Controlled inverter-type fluorescent lamp ballast

• US 6,121,733 A
• Filed: 07/13/1994
• Issued: 09/19/2000
• Est. Priority Date: 06/10/1991
• Status: Expired due to Fees

• Current Assignee: Ole K Nilssen
• Original Assignee: Ole K Nilssen
• Inventors: Nilssen, Ole K.
• Primary Examiner(s): KINKEAD, ARNOLD M
• Application Number:
  US08/274,481
• Time in Patent Office: 2,260 Days
• Field of Search: 315/247, 315/226, 315/205, 315/DIG. 7, 315/DIG. 5, 315/219, 315/224, 363/37, 363/101, 363/16, 363/65, 363/71, 323/205, 323/206, 323/207
• US Class Current: 315/224
• CPC Class Codes: H05B 41/28 using static converters
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

Unfiltered full-wave-rectified 60 Hz power line voltage is supplied to a first self-oscillating series-resonance-loaded inverter, the high frequency output current from which is magnitude-controlled, rectified and used for maintaining a substantially constant-magnitude DC voltage on an energy-storing capacitor. This constant-magnitude DC voltage is used in combination with the unfiltered full-wave-rectified 60 Hz power line voltage for powering a second self-oscillating series-resonance-loaded inverter, the high frequency current output from which is used for powering a fluorescent lamp load. By frequency-modulating the first inverter at a 120 Hz rate, the current drawn from the power line is made to be of such waveshape as to result in a power factor well in excess of 90% while at the same time having a content of under 20% of odd triplets of third harmonic currents. The high frequency current provided to the fluorescent lamp load has a crest factor not in excess of 1.7.

Claims

1. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being characterized by;

(a) being operative to draw a low-frequency line current from the power line terminals;

(b) including an inverter sub-circuit powered from a unidirectional voltage whose instantaneous absolute magnitude is equal to the larger of;

(i) the absolute instantaneous magnitude of a substantially constant DC voltage; and

(ii) the absolute instantaneous magnitude of a sinusoidal voltage whose peak absolute magnitude is higher than that of the substantially constant DC voltage;

(c) being operative to draw current from the power line terminals even at times when the absolute instantaneous magnitude of the AC power line voltage is lower than that of the substantially constant DC voltage; and

(d) supplying a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the crest factor of the high-frequency lamp current being equal to or lower than 1.7.

2. The arrangement of claim 1 wherein the conditioner circuit is additionally characterized by being operative to cause the instantaneous magnitude of the low-frequency line current to be substantially proportional to the instantaneous magnitude of the AC power line voltage.

3. The arrangement of claim 1 wherein the conditioner circuit is additionally characterized by including at least two separate inverter circuits;

each inverter circuit having a pair of series-connected switching transistors.

4. The arrangement of claim 1 wherein the conditioner circuit is additionally characterized by including at least two separate inverter circuits;

each inverter circuit being operative to provide a non-sinusoidal output voltage across a pair of inverter output terminals;

the one inverter output voltage being substantially different from the other inverter output voltage.

5. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by;

(a) being operative to cause;

(i) the instantaneous magnitude of the low-frequency line current to be substantially proportional to the instantaneous magnitude of the AC power line voltage; and

(ii) the crest factor of the high-frequency lamp current to be equal to or lower than 1.7; and

(b) including;

(i) a first inverter circuit having a first pair of DC power supply terminals across which is supplied a first DC voltage; and

(ii) a second inverter circuit having a second pair of DC power supply terminals across which is supplied a second DC voltage;

at least part of the time, the instantaneous magnitude of the second DC voltage being distinctly different from that of the first DC voltage.

6. The arrangement of claim 5 wherein the absolute instantaneous magnitude of the first DC voltage is substantially equal to the absolute instantaneous magnitude of an alternating voltage of sinusoidal waveform.

7. The arrangement of claim 6 wherein the conditioner circuit is additionally characterized in that frequency of said alternating voltage is equal to that of the AC power line voltage.

8. The arrangement of claim 7 wherein the conditioner circuit is additionally characterized in that it draws current from the power line terminals even during times when the absolute instantaneous magnitude of the first DC voltage is lower than that of the second DC voltage.

9. The arrangement of claim 5 wherein the conditioner circuit is additionally characterized by causing the low-frequency line current to have an instantaneous magnitude that is substantially proportional to that of the AC power line voltage.

10. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further operative to cause the crest factor of the high-frequency lamp current to be equal to or lower than 1.7;

the conditioner circuit being further characterized by;

(a) having a pair of DC power supply terminals across which exists a unidirectional supply voltage whose absolute instantaneous magnitude is equal to the sum of;

(i) the absolute instantaneous magnitude of a substantially constant DC voltage; and

(ii) the absolute instantaneous magnitude of an alternating voltage having a substantially sinusoidal waveshape; and

(b) drawing current from the power line terminals even during periods when the absolute instantaneous magnitude of the alternating voltage is lower than that of the substantially constant DC voltage.

11. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by;

(a) being operative to cause the crest factor of the high-frequency lamp current to be equal to or lower than 1.7;

(b) having a pair of DC terminals across which exists a unidirectional supply voltage whose absolute instantaneous magnitude is equal to the larger of;

(i) the absolute magnitude of a substantially constant DC voltage; and

(ii) the absolute instantaneous magnitude of an alternating voltage having a substantially sinusoidal waveform and a peak absolute magnitude higher than the absolute magnitude of the DC voltage; and

(c) drawing current from the power line terminals even during times when the absolute instantaneous magnitude of the unidirectional supply voltage is equal to that of the substantially constant DC voltage.

12. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by;

(a) being operative to cause the crest factor of the high-frequency lamp current to be equal to or lower than 1.7;

(b) having a pair of DC terminals across which exists a unidirectional supply voltage whose absolute instantaneous magnitude is equal to the larger of;

(i) the absolute magnitude of a substantially constant DC voltage; and

(ii) the absolute instantaneous magnitude of an alternating voltage having a substantially sinusoidal waveform and a peak absolute magnitude higher than the absolute magnitude of the substantially constant DC voltage; and

(c) including;

(i) a first transistor conducting periodically and intermittently at a frequency equal to the frequency of the high-frequency lamp current, and (ii) a second transistor conducting periodically and intermittently at a different frequency.

13. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by having a pair of DC supply terminals across which exists a unidirectional supply voltage whose absolute instantaneous magnitude is equal to the sum of;

(i) the absolute instantaneous magnitude of a substantially constant DC voltage; and

(ii) the absolute instantaneous magnitude of an alternating voltage having a substantially sinusoidal waveform and a frequency equal to that of the AC power line voltage.

14. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by having a pair of DC supply terminals across which exists a unidirectional supply voltage whose absolute instantaneous magnitude is equal to the sum of;

(i) the absolute magnitude of a substantially constant DC voltage; and

(ii) the absolute instantaneous magnitude of an alternating voltage having a substantially sinusoidal waveform and an absolute peak magnitude equal to at least half of the absolute magnitude of the substantially constant DC voltage.

15. The arrangement of claim 14 wherein the conditioner circuit is additionally characterized by causing the low-frequency line current to flow during at least 90% percent of each complete cycle of the AC power line voltage.

16. The arrangement of claim 14 wherein the conditioner circuit is additionally characterized by drawing current from the power line terminals during at least 90% of the total duration of each complete cycle of the AC power line voltage.

17. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by;

(a) drawing current from the power line terminals during more than 90% of the total duration of each complete cycle of the AC power line voltage; and

(b) including a first inverter having a first transistor conducting periodically at a first frequency, and a second inverter having a second transistor also conducting periodically but at a frequency different from the first frequency.

18. The arrangement of claim 17 wherein the conditioner circuit is additionally characterized in that the low-frequency line current, when indeed being drawn, has an instantaneous magnitude that is substantially proportional to that of the AC power line voltage.

19. The arrangement of claim 17 wherein the conditioner circuit is additionally characterized by causing the high-frequency lamp current to have a crest factor no higher than about 1.7.

20. An arrangement comprising:

an AC source operative to provide an AC power line voltage at a pair of power line terminals;

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

conditioner circuit connected between the power line terminals and the lamp terminals;

the conditioner circuit being operative to draw a low-frequency line current from the power line terminals and to supply a high-frequency lamp current to the lamp terminals and thereby to the gas discharge lamp;

the frequency of the high-frequency lamp current being substantially higher than that of the AC power line voltage;

the conditioner circuit being further characterized by;

(a) drawing current from the power line terminals during more than 90% of the total duration of each complete cycle of the AC power line voltage; and

(b) having a pair of DC terminals across which exists a DC voltage whose instantaneous absolute magnitude is the larger of (i) a substantially constant magnitude, and (ii) the instantaneous absolute magnitude of an alternating voltage whose peak absolute magnitude is larger than said substantially constant magnitude.