CN201032750Y - Fluorescent lamp driving power supply - Google Patents

Abstract

The utility model discloses a fluorescent lamp driving power, which comprises a multiple-switch convert circuit, a power transformer (T 1), a resonant inductor (L 1), a resonant capacitor (C 3), a transformer booster (T 2). And the primary winding of the power transformer (T 1) is connected with the alternating current output of the multiple-switch converting circuit, when the resonant inductor (L 1) is in-bridged with the resonant capacitor (C 3), the secondary line winding of the power transformer (T 1) is connected with the resonant inductor (L 1) and the resonant capacitor (C 3) through the primary line winding of the transformer booster (T 2); the secondary line winding of the transformer booster (T 2) is connected with the load output. By in-bridging a resonant inductor on the oscillation of the utility model, the frequency and voltage modulation is achieved, meanwhile, the soft-switching function of the power transformer original side power switch is also achieved.

Description

A kind of fluorescent lamp drive power supply

Technical field

The utility model relates to appliance field, relates in particular to a kind of fluorescent lamp drive power supply.

Background technology

Liquid crystal indicator comprises backlight module and liquid crystal panel, and backlight module is used to described non-luminous liquid crystal panel own that light source is provided.No matter backlight module or liquid crystal panel, all needing power supply is its power supply.

In existing application, as shown in Figure 1, comprise circuit of power factor correction, power transformer T1, step-up transformer T2, first switch S 1, second switch S2, the 3rd switch S 3 and the 4th switch S 4, described first switch S 1 and second switch S2 series connection back also are connected in input Vin, described the 3rd switch S 3 and the 4th switch S 4 series connection backs also are connected in input Vin, one end of described capacitor C 2 links to each other with the mid point of first switch S 1 and second switch S2, the other end links to each other with the mid point of the 3rd switch S 3 and the 4th switch S 4 by the former limit winding of power transformer T1, the former limit winding of described power transformer T1 connects many switch transformed circuits and exchanges output, the secondary winding of step-up transformer T2 connects load output, the secondary winding of power transformer T1 links to each other with the former limit winding of step-up transformer T2, the leakage inductance and the capacitor C 2 of the former limit of step-up transformer T2 winding constitute oscillation circuit together, offer the alternating current that load needs.

The frequency relation figure of existing as shown in Figure 2 voltage and excitation power supply, when the step-up transformer parallel connection was more and more, the equivalent inductance Lr=Lr '/n that converts resonant tank was more little.(n is a step-up transformer quantity, and Lr ' is the leakage inductance of converting former limit) when resonant inductance is too little, the Q value is low, and when frequency f 1 changed to f2, the variation of the voltage Δ v on the tube load Rlamp was too little, can not satisfy the requirement of adjusting the load voltage scope.

The shortcoming of prior art: when and be connected to the words that a plurality of step-up transformers drive load, equivalent inductance after the leakage inductance parallel connection of the secondary winding of step-up transformer reduces greatly, the oscillation circuit that itself and capacitor C 2 are formed is because inductance is too little, the Q value is low, oscillation circuit does not get up, and can't realize that frequency modulation transfers the voltage in the load; Because inductance is little, the resonance frequency height can not be realized the soft switching function of the former limit of power transformer power circuit switch in the operating frequency section of appointment in addition.

The utility model content

The technical problems to be solved in the utility model provides a kind of fluorescent lamp drive power supply, makes can normally realize frequency modulation and voltage modulation behind a plurality of step-up transformers of parallel connection, realizes the soft switching function of the former limit of power transformer power circuit switch simultaneously.

For solving the problems of the technologies described above, the purpose of this utility model is achieved through the following technical solutions.

A kind of fluorescent lamp drive power supply, comprise many switch transformed circuits, power transformer (T1), resonant inductance (L1), resonant capacitance (C3), step-up transformer (T2), the former limit winding of described power transformer (T1) connects the interchange output of described many switch transformed circuits, and described resonant inductance (L1) links to each other with the secondary winding of described power transformer (T1) with the former limit winding of resonant capacitance (C3) series connection back by step-up transformer (T2); The secondary winding of described step-up transformer (T2) connects load output.

Wherein, further comprise capacitance (C2), described capacitance (C2) is connected with the former limit winding of described power transformer (T1) and the output of described many switch transformed circuits.

Wherein, described many switch transformed circuits are the half-bridge topology circuit.

Wherein, described many switch transformed circuits are the full-bridge topological circuit.

Wherein, further comprise circuit of power factor correction, its output high voltage direct current is to the input of described many switch transformed circuits.

Wherein, comprise at least two described step-up transformers, the former limit winding of described each step-up transformer is connected in parallel, and its secondary winding connects load output respectively.

Above technical scheme as can be seen, pass through resonant inductance of series connection in resonant tank in the utility model, increased the inductance value of resonant tank, improved the Q value, reduced resonance frequency, thereby the frequency change that realizes former limit switching circuit is controlled the variation of step-up transformer secondary load voltage, realizes the soft switching function of the former limit of power transformer power circuit switch simultaneously.

Description of drawings

Fig. 1 is the circuit theory diagrams of prior art liquid crystal indicator power supply;

Fig. 2 is the frequency relation figure of existing voltage and excitation power supply;

Fig. 3 is power circuit principle figure provided by the utility model;

Fig. 4 is the utility model first embodiment circuit theory diagrams;

Fig. 5 is the utility model second embodiment circuit theory diagrams;

Fig. 6 is the utility model the 3rd embodiment circuit theory diagrams;

Fig. 7 is the equivalent circuit diagram of the utility model Fig. 5 circuit;

Fig. 8 is the voltage on the utility model fluorescent tube and the frequency relation figure of excitation power supply.

Embodiment

For ease of the utility model is further understood, now reach specific embodiment in conjunction with the accompanying drawings the utility model is described in detail.

Fig. 3 is power circuit principle figure provided by the utility model, and this circuit comprises circuit of power factor correction, meets many switch transformed circuits, power transformer T1 and step-up transformer T2, rectification circuit, resonant inductance L1, the resonant capacitance C3 of the output of circuit of power factor correction high voltage direct current.

The former limit of described power transformer T1 winding connects many switch transformed circuits and exchanges output, and its secondary winding links to each other with the former limit winding of step-up transformer T2 with resonance capacitor C 3 by resonant inductance L1; The secondary winding of described step-up transformer T2 connects load output.

It is similar with circuit diagram shown in Figure 3 to see also the utility model first embodiment circuit diagram shown in Figure 4, and difference is, comprises at least two described step-up transformers, and each former limit winding that becomes device that boosts is connected in parallel, and its secondary winding connects load output respectively.

Many switching circuits can adopt full-bridge circuit topological circuit or half-bridge circuit topology, below for example with the half-bridge circuit topology, see also the utility model second embodiment circuit diagram shown in Figure 5, many switching circuits adopt the half-bridge circuit topology, comprise circuit of power factor correction, meet many switch transformed circuits, power transformer T1 and step-up transformer T2, rectification circuit, resonant inductance L1, resonant capacitance C3, capacitance C2 that the circuit of power factor correction high voltage direct current is exported.

Described many switch transformed circuits comprise first switch S 1 and second switch S2, first switch S 1 and second switch S2 series connection back also are connected in input Vin, the end of capacitance C2 links to each other with the mid point of first switch S 1 and second switch S2, and the other end links to each other with input Vin by the former limit winding of power transformer T1.

Described resonant inductance L1 links to each other with the secondary winding of power transformer T1 with the former limit winding of resonant capacitance C3 series connection back by step-up transformer T2, and the secondary winding of described step-up transformer T2 connects load output.

It is similar with the second embodiment circuit diagram to see also the utility model the 3rd embodiment circuit diagram shown in Figure 6, difference is, described many switching circuits adopt the full-bridge circuit topology, comprise circuit of power factor correction, meet many switch transformed circuits, power transformer T1 and step-up transformer T2, rectification circuit, resonant inductance L1, resonant capacitance C3, capacitance C2 that the circuit of power factor correction high voltage direct current is exported.

Described many switch transformed circuits comprise first switch S 1, second switch S2, the 3rd switch S 3 and the 4th switch S 4, described first switch S 1 and second switch S2 series connection back also are connected in input Vin, described the 3rd switch S 3 and the 4th switch S 4 series connection backs also are connected in input Vin, the end of described capacitance C2 links to each other with the mid point of first switch S 1 and second switch S2, and the other end links to each other with the mid point of the 3rd switch S 3 and the 4th switch S 4 by the former limit winding of power transformer T1.Present embodiment has the advantage that is had with described first execution mode.

Fig. 5 is more a kind of in the utility model scheme, and the operation principle of other embodiment and Fig. 5's is identical in the utility model, will be that example is introduced operation principle of the present utility model below with Fig. 5.

Consult the equivalent circuit diagram of Fig. 5 circuit shown in Figure 7, the leakage inductance equivalence of the step-up transformer T2 among Fig. 5 is Ld, and the resonance frequency fr of circuit is:

$\mathrm{fr}=1/2\mathrm{\&pi;}\sqrt{C3(\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="Y20072011932500081.png,Y20072011932500091.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{Ld})}$

The frequency relation of voltage on the tube load Rlamp and excitation power supply Vin/2N such as Fig. 8, as shown in Figure 8, when changing frequency, when f1 changes to f2, voltage on the tube load Rlamp increases greatly, thereby the change frequency just can satisfy the adjustment on a large scale to load voltage, changes the brightness of fluorescent tube.When changing frequency, select operating frequency to be higher than resonance frequency fr, do to make that the power switch of half-bridge circuit is operated in the zero voltage switch state among Fig. 5 like this, thereby reduce the switching loss of power switch, also can realize the soft switching function of the former limit of power transformer power circuit switch simultaneously.

More than a kind of fluorescent lamp drive power supply provided by the utility model is described in detail, used specific case herein principle of the present utility model and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present utility model and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present utility model, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as restriction of the present utility model.

Claims (6)

1. fluorescent lamp drive power supply, comprise many switch transformed circuits, power transformer (T1), resonant inductance (L1), resonant capacitance (C3), step-up transformer (T2), it is characterized in that: the former limit winding of described power transformer (T1) connects the interchange output of described many switch transformed circuits, and described resonant inductance (L1) links to each other with the secondary winding of described power transformer (T1) with the former limit winding of resonant capacitance (C3) series connection back by step-up transformer (T2); The secondary winding of described step-up transformer (T2) connects load output.

2. fluorescent lamp drive power supply according to claim 1 is characterized in that: further comprise capacitance (C2), described capacitance (C2) is connected with the former limit winding of described power transformer (T1) and the output of described many switch transformed circuits.

3. fluorescent lamp drive power supply according to claim 1 and 2 is characterized in that: described many switch transformed circuits are the half-bridge topology circuit.

4. fluorescent lamp drive power supply according to claim 1 and 2 is characterized in that: described many switch transformed circuits are the full-bridge topological circuit.

5. according to each described fluorescent lamp drive power supply of claim 1 to 2, it is characterized in that: further comprise circuit of power factor correction, its output high voltage direct current is to the input of described many switch transformed circuits.

6. according to each described fluorescent lamp drive power supply of claim 1 to 2, it is characterized in that: comprise at least two described step-up transformers, the former limit winding of described each step-up transformer is connected in parallel, and its secondary winding connects load output respectively.

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