US 5,677,602 A · High efficiency electronic ballast for high intensity discharge lamps

Abstract

An electronic ballast is powered by power source (102) and (104). The ballast controls the electrical power supplied to a gas discharge lamp (116), providing the voltages and currents required to start, warm-up and operate the lamp (116). Line power conditioner (100) reduces interference and harmonic generation, and provides a source of DC power (103), which may be regulated. DC power (103) is applied to inverter (105), which generates a square-wave voltage at a variable frequency determined by control circuit (200). Inverter (105) output is connected to resonant circuit (600) consisting of series inductor (110), series capacitors (112) and (118), and parallel inductor (114), across which gas discharge lamp (116) is connected. Operation begins with inverter (105) running at a frequency initially near but above the unloaded series resonance frequency of resonant circuit (600). Controller (200) reduces the frequency until resonant circuit (600) gives sufficient voltage to start lamp (116). After lamp (116) starts, controller (200) increases inverter (105) frequency to an intermediate frequency near but above one-third of the resonance of the series inductor (110) and the capacitors ( 112) and (118 causing a high current to flow in lamp (116), for warm-up. After a warm-up interval, controller (200) further increases inverter (105) frequency to a final value which is also above the frequency of acoustic arc resonance and above the loaded resonance frequency of resonant circuit (600).

Claims9

Dependent claims

An electronic ballast for connection between a source of direct current power and a gas discharge lamp, comprising:

an inverter connectable to said source of direct current power for generating an alternating voltage at a variable frequency;
a capacitor having a first and a second terminal, and
a network having an input port and an output port and comprising substantially inductive components;
said inverter including first and second output terminals;
said input port of said network having a first and a second terminal;
said first terminal of said capacitor connected to said first output terminal of said inverter, said second terminal of said capacitor connected to said first terminal of said input port of said network;
said second terminal of said input port of said network connected to said second output terminal of said inverter;
said output port of said network connected to said gas discharge lamp;
said input port of said network having a first value of inductance when said output port is short circuited, and
said input port of said network having a second value of inductance substantially greater than said first value of inductance when said output port is open circuited.

7 more elements

An electronic ballast for connection between a source of direct current power and a gas discharge lamp capable of operation in either a glow mode or an arc mode, comprising:

an inverter connectable to said source of direct current power for generating an alternating voltage at a variable frequency;
a capacitor having a first and a second terminal, and
a network having an input port and an output port and comprising substantially inductive components;
said inverter including first and second output terminals;
said input port of said network having a first and a second terminal;
said first terminal of said capacitor connected to said first output terminal of said inverter, said second terminal of said capacitor connected to said first terminal of said input port of said network;
said second terminal of said input port of said network connected to said second output terminal of said inverter;
said output port of said network connected to said gas discharge lamp;
said input port of said network having a first inductance value when said output port is short circuited, and
said input port of said network having a second inductance value substantially greater than said first inductance value when said output port is open circuited;
said inverter being arranged to operate at a first frequency before said gas discharge lamp starts, said first frequency being above a second frequency equal to the resonant frequency of said second inductance value and the capacitance of said capacitor, but below a third frequency equal to the resonant frequency of said first inductance and the capacitance of said capacitor,
said inverter being arranged to subsequently operate at a frequency which decreases towards said second frequency until said gas discharge lamp starts, and after said gas discharge lamp starts,
said inverter being arranged to operate at a frequency which increases towards a frequency near said first frequency, at least until said gas discharge lamp changes operation from said glow mode to said arc mode, and
said inverter being arranged to operate at a frequency above said third frequency after said gas discharge lamp changes operation from said glow mode to said arc mode,
whereby said gas discharge lamp is started, transitions from said glow mode to said arc mode and operates in a steady state.

12 more elements

Dependencies are inferred from the claim text.

High efficiency electronic ballast for high intensity discharge lamps

Life of this patent

High efficiency electronic ballast for high intensity discharge lamps

Life of this patent

Abstract

Claims9