CN201039552Y - A fluorescent lamp driving power supply - Google Patents

Abstract

The utility model discloses a driving power supply for a fluorescent lamp, which comprises a multi-switch conversion circuit, a power transformer, a resonant inductor, a resonant capacitor, a step-up transformer, and a rectifier circuit. Output, after the resonant inductor is connected in series with the resonant capacitor through the primary winding of the step-up transformer and the secondary winding of the power transformer, the secondary winding of the power transformer is also connected with a rectifier circuit; the step-up transformer The secondary winding is connected to the load output. In the utility model, the driving power supply of the fluorescent lamp and the power supply of the control system are combined into one, so that only one energy change is needed from the output of the power factor correction circuit to the lamp tube, and compared with the existing two converters, the system cost is reduced. It is greatly reduced, the efficiency is greatly improved, and the stability of the system is also greatly improved.

Description

A fluorescent lamp driving power supply

technical field

The utility model relates to the field of electrical appliances, in particular to a fluorescent lamp driving power supply.

Background technique

The liquid crystal display device includes a backlight module and a liquid crystal panel, and the backlight module is used to provide a light source for the liquid crystal panel which itself does not emit light. Regardless of the backlight module or the liquid crystal panel, a power supply is required for it.

In existing applications, the fluorescent lamp driving power supply and the power supply of the control system are two completely different power supplies, please refer to Figure 1. In some liquid crystal display device applications, such as the application of two-in-one power supplies for LCD TVs, In addition to providing high-voltage AC for the lamp in the backlight module to drive the lamp load, it is also necessary to provide an isolated low-voltage direct current to supply power to the control and image processing circuits and power amplifier circuits in the LCD panel. This low-voltage direct current power supply is called the control power supply. . In Figure 1, the AC power needs to be converted into a stable 24V DC first, and then supplied to the inverter to work, so that the energy from the output of the power factor correction circuit to the lamp tube has undergone two changes, and an independent control power conversion is also required device, the power supply system of the entire liquid crystal display device has many energy conversion times, low efficiency, complex circuit cost and high cost, and high failure rate.

Utility model content

The technical problem to be solved by the utility model is to provide a fluorescent lamp drive power supply integrated with control power supply.

In order to solve the above technical problems, the purpose of this utility model is achieved through the following technical solutions.

A fluorescent lamp drive power supply, comprising a multi-switch conversion circuit, a power transformer, a resonant inductor, a resonant capacitor, a step-up transformer, and a rectifier circuit, the primary winding of the power transformer is connected to the AC output of the multi-switch conversion circuit, and the resonant After the inductance and the resonant capacitor are connected in series, the primary winding of the step-up transformer is connected to the secondary winding of the power transformer, and the secondary winding of the power transformer is also connected with a rectifier circuit; the secondary winding of the step-up transformer is connected to the load output.

Wherein, the secondary winding of the power transformer has at least two pairs of outputs, one pair of outputs is connected in series with the resonant inductor, resonant capacitor and the primary winding of the step-up transformer, and the other pairs of outputs are respectively connected to a rectifier circuit.

Wherein, the power transformer has at least two secondary windings, the output of one of the secondary windings is connected in series with the resonant inductor, the resonant capacitor and the primary winding of the step-up transformer, and the other secondary windings are respectively connected to the rectifier circuit.

Wherein, at least two power transformers are included, the primary windings of each power transformer are connected in parallel, and the secondary windings of each power transformer are connected in series with the resonant inductor, resonant capacitor and step-up transformer. The primary windings are connected in series, and the secondary windings of each power transformer are connected in series with a rectifier circuit.

Wherein, at least two power transformers are included, the primary windings of each power transformer are connected in parallel, and the secondary winding of one of the power transformers is connected in series with the resonant inductor, resonant capacitor and the primary winding of the step-up transformer. side windings, and the secondary windings of the other power transformers are respectively connected to rectification circuits.

Wherein, at least two power transformers are included, the primary windings of each power transformer are connected in parallel, the secondary windings of each power transformer have at least two pairs of outputs, and the secondary windings of each power transformer One pair of outputs of the windings is connected in series to the resonant inductor, the resonant capacitor and the primary winding of the step-up transformer, and the other pair of outputs are respectively connected to the rectifier circuit.

Among them, at least two power transformers are included, the primary windings of each power transformer are connected in parallel, each power transformer has at least two secondary windings, and the secondary windings of one or more power transformers are The side windings are connected directly or in series with the resonant inductor, the resonant capacitor and the primary winding of the step-up transformer, and the secondary windings of the other power transformers are respectively connected directly or in series with the rectifier circuit.

Wherein, it further includes a power factor correction circuit, which outputs a stable high-voltage direct current to the input of the multi-switch conversion circuit.

Wherein, at least two step-up transformers are included, the primary windings of each step-up transformer are connected in parallel, and the secondary windings are respectively connected to load output.

Wherein, the rectification circuit is a full-bridge rectification circuit, a full-wave rectification circuit or a half-wave rectification circuit.

It can be seen from the above technical solutions that the utility model combines the fluorescent lamp driving power and the power supply of the control system into one, so that only one energy change is needed from the output of the power factor correction circuit to the lamp tube, compared with the existing With two converters, the cost of the system is greatly reduced, the efficiency is greatly improved, and the stability of the system is also greatly improved.

Description of drawings

Fig. 1 is the circuit schematic diagram of the power supply of the prior art liquid crystal display device;

Fig. 2 is the functional block diagram of the power supply circuit provided by the utility model;

Fig. 3 is the schematic diagram of the power supply circuit provided by the utility model;

Fig. 4 is the schematic circuit diagram of the first embodiment of the utility model;

Fig. 5 is the schematic circuit diagram of the second embodiment of the utility model;

Fig. 6 is the schematic circuit diagram of the third embodiment of the utility model;

Fig. 7 is the schematic circuit diagram of the fourth embodiment of the utility model;

Fig. 8 is the schematic circuit diagram of the fifth embodiment of the utility model;

Fig. 9 is a circuit schematic diagram of the sixth embodiment of the present invention;

Fig. 10 is the schematic circuit diagram of the seventh embodiment of the utility model;

Fig. 11 is the equivalent circuit diagram of the utility model Fig. 4 circuit;

Fig. 12 is a graph showing the relationship between the voltage on the lamp tube of the present invention and the frequency of the excitation power supply.

Detailed ways

In order to facilitate a further understanding of the utility model, the utility model is now described in detail in conjunction with the accompanying drawings and specific embodiments.

Fig. 2 is the principle block diagram of the power supply circuit provided by the utility model, and its core idea is: the driving power supply of the fluorescent lamp and the power supply supply of the control system adopt a two-in-one conversion circuit, and the secondary winding of the power transformer passes through a resonant circuit and a step-up transformer The primary winding of the step-up transformer is connected to the primary winding, and the secondary winding of the step-up transformer is connected to the fluorescent lamp to drive the fluorescent lamp. The secondary winding of the power transformer is also connected to a rectifier circuit to provide the power supply for the control system; in this way, the brightness of the fluorescent lamp can be adjusted by changing the switching frequency , while the output of the power supply of the control system remains unchanged, the power supply realizes the control and driving of the fluorescent lamp while providing a stable power supply for the control system.

Fig. 3 is the schematic diagram of the power supply circuit provided by the utility model, the circuit includes a power factor correction circuit, a multi-switch conversion circuit connected to the high voltage DC output of the power factor correction circuit, a power transformer T1 and a step-up transformer T2, a rectifier circuit, and a resonant circuit .

The primary winding of the power transformer T1 is connected to the AC output of the multi-switch switching circuit, and its secondary winding is connected to the primary winding of the step-up transformer T2 through a resonant circuit; the resonant circuit is connected in series by a resonant inductor L1 and a resonant capacitor C4, and the The secondary winding of the voltage transformer T2 is connected to the load output; the secondary winding of the power transformer is also connected to a rectifier circuit to provide control power supply.

Please refer to the circuit diagram of the first embodiment of the utility model shown in Figure 4, which includes a power factor correction circuit, a multi-switch conversion circuit connected to the high voltage DC output of the power factor correction circuit, a power transformer T1 and a step-up transformer T2, a rectifier circuit, a resonant circuit, DC blocking capacitor C2.

The multi-switch conversion circuit includes a first switch S1 and a second switch S2, the first switch S1 and the second switch S2 are connected in series with the power factor correction capacitor C1 to the input terminal Vin, and one end of the DC blocking capacitor C2 is connected to the first The middle point of the switch S1 is connected to the second switch S2, and the other end is connected to the input terminal Vin through the primary winding of the power transformer T1.

The resonant circuit includes a resonant inductance L1 and a resonant capacitor C4. The resonant inductance L1 and the resonant capacitor C4 are connected in series with the secondary winding of the power transformer T1 through the primary winding of the step-up transformer T2. The secondary winding of the power transformer T1 It is also connected with the rectifier circuit; the secondary winding of the step-up transformer T2 is connected to the load output.

Wherein, the rectifier circuit is a half-wave or full-wave or full-bridge rectifier circuit, and the multi-switch conversion circuit is a half-bridge topology or a full-bridge topology.

Please refer to the circuit diagram of the second embodiment of the utility model shown in Fig. 5 and the circuit diagram of the first embodiment is similar, the secondary winding of the power transformer T1 has multiple outputs, the difference is that the secondary winding of the power transformer T1 The output of the rectifier circuit and the connection of the resonant circuit are different. The present embodiment has the same advantages as those of the first embodiment described above.

Please refer to the circuit diagram of the third embodiment of the utility model shown in Fig. 6, which is similar to the circuit diagrams of the first and second embodiments, except that the secondary winding of the power transformer T1 is a plurality of windings, one of which is connected to the The resonant circuit and the primary winding of the step-up transformer T2 are connected in series, and the other windings of the secondary side are respectively connected to the output of the rectifier circuit. The present embodiment has the same advantages as those of the second embodiment described above.

Please refer to the circuit diagram of the fourth embodiment of the utility model shown in FIG. 7 and the circuit diagram of the third embodiment. The difference is that there are multiple power transformers, and the primary windings of the multiple power transformers are connected in parallel. The secondary windings of multiple power transformers are connected in series with the resonant circuit and the primary winding of the step-up transformer T2, and the secondary windings of the multiple power transformers are connected in series with rectifier circuit output. This embodiment mode has the same advantages as those of the third embodiment mode described above.

Please refer to the circuit diagram of the fifth embodiment of the utility model shown in Figure 8 and the circuit diagram of the fourth embodiment is similar, the difference is that one of the secondary windings of the multiple power transformers is connected to the resonant circuit and the step-up transformer The primary side windings of T2 are connected in series, and the other windings of the secondary side are respectively connected to the output of the rectifier circuit. This embodiment mode has the same advantages as those of the fourth embodiment mode described above.

Please refer to the circuit diagram of the sixth embodiment of the utility model shown in Figure 9 and the circuit diagram of the fifth embodiment is similar, the difference is that each power transformer in the plurality of power transformers has a plurality of secondary windings, one or more The secondary windings of each power transformer are connected in series with the resonant circuit and the primary winding of the step-up transformer T2 directly or in series, and the other secondary windings of the power transformer are respectively connected directly or in series with the output of the rectifier circuit. This embodiment mode has the same advantages as those of the fifth embodiment mode described above.

Please refer to the circuit diagram of the seventh embodiment of the utility model shown in Fig. 10 and the circuit diagram of the fifth embodiment, the difference is that the secondary windings of the multiple power transformers are connected in series with the resonant circuit and the step-up transformer T2 The primary windings of the multiple power transformers are connected in series, and the secondary windings of the plurality of power transformers are connected in series with rectifier circuit output. This embodiment mode has the same advantages as those of the fifth embodiment mode described above.

In addition, the utility model can be provided with a plurality of step-up transformers according to the actual needs, and can be combined in any way to form multiple outputs with more quantities than the transformers, which can also reduce the cost.

Fig. 4 is a more typical one in the utility model scheme, and the working principle of other embodiments in the utility model is the same as that of Fig. 4, and the working principle of the utility model will be introduced below with Fig. 4 as an example.

In Figure 4, Vin is the output of the power factor correction circuit, generally between 380 and 400V, the voltage is stable, and the accuracy can be controlled within ±3%. The power transformer T1 is a near-ideal transformer with a turn ratio of N , when the half-bridge circuit operates at a 50% duty cycle, the rectified output voltage Vo is approximately:

Vo≈Vin/2N, since the half-bridge circuit works with frequency conversion, the duty cycle of 50% remains unchanged, so the value of Vo remains unchanged, and its stability depends on Vin. Since the accuracy of Vin is ±3%, it can be used The accuracy of Vo is controlled within ±5%.

Referring to the equivalent circuit diagram of the circuit in Figure 4 shown in Figure 11, the leakage inductance of the step-up transformer T2 in Figure 4 is equivalent to Ld, and the resonant frequency fr of the circuit is:

$\mathrm{<span\; class="notranslate">\; fr</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\text{<span class="notranslate"> Ld</span>}<span\; class="notranslate">\; )</span>}$

The relationship between the voltage on the lamp load Rlamp and the frequency of the excitation power supply Vin/2N is shown in Figure 12. It can be seen from Figure 12 that when the frequency is changed, when f1 changes to f2, the voltage on the lamp load Rlamp rises, so changing the frequency can Change the brightness of the lamp. When changing the frequency, the operating frequency should be higher than the resonant frequency fr, which can make the power switch of the half-bridge circuit in Figure 4 work in a zero-voltage switching state, thereby reducing the switching loss of the power switch.

The above is a detailed introduction of a fluorescent lamp driving power provided by the utility model. In this paper, specific examples are used to illustrate the principle and implementation of the utility model. The description of the above embodiments is only used to help understand the utility model. method and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the utility model, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be understood as Limitations on the Invention.

Claims (10)

1. A fluorescent lamp drive power supply, comprising a multi-switch conversion circuit, a power transformer, a resonant inductor, a resonant capacitor, a step-up transformer, and a rectifier circuit, characterized in that: the primary side winding of the power transformer is connected to the multi-switch conversion circuit AC output, the resonant inductor is connected in series with the resonant capacitor through the primary winding of the step-up transformer and the secondary winding of the power transformer, and the secondary winding of the power transformer is also connected with a rectifier circuit; the step-up transformer The secondary winding is connected to the load output. 2. The fluorescent lamp driving power supply according to claim 1, characterized in that: the secondary winding of the power transformer has at least two pairs of outputs, and one pair of outputs is connected in series with the resonant inductor, resonant capacitor and step-up transformer The primary windings of the other pairs are respectively connected to the rectifier circuit. 3. The fluorescent lamp driving power supply according to claim 1, characterized in that: the power transformer has at least two secondary windings, and the output of one of the secondary windings is connected in series with the resonant inductor, resonant capacitor and boost voltage The primary winding of the transformer and the other secondary windings are respectively connected to the rectification circuit. 4. The fluorescent lamp driving power supply according to claim 1, characterized in that it comprises at least two power transformers, the primary windings of each power transformer are connected in parallel, and the secondary windings of each power transformer After being connected in series with the resonant inductor, the resonant capacitor and the primary winding of the step-up transformer, the secondary winding of each power transformer is also connected with a rectifier circuit after being connected in series. 5. The fluorescent lamp driving power supply according to claim 1, characterized in that it comprises at least two power transformers, the primary windings of each power transformer are connected in parallel, and the secondary winding of one of the power transformers The resonant inductor, the resonant capacitor and the primary winding of the step-up transformer are connected in series, and the secondary windings of the other power transformers are respectively connected to the rectification circuit. 6. The fluorescent lamp driving power supply according to claim 1, characterized in that it comprises at least two power transformers, the primary windings of each power transformer are connected in parallel, and the secondary windings of each power transformer There are at least two pairs of outputs, one pair of outputs of the secondary winding of each power transformer is connected in series to the resonant inductor, resonant capacitor and primary winding of the step-up transformer, and the other pair of outputs are respectively connected to a rectifier circuit. 7. The fluorescent lamp driving power supply according to claim 1, characterized in that it comprises at least two power transformers, the primary windings of each power transformer are connected in parallel, and each power transformer has at least two The secondary windings of one or more of the power transformers are connected directly or in series to the primary windings of the resonant inductor, resonant capacitor and step-up transformer, and the secondary windings of the other power transformers are directly connected to each other. Or connected in series and then rectified circuit. 8. The fluorescent lamp driving power supply according to any one of claims 1 to 7, further comprising a power factor correction circuit, which outputs a high voltage direct current to the input of the multi-switch conversion circuit. 9. The fluorescent lamp driving power supply according to any one of claims 1 to 7, characterized in that it comprises at least two step-up transformers, the primary side windings of each step-up transformer are connected in parallel, and its secondary side The windings are respectively connected to the load output. 10. The fluorescent lamp driving power supply according to any one of claims 1 to 7, wherein the rectification circuit is a full-bridge rectification circuit, a full-wave rectification circuit or a half-wave rectification circuit.

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