Preheating circuit applied to fluorescent lamp electronic ballast

A technology for electronic ballasts and preheating circuits, applied to light sources, electric light sources, electrical components, etc., can solve problems such as reducing the efficiency of ballasts, and achieve the effect of improving efficiency

Inactive Publication Date: 2011-08-31
WUJIANG HUANENG ELECTRONICS
6 Cites 1 Cited by

AI-Extracted Technical Summary

Problems solved by technology

In the prior art, there is also a PTC thermistor at both ends of the output to realize the preheating and starting of the lamp tube. Although this method can effectively improve the ...
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Method used

The preheating circuit of present embodiment changes the operating frequency of the half-bridge circuit by controlling the secondary side current of the magnetic ring, so as to achieve the preheating start of the lamp tube to achie...
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Abstract

The invention relates to a preheating circuit applied to a fluorescent lamp electronic ballast, which comprises a diode and a first capacitor which are connected in series and are then connected with a secondary winding of a magnetic ring in parallel, a third resistor and a second capacitor which are connected in series and are then connected with the first capacitor in parallel, a first controlswitch which are connected with the diode and the serial-connecting branch of the first capacitor in parallel, and a second control switch which is connected with the third resistor and the serial-connecting branch of the second capacitor in parallel, when a self-exciting magnetic ring driving circuit to start, the first capacitor and the second capacitor are sequentially charged, and the first control switch and the second control switch are alternatively closed and opened. In the preheating circuit, the control switch drives the secondary side current of the magnetic ring to change the working efficiency of a half-bridge line, so that the preheating start to a lamp tube is realized by controlling the voltages at the two ends of the lamp tube, no extra energy consumption is needed, and the efficiency of the ballast is improved.

Application Domain

Electrical apparatusElectric lighting sources

Technology Topic

CapacitanceControl switch +12

Image

  • Preheating circuit applied to fluorescent lamp electronic ballast
  • Preheating circuit applied to fluorescent lamp electronic ballast

Examples

  • Experimental program(1)

Example Embodiment

[0010] The preferred specific embodiments of the present invention will be described below with reference to the accompanying drawings:
[0011] For example, 1 shows the electronic ballast part of the circuit, which mainly includes a self-excited magnetic ring drive circuit and a preheating circuit. The self-excited magnetic ring drive circuit includes a magnetic ring secondary winding T, and a second series connected to both ends of the magnetic ring secondary winding T A drive resistor R1 and a second drive resistor R2, a power transistor Q1 whose base is connected between the first drive resistor R1 and the second drive resistor R2, and the emitter of the power transistor Q1 is connected to the other end of the second drive resistor R2.
[0012] The preheating circuit includes a diode D and a first capacitor C1 connected in series and then connected in parallel with the secondary winding T of the magnetic ring, a third resistor R3 and a second capacitor C2 connected in parallel with the first capacitor C1 after being connected in series, and a diode The first control switch S1 connected in parallel with the series branch of D and the first capacitor C1, the second control switch S2 connected in parallel with the series branch of the third resistor R3 and the second capacitor C2, the high voltage terminal of the first capacitor C1 The fourth resistor R4 is electrically connected to the first control switch S1, and the high voltage end of the second capacitor C2 is electrically connected to the second control switch S2 through a fifth resistor R5 or a diode and a Zener tube. The first control switch S1 and the second control switch S2 are transistors or field effect transistors.
[0013] The working principle of the preheating circuit of this embodiment will be described below:
[0014] When the self-excited magnetic ring drive circuit starts to work, it charges the first capacitor C1 through the diode D, and at the same time charges the second capacitor C2 through the third resistor R3. When the voltage of the second capacitor C2 does not reach the second control switch S2 is closed Before, the voltage of the first capacitor C1 rises to the point that the first control switch S1 can be closed through the fourth resistor R4. At this time, by controlling the drive current of the secondary winding of the magnetic ring, the operating frequency of the half-bridge circuit can be controlled to reach the lamp The purpose of preheating the tube. When the voltage of the second capacitor C2 rises to close the second control switch S2, and the first control switch S1 is opened, the control of the driving current of the magnetic ring secondary winding is stopped, and the self-excited circuit normally starts to light up the lamp.
[0015] The preheating circuit of this embodiment changes the operating frequency of the half-bridge circuit by controlling the secondary side current of the magnetic ring, so as to control the voltage across the lamp tube to realize the preheating start of the lamp, without additional energy loss, and the preheating effect is excellent. Preheating of the PTC, thereby improving the efficiency of the entire electronic ballast.
[0016] The preheating circuit of the present invention is illustrated and described in combination with the above embodiments. The preheating circuit can be applied to fluorescent lamp electronic ballasts, and other circuit parts related to electronic ballasts, such as filter circuits, rectifier circuits, and output circuits. The existing circuits can be used, and the details of these circuits will not be repeated here. All equivalent transformations made according to the present invention should fall within the protection scope of the present invention.

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