Inverter oscillator with current feedback

• US 4,127,797 A
• Filed: 09/19/1977
• Issued: 11/28/1978
• Est. Priority Date: 04/04/1977
• Status: Expired due to Term

• Current Assignee: Clark Engineering Incorporated
• Original Assignee: IOTA Engineering Incorporated
• Inventors: Perper, Lloyd J.
• Primary Examiner(s): Chatmon, Jr., Saxfield
• Application Number:
  US05/824,440
• Time in Patent Office: 435 Days
• Field of Search: 331/113 A, 315/DIG. 2, 315/DIG. 5, 315/DIG. 7, 315/276, 315/101, 315/105, 315/106, 315/107, 315/279, 315/206, 315/209
• US Class Current: 315/209.00R
• CPC Class Codes: H02M 3/3385 with automatic control of output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H05B 41/2855 against abnormal lamp operating conditions
• CPC Class Codes: Y10S 315/05 Starting and operating circuit for fluorescent lamp
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

A power source for operating gas discharge lamps and other loads at high frequency, typically utilizing a 120 volt ac source rectified to provide a 150 volt dc input and providing a 20,000 hertz output. An inverter with current feedback in place of the conventional voltage feedback providing voltage turn off and voltage turn on in less time and providing increased base current during the conduction time for reducing the voltage-current product and heat generated in the inverter. Voltage limiting and current limiting features are provided for the basic circuit. Inverter circuits with two transistors for increased loads are also provided.

Claims

1. In a high frequency power supply system for supplying power to a gas discharge lamp load or the like, including inverter means connected across a pair of direct-current input terminal means, said inverter means including an oscillator circuit including a first transistor having base, emitter and collector electrodes, and a first transformer having primary and secondary windings;

the improvement which comprises

(a) a second transformer (T2) having first (12;

     27) and second windings;

(b) said first transistor (Q1) including an emitter-to-collector circuit connected in series with said primary winding (10) to define a series path which is connected across the input terminal means;

(c) a starter resistor (R1) connected at one end with the base electrode of said first transistor, the other end of said starter resistor being connected with one end of said primary winding;

(d) a second resistor (R2) and first diode means (D1) connected in series between one end of said second winding (13) and the base electrode of said first transistor, the other end of said second winding being connected with one of the emitter and collector electrodes of said first transistor;

(e) second diode means (D2, D3) connected across said second winding, the polarities of said first and second diode means being such that when said second winding has alternate states of energization, said second winding is connected in series with, and isolated from, the circuit defined between the base electrode and one of the emitter and collector electrodes of said first transistor, respectively; and

(f) means connecting said first winding (12;

     27) in series with one (10;

     11) of said primary and secondary windings of said first transformer (T1).

2. In a high frequency power supply system for supplying power to a gas discharge lamp load or the like, including inverter means connected across a pair of direct-current input terminal means, said inverter means including an oscillator circuit including a first transistor, having base, emitter and collector electrodes, and a first transformer having primary and secondary windings;

the improvement which comprises

(a) a second transformer having first (12) and second (13) windings joined at one end by a junction, said primary winding (10), the emitter-to-collector circuit of said first transistor, and said first winding being connected successively in series to define a series path connected across the direct-current input terminal means;

(b) a starter resistor (R1) connected at one end with the base electrode of said first transistor, the other end of said starter resistor being connected with one end of said primary winding;

(c) a second resistor (R2) and first diode means (D1) connected in series between the other end of said second winding and the base electrode of said first transistor; and

(d) second diode means (D2, D3) connected across said second winding, the polarities of said first and second diode means being such that when said second winding has alternate states of energization, said second winding is connected in series with, and isolated from, the circuit between said base electrode and one of the collector and emitter electrodes of said first transistor, respectively.

3. Apparatus as defined in claim 2, and further including

(e) a second transistor (Q2) having an emitter-to-collector circuit connected across the remote ends of said first (12) and second (13) windings, said second transistor also including a base electrode;

(f) said first transformer including a feedback winding (20); and

(g) first rectifier and voltage threshold circuit means (D4, R3, Z1) connecting one end of said feedback winding with the base electrode of said second transistor, the other end of said feedback winding being connected with one of the collector and emitter electrodes of said second transistor.

4. Apparatus as defined in claim 3, and further wherein

(h) said second transformer includes a third winding (21) connected at one end with the end of said first winding (12) remote from said second winding;

and

(i) second rectifier and voltage threshold control means (D6, R4, Z2) connecting the other end of said third winding with the base electrode of said second transistor.

5. Apparatus as defined in claim 2, and further including

(e) a second transistor (Q2) having an emitter-to-collector circuit connected between the remote ends of said first and second windings, said second transistor also including a base electrode;

(f) said second transformer including a third winding (21) connected at one end with the remote end of one of said first and second windings; and

(g) rectifier and voltage threshold control means (D6, R4, Z2) connecting the other end of said third winding with the base electrode of said second transistor.

6. Apparatus as defined in claim 2, and further including a second transistor (Q1a) including base, emitter, and collector electrodes connected with the base, emitter, and collector electrodes of said first transistor (Q1).

7. Apparatus as defined in claim 6, and further including a pair of resistors connecting the base electrodes of said first and second transistors, respectively, in series with said starter resistor (R1).

8. Apparatus as defined in claim 2, and further including

(e) a second transistor (Q2) having an emitter-to-collector circuit connected between the remote ends of said first and second windings, said second transistor also having a base electrode;

(f) a third transistor (Q3) having an emitter-to-collector circuit connected between the base electrode and one of said emitter and collector electrodes of said second transistor, said third transistor also having a base electrode;

(g) said first transformer including a feedback winding (20); and

(h) rectifier and voltage control means (D4, Z1, R8, R9, Z3) connecting one end of said feedback winding with the base electrode of one of said second and third transistors, the other end of said feedback winding being connected with the base electrode of the other of said second and third transistors.

9. Apparatus as defined in claim 8, wherein said rectifier and voltage control means further includes filter means.

10. Apparatus as defined in claim 8, wherein said second transformer further includes a third winding (21) connected at one end with the remote end of one of said first and second windings and connected at the other end with one of said collector and emitter electrodes of said second transistor.

11. Apparatus as defined in claim 2, and further including

(e) a second transistor (Q4), and primary winding (10) and the emitter-to-collector circuit of said second transistor being connected to define a series path connected across the direct-current input terminal means;

(f) voltage threshold control means (Z4) connecting the base electrode of said second transistor with said junction of said first (12) and second (13) windings; and

(g) impedance means (R10) connecting the base electrode of said second transistor and one of said direct-current input terminal means.

12. In a high frequency power supply system for supplying power to a gas discharge lamp load or the like, including inverter means connected across a pair of direct-current input terminal means, said inverter means including an oscillator circuit including a first transistor having base, emitter and collector electrodes, and a first transformer having primary (10), secondary (11) and feedback (24) windings, said feedback winding being connected between said base electrode and one of said input terminal means;

the improvement which comprises

(a) impedance means (L) connected in series with said primary winding and the emitter-to-collector circuit of said first transistor to define a series path connected across the direct-current input terminal means;

(b) a second transistor (Q4) including an emitter-to-collector circuit connected in parallel across the series branch including said impedance means and the emitter to collector circuit of said first transistor, said second transistor including also a base electrode; and

(c) voltage threshold control means (Z4) connecting the base electrode of said second transistor with the junction of said emitter-to-collector circuit of said first transistor and said impedance means.

13. Apparatus as defined in claim 12, wherein said impedance means comprises an inductance.

14. In a high frequency power source for a load such as gas discharge lamps, and having an inverter with oscillator circuit and first transformer, said first transformer having primary and secondary windings, said oscillator including a first transistor, the improvement comprising in combination:

a second transformer having first and second windings, with said first winding connected in series with said secondary winding and lamps, and with said primary windings connected in series with said first transistor emitter and collector across a pair of dc input terminals;

a starter resistor connected between the base of said transistor and one of said input terminals across said primary winding;

a first diode and second resistor connceted in series between the base of said transistor and said second winding;

second diode means; and

means connecting said second diode means across said second winding.

15. A power source as defined in claim 14 wherein said second diode means includes two diodes connected in series.