US3740629A
Expired / Lapsed
US
⏱️ 0.0 years remaining
A.c. motor drive circuit
Assignee: Individual
•
Filing: 1971-03-11
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Granted: 1973-06-19
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Expires: 1991-03-11
Abstract
Abstract A synchronous self-starting motor is driven with constant rotational velocity in response to current fed to an excitation winding thereof from a D.C. power source. Switch means is responsive to gating voltages derived from a time reference source having first and second consecutive time periods. During the two time periods, current is smoothly flowing with constantly changing slope in a series circuit including the excitation winding and a capacitor. The relative length of each period and the natural frequency of the drive circuit and excitation winding are equal to or less than the average frequency of the time reference source to achieve a sine-like voltage waveform across the capacitor. The switching means can be either like or complementary type transistors, having the ability to conduct current in either direction when forward biased, as well as electromechanical switches or vacuum tubes with shunting diodes. A flywheel is freely mounted relative to the motor shaft to assist in maintaining constant rotational velocity of the shaft. The first and second time periods can be of the same duration or of different durations as long as approximately the same force is applied to the motor rotor during each period. the same force is applied to the motor rotor during each period.
Inventors
- 👤 W Kohlhagen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:17
CPC Classifications
G; G04; G04C; G04C3/00; G04C3/16; G04C3/14; G04D; G04D3/00; G04D3/0074; H; H02; H02P; H02P25/00; H02P25/02; H02P25/022; H02P25/024
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
236 words
A system for driving a synchronous motor, having an excitation winding means, from a DC source and a time reference source means, said motor being driven at constant rotational velocity over a possible wide range of component values relative to nominal values thereof, comprising: capacitance means connected in series circuit with said winding; switch means controlled in response to said time reference source for alternately connecting said series circuit (a) to be responsive to said DC source during a first time period of said time reference source so that a single peak current amplitude is derived in said series circuit during said first period, and (b) in a path during a second time period of said reference source so that a single peak current amplitude is derived in said series circuit during said second period, said first and second time periods immediately following one after the other, said two peak currents being oppositely directed; the capacity of the capacitance means, inductance of the winding means and the length of each of said periods of said time reference source means being such that current in the series circuit has a waveform always having a changing slope between the beginning and end of each of said time periods and the maximum voltage across the capacitance means during each of the periods is less than the voltage of the DC source for all of said range of component values.
Claim 2
Independent Claim
236 words
A system for driving a synchronous motor, having an excitation winding means, from a DC source and a time reference source means, said motor being driven at constant rotational velocity over a possible wide range of component values relative to nominal values thereof, comprising: capacitance means connected in series circuit with said winding; switch means controlled in response to said time reference source for alternately connecting said series circuit (a) to be responsive to said DC source during a first time period of said time reference source so that a single peak current amplitude is derived in said series circuit during said first period, and (b) in a path during a second time period of said reference source so that a single peak current amplitude is derived in said series circuit during said second period, said first and second time periods immediately following one after the other, said two peak currents being oppositely directed; the capacity of the capacitance means, inductance of the winding means and the length of each of said periods of said time reference source means being such that current in the series circuit has a waveform always having a changing slope between the beginning and end of each of said time periods and the maximum voltage across the capacitance means during each of the periods is less than the voltage of the DC source for all of said range of component values.
Claim 3
Dependent Claim
76 words
The circuit of claim 1 wherein said switch means includes first and second switching elements connected in another series circuit across opposite polarity terminals of the DC source, and means, including the time reference source, for activating said first switching element into a coNducting state while activating the second switching element into a cut-off state and for activating said second switching element into a conducting state while activating the first switching element into a cut-off state.
Claim 4
Dependent Claim
19 words
The circuit of claim 2 wherein each of said switching elements is a transistor of the same conductivity type.
Claim 5
Dependent Claim
19 words
The circuit of claim 2 wherein each of said switching elements is a transistor of the opposite conductivity type.
Claim 6
Dependent Claim
15 words
The circuit of claim 2 wherein each of said switching elements is a bipolar transistor.
Claim 7
Dependent Claim
49 words
The circuit of claim 2 wherein each of said switching elements is a metal oxide semiconductor field effect transistor, and the time reference source applies gating voltages to the transistors so that one transistor is activated into a conducting state as the other transistor is being driven to cut-off.
Claim 8
Dependent Claim
75 words
The circuit of claim 2 wherein each of said switching elements includes: a first unidirectional conducting device, each of said devices having a control electrode responsive to said means for activating, a second unidirectional device shunting the first unidirectional device poled to pass current from the series circuit in the opposite direction from the first unidirectional device, said second device being rendered conductive in response to the voltage developed across it by the series circuit.
Claim 9
Dependent Claim
161 words
The circuit of claim 1 wherein the switch means includes a bidirectional conducting device having: a first terminal connected to one electrode of the DC source, a second terminal connected to a second electrode of the DC source and one end of the series circuit, and an electromechanical switching element responsive to the time reference source for successively and alternately connecting said first and second terminals to the other end of the series circuit, first diode means connected between the other end of the series circuit and said first terminal for enabling current to flow between the one end of the series circuit and the first terminal only in a first direction, and second diode means connected between the other end of the series circuit and said second terminal for enabling current to flow between the one end of the series circuit and the second terminal only in a second direction, said first and second directions being opposite to each other.
Claim 10
Dependent Claim
22 words
The combination of claim 1 further including a flywheel freely mounted about said shaft to form an inertia disc for the shaft.
Claim 11
Dependent Claim
69 words
The circuit of claim 1 wherein the durations of at least some of said first and second time periods differ from each other, the relative durations of said periods changing over number of cycles of the source so that the average durations of the first and second periods are substantially equal, and further including a flywheel freely mounted on the shaft to form an inertia means for the shaft.
Claim 12
Dependent Claim
19 words
The circuit of claim 1 wherein the durations of said first and second time periods are substantially the same.
Claim 13
Dependent Claim
167 words
A combination adapted to be driven by a DC power source comprising: synchronous motor means having excitation winding means; a time reference source generating an output having a predetermined frequency; a capacitor connected in series circuit with said winding means; said capacitor and winding means having a possible wide range of values relative to nominal values thereof; circuit means responsive to the time reference source and DC power source for causing currents derived from the DC power source and having opposite polarity peak amplitudes and a waveform with always changing slope to flow in said series circuit during alternate half cycles of the time reference source, the nominal value of the capacitor being such that the natural frequency of said series circuit is less than the frequency of the time reference source over said range of values, whereby the motor is driven at constant rotational velocity over said range of values, the value of said current being sufficiently great to provide self starting for the motoR means.
Claim 14
Dependent Claim
167 words
A combination adapted to be driven by a DC power source comprising: synchronous motor means having excitation winding means; a time reference source generating an output having a predetermined frequency; a capacitor connected in series circuit with said winding means; said capacitor and winding means having a possible wide range of values relative to nominal values thereof; circuit means responsive to the time reference source and DC power source for causing currents derived from the DC power source and having opposite polarity peak amplitudes and a waveform with always changing slope to flow in said series circuit during alternate half cycles of the time reference source, the nominal value of the capacitor being such that the natural frequency of said series circuit is less than the frequency of the time reference source over said range of values, whereby the motor is driven at constant rotational velocity over said range of values, the value of said current being sufficiently great to provide self starting for the motoR means.
Claim 15
Dependent Claim
37 words
The combination of claim 12 wherein the synchronous motor means includes a plurality of excitation windings connected in parallel with each other, each of said windings being coupled in exciting relationship with a different synchronous motor rotor.
Claim 16
Dependent Claim
58 words
The circuit of claim 12 wherein the motor means includes an output shaft and further comprising an automobile clock indicating means, and gear means connecting the shaft to drive the indicating means, said clock being capable of operating over a temperature range of between approximately -40*F. and +175*F., said components having low tolerances and not being temperature compensated.
Claim 17
Dependent Claim
189 words
A circuit for energizing excitation winding means of synchronous motor means from a DC source at a frequency determined by the frequency of a periodic source comprising a capacitor connected in series circuit with said winding means, said capacitor and winding means having a possible wide range of values relative to nominal values thereof, the nominal value of the capacitor being such that the series circuit has a natural frequency less than the frequency of the periodic source over said range of values, switch means responsive to the periodic source for alternately connecting at the frequency of the periodic source said series circuit with the DC source so that currents having opposite polarity, substantially instantaneous peak amplitudes and a waveform with always changing slope flow in the series circuit during alternate half cycles of the periodic source, peak voltages developed across said capacitor during each half cycle being less than the voltage of the DC source applied to the series circuit, said switch means including means for conducting current during each half cycle in a direction opposite to the direction of the peak amplitude current during the half cycle.
Claim 18
Dependent Claim
189 words
A circuit for energizing excitation winding means of synchronous motor means from a DC source at a frequency determined by the frequency of a periodic source comprising a capacitor connected in series circuit with said winding means, said capacitor and winding means having a possible wide range of values relative to nominal values thereof, the nominal value of the capacitor being such that the series circuit has a natural frequency less than the frequency of the periodic source over said range of values, switch means responsive to the periodic source for alternately connecting at the frequency of the periodic source said series circuit with the DC source so that currents having opposite polarity, substantially instantaneous peak amplitudes and a waveform with always changing slope flow in the series circuit during alternate half cycles of the periodic source, peak voltages developed across said capacitor during each half cycle being less than the voltage of the DC source applied to the series circuit, said switch means including means for conducting current during each half cycle in a direction opposite to the direction of the peak amplitude current during the half cycle.
Claim 19
Dependent Claim
94 words
The circuit of claim 15 wherein the switch means includes a pair of switching elements each having a control electrode, said periodic source being a square wave reference time source connected to said control electrodes for alternately activating only one of the switching elements into a conducting condition at a time, each of said switching elements having bidirectional current carrying capabilities when actuated into a conducting condition in response to the periodic source, each of said switching elements being actuated into a conducting condition substantially simultaneously with the other switching element being cut off.
Claim 20
Dependent Claim
16 words
The circuit of claim 16 wherein each of the switching elements is a field effect transistor.
Claim 21
Dependent Claim
95 words
The circuit of claim 15 wherein the switch means includes a pair of switching elements each having a control electrode, said periodic source being a reference time source connected to said control electrodes for alternately actuating only one of the switching elements into a conducting condition at a time, each of said switching elements including unidirectional current conducting means rendered into a conducting state only in response to voltages generated in the series circuit for conducting the current during each half cycle opposite to the direction of the peak amplitude current during the half cycle.
Claim 22
Dependent Claim
15 words
The circuit of claim 18 wherein each of the switching elements comprises a bipolar transistor.
Claim 23
Dependent Claim
49 words
The circuit of claim 18 wherein each of the switching elements comprises: a unidirectional current carrying device having the control electrode, a diode shunting the device, said diode and element being poled and connected to said series circuit to conduct current flowing in the series circuit in opposite directions.
Claim 24
Dependent Claim
160 words
The circuit of claim 15 wherein the switch means includes a bidirectional conducting device having: a first terminal connected to one electrode of the DC source, a second terminal connected to a second electrode of the DC source and one end of the series circuit, and an electromechanical switching element responsive to the periodic source for successively And alternately connecting said first and second terminals to the other end of the series circuit, first diode means connected between the other end of the series circuit and said first terminal for enabling current to flow between the one end of the series circuit and the first terminal only in a first direction, and second diode means connected between the other end of the series circuit and said second terminal for enabling current to flow between the one end of the series circuit and the second terminal only in a second direction, said first and second directions being opposite to each other.
Claim 25
Dependent Claim
37 words
The combination of claim 15 wherein the synchronous motor means includes a plurality of excitation windings connected in parallel with each other, each of said windings being coupled in exciting relationship with a different synchronous motor rotor.
Claim 26
Independent Claim
259 words
A system for driving a synchronous motor having an excitation winding means from a DC source and a time reference source means, said motor being driven at constant rotational velocity over a possible wide range of component values relative to nominal values thereof, comprising: capacitance means connected in series circuit with said winding; switch means controlled in response to said time reference source for alternately connecting said series circuit (a) to be responsive to said DC source during a first time period of said time reference source so that a single peak current amplitude is derived in said series circuit during said first period, and (b) in a path during a second time period of said reference source so that a single peak current amplitude is derived in said series circuit during said second period, said first and second time periods immediately following one after the other, said two peak currents being oppositely directed; the capacity of the capacitance means, inductance means of the winding and the length of each of said periods of said time reference source means being such that: current in the series circuit has a waveform always having a changing slope between the beginning and end of each of said time periods, there is a substantial current flowing in the circuit at the end of each period, and the maximum voltage across the capacitance means during each of the periods is less than the voltage of the DC source for all of said values; and means for providing a discharge path for said substantial current.
Claim 27
Independent Claim
259 words
A system for driving a synchronous motor having an excitation winding means from a DC source and a time reference source means, said motor being driven at constant rotational velocity over a possible wide range of component values relative to nominal values thereof, comprising: capacitance means connected in series circuit with said winding; switch means controlled in response to said time reference source for alternately connecting said series circuit (a) to be responsive to said DC source during a first time period of said time reference source so that a single peak current amplitude is derived in said series circuit during said first period, and (b) in a path during a second time period of said reference source so that a single peak current amplitude is derived in said series circuit during said second period, said first and second time periods immediately following one after the other, said two peak currents being oppositely directed; the capacity of the capacitance means, inductance means of the winding and the length of each of said periods of said time reference source means being such that: current in the series circuit has a waveform always having a changing slope between the beginning and end of each of said time periods, there is a substantial current flowing in the circuit at the end of each period, and the maximum voltage across the capacitance means during each of the periods is less than the voltage of the DC source for all of said values; and means for providing a discharge path for said substantial current.
Claim 28
Dependent Claim
83 words
The circuit of claim 23 wherein the durations of at least some of said first and second time periods differ from each other, the relative durations of said periods changing over a number of cycles of the source so that the average durations of the first and second periods are substantially equal, and further including a flywheel freely mounted on the shaft to form an inertia means for the shaft, whereby a shaft of the motor means is driven with constant rotational velocity.
Claim 29
Dependent Claim
83 words
The circuit of claim 23 wherein the durations of at least some of said first and second time periods differ from each other, the relative durations of said periods changing over a number of cycles of the source so that the average durations of the first and second periods are substantially equal, and further including a flywheel freely mounted on the shaft to form an inertia means for the shaft, whereby a shaft of the motor means is driven with constant rotational velocity.
Claim 30
Dependent Claim
32 words
The circuit of claim 23 wherein the durations of said first and second time periods are substantially the same, whereby a shaft of the motor means is driven with constant rotational velocity.
References Cited (Backward Citations)
US3379946A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |