio change so that the fundamental component of the inverter output modulation frequency has a minimum variation at the carrier ratio change.
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) | 1974-10-04 | 1975-04-05 | 1975-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-04 | 1979-04-05 | 1979-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-04 | 1983-04-05 | 1983-10-05 | $7700.00 | Window Closed / Lapsed |