CN202978737U

CN202978737U - Flyback circuit with wide input voltage range

Info

Publication number: CN202978737U
Application number: CN 201220367022
Authority: CN
Inventors: 朱维杨; 陈扬宾; 吕韬; 汤斌
Original assignee: SANHE POWER TECH (SHENZHEN) Co Ltd
Current assignee: SANHE POWER TECH (SHENZHEN) Co Ltd
Priority date: 2012-07-27
Filing date: 2012-07-27
Publication date: 2013-06-05
Anticipated expiration: 2022-07-27

Abstract

The utility model discloses a flyback circuit with a wide input voltage range, mainly comprising a power transformation circuit, an EMI filter circuit and a PWM controller. The EMI filter circuit is input to the power transformation circuit after rectification filtration, the power transformation circuit is output after rectification filtration, output electric signals are acquired and transmitted to the PWM controller through a feedback loop, and the PWM controller modulates the pulse width of the acquired signals and inputs the modulated signals to the EMI filter circuit to adjust the output of the power transformation circuit. DC voltage with small ripples is obtained after rectification filtration by the EMI filter circuit, the DC voltage is used for supplying power for the VCC of a power supply chip after voltage reduction by a resistor, a high frequency pulse signal is emitted by an IC to control a switch tube to be conducted and cut off, the power transformation circuit comprising the flyback transformer plays transmission, energy storage and electrical input and output isolation effects, the feedback comprising an optical coupler and a TL431 is used for feedback, through comparison process to a feedback voltage and an original current, the frequency and duty ratio of the high frequency pulse signal are controlled, and thereby output voltage and current are stable.

Description

A kind of wide input voltage range circuit of reversed excitation

Technical field

The utility model relates to a kind of circuit of reversed excitation, relates in particular to the circuit of reversed excitation of the field of power supplies of the middle low power that is applied to high input voltage and wide input voltage range, multichannel output.

Background technology

With respect to forward converter, anti exciting converter does not need output inductor, and is simple in structure, cost; With respect to half-bridge converter, the anti exciting converter input voltage range is wide, is fit to various different electric pressure occasions; With respect to other input non-isolated converters, counterattack converter input and output electrical isolation, security reliability is high.But for the higher occasion of input voltage, the switching tube of single switch flyback converter will bear the approximately high pressure of twice input voltage, and this selection to the reliability of system and switching tube is very unfavorable.Employing double-transistor flyback converter has increased the voltage stress of switching tube greatly, for high input voltage anti exciting converter successful.But the double-transistor flyback topology adopts transformer driving switch pipe more at present, and circuit topological structure is complicated, and cost is high, and the loss of regular tap pipe is large.

The utility model content

The purpose of this utility model is in order to overcome the deficiencies in the prior art, provide a kind of and can be that to improve the switching tube loss large, drive circuit is complicated, the circuit of reversed excitation of high in cost of production problem, power supply chip and outside COOLMOS series connection that it adopts integrated COOLMOS just easily realize two-tube while conducting, shutoff by price reduction resistance and voltage-stabiliser tube.

To achieve these goals, the utility model is by the following technical solutions:

A kind of wide input voltage range circuit of reversed excitation mainly comprises a power conversion circuit, an EMI filter circuit, a PWM controller; The EMI filter circuit inputs to power conversion circuit after rectifying and wave-filtering, power conversion circuit is exported after rectifying and wave-filtering, gather simultaneously output electrical signals through feedback control loop to the PWM controller, input to the EMI filter circuit with the output of Modulating Power translation circuit after PWM controller modulation pulsewidth.

Described EMI filter circuit and power conversion circuit input over under-voltage protection circuit, the PWM controller input voltage in order to the Modulating Power translation circuit that also is linked in sequence.

Described power conversion circuit is the power supply chip series connection of outside COOLMOS and inner integrated MOS FET.

By obtaining the less direct voltage of stable ripple after EMI filter circuit, rectifying and wave-filtering, give the VCC power supply of power supply chip ICE2B265 after the resistance step-down, IC sends conducting and the shutoff of high-frequency pulse signal control switch pipe, the power conversion circuit that flyback transformer forms plays transmission, storage power and input and output electrical isolation, the feedback control loop that forms by optocoupler and TL431 with feedback voltage to IC, power supply IC passes through feedback voltage and primary current comparison process, thereby frequency and the duty ratio of controlling high-frequency pulse signal make output voltage and current stabilization.

When power supply chip VCC reaches its starting resistor, IC work, inner MOSFET conducting, thus the source voltage that makes outside MOSFET is near former limit reference voltage GND.Meanwhile the grid of outside MOSFET and source electrode produce voltage difference Vgs and make its conducting, the voltage-stabiliser tube between grid and source electrode with the Maximum constraint of Vgs within 15V.Almost conducting simultaneously of the switching tube of IC inside and external switch pipe in this way; Can reliably, effectively increase the voltage stress of switching tube by the utility model, make the topology of double-transistor flyback converter simpler, cost.Owing to adopting COOLMOS that the loss of switching tube is also reduced.

Description of drawings

Fig. 1 is fundamental diagram of the present utility model.

Embodiment

The below is described in further detail the utility model according to accompanying drawing:

A kind of wide input voltage range circuit of reversed excitation as shown in Figure 1: mainly comprise EMI circuit, input rectifying filtering, power conversion circuit, input overvoltage circuit under proteciton, PWM controller, output rectification filter, feedback control loop.

EMI circuit wherein is mainly that electromagnetic noise and the noise signal to input power suppresses, and prevents the interference to power supply, prevents that also the high frequency clutter of power supply own is on the impact of electrical network simultaneously.

Input rectifying filtering is that alternating voltage is obtained purer direct voltage after rectification and rectifying and wave-filtering electric capacity, directly determines the size of voltage ripple.

Power conversion circuit adopts the anti-topology that swashs, when switching tube is opened, and the transformer storage power; Transferring energy during cut-off.Adopt the power supply chip series connection of outside COOLMOS and inner integrated MOS FET, improve the voltage stress of switching tube.

Input overvoltage circuit under proteciton, when input voltage was too high or too low, power supply chip is inner to be adjusted automatically, stops sending out pulse, on-off switching tube.

The PWM controller, in the integrated power supply chip, according to feedback output voltage and former limit peak current relatively, thereby the duty ratio of adjusting PWM is controlled conducting, the turn-off time of closing switch, and the ON time energy storage capacity that more lives forever is more.

Output rectification filter, during the switching tube conducting, rectifier diode is ended by reverse voltage, and only when switching tube turn-offed, output rectifier and filter was just worked.Obtain the less output voltage of ripple through rectifier diode, filter capacitor, the pi type filter device suppresses High-frequency Interference, output DC12V.

Sampling is take the 2.5V of TL431 as benchmark, by two sampling resistors, the size of sampling and outputting voltage.

Feedback control loop, the feedback control loop that TL431 and PC817 form feeds back to the PWM controller with output voltage information, adjusts duty ratio, is output voltage stabilization.

During work, at first the EMI filter circuit inputs to power conversion circuit after rectifying and wave-filtering, power conversion circuit is exported after rectifying and wave-filtering, gather simultaneously output electrical signals through feedback control loop to the PWM controller, input to the EMI filter circuit with the output of Modulating Power translation circuit after PWM controller modulation pulsewidth.

EMI filter circuit and power conversion circuit input over under-voltage protection circuit, the PWM controller input voltage in order to the Modulating Power translation circuit that also is linked in sequence.

Can reliably, effectively increase the voltage stress of switching tube by the utility model, make the topology of double-transistor flyback converter simpler, cost is owing to adopting COOLMOS that the loss of switching tube is also reduced.

Claims

1. a wide input voltage range circuit of reversed excitation, is characterized in that: mainly comprise a power conversion circuit, an EMI filter circuit, a PWM controller; The EMI filter circuit inputs to power conversion circuit after rectifying and wave-filtering, power conversion circuit is exported after rectifying and wave-filtering, gather simultaneously output electrical signals through feedback control loop to the PWM controller, input to the EMI filter circuit with the output of Modulating Power translation circuit after PWM controller modulation pulsewidth.

2. a kind of wide input voltage range circuit of reversed excitation according to claim 1 is characterized in that: described EMI filter circuit and power conversion circuit input over under-voltage protection circuit, the PWM controller input voltage in order to the Modulating Power translation circuit that also is linked in sequence.

3. a kind of wide input voltage range circuit of reversed excitation according to claim 1 is characterized in that: described power conversion circuit is the power supply chip series connection of outside COOLMOS and inner integrated MOS FET.