Parallel-tuned electronic ballast with special output voltage waveform

• US 5,736,819 A
• Filed: 03/14/1995
• Issued: 04/07/1998
• Est. Priority Date: 03/20/1978
• Status: Expired due to Term

• Current Assignee: Beacon Point Capital LLC
• Original Assignee: Ole K Nilssen
• Inventors: Nilssen, Ole K.
• Primary Examiner(s): Gonzalez, Frank
• Assistant Examiner(s): Ratliff, Reginald A.
• Application Number:
  US08/404,090
• Time in Patent Office: 1,120 Days
• Field of Search: 315/209 R, 315/291, 315/307, 315/227 R, 315/308, 315/243, 315/244, 315/241 R, 315/DIG. 5
• US Class Current: 315/209.00R
• CPC Class Codes: H02M 7/53832 in a push-pull arrangement
• CPC Class Codes: H02M 7/53835 of the parallel type
• CPC Class Codes: H02M 7/53846 Control circuits
• CPC Class Codes: H02M 7/53873 with digital control
• 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 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• 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 315/05 Starting and operating circuit for fluorescent lamp

Abstract

Power to a self-oscillating inverter ballast is supplied from a DC voltage source through an inductor means having two separate windings on a common magnetic core--with one winding being positioned in each leg of the power supply. The inverter is loaded by way of a parallel-tuned L-C circuit connected across the inverter'"'"'s output, thereby providing an output voltage thereat. The output voltage consists of sinusoidally-shaped voltage pulses of alternating polarity, with a distinct brief period of discontinuity at or near the cross-over points. A fluorescent lamp is connected by way of a current-limiting capacitor with the inverter'"'"'s output.

Claims

1. An arrangement comprising:

a DC source functional to provide a DC supply voltage between a first and a second DC supply terminal;

an inverter connected between the first and second DC supply terminals;

the inverter being functional to cause a high-frequency AC inverter voltage to exist between a first and a second AC terminal;

the high-frequency AC inverter voltage being of frequency several times higher than 60 Hz;

any high-frequency AC voltage that might exist between the second AC terminal and one of the DC supply terminals being of very small magnitude compared with the magnitude of the high-frequency AC inverter voltage;

the inverter being further characterized by including;

(i) a first transistor having a first control input terminal, a first output terminal, and a first common terminal; and

(ii) a second transistor having a second control input terminal, a second output terminal, and a second common terminal;

the second output terminal being connected with the first common terminal, thereby to form a junction terminal;

the junction terminal being connected with the first AC terminal in such manner that;

(i) substantially no unidirectional voltage drop can exist between the junction terminal and the first AC terminal, and (ii) any alternating voltage existing between the junction terminal and the first AC terminal is of very small magnitude compared with the magnitude of the high-frequency AC inverter voltage;

a unidirectional voltage existing between the second common terminal and the first output terminal;

the average magnitude of the unidirectional voltage being substantially equal to that of the DC supply voltage;

the inverter being additionally characterized by including a control circuit functional to cause the AC inverter voltage to consist of a continuous sequence of sinusoidally-shaped voltage pulses of alternating polarity;

each such voltage pulse being separated from the next-following voltage pulse by a brief period during which the intantaneous magnitude of the AC inverter voltage undergoes a discontinuous change; and

a gas discharge lamp connected in circuit with the AC output terminals.

2. The arrangement of claim 1 wherein, during most of the brief period, the instantaneous magnitude of the AC inverter voltage remains at a substantially constant level.

3. The arrangement of claim 2 wherein the substantially constant level is of near zero magnitude.

4. The arrangement of claim 1 wherein, during the brief period, the absolute value of the rate-of-change of the instantanous magnitude of the AC inverter voltage decreases temporarily from a first level to a second level;

the first level being distinctly higher than the second level.

5. The arrangement of claim 4 wherein the second level is equal to zero.

6. The arrangement of claim 1 wherein the absolute value of the rate-of-change of the instantaneous magnitude of the AC inverter voltage is substantially lower during most of the brief period as compared with just before and just after the brief period.

7. An arrangement comprising:

an AC source functional to supply an AC power line voltage at a pair of AC power line terminals;

rectifying and filtering circuit connected with the AC power line terminals and functional to provide a DC supply voltage at a pair of DC supply terminals;

a gas discharge lamp having lamp terminals; and

a ballasting circuit having DC input terminals connected with the DC supply terminals and AC output terminals connected with the lamp terminals;

the ballasting circuit being functional to power the gas discharge lamp and being otherwise characterized by having;

(i) a first transistor with a first transistor terminal connected with a second transistor terminal of a second transistor;

the two transistors being series-connected between a pair of terminals across which is provided a unidirectional voltage; and

(ii) a sub-circuit functional, by way of positive feedback, to cause an AC inverter voltage to exist between the first transistor terminal and one of the DC input terminals;

the frequency of the AC inverter voltage being several times higher than that of the AC power line voltage;

the waveform of the AC inverter voltage being substantially sinusoidal.

8. An arrangement comprising:

an AC source functional to supply an AC power line voltage at a pair of AC power line terminals;

rectifying and filtering circuit connected with the AC power line terminals and functional to provide a substantially constant-magnitude DC supply voltage between a first and a second DC supply terminal;

an inductor having a first winding and a second winding;

a lamp load having a pair of lamp load terminals and including a series-combination of a gas discharge lamp and a current-limiting reactance means; and

an inverter circuit including;

(i) at least two transistors, each having transistor control terminals;

(ii) a pair of AC output terminals connected with the load terminals;

(iii) circuitry connected with the AC output terminals as well as with the transistor control terminals, the circuitry being functional via positive feedback to cause an AC output voltage to exist across the AC output terminals;

(iv) a first DC input terminal connected with the first DC supply terminal by way of the first winding;

the first DC input terminal being connected with a terminal of a first one of said at least two transistors; and

(v) a second DC input terminal connected with the second DC supply terminal by way of the second winding;

the second DC input terminal being connected with a terminal of a second one of said at least two transistors.

9. The arrangement of claim 8 wherein the AC output voltage consists of a continuous sequence of sinusoidally-shaped voltage pulses of alternating polarity.

10. An arrangement comprising:

an AC source functional to supply an AC power line voltage at a pair of AC power line terminals;

rectifying and filtering circuit connected with the AC power line terminals and functional to provide a filtered DC supply voltage between a first and a second DC supply terminal;

the magnitude of the DC supply voltage being substantially constant;

an inductor having a first winding and a second winding;

a lamp load having a pair of load terminals; and

an inverter circuit characterized by including;

(i) at least two transistors, each having control terminals;

(ii) AC output terminals operable to connect with the load terminals;

(iii) control circuitry connected with AC output terminals as well as with the control terminals, thereby via positive feedback to cause an AC output voltage to exists at the AC output terminals; and

(iv) having a first DC input terminal connected with the first DC supply terminal by way of the first winding; and

(v) having a second DC input terminal connected with the second DC supply terminal by way of the second winding;

the inverter circuit being further characterized in that said at least two transistors are series-connected across the DC input terminals.

11. An arrangement comprising:

an AC source functional to supply an AC power line voltage at a pair of AC power line terminals;

rectifying and filtering circuit connected with the AC power line terminals and functional to provide a filtered DC supply voltage between a first and a second DC supply terminal;

an inductor having a first winding and a second winding;

a lamp load having a pair of load terminals;

the lamp load being additionally characterized by including an impedance device series-connected with a fluorescent lamp; and

an inverter characterized by including;

(i) transistors, each having control terminals;

(ii) output terminals connected with the load terminals, an inverter voltage being provided across the output terminals;

(iii) control circuitry connected within the inverter and functional to cause the inverter voltage to consist of a continuous sequence of sinusoidally-shaped voltage pulses of alternating polarity;

the inverter voltage being additionally characterized in that;

(a) adjacent voltage pulses are separated by a brief cross-over period during which polarity of the inverter voltage reverses; and

(b) the rate-of-change of the inverter voltage is substantially different during most of the cross-over period as compared with just before or just after the cross-over period;

(iv) having a first DC input terminal connected with the first DC supply terminal by way of the first winding; and

(v) having a second DC input terminal connected with the second DC supply terminal by way of the second winding.

12. An arrangement comprising:

an AC source functional to supply an AC power line voltage at a pair of AC power line terminals;

rectifying and filtering circuit connected with the AC power line terminals and functional to provide a DC supply voltage at a pair of DC supply terminals;

a lamp load having a pair of lamp terminals;

the lamp load being additionally characterized by including a reactance device series-connected with a gas discharge lamp; and

a ballasting circuit having DC input terminals connected with the DC supply terminals and AC output terminals connected with the lamp terminals;

the ballasting circuit being functional to power the gas discharge lamp and being otherwise characterized by having;

(i) a first transistor with a first transistor terminal connected with a second transistor terminal of a second transistor; and

(ii) a sub-circuit functional to cause an AC inverter voltage to exist between the first transistor terminal and one of the DC input terminals;

the AC inverter voltage consisting of sinusoidally-shaped voltage pulses of alternating polarity;

adjacent voltage pulses being separated by a brief period of discontinuity in the rate-of-change of voltage.

13. An arrangement comprising:

an AC source functional to supply an AC power line voltage at a pair of AC power line terminals;

rectifying and filtering circuit connected with the AC power line terminals and functional to provide a DC supply voltage at a pair of DC supply terminals;

a gas discharge lamp having lamp terminals; and

a ballasting circuit having DC input terminals connected with the DC supply terminals and AC output terminals connected with the lamp terminals;

the ballasting circuit being functional to power the gas discharge lamp and being otherwise characterized by having;

(i) a first transistor with a first transistor terminal connected with a second transistor terminal of a second transistor; and

(ii) a sub-circuit functional (a) to cause a substantially sinusoidal AC inverter voltage to exist between the first transistor terminal and one of the DC input terminals; and

(b) to cause the transistors to conduct current alternatingly, except for a brief period once each complete cycle of the AC inverter voltage, during which brief period both transistors conduct current simultaneously.

14. An arrangement comprising:

a first electronic assembly having AC power input terminals connected an AC power line voltage and DC output terminals at which is provided a DC supply voltage of substantially constant magnitude;

a gas discharge lamp having lamp terminals; and

a second electronic assembly characterized by including;

(i) DC input terminals connected with the DC supply terminals;

(ii) a pair of transistors connected together at a junction terminal;

(iii) a pair of output terminals;

(iv) a sub-assembly operative via positive feedback (a) to cause the transistors to conduct alternatingly, (b) to cause a first inverter voltage to exist between the junction terminal and one of the DC supply terminals, which first inverter voltage consists of a sequence of sinusoidally-shaped voltage pulses of alternating polarity, and (c) to cause a second inverter voltage to exist between the output terminals; and

(v) a sub-circuit connected with the output terminals as well as with the lamp terminals, thereby to provide power to the gas discharge lamp.

15. The arrangement of claim 14 wherein adjacent ones of the sinusoidally-shaped voltage pulses are separated by a brief period during which the rate-of-change of the inverter voltage exhibits a distinct discontinuity.

16. An arrangement comprising:

a first electronic assembly having AC power input terminals connected with an AC power line voltage and being functional to provide a DC supply voltage between a negative DC supply terminal and a positive DC supply terminal;

a gas discharge lamp having lamp terminals; and

a second electronic assembly having;

(i) DC input terminals connected with the DC supply terminals;

(ii) a pair of transistors connected together at a junction terminal;

each transistor having transistor control terminals;

(iii) a pair of output terminals;

(iv) circuitry operative to connect the transistors in circuit with the DC input terminals as well as to provide feedback between the output terminals and the transistor control terminals, thereby to cause the transistors to conduct alternatingly and in such manner as to cause an alternating inverter voltage to exist between the junction terminal and one of the DC supply terminals as well as to cause an alternating output voltage to exist between the output terminals;

the alternating inverter voltage consisting of a train of sinusoidally-shaped voltage pulses of alternating polarity; and

(v) a sub-structure connected between the output terminals and the lamp terminals, thereby to provide power to the gas discharge lamp.

17. An arrangement comprising:

a source operative to provide, between a first and a second DC terminal, a DC voltage of substantially constant magnitude;

an inverter circuit connected with the DC terminals and functional to provide an alternating inverter voltage between a reference terminal and an inverter output terminal;

the alternating inverter voltage consisting of a train of sinusoidally-shaped voltage pulses of alternating polarity, with adjacent voltage pulses being separated by a brief period during which the rate-of-change of the instantaneous magnitude of the alternating inverter voltage exhibits a distinct discontinuity;

the inverter circuit including a tuned L-C circuit connected in circuit with the inverter output terminal and the reference terminal;

the L-C circuit having a tank inductor parallel-connected with a tank capacitor means and being resonant at or near the frequency of the alternating inverter voltage;

the inverter circuit being further characterized in that;

(i) it includes a first intermittently conducting transistor having a first transistor terminal connected with the inverter output terminal in such manner that no voltage of substantial magnitude can exist between the transistor terminal and the inverter output terminal, the term substantial magnitude being defined as a magnitude larger than one tenth the magnitude of the alternating inverter voltage;

(ii) any AC voltage, of frequency equal to that of the inverter AC voltage, existing between the reference terminal and the first DC terminal is of negligible magnitude compared with the magnitude of the alternating inverter voltage; and

(iii) any AC voltage, of frequency equal to that of the inverter AC voltage, existing between the first and second DC terminals is of negligible magnitude compared with the magnitude of the alternating inverter voltage; and

gas discharge lamp means connected in circuit with the L-C circuit.

18. An arrangement comprising:

a source operative to provide, between a first and a second DC terminal, a DC voltage of substantially constant magnitude;

an inverter circuit connected with the DC terminals and functional to provide an inverter voltage between a reference terminal and an inverter output terminal;

the inverter voltage being an alternating voltage of frequency several times higher than 60 Hz and otherwise characterized by consisting of a train of sinusoidally-shaped voltage pulses of alternating polarity, with adjacent voltage pulses being separated by a brief period during which the rate-of-change of the inverter voltage exhibits a distinct discontinuity;

the inverter circuit including a tuned L-C circuit connected in circuit with the inverter output terminal and the reference terminal;

the L-C circuit having a tank inductor parallel-connected with a tank capacitor means and being resonant at or near the frequency of the inverter voltage;

the inverter circuit being further characterized in that it includes two alternatingly conducting transistors series-connected between two auxiliary terminals between which exists a unidirectional voltage consisting of sinusoidally-shaped unidirectional voltage pulses, and having an average magnitude substantially equal to that of the DC voltage.

19. An arrangement comprising:

a source providing, between a first and a second DC supply terminal, a constant-magnitude DC supply voltage;

an electronic circuit having a first and a second input terminal as well as a pair of output terminals;

the electronic circuit including a sub-assembly functional to cause an output voltage to exist across the output terminals, but only as long as unidirectional current is supplied to the input terminals;

the output voltage consisting of a train of sinusoidally-shaped voltage pulses of alternating polarity, with adjacent voltage pulses being separated by a brief period during which the rate-of-change of the output voltage exhibits a distinct discontinuity;

inductor having a first winding and a second winding;

the first winding being connected between the first DC supply terminal and the first input terminal;

the second winding being connected between the second DC supply terminal and the second input terminal;

thereby to supply unidirectional current to the input terminals; and

output means connected with the output terminals;

the output means having lamp output terminals adapted to connect with a gas discharge lamp.

20. The arrangement of claim 19 wherein the electronic circuit is additionally characterized in that, as long as unidirectional current is indeed supplied to the input terminals, a pulsating unirectional voltage exists across these input terminals;

the pulsating unidirectional voltage consisting of a train of unidirectional sinusoidally-shaped voltage pulses, with adjacent voltage pulses being separated by a brief period during which the rate-of-change of the absolute instantaneous magnitude of the pulsating unidirectional voltage exhibits a distinct discontinuity.