Low frequency electronic ballast for gas discharge lamps

• US 20060232220A1
• Filed: 04/13/2005
• Published: 10/19/2006
• Est. Priority Date: 04/13/2005
• Status: Active Grant

• Current Assignee: Ballastronic, Inc.
• Original Assignee: Ballastronic, Inc.
• Inventors: Melis, Janos
• Granted Patent: US 7,221,107 B2
• Time in Patent Office: Days
• US Class Current: 315/209.R
• CPC Class Codes: H05B 41/2888 the bridge being commutated at low frequency, e.g. 1kHz
• CPC Class Codes: H05B 41/3928 for high-pressure lamps, e.g. high-intensity discharge lamps, high-pressure mercury or sodium lamps

Abstract

An electronic ballast for high intensity gas discharge lamps where the wave form of the lamp current is square wave providing acoustic resonance and flickering free operation. The circuit, having high efficiency, operates in a wide temperature range providing ideal ballast curve and reliable ignition for the lamps. Furthermore, significant energy saving can be achieved by its externally controlled built in dimming capability.

Claims

1. (canceled)

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11. (canceled)

12. A high efficient low frequency square wave electronic ballast for high intensity discharge lamps, comprising:

a high power factor preregulator providing approximately sinusoidal input current, therefore high power factor, and further providing a constant average DC voltage source; and

further comprising,

a constant power DC current source implementing the ideal ballast curve for high intensity discharge lamps in their typical voltage range, especially for metal halide and high pressure sodium lamps; and

still further comprising,

an output unit providing low frequency symmetrical square wave current avoiding cataphoretic phenomenon, and further providing an appropriate high frequency ignition voltage source for high intensity discharge lamps;

wherein,

the input of high power factor preregulator is connected to a sinusoidal AC voltage source typically the line voltage, and the output of high power factor preregulator is connected to the input of constant power DC current source, and the output of constant power DC current source is connected to the input of output unit, and the output of output unit is connected to a high intensity discharge lamp.

13. A high power factor preregulator in accordance with claim 12, comprising:

a boost converter, having an inductor, a controlled electronic switch, an output capacitor, a first rectifier, a second rectifier, a low voltage comparator and a stabilized reference DC voltage source;

wherein,

the anode of second rectifier is connected to the lower potential end of controlled electronic switch and the cathode of second rectifier is connected to the lower potential end of output capacitor; and

further wherein,

the anode of second rectifier is connected to the noninverting input of low voltage comparator, and the inverting input of low voltage comparator is connected to the stabilized reference DC voltage source.

14. A constant power DC current source in accordance with claim 12, comprising:

a buck converter having an inductor, a controlled electronic switch, first capacitor as output capacitor, a second capacitor, a first rectifier, a second rectifier, a third rectifier, a fourth rectifier, a fifth rectifier, a Zener diode, a first resistor, a second resistor, an optocoupler, and a logic control unit;

wherein,

the anode of second rectifier is connected to the anode of first rectifier, the cathode of second rectifier is connected to the anode of third rectifier and digital control unit, and the cathode of third rectifier is connected to the cathode of first rectifier;

still further wherein,

the anode of fourth rectifier is connected to first capacitor as output capacitor, the cathode of fourth rectifier is connected to the first end of second capacitor and digital control unit, and the other end of second capacitor is connected to the common point of the controlled electronic switch, inductor and first rectifier;

further wherein,

the cathode of Zener diode is connected to an end of second resistor, another end of second resistor is connected to the input of optocoupler, and the output of optocoupler is connected to digital control unit;

still further wherein,

the cathode of fifth rectifier is connected to first capacitor as output capacitor, the anode of fifth rectifier is connected to an end of first resistor, and the other end of first resistor is connected to digital control unit.

15. A logic control unit in accordance with claim 14, comprising:

a nonlinear function generator, a first and a second comparators, a third capacitor connected parallel with a transistor, a stabilized DC voltage source;

wherein,

the said first resistor is connected to an end of third capacitor, the other end of third capacitor is connected to the stabilized DC voltage source, the anode of said third rectifier is connected to the inverting input of second comparator, the noninverting input of second comparator is connected to a reference DC voltage source, the output of second comparator is connected to transistor, the inverting input of first comparator is connected to nonlinear function generator, and the noninverting input of first comparator is connected to the common point of said first resistor and third capacitor.

16. A nonlinear function generator in accordance with claim 15, comprising:

a second resistor, a third resistor, fourth resistor, fifth resistor, sixth resistor, a sixth rectifier, a seventh rectifier, and a Zener diode;

wherein,

the first end of second resistor is connected to first end of said second capacitor, the second end of second resistor is connected to the first end of third resistor, the second end of third resistor is connected to the anode of sixth rectifier, the cathode of sixth rectifier is connected to a constant voltage source, the common point of second and third resistor is connected to the first end of the fourth resistor, the second end of fourth resistor is connected to the first end of the fifth resistor, the second end of fifth resistor is connected to the zero level of the constant voltage source, the first and of the seventh resistor is connected to the constant voltage source, the second end of the seventh resistor is connected to the cathode of the Zener diode, the anode of Zener diode is connected to the zero level of said DC voltage source, the common point of seventh resistor and Zener diode is connected to the anode of seventh rectifier, the cathode of seventh rectifier is connected to the common point of fourth and fifth resistors, and the common point of fourth and fifth resistors is connected to the noninverting input of said first comparator.

17. An output unit in accordance with claim 12, comprising:

a full-bridge inverter having, a first, second, third and a fourth electronically controlled switches, an ignition transformer having a first and a second winding, a first and a second rectifier, a first, a second capacitor, a shunt resistor, a control unit, a logic supply, and a high intensity discharge lamp as load;

wherein,

the first winding of ignition transformer is connected to an end of high intensity discharge lamp and the first output connecting point of fall-bridge inverter, the second winding of ignition transformer is connected to the an end second capacitor and the first output connecting point of fill-bridge inverter, the other end of second capacitor is connected to second output connecting point of full-bridge inverter, the other end of high intensity discharge lamp is connected to the second output connecting point of full-bridge inverter, the common point of the third and fourth electronically controlled switches is connected to an end of first capacitor, the common point of first and second electronically controlled switches is connected to an and of shunt resistor, and the another end of shunt resistor is connected to another end of first capacitor, the control inputs of first, second, third and fourth electronically controlled switches are connected to control unit, and the cathode of first and second rectifier is connected to the fourth and third electronically controlled switches respectively, and the common anode of first and second rectifiers are connected to the logic supply.

18. A control unit in accordance with claim 17, comprising:

a comparator unit, having an input, a first and a second output;

a timer unit, having a first and a second input, a first and a second output, a dual frequency oscillator and driver unit, having a first, a second, and a third input, further having a first, a second, a third, and a fourth output, a current limiter unit, having, a first and a second input, a first and a second output;

wherein,

the first input of comparator unit is connected to the input of said full-bridge inverter, the first output of comparator unit is connected to the first input of timer unit, the second output of comparator unit is connected to the second input of dual frequency oscillator unit;

further wherein,

the second input of timer unit is connected to the second output of current limiter unit, the firs%t output of timer unit is connected to the first input of dual frequency oscillator unit, the second output of timer unit is connected to the second input of logic driver unit;

still further wherein,

the output of dual frequency oscillator unit is connected to the first input of logic driver, the first output of the logic driver is connected to said first electronically controlled switch, the second output of the logic driver is connected to said second electronically controlled switch, the third output of the logic driver is connected to said third electronically controlled switch, the fourth output of the logic driver is connected to said fourth electronically controlled switch;

still further wherein,

the first input of current limiter unit is connected to said shunt resistor, the second input of current limiter unit is connected to the input of the said full-bridge inverter, the first output of current limiter is connected to the second input of timer unit, and the second output of current limiter is connected to the input of said optocoupler of claim 14.

19. A comparator unit in accordance with claim 18, comprising:

a first and a second voltage comparator, a first and a second DC voltage source;

wherein,

the common point of the inverting inputs of the first and the second voltage comparators act as the input of the said comparator unit, the output of the first voltage comparator acts as the first input of said comparator unit, and the output of the second voltage comparator acts as the second output of said comparator unit;

further wherein,

the noninverting input of first voltage comparator is connected to the first DC voltage source, the noninverting input of second voltage comparator is connected to second DC voltage source.

20. A timer unit in accordance with claim 18, comprising:

a digital ripple counter having a first, a second, a third and a fourth output, a digital oscillator, a dual input NAND-gate, a monostable multivibrator, and a resistor, wherein,

the reset input of the digital ripple counter acts as the first input of the said timer unit, the input of the monostable multivibrator act as the second input of said timer unit, the output of the dual input NAND-gate act as the first output of said timer unit, and the signal of on the resistor act as the second output of said timer unit;

further wherein,

the digital oscillator is connected to the digital ripple counter providing clock signal, the first, second and third outputs of digital ripple counter are OR-gated to the resistor, the inverted fourth output of digital ripple counter is connected to an input of dual input NAND-gate, and the output of monostable multivibrator is connected to another input of dual input NAND-gate.

21. A dual frequency oscillator and driver unit in accordance with claim 18, comprising:

a dual frequency digital oscillator having a control input, a noninverting and an inverted output, a dual input NOR-gate, a first, a second, a third and a fourth dual input NAND-gate, a first and a second capacitor, a first and a second resistor;

wherein,

the inputs of dual input NOR-gate act as the first and the second inputs of said dual frequency digital oscillator and driver unit, the third input of said dual frequency digital oscillator and driver unit is connected to an input of first and the fourth dual input NOR-gate, the output of dual input NOR-gate is connected to the control input of the dual frequency digital oscillator, the noninverting output of the dual frequency digital oscillator is connected to an input of third the dual input NAND-gate, the inverted output of the dual frequency digital oscillator is connected to an input of second dual input NAND-gate;

further wherein,

the noninverting output of dual frequency digital oscillator is connected to an end of the first resistor, another end of the first resistor is connected to the first capacitor, the common point of first resistor and first capacitor is connected to an input of second dual input NAND-gate, the inverted output of dual frequency digital oscillator is connected to an end of the second resistor, another end of the second resistor is connected to the second capacitor, the common point of second resistor and second capacitor is connected to an input of third dual input NAND-gate, the outputs of the first, second, third and the fourth dual input NAND-gates act as the first, second, third and the fourth outputs of dual frequency oscillator and driver unit.

22. A current limiter unit in accordance with claim 18, comprising:

a first and a second voltage comparator, a first and a second reference voltage source, a first, a second, and a third resistor, a rectifier, and a capacitor;

wherein,

an end of the first resistor act as the first input of said current limiter unit, another end of the first resistor is connected to the inverting input of first voltage comparator, the noninverting input of first voltage comparator is connected to the first reference voltage source, the output of first comparator act as the first output of said current limiter unit;

further wherein,

an end of the second resistor is connected to an end of third resistor and to the anode of rectifier, the cathode of rectifier acts as the second input of said current limiter unit, an another end of third resistor is connected to the capacitor, the common point of third resistor and the capacitor is connected to the inverting input of the second voltage comparator, the noninverting input of second voltage comparator is connected to the second reference voltage source, the output of the second voltage comparator acts as the second output of current limiter unit