CN201869093U

CN201869093U - Switch power supply discharging circuit

Info

Publication number: CN201869093U
Application number: CN201020577393XU
Authority: CN
Inventors: 钟小斌; 庄万春; 鲍晓杰
Original assignee: Shenzhen Skyworth RGB Electronics Co Ltd
Current assignee: Shenzhen Skyworth RGB Electronics Co Ltd
Priority date: 2010-10-26
Filing date: 2010-10-26
Publication date: 2011-06-15
Anticipated expiration: 2020-10-26

Abstract

The utility model is applied to the field of electronics and provides a switch power supply discharging circuit. The switch power supply discharging circuit comprises an alternating current power supply, a switch, a common mode inductor, a capacitor X, a rectifying bridge, a first bleeder resistor, a second bleeder resistor, and a controlled voltage source. According to the utility model, the two bleeder resistors are connected in series and are then connected with the capacitor X in parallel; the bleeder resistors are connected with the rectifying bridge by the controlled power supply; and the voltage at two ends of the bleeder resistors can be reduced without changing the discharging time, thereby achieving the aim of reducing the insertion loss and reducing the standby power consumption of the switch power supply circuit.

Description

A kind of Switching Power Supply discharge circuit

Technical field

The utility model belongs to electronic applications, relates in particular to a kind of Switching Power Supply discharge circuit.

Background technology

Regulation according to national electronic product safety and electromagnetic compatibility authentication (3C authentication), after the appliances power source line in the work is cut off, in two seconds, the charged voltage in power-line plug two ends must be lower than 30% of rated operational voltage, in order to reach this requirement, usually adopt and between the ac power input end of Switching Power Supply and rectifier bridge, insert a bleed-off circuit and realize, and, add a filter circuit usually in the bleed-off circuit front in order to suppress electromagnetism Interference effectively.

Fig. 1 shows the filtering discharge circuit in the existing Switching Power Supply, X capacitor C X in parallel between live wire L and the zero line N wherein, the common mode inductance LX that connects between ac power input end and the X capacitor C X, X capacitor C X two ends bleeder resistance RX in parallel, rectifier bridge 1 is made up of diode D1, D2, D3, D4 in addition.

When the appliances power source line was closed, common mode inductance LX in Fig. 1 structure and X capacitor C X realized suppressing common mode disturbances as filter circuit, but the voltage at bleeder resistance RX two ends is approximately equal to AC supply voltage at this moment, has produced certain power consumption and has promptly inserted loss.

When the appliances power source line is cut off moment, the equivalent electric circuit of Fig. 1 as shown in Figure 2, when X capacitance voltage upper end be positive lower end when negative, the discharge loop of this electric capacity and bleeder resistance RX formation is shown in solid line; For negative lower end is timing, the discharge loop that this electric capacity and bleeder resistance RX form is shown in dotted line on the X capacitance voltage, depends on discharge constant τ=CX*RX discharge time.

But, because the excessive voltage difference in bleeder resistance two ends produces bigger insertion loss inevitably, increased the energy consumption of switching power circuit, run counter to country to consumption electric appliances energy conservation and environment protection.

The utility model content

The purpose of this utility model is to provide a kind of Switching Power Supply discharge circuit, is intended to solve in the existing switching power circuit and inserts the big problem of loss.

The utility model is achieved in that a kind of Switching Power Supply discharge circuit, comprises AC power, switch, common mode inductance, X electric capacity and rectifier bridge, and described circuit also comprises:

First bleeder resistance, second bleeder resistance and controlled voltage source;

Described first bleeder resistance is connected with second bleeder resistance;

Described X electric capacity is in parallel with the series arm of described first bleeder resistance and second bleeder resistance;

The anodal common port that connects described first bleeder resistance and described second bleeder resistance of described controlled voltage source, negative pole connects rectifier bridge.

Further, described first bleeder resistance is identical with the resistance of described second bleeder resistance.

Further, described controlled voltage source meets the following conditions:

When the switch closure of described circuit, described controlled voltage source both end voltage equals constant voltage Vcc voltage;

When the switch of described circuit disconnected, described controlled voltage source both end voltage was zero.

Further, described circuit also comprises:

The 3rd bleeder resistance;

The resistance of described the 3rd bleeder resistance is less than the resistance of described first bleeder resistance and second bleeder resistance.

In the utility model, after first bleeder resistance that two resistances is identical and the series connection of second bleeder resistance, in parallel with X electric capacity, and by controlled voltage source connection bleeder resistance and rectifier bridge, make when not changing discharge time, reduce the voltage at bleeder resistance two ends, thereby reached the purpose that reduces to insert loss, reduced the energy consumption of Switching Power Supply.

Description of drawings

Filtering discharge circuit figure in the Switching Power Supply that Fig. 1 provides for prior art;

Fig. 2 is the equivalent circuit diagram of power line Fig. 1 breaking moment;

Switching Power Supply discharge circuit figure in the Switching Power Supply that Fig. 3 provides for the utility model first embodiment;

Fig. 4 is the equivalent circuit diagram of Fig. 3 when being in electrical network;

Fig. 5 is the equivalent circuit diagram of Fig. 3 when cutting off electrical network;

Switching Power Supply discharge circuit figure in the Switching Power Supply that Fig. 6 provides for the utility model second embodiment.

Embodiment

In order to make the purpose of this utility model, technical scheme and advantage clearer,, the utility model is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the utility model, and be not used in qualification the utility model.

After first bleeder resistance that the utility model embodiment is identical with two resistances and the series connection of second bleeder resistance, in parallel with X electric capacity, and by controlled voltage source connection bleeder resistance and rectifier bridge, make when not changing discharge time, reduced the voltage at bleeder resistance two ends, thereby reached the purpose that reduces to insert loss, reduced the energy consumption of Switching Power Supply.

Fig. 3 shows the Switching Power Supply discharge circuit in the Switching Power Supply that the utility model first embodiment provides, and for convenience of explanation, only shows the part relevant with the utility model.

In the utility model embodiment, the first bleeder resistance RX1 connects with the second bleeder resistance RX2, X capacitor C X is in parallel with the series arm of the first bleeder resistance RX1 and the second bleeder resistance RX2, the anodal common port that connects the first bleeder resistance RX1 and the second bleeder resistance RX2 of controlled voltage source Vcc (SW), negative pole connects second end of rectifier bridge 1.

Below in conjunction with specific embodiment realization of the present utility model is elaborated.

Fig. 4 shows in the utility model embodiment, when the switch SW closure, and the equivalent electric circuit when this circuit is in electrical network.

When this AC power is in positive half period, the first bleeder resistance RX1 and diode D2 conducting, shown in solid line among Fig. 4, controlled voltage source Vcc (SW)=Vcc, this moment, the voltage at the first bleeder resistance RX1 two ends was the poor of this AC supply voltage and controlled voltage source voltage vcc, bleeder resistance two ends AC supply voltage in the prior art.

When this AC power is in negative half-cycle, the second bleeder resistance RX2 and diode D1 conducting, as shown in phantom in Figure 4, controlled voltage source Vcc (SW)=Vcc, this moment, the voltage at the second bleeder resistance RX2 two ends also was the poor of this AC supply voltage and controlled voltage source voltage vcc, less than bleeder resistance two ends AC supply voltage in the prior art, reduce the purpose of inserting loss equally thereby reached.

Fig. 5 shows in the utility model embodiment, when switch SW disconnects the equivalent electric circuit during this circuitry cuts electrical network.

When X capacitor C X voltage upper end be positive lower end when negative, the X capacitor C X loop discharge that the first bleeder resistance RX1 and diode D2 form of flowing through, shown in Fig. 5 solid line, the constant that discharges is τ 1=CX*RX1.

When X capacitor C X voltage upper end is timing for negative lower end, the X capacitor C X loop discharge that the second bleeder resistance RX2 and diode D1 form of flowing through, shown in Fig. 5 dotted line, the discharge constant is τ 2=CX*RX2.

As a preferred embodiment of the present utility model, satisfy resistance R X1=RX2=RX, according to discharge constant formula τ=CX*RX, draw discharge constant τ 1=τ 2=τ, promptly this circuit does not increase the discharge time of primary circuit.

The Switching Power Supply discharge circuit of the another kind of structure that Fig. 6 provides for second embodiment of the present utility model, this circuit has increased by the 3rd bleeder resistance RX3 on the basis of the utility model first embodiment, this resistance one end connects the common port of the first bleeder resistance RX1 and the second bleeder resistance RX2, and the other end connects the positive pole of controlled voltage source Vcc (SW).

The resistance that satisfies the 3rd bleeder resistance RX3 is far smaller than bleeder resistance RX, this moment bleeder resistance RX1, RX3 two ends voltage and be approximately equal to the voltage at the first bleeder resistance RX1 two ends, much smaller than the voltage at bleeder resistance RX two ends, reduce the purpose of inserting loss thereby reached.As a preferred embodiment of the present utility model, the 3rd bleeder resistance RX3 also plays the restriction instantaneous large-current by this branch road, the purpose of protection controlled voltage source Vcc (SW) simultaneously.

The low-power consumption discharge circuit that the utility model embodiment provides is applicable to the switching power circuit of any consumer electrical equipment, is particularly useful for the switching power circuit of television set.

In the utility model embodiment; after first bleeder resistance that two resistances is identical and the series connection of second bleeder resistance; in parallel with X electric capacity; and by controlled voltage source connection bleeder resistance and rectifier bridge; make when not changing discharge time, reduced the voltage at first bleeder resistance or the second bleeder resistance two ends, thereby reduced the insertion loss; reduced the energy consumption of Switching Power Supply, and the 3rd bleeder resistance can also play the effect of protection controlled voltage source.

The above only is preferred embodiment of the present utility model; not in order to restriction the utility model; all any modifications of within spirit of the present utility model and principle, being done, be equal to and replace and improvement etc., all should be included within the protection range of the present utility model.

Claims

1. a Switching Power Supply discharge circuit comprises AC power, switch, common mode inductance, X electric capacity and rectifier bridge, it is characterized in that described circuit also comprises:

Described first bleeder resistance is connected with second bleeder resistance;

2. circuit as claimed in claim 1 is characterized in that, described first bleeder resistance is identical with the resistance of described second bleeder resistance.

3. circuit as claimed in claim 1 is characterized in that, described controlled voltage source meets the following conditions:

4. circuit as claimed in claim 1 is characterized in that, described circuit also comprises:

The 3rd bleeder resistance;