US3846694A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Constant power supply employing a variable frequency inverter
Assignee: Individual
•
Filing: 1973-03-30
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Granted: 1974-11-05
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Expires: 1993-03-30
Abstract
Abstract A power supply useful for delivering substantially constant power to a plasma arc lamp or other load includes a variable frequency inverter having a substantially fixed pulse width. A constant power control circuit adjusts the inverter frequency to compensate for deviation of the output power away from a linear approximation of a constant power curve. In the control circuit, signals proportional to the output current and voltage are fed to a function generator which implements the linear approximation function. An error signal derived by comparing the function generator output with a reference voltage controls the frequency of an oscillator which in turn establishes the triggering rate of silicon controlled rectifiers (SCRs) in the inverter. The SCRs commutate off after a relatively constant time period, thus inverter output is proportional to the SCR triggering frequency. Cooperation of the control circuit and inverter maintains the supply output power at a constant level.
Inventors
- 👤 A Archer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:49
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/305; H02M3/315; H02M3/3155
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
86 words
A power supply having regulated power output, comprising: a power output stage including a variable frequency, substantially constant pulse width inverter for supplying dc power to a load, and constant power control circuit means for sensing deviation of the supply output power from a linear approximation of a constant power curve and for adjusting the frequency of said inverter to compensate for such sensed deviation, said control circuit and said output stage thereby cooperating to maintain the output power from said supply at a constant value.
Claim 2
Dependent Claim
86 words
A power supply having regulated power output, comprising: a power output stage including a variable frequency, substantially constant pulse width inverter for supplying dc power to a load, and constant power control circuit means for sensing deviation of the supply output power from a linear approximation of a constant power curve and for adjusting the frequency of said inverter to compensate for such sensed deviation, said control circuit and said output stage thereby cooperating to maintain the output power from said supply at a constant value.
Claim 3
Dependent Claim
66 words
A power supply according to claim 1 wherein said control circuit comprises; a function generator receiving signals proportional to the supply output voltage and current, said generator providing an output voltage which is of certain value if the supply output lies along said linear approximation, and means for adjusting the inverter frequency in response to variation of the function generator output away from said certain value.
Claim 4
Dependent Claim
50 words
A power supply according to claim 2 wherein said function generator implements the function Vf A(BVVo + VIo), wherein A and B are constants, wherein VVo and VIo are voltages proportional respectively to the supply output voltage and current, and where Vf is the output voltage obtained from said generator.
Claim 5
Dependent Claim
62 words
A power supply according to claim 3 wherein said means for adjusting the frequency comprises: an oscillator, means for supplying a reference voltage Vref equal to said certain value, means for controlling the frequency of said oscillator in response to the difference voltage between Vf and Vref, and means for changing the frequency of said inverter to correspond to said oscillator frequency.
Claim 6
Dependent Claim
44 words
A power supply according to claim 4 wherein said means for changing includes: a flip-flop toggled in response to the output of said oscillator, pulse supply means for providing trigger pulses to switching devices in said inverter in response to toggling of said flip-flop.
Claim 7
Dependent Claim
52 words
A power supply according to claim 1 wherein said inverter includes at least one semiconductive switching device which is switched on at a frequency established by said control circuit means, and which remains on for a substantially constant time duration less than the minimum period of the minimum frequency of said inverter.
Claim 8
Dependent Claim
29 words
A power supply according to claim 6 wherein said semiconductor switching device comprises a silicon controlled rectifier, said rectifier being commutated off by other circuit components of said inverter.
Claim 9
Dependent Claim
23 words
In combination, a power supply according to claim 1, together with a plasma arc lamp connected to receive constant power from said supply.
Claim 10
Dependent Claim
46 words
A power supply according to claim 2 and adapted for use with an arc lamp load, said supply further comprising; means for sensing when no current is supplied to said load, whereupon said output function generator is disabled and a starter for said lamp is enabled.
Claim 11
Dependent Claim
140 words
In a power supply of the type wherein rectified ac line voltage is provided to a high frequency inverter, the output of said inverter beinG supplied via a transformer and a rectifier to a load, the improvement for regulating said supply to obtain substantially constant output power wherein said inverter is of adjustable frequency, and comprising: function generator means for providing an output voltage Vf A(BVVo + VIo) in response to input voltages VVo and VIo proportional respectively to the output voltage and current supplied to said load, A and B being constants, an oscillator, error voltage means for controlling the frequency of said oscillator in response to the difference between said voltage Vf and a fixed reference voltage, and means, interconnecting said oscillator and said inverter, for adjusting the frequency of said inverter to correspond to said oscillator frequency.
Claim 12
Dependent Claim
140 words
In a power supply of the type wherein rectified ac line voltage is provided to a high frequency inverter, the output of said inverter beinG supplied via a transformer and a rectifier to a load, the improvement for regulating said supply to obtain substantially constant output power wherein said inverter is of adjustable frequency, and comprising: function generator means for providing an output voltage Vf A(BVVo + VIo) in response to input voltages VVo and VIo proportional respectively to the output voltage and current supplied to said load, A and B being constants, an oscillator, error voltage means for controlling the frequency of said oscillator in response to the difference between said voltage Vf and a fixed reference voltage, and means, interconnecting said oscillator and said inverter, for adjusting the frequency of said inverter to correspond to said oscillator frequency.
Claim 13
Dependent Claim
45 words
A power supply according to claim 10, wherein said oscillator comprises a relaxation oscillator, said oscillator frequency being established by the rate at which a capacitor is charged, and wherein said error voltage means controls said capacitor charging rate in response to said voltage difference.
Claim 14
Dependent Claim
40 words
A power supply according to claim 10, wherein said inverter utilizes at least one silicon controlled rectifier triggered on at a rate established by said oscillator frequency, and wherein said rectifier is commutated off after a relatively fixed time period.
Claim 15
Dependent Claim
86 words
A power supply according to claim 12, wherein said inverter utilizes a pair of silicon controlled rectifiers each commutated off after a relatively fixed time period, said means for adjusting comprising: a bistable multivibrator, said multivibrator being alternatively switched between its first and second stable states in response to pulses from said oscillator, and first and second triggering means each providing a triggering pulse to a respective one of said silicon controlled rectifiers when said multivibrator is switched into the respective first or second stable state.
Claim 16
Dependent Claim
100 words
A power supply according to claim 13, wherein said inverter comprises an inductor connected in series with said two silicon controlled rectifiers across the rectified ac line source, a pair of commutation capacitors connected in series across said rectified ac line source, and an output transformer having a primary winding connected between a tap on said inductor and the common junction of said commutation capacitors, the values of said inductor and said capacitors establishing said fixed time period during which each silicon controlled rectifier remains on, said time period being shorter than the period of said oscillator at maximum frequency.
Claim 17
Dependent Claim
28 words
A power supply according to claim 10, further comprising means for causing said oscillator to operate at maximum frequency when no current is being drawn by said load.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-04 | 1978-05-06 | 1978-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-04 | 1982-05-06 | 1982-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-04 | 1986-05-06 | 1986-11-05 | $7700.00 | Window Closed / Lapsed |