Inverter circuits

• US 4,677,345 A
• Filed: 05/11/1981
• Issued: 06/30/1987
• Est. Priority Date: 08/14/1980
• Status: Expired due to Term

• Current Assignee: Ole K Nilssen
• Original Assignee: Ole K Nilssen
• Inventors: Nilssen, Ole K.
• Primary Examiner(s): Chatmon, Saxfield
• Application Number:
  US06/262,542
• Time in Patent Office: 2,241 Days
• Field of Search: 315/53, 315/DIG.4, 315/DIG. 5, 315/DIG. 7, 315/209, 315/219, 315/220, 315/240, 315/276, 315/278, 315/279, 331/113 A
• US Class Current: 315/209.00R
• CPC Class Codes: H02M 7/53832 in a push-pull arrangement
• CPC Class Codes: H03K 3/30 using a transformer for feedback, e.g. blocking oscillator
• CPC Class Codes: H05B 41/245 for a plurality of lamps
• CPC Class Codes: H05B 41/28 using static converters
• CPC Class Codes: H05B 41/2827 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: H05B 41/295 with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
• CPC Class Codes: H05B 41/38 Controlling the intensity of light
• CPC Class Codes: H05B 41/3925 by frequency variation H05B41/3922 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

High-efficiency inverter circuits, particularly half-bridge devices, are especially suitable for energizing gas discharge lamps. The inverters preferably employ a series-connected combination of an inductor and a capacitor to be energized upon periodic transistor conduction. Transistor drive current is preferably provided through the use of at least one saturable inductor to control the transistor inversion frequency to be equal to or higher than the natural resonant frequency of the inductor and capacitor combination. The inverters can develop high output voltages to supply external loads connected to the inductor-capacitor combinations.

Claims

1. A power supply operable to energize a gas discharge lamp at adjustable illumination levels, comprising:

an inverter circuit having at least one periodically conducting transistor in circuit with a DC voltage input and being operable to provide an AC voltage output;

frequency dependent impedance means connected in circuit between the AC voltage output and the lamp; and

an AC current output operable to connect with

control means connected with the inverter circuit and operative to control the transistor inversion frequency and correspondly;

(i) the impedance of the frequency dependent impedance means, and (ii) the magnitude of the AC current supplied to the lamp;

the control means being separate from and independent of the frequency dependent impedance means.

2. The power supply of claim 1 wherein the controlling means comprises a saturable inductor means.

3. The power supply of claim 2 wherein the saturable inductor means has an adjustable saturation flux density for control of its saturation time.

4. A lamp unit operable to be powered from a source of AC voltage, said source having a pair of output terminals and an internal substantially inductive source impedance, said AC voltage being of frequency substantially higher than that of the voltage on an ordinary electric utility power line, said lamp unit comprising:

a gas discharge lamp with a pair of electrodes;

capacitor means connected in circuit between said electrodes, said capacitor means being substantially resonant with said inductive source impedance at the fundamental frequency of said AC voltage;

connect means operative to permit disconnectable connection of said electrodes with said output terminals;

whereby, when the lamp unit is indeed so connected, there is reasonant interaction between said capacitor means and said inductive source impedance; and

structure means operative to support and integrate into a single mechanical entity said gas discharge lamp, said capacitor means, and said connect means;

whereby, when said lamp unit is physically removed from said output terminals, said capacitor means is also physically removed therefrom.

5. A system for powering a gas discharge lamp, said lamp having a pair of electrodes with a shunting means connected thereacross, said system comprising:

a source of DC voltage;

an inverter circuit connected with said DC voltage and having a pair of output terminals, said inverter circuit;

(i) being rendered operative as an inverter whenever output current is permitted to flow between said output terminals, thereby providing an AC voltage of relatively high frequency across said output terminals, and (ii) being rendered inoperative as an inverter whenever output current is prevented from flowing between said output terminals, thereby preventing said AC voltage from appearing across said output terminals; and

connect means operative to disconnectably connect said lamp in circuit across said output terminals, whereby;

(i) whenever said lamp with its shunting means is connected thereacross, said shunting means is operative to permit output current to flow, thereby rendering said inverter circuit operative to provide said AC voltage across said output terminals and thereby operable to start and power said lamp, and (ii) whenever said lamp with its shunting means is not connected thereacross, said inverter circuit is rendered inoperative as an inverter thereby ensuring that no AC voltage is provided across said output terminals.

6. The system of claim 5 wherein the magnitude of the impedance of said shunting means is comparable to that of the impedance of the lamp when lighted.

7. A ballasting means for a gas discharge lamp, comprising:

a source of DC voltage;

an inverter means connected with said DC voltage and operative to provide an AC voltage at a set of output terminals, said AC voltage being of frequency substantially higher than that of the voltage on an ordinary electric utility power line, said inverter means comprising at least one periodically conducting transistor connected in circuit with a saturable inductor means, said saturable inductor means being operative to determine the conduction period of said periodically conducting transistor;

tank circuit means having an inductor and a capacitor connected in circuit with said output terminals, said tank circuit having a natural resonance frequency; and

connect means operative to permit connection of said lamp with said tank circuit, thereby effectively to provide starting voltage and operating power for said lamp;

whereby said tank circuit and said saturable inductor means co-operate to determine the frequency of said AC voltage, the length of said conduction period being determinative of the amount of operating power provided to said lamp.

8. The ballasting means of claim 7 wherein said conduction period is approximately equal to or shorter than half of the period of said natural resonance frequency.

9. The ballasting means of claim 7 and means for adjustably varying said conduction period, thereby permitting adjustment of the amount of power provided to said lamp.

10. An assembly comprising:

a gas discharge lamp having a pair of lamp electrodes; and

a mechanical structure secured to said lamp and containing;

(i) a screw-base adapted for insertion into an Edison-type lamp socket, said screw-base having a pair of base electrodes, (ii) an inverter type power supply connected in circuit between said base electrodes and said lamp electrodes and operable to provide AC starting voltage and operating power for said lamp, the starting voltage and operating power being provided at a frequency substantially higher than that of the voltage on an ordinary electric utility power line, and (iii) adjust means connected in circuit with said power supply and operable to permit manual adjustment of the magnitude of the operating current;

thereby to combine said gas discharge lamp, said screw base, said inverter type power supply, and said adjust means into a single substantially rigid mechanical lamp unit having manually operable means for adjusting the light output provided therefrom.

11. An assembly comprising:

a gas discharge lamp having a pair of lamp electrodes; and

a mechanical structure secured to said lamp and containing;

(i) screw-base adapted for insertion into an ordinary Edison-type lamp socket, said screw-base having a pair of base electrodes, (ii) frequency converter means, said converter means connected in circuit with said base electrodes and comprising at least one periodically conducting transistor and being operable to provide an AC voltage at a set of output terminals, the frequency of the AC voltage being substantially higher than that of the voltage on an ordinary electric utility power line, (iii) an L-C circuit connected with said output terminals, the L-C circuit being resonant at or near the fundamental frequency of the AC voltage, (iv) connect means operative to connect said lamp electrodes in circuit with said L-C circuit, and (v) adjust means operative to permit manual adjustment of the magnitude of current provided to said lamp.

12. A lamp assembly for use with a source of AC voltage having a substantially reactive internal impedance, said AC voltage being of frequency substantially higher than that of the voltage on an ordinary electric utility power line, said lamp assembly comprising:

a gas discharge lamp having two electrodes;

reactive shunt impedance means connected in circuit between said electrodes and having a reactance that, at the fundamental frequency of said AC voltage, is substantially the conjugate of that of said internal impedance;

connect means operative to permit disconnectable connection of said electrodes with said scource of AC voltage; and

structure means operative to support and integrate into a single mechanical structure said lamp, said reactive shunt impedance means, and said connect means;

whereby;

(i) whenever said lamp assembly is connected with said source, resonant or near-resonant action takes place, while (ii) whenever said lamp assembly is disconnected from said source, such resonant or near-resonant action is prevented from taking place.

13. The system of claim 12 wherein said AC voltage is provided by way of an inverter, and wherein said inverter ceases to provide said AC voltage whenever said lamp assembly is disconnected from said source.

14. A system for powering a gas discharge lamp, comprising:

a source of DC voltage;

an inverter connected with said DC voltage and providing an AC voltage at a set of output terminals, said inverter having temperature responsive control means by which the frequency of said AC voltage is operative to be changed as a function of the degree of heating supplied to said control means, the frequency of the AC voltage being substantially higher than that of the voltage on an ordinary electric utility power line; and

frequency responsive impedance means connected in circuit between said output terminals and said lamp, and operative to limit the magnitude of the current supplied to said lamp, the magnitude of the current supplied being a function of the frequency of said AC voltage;

whereby said lamp is operative to provide light output to a degree that is a function of the degree of heating provided to said control means.

15. A lighting system comprising:

a source of AC voltage, said source having a substantially reactive internal source impedance and a set of source output terminals, said AC voltage being of frequency substantially higher than that of the voltage present on an ordinary electric utility power line; and

a gas discharge lamp, said lamp having;

(i) a pair of lamp electrodes with a substantially reactive lamp impedance connected therebetween, and (ii) connect means operable to permit disconnectable connection between said electrodes and said output terminals;

said lamp impedance being;

(a) of substantially conjugate impedance value as compared with said source impedance at the fundamental frequency of said AC voltage, and (b) physically and non-disconnectably attached to said lamp electrodes;

whereby resonant or near-resonant action takes place whenever said lamp is connected with said source, thereby providing for effective lamp starting voltage and operating current;

yet, whenever said lamp is disconnected from said source, no such resonant or near-resonant action takes place.

16. The system of claim 15 wherein said source impedance comprises an inductor means and wherein said lamp impedance comprises a capacitor means.

17. A system for powering a gas discharge lamp, comprising:

a source of DC voltage;

an inverter connected with said DC voltage and providing an AC voltage at a set of output terminals, the AC voltage being of frequency substantially higher than that of the voltage on an ordinary electric utility power line, said inverter having at least one periodically conducting transistor connected in circuit with a temperature-responsive control means operative to control the length of the conduction time of said transistor;

heating means in thermal connection with said control means and operative to control the temperature thereof; and

reactive impedance circuit connected between said output terminals and said lamp and co-operative to determine the amount of current provided to said lamp, said magnitude of the current supplied also being dependent on the length of said transistor conduction time;

whereby the light output of said lamp can be controlled by way of said heating means.

18. A lamp assembly adapted to be screwed into and powered from an ordinary Edison-type lamp socket, comprising:

a gas discharge lamp having a pair of electrodes;

a source of AC voltage, the frequency of this AC voltage being substantially higher than that of the voltage present on an ordinary electric utility power line;

impedance means connected in circuit between said source of AC voltage and said gas discharge lamp and operative to determine the magnitude of the power provided thereto;

adjust means operative to permit manual control of the impedance exhibited by said impedance means, thereby permitting manual control of the amount of power provided to said gas discharge lamp; and

structural means operative to support and hold together said gas discharge lamp, said source of AC voltage, said impedance means, and said adjust means;

whereby the degree of light output provided by said gas discharge lamp can be manually adjusted by way of said adjust means.

19. The system of claim 18 wherein said impedance means comprises a reactor means, and wherein said adjust means comprises means for mechanically adjusting the magnitude of the reactance of said reactor means.