WO2008064594A1

WO2008064594A1 - A power supply device

Info

Publication number: WO2008064594A1
Application number: PCT/CN2007/070851
Authority: WO
Inventors: Dongping Yang
Original assignee: Dongping Yang
Priority date: 2006-11-28
Filing date: 2007-10-09
Publication date: 2008-06-05
Also published as: CN201001089Y

Abstract

A power supply device comprises a first transformer (T1) with a primary winding (N1) and at least one tightly coupled secondary winding (N2, N2'), and a second transformer (T2) with loosely coupled primary (N21) and secondary (N22) windings. The primary winding of the first transformer is connected in parallel with the primary winding of the secondary transformer, and the input terminals connected in parallel are coupled to the outputs of a multi-switch converter circuit (3). The output of the secondary winding of the second transformer is provided with capacitors (C21, C22), the secondary winding and the capacitors are formed into an oscillation circuit to drive a load (RL).

Description

Power supply device

The present application claims priority to Chinese Patent Application No. 2006-A.

Technical field

The utility model relates to the field of electrical appliances, in particular to a two-output power supply device used in an electric appliance.

Background technique

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

Referring to Figure 1, in some applications of liquid crystal display devices, such as LCD TV two-in-one power supply applications, in addition to providing high-voltage AC drive power for the lamps in the backlight module, it is also necessary to provide an isolated low-voltage DC power supply to the LCD. The control and image processing circuits in the panel and the power amplifier circuit are powered. The low voltage DC power supply is called a control power supply.

In Figure 1, the control power supply outputs 18 ~ 24V DC to the power amplifier circuit, and outputs 12V, 5V, 5VSTB DC to the control and image processing circuits.

In addition, after the AC rectification input, a power factor correction circuit must be added between the rectifier circuit and the lamp drive circuit. Therefore, the LCD TV power supply generally has at least three power circuits with larger power. Among the three power supply circuits, the lamp driving circuit and the power factor correction circuit have a single control circuit and the circuit is relatively standard; and the control power supply has the worst standard because of different user circuits, different timings, and different output voltages, thus not Conducive to standardization and mass production of power supply for liquid crystal display devices. In addition, the three high-power power sources are also high in cost and the conversion efficiency is also poor.

Utility model content

The technical problem to be solved by the present invention is to provide a two-output, low-cost power supply device.

In order to solve the above technical problems, the utility model is realized by the following technical solutions:

The utility model relates to a power supply device, which comprises a first transformer and a second transformer. The primary winding of the first transformer is connected in parallel with the primary winding of the second transformer, and the primary winding and the second transformer of the first transformer The input terminal of the primary winding of the voltage device is connected in parallel with the alternating current;

The first transformer includes a primary winding and at least one secondary winding, the at least one secondary winding and the primary winding are tightly coupled;

The second transformer includes a primary winding and a secondary winding, the secondary winding and the primary winding are loosely coupled, the secondary winding output is connected to a capacitor, and the secondary winding and the capacitor form an oscillating circuit and are driven together load.

Preferably, the at least one secondary winding has a number of secondary windings that are tightly coupled to the primary winding, and is diode-connected to form a full-wave rectifier circuit.

Preferably, the power supply unit further includes a multi-switch conversion circuit that provides an AC input to the transformer.

Preferably, the multi-switch conversion circuit is a push-pull circuit topology, a half-bridge circuit topology or a full-bridge circuit topology circuit.

Preferably, further comprising a power factor correction circuit that outputs a high voltage direct current to the input of said multi-switch conversion circuit.

Preferably, the at least one secondary winding is closely coupled to the primary winding, wherein the secondary winding and the primary winding are located in the same concentric plane, and the secondary winding is located between the primary windings to form a concentric circular sandwich structure; The decoupling of the secondary winding from the primary winding means that the primary winding and the secondary winding are not in the same concentric plane, and the secondary winding is spaced apart from the primary winding to form a creepage distance of at least greater than 6 mm.

The above technical solution can be seen that the power supply device provided by the utility model comprises two transformers, the primary winding of the first transformer is connected in parallel with the primary winding of the second transformer, and the primary winding and the secondary winding of the first transformer are tightly coupled. The secondary winding can be used to supply power to the user circuit; the primary winding and the secondary winding of the second transformer are loosely coupled, and the secondary winding can be used to drive the lamp. Compared with the existing power supply technology, the power supply of the larger power is omitted, thereby reducing the cost of the power supply.

In addition, since the primary winding and the secondary winding of the first transformer are tightly coupled, the low voltage DC voltage of the secondary winding rectified output is independent of the control frequency of the multi-switching conversion circuit, and its stability depends on the stability of the output of the power factor correction circuit. It can supply power to the power amplifier circuit and supply power to the user's DC/DC circuit, providing various voltages and timings required for control and image processing circuits. Vice of the second transformer The output of the side winding is directly controlled by the control frequency of the multi-switching conversion circuit, and the current of the lamp can be changed to control the brightness. Thus, the two outputs can be independently controlled and decoupled from each other. When the multi-switching conversion circuit uses the bridge circuit topology, since the zero voltage switching is realized, the switching loss of the power tube is effectively reduced. In this way, a low-cost, high-efficiency two-output power supply unit is realized. DRAWINGS

1 is a circuit schematic diagram of a power supply device of a prior art liquid crystal television;

2 is a schematic diagram of a power supply device provided by the present invention;

3 is a circuit diagram of a power supply device provided by the present invention;

Figure 4 is a schematic cross-sectional view showing the tight coupling of the transformer provided by the present invention;

Figure 5 is a schematic cross-sectional view showing the loose coupling of the transformer provided by the present invention;

Figure 6 is a circuit diagram of an embodiment of the present invention;

7 is a circuit diagram of a combination of a push-pull circuit and a transformer provided by the present invention;

8 is a circuit diagram of a combination of a half bridge circuit and a transformer provided by the present invention;

9 is a circuit diagram of a quasi-half bridge circuit and a transformer combination provided by the present invention;

10 is a circuit diagram of a quasi-half bridge circuit and a transformer combination provided by the present invention; FIG. 11 is a circuit diagram of a full bridge circuit and a transformer combination provided by the present invention.

detailed description

2 is a schematic diagram of a power supply device provided by the present invention, wherein: two transformers are used in the lamp driving circuit, and two outputs are correspondingly arranged. First, the primary winding of the first transformer is tightly coupled with the secondary winding. The secondary winding outputs a low-voltage DC voltage to the power amplifier and the control circuit, and the low-voltage DC voltage is independent of the switching frequency, and the stability depends on the stability of the power factor correction circuit PFC output voltage; second, the second transformer primary winding and the secondary winding ^Dispersion, its secondary winding drives the lamp, and the lamp current can be controlled by changing the switching frequency. Thus, as long as a standby power supply of a small power is set, the control power of the larger power in the two-in-one power supply of the prior art LCD TV shown in Fig. 1 can be omitted.

3 is a circuit diagram of a power supply device provided by the utility model, the power supply device includes a rectifier circuit connected to the power grid, a power factor correction circuit connected to the DC output of the rectifier circuit, a multi-switch conversion circuit connected to the power factor correction circuit, and a high-voltage DC output, and a transformer. The primary winding of Ί\ and the primary winding of transformer Τ ₂ are connected to a multi-switch conversion circuit; The transformer Ί\ includes a primary winding and a secondary winding N ₂ and Ν ₂ ', and the secondary windings Ν ₂ and Ν ₂ ' are tightly coupled to the primary winding, and the input of the primary winding is connected to a multi-switch switching circuit. Output, the secondary windings N ₂ and Ν ₂ ' are respectively connected in series with the diode D o D ₂ to form a full-wave rectifier circuit, and the resistor and the capacitor d are coupled to the output of the full-wave rectifier circuit;

Since the primary winding of the transformer Ί\ and the secondary windings N ₂ and Ν ₂ ' are tightly coupled, the primary winding

For the Ni and the secondary winding N ₂ , the impedance between the primary winding and the secondary winding N ₂ is small, and the rectified output voltage of the transformer secondary winding N ₂ driving the other circuits is:

ν ₂ = ν^Ν ₂ ΙΝ

It can be seen that the rectified output voltage of the secondary winding Ν ₂ is only determined by the input voltage and the transformer ratio, independent of the switching frequency; the input voltage is the output voltage of the multi-switch conversion circuit; as can be seen from the above analysis, as long as it is stable, It will be stable. In practical applications, the stable value can be controlled within 5%, so the stable value can be controlled within 5%, and the power can be normally supplied to the amplifier circuit to meet the needs of users.

The transformer Τ ₂ includes a primary winding Ν ₂₁ and a secondary winding Ν ₂₂ , the input of the primary winding Ν ₂₁ is connected to the AC output of the multi-switch switching circuit, and the secondary winding Ν ₂₂ is loosely coupled to the primary winding Ν ₂₁ , the capacitor C ₂₂ in series with the lamp, and finally the capacitor C ₂₁ is coupled a secondary winding N _22.

Since the transformer winding T ₂ Central v ₂₁ v ₂₂ and the loose coupling secondary winding, the primary winding and the secondary winding ₂₁ v v ₂₂ forming the leakage inductance of the inductor L, the capacitor ₂₁ billion and ₂₂ billion form a resonance circuit, the driving The lamp R _L , the current passing through the lamp R _L is a function of frequency, and decreases with increasing frequency, thereby realizing the dimming function, so that the lamp current and brightness can be controlled by changing the frequency.

Referring to FIG. 4, the secondary winding N _{2 is} tightly coupled to the primary winding, which means that the secondary winding N ₂ and the primary winding are located in the same concentric plane, and the secondary winding N ₂ is located between the primary windings to form a concentric circle. Sandwich structure.

Referring to FIG. 5, the loose coupling of the secondary winding N ₂₂ with the primary winding N ₂₁ means that the primary winding N ₂₁ and the secondary winding N ₂₂ are not in the same concentric plane, and the secondary winding N ₂₂ and the primary winding The N _{21 is} spaced apart to form a creepage giant that is at least greater than 6 mm.

The multi-switch circuit can use the push-pull circuit topology, the full-bridge circuit topology circuit or the half-bridge circuit topology. The following is a detailed description of the half-bridge circuit topology: Referring to FIG. 6, the multi-switch circuit uses a half-bridge circuit topology, a primary winding of the transformer Ί\ and a primary winding Ν _{21 of the} transformer T ₂ and connects the output of the half-bridge circuit; the secondary winding voltage of the transformer Τ ₂ is fed back to The frequency conversion control circuit and the driving circuit, the driving circuit performs signal processing for amplifying the result signal of the frequency conversion control circuit, and the output of the driving circuit is respectively connected to the gate of the FET and the gate of the FET Q ₂ , the source of the FET Connected to the drain of the FET Q ₂ , the capacitor is connected in series with CQ ₂ , and the capacitor C _{01 is} connected to the drain of the FET, the capacitor C _Q2 is connected to the source of the FET Q ₂ , and the primary winding of the transformer Ί It is connected in parallel with the primary winding Ν _{21 of the} transformer T ₂ , one end of which is connected to the source of the FET, and the other end is connected to the midpoint of the connection between the capacitor and the CQ ₂ ; the current of the lamp can also be fed back to the inverter control circuit and the driving circuit. , does not affect the implementation of the utility model.

The multi-switch circuit uses a push-pull circuit, and the circuit diagram combined with the transformer is shown in Figure 7. The change of the switching frequency of the switches Si and S ₂ can control the change of the lamp R _L current;

The multi-switch circuit uses a half-bridge circuit, and the circuit diagram combined with the transformer is shown in Fig. 8. The change of the switching frequency of the switches Si and S ₂ can control the change of the lamp R _L current;

The multi-switch circuit uses a quasi-half bridge circuit, and the circuit diagram combined with the transformer is shown in FIG. 9 or FIG. 10, and the change of the switching frequency of the switch and S ₂ can control the change of the lamp R _L current;

The multi-switch circuit uses a full-bridge circuit. The circuit diagram combined with the transformer is shown in Fig. 11. The change of the switching frequency of the switches s ₁ S ₂ , S ₃ and S ₄ can control the change of the lamp _RL current.

As can be seen from the above, the power supply device provided by the present invention requires two transformers 1\ and τ ₂ for respectively driving the lamp tube and the user circuit, and omitting a large dedicated for driving the user circuit compared to the existing power supply technology. Power control power supply saves production costs. The utility model only needs to supplement a small power standby power supply to supply power to the CPU circuit, thereby realizing the application of the liquid crystal television two-in-one power supply and the like, and the cost is greatly reduced, and the power consumption is effectively reduced.

Since the half-bridge conversion circuit is still operating in the zero voltage switching state, the conversion efficiency is still high, and the efficiency of the entire power supply device is also improved. Because the primary winding and the secondary winding of the transformer 紧密\ are tightly coupled, the low-voltage DC voltage of the secondary winding rectified output is independent of the control frequency of the multi-switching conversion circuit, and its stability depends on the stability of the output of the power factor correction circuit. To meet user requirements, its low-voltage DC voltage is designed to be any voltage between 18-24V, which can directly supply power to the power amplifier circuit. As for the various control voltages required for control and image processing circuits, it can be added to the user circuit board. Add some simple DC/DC change circuits so that the control voltage and its timing can be directly controlled by the control and image processing circuits.

After using the power supply device provided by the utility model, the liquid crystal television power supply can be directly provided by the liquid crystal panel manufacturer, and the user interface has only one 5V standby voltage and 18 24V voltage output after startup, and the user can save a large amount of power on the power supply. Time and effort, and the cost of LCD TV power supplies is greatly reduced due to large-scale standardized production. After the transformer is used as a power supply unit and the liquid crystal panel is integrated, the output of the power supply can be normalized into a voltage, which is easy to form a standard and is convenient for the user to use, thereby laying a foundation for mass production.

In addition to the application on the LCD TV power supply, the power supply device provided by the present invention can also be applied to similar applications.

The above is a detailed description of a power supply device provided by the present invention. The principle and embodiment of the present invention are described in the following by using specific examples. The description of the above embodiments is only for helping to understand the method of the present invention. And the core idea of the present invention; at the same time, according to the idea of the present invention, there will be changes in the specific implementation manner and the scope of application. In summary, the contents of this specification should not be construed as Limitations of utility models.

Claims

Rights request

A power supply device, comprising: a first transformer and a second transformer, wherein a primary winding of the first transformer is connected in parallel with a primary winding of the second transformer, a primary winding of the first transformer and a second transformer The input terminals of the primary windings connected in parallel are connected to each other;

2. The power supply apparatus according to claim 1, wherein: said at least one secondary winding having a close coupling with said primary winding is two in number, and said diode is connected in series to constitute a full-wave rectifier circuit.

3. The power supply apparatus according to claim 2, further comprising a multi-switch conversion circuit that provides an alternating current input to said transformer.

4. The power supply apparatus according to claim 3, wherein the multi-switch conversion circuit uses a push-pull circuit topology, a half-bridge circuit topology, or a full-bridge circuit topology circuit structure.

5. The power supply apparatus according to claim 3, further comprising a power factor correction circuit that outputs a high voltage direct current to an input of said multi-switch conversion circuit.

6. The power supply apparatus according to claim 1, wherein: the at least one secondary winding is closely coupled to the primary winding, wherein the secondary winding and the primary winding are in the same concentric plane, and the secondary winding is located. A concentric circular sandwich structure is formed between the primary windings; the loose coupling of the secondary winding and the primary winding means that the primary winding and the secondary winding are not in the same concentric plane, and the secondary winding is separated from the primary winding. A creepage large separation of at least greater than 6 mm is formed.