CN205430699U - Two -stage formula LED drive power supply with PFC function - Google Patents

Abstract

The utility model discloses a two -stage formula LED drive power supply with PFC function comprises preceding, back two -stage circuit and control chip, and the preceding stage circuit be the PFC circuit based on the BOOST chopper, and the back level is the anti - sharp formula DCDC transfer circuit of quasi -resonance, control chip control main switch pipe Q2's break -make, control chip is equipped with eight pins, and pin 1 is the system output, mainly provides the gate pole drive for the MOSFET switch, pin 2 is voltage detecting, pin 3 detects for rectification input voltage, pin 4 is the restriction of outside power and turn -offs the control end, pin 5 is the earthing terminal, pin 6 is the primary current sense terminal, pin 7 is the drive of the outside MOSFET switch tube of output, pin 8 is the chip power supply end. Because the system has adopted two -stage formula structure, has simplified circuit structure greatly, can realize LED's constant current steady voltage control to higher power factor has.

Description

A kind of two-stage type LED drive power with PFC function

Technical field

The present invention relates to power technique fields, be specifically related to the Power Management Design of electrically-based electronic technology, be mainly used in LED and drive.

Background technology

The saving energy, protection environment, development green illumination product are the major tasks the most always actively developed from the early 1990s in last century China's Lighting Industry.LED is because having energy-conservation, life-span length, environmental protection, the advantage such as volume is little, control is flexible, fast response time, to spread to huge numbers of families.But, the power factor of tradition LED drive power is relatively low, and input current has serious harmonic wave, causes the quality of power supply poor, electrical network is formed severe contamination, limits being widely used of LED the most to a certain extent.PFC correction and DC/DC conversion are integrated by traditional single stage type LED drive power, and device used is few, low cost, but its secondary side need to add big electrochemical capacitor, to overcome ripple and low frequency voltage flicker, input current spike is relatively big, has a strong impact on the service life of LED.PFC and DC/DC changer is independently arranged by tradition two-stage type LED drive power, although mutual independence is good, and carrying load ability is strong, but device used is many, poor reliability, efficiency is low, control circuit is the most more complicated, causes high cost, also limit the application in low power applications.In view of this, this patent proposes a kind of two-stage type LED drive power with PFC function, it is intended to solves the problems referred to above, thus accelerates the use of LED light source.

Summary of the invention

The purpose of this utility model is to provide a kind of new two-stage type LED drive power with PFC function.

For achieving the above object, this utility model be have employed following technical scheme: a kind of two-stage type LED drive power with PFC function, it is made up of forward and backward two-stage circuit and control chip, front stage circuits is pfc circuit based on BOOST chopper, and rear class is quasi-resonance inverse-excitation type DC/DC translation circuit；

Described control chip controls the break-make of main switch Q2, and described control chip is provided with eight pins, and pin 1 exports for system, and predominantly switch mosfet provides gate-drive；Pin 2 is voltage detecting, predominantly detects the input signal from auxiliary winding, thus provides secondary voltage feedback output regulation；Pin 3 detects for rectified input voltage, and for input undervoltage and overvoltage protection, this pin starts for chip simultaneously provides electric current；Pin 4 limits for external power and turns off and controls end；Pin 5 is earth terminal；Pin 6 is primary current test side；It is mainly used in loop cycle peak current detection；Pin 7 drives for the outside switch mosfet pipe of output；Pin 8 is chip power end.

Preferably, in described a kind of two-stage type LED drive power with PFC function, described control chip uses control chip iw3614 as the master element of system, controls the break-make of main switch.

nullPreferably，In described a kind of two-stage type LED drive power with PFC function，Including the first resistance、Second resistance、3rd resistance、4th resistance、5th resistance、6th resistance、7th resistance、8th resistance、9th resistance、First electric capacity、Second electric capacity、3rd electric capacity、4th electric capacity、5th electric capacity、6th electric capacity、First diode、Second diode、3rd diode、4th diode、First switching tube and second switch pipe，Described 4th resistance and the 5th resistant series，Described 4th diode and the 7th resistant series，The pin 8 of described control chip is connected with the 4th diode，The pin 7 of described control chip is connected with second switch pipe by the 8th resistance，The pin 1 of described control chip respectively with the second resistance、3rd resistance and the first switching tube connect，First switching tube and the first resistance connect.

Preferably, in described a kind of two-stage type LED drive power with PFC function, described front stage circuits includes PFC correcting circuit, a rectifying and wave-filtering output circuit, one is located at the feedback control unit between described PFC correcting circuit and rectifying and wave-filtering output circuit, and described PFC correcting circuit includes a PFC capability correction chip and the flyback output voltage circuit being connected respectively, PWM boost topology circuit with this PFC capability correction chip；Described flyback output voltage circuit includes a degaussing time and valley voltage sample circuit, a flyback input control circuit；Described feedback control unit includes an isolation optocoupler feedback circuit, first, second amplifier unit and for the auxiliary power circuit powered to described isolation optocoupler feedback unit, first, second amplifier unit；The PWM constant current topological structure unit that one is connected with described feedback control unit.

Providing the benefit that relative to prior art, using such scheme, system have employed two-stage type structure, PFC and DC/DC translation circuit shares a control chip, enormously simplify circuit structure, it is possible to the constant-current voltage-stabilizing realizing LED controls, and has higher power factor.

Accompanying drawing explanation

Fig. 1 is circuit structure diagram of the present utility model.

Detailed description of the invention

It is better understood when the present invention program to make to be engaged in LED drive power technology pertinent art, concrete circuit design step is given below.

As it is shown in figure 1, a kind of two-stage type LED drive power with PFC function, being made up of forward and backward two-stage circuit and control chip, front stage circuits is pfc circuit based on BOOST chopper, and rear class is quasi-resonance inverse-excitation type DC/DC translation circuit；

Described control chip controls the break-make of main switch Q2, and described control chip is provided with eight pins, and pin 1 exports for system, and predominantly switch mosfet provides gate-drive；Pin 2 is voltage detecting, predominantly detects the input signal from auxiliary winding, thus provides secondary voltage feedback output regulation；Pin 3 detects for rectified input voltage, and for input undervoltage and overvoltage protection, this pin starts for chip simultaneously provides electric current；Pin 4 limits for external power and turns off and controls end；Pin 5 is earth terminal；Pin 6 is primary current test side；It is mainly used in loop cycle peak current detection；Pin 7 drives for the outside switch mosfet pipe of output；Pin 8 is chip power end.

Preferably, in described a kind of two-stage type LED drive power with PFC function, described control chip uses control chip iw3614 as the master element of system, controls the break-make of main switch.

nullPreferably，In described a kind of two-stage type LED drive power with PFC function，Including the first resistance、Second resistance、3rd resistance、4th resistance、5th resistance、6th resistance、7th resistance、8th resistance、9th resistance、First electric capacity、Second electric capacity、3rd electric capacity、4th electric capacity、5th electric capacity、6th electric capacity、First diode、Second diode、3rd diode、4th diode、First switching tube and second switch pipe，Described 4th resistance and the 5th resistant series，Described 4th diode and the 7th resistant series，The pin 8 of described control chip is connected with the 4th diode，The pin 7 of described control chip is connected with second switch pipe by the 8th resistance，The pin 1 of described control chip respectively with the second resistance、3rd resistance and the first switching tube connect，First switching tube and the first resistance connect.

Preferably, in described a kind of two-stage type LED drive power with PFC function, described front stage circuits includes PFC correcting circuit, a rectifying and wave-filtering output circuit, one is located at the feedback control unit between described PFC correcting circuit and rectifying and wave-filtering output circuit, and described PFC correcting circuit includes a PFC capability correction chip and the flyback output voltage circuit being connected respectively, PWM boost topology circuit with this PFC capability correction chip；Described flyback output voltage circuit includes a degaussing time and valley voltage sample circuit, a flyback input control circuit；Described feedback control unit includes an isolation optocoupler feedback circuit, first, second amplifier unit and for the auxiliary power circuit powered to described isolation optocoupler feedback unit, first, second amplifier unit；The PWM constant current topological structure unit that one is connected with described feedback control unit.

First, according to input voltage size, choose acceleration starting circuit R_stResistance, this resistance will affect ON time and the cycle of switching tube Q2, thus affect the effect of PFC.Due to by 3 pins of this resistance access chip, inner setting dividing potential drop coefficient is 0.0043, and as a example by input voltage is as 230V, pin internal resistance is R_vin=2.5k Ω, starting resistance can elect as:

$R_{st}=\frac{R_{vin}}{K_{vin}}-R_{vin}=580k\mathrm{\Ω}$

Secondly, BLEEDER resistance is selected.When chip starts, having three half period ON times, about 30ms, initialize dimmer state, select BLEEDER resistance, it is provided that fixing maintenance electric current, with limit input circuit peak value, rule of thumb, when selecting 47 Ω resistance, electric current is less than 148mA.

3rd, the inductance of design PFC, chopper circuit ON time is:

T_on=4 μ s-2.2 μ s/v × V_{in_a}

T=12.2 μ s+8.8 μ s/v × V_{in_a}

Adjust inductance value, chopper can be made to work in electric current continuously and saturation.As a example by 230V, the LED power of a 18-20W, inductance can elect 3.2mH as, and power factor is up to more than 90%.

4th, Design of Transformer and selection MOSFET and rectifier tube.Design of transformer can directly carry out selecting design according to the data page of iw3614, can select rectifier tube and MOSFET according to data page simultaneously.

5th, in order to improve the anti-electromagnetic interference capability of system, carry out electromagnetism interference EMI design, in the case of high powe design, I-type magnetic core coil can be used, carry out the design of two-stage LC wave filter simultaneously.

Owing to system have employed two-stage type structure, PFC and DC/DC translation circuit shares a control chip, enormously simplify circuit structure, it is possible to the constant-current voltage-stabilizing realizing LED controls, and has higher power factor.

Above content is to combine the detailed description that the present invention is done by optimal technical scheme, it is impossible to what identification was invented is embodied as being only limitted to these, for the simple deduction made under without departing from inventive concept premise and replacement, all should be considered as protection scope of the present invention.

Claims (4)

1. the two-stage type LED drive power with PFC function, it is characterised in that: being made up of forward and backward two-stage circuit and control chip, front stage circuits is pfc circuit based on BOOST chopper, and rear class is quasi-resonance inverse-excitation type DC/DC translation circuit；

Described control chip controls the break-make of main switch Q2, and described control chip is provided with eight pins, and pin 1 exports for system, and predominantly switch mosfet provides gate-drive；Pin 2 is voltage detecting, predominantly detects the input signal from auxiliary winding, thus provides secondary voltage feedback output regulation；Pin 3 detects for rectified input voltage, and for input undervoltage and overvoltage protection, this pin starts for chip simultaneously provides electric current；Pin 4 limits for external power and turns off and controls end；Pin 5 is earth terminal；Pin 6 is primary current test side；It is mainly used in loop cycle peak current detection；Pin 7 drives for the outside switch mosfet pipe of output；Pin 8 is chip power end.

A kind of two-stage type LED drive power with PFC function the most according to claim 1, it is characterised in that described control chip uses control chip iw3614 as the master element of system, controls the break-make of main switch.

nullA kind of two-stage type LED drive power with PFC function the most according to claim 1，It is characterized in that，Including the first resistance、Second resistance、3rd resistance、4th resistance、5th resistance、6th resistance、7th resistance、8th resistance、9th resistance、First electric capacity、Second electric capacity、3rd electric capacity、4th electric capacity、5th electric capacity、6th electric capacity、First diode、Second diode、3rd diode、4th diode、First switching tube and second switch pipe，Described 4th resistance and the 5th resistant series，Described 4th diode and the 7th resistant series，The pin 8 of described control chip is connected with the 4th diode，The pin 7 of described control chip is connected with second switch pipe by the 8th resistance，The pin 1 of described control chip respectively with the second resistance、3rd resistance and the first switching tube connect，First switching tube and the first resistance connect.

A kind of two-stage type LED drive power with PFC function the most according to claim 1, it is characterized in that, described front stage circuits includes PFC correcting circuit, a rectifying and wave-filtering output circuit, one is located at the feedback control unit between described PFC correcting circuit and rectifying and wave-filtering output circuit, and described PFC correcting circuit includes a PFC capability correction chip and the flyback output voltage circuit being connected respectively, PWM boost topology circuit with this PFC capability correction chip；Described flyback output voltage circuit includes a degaussing time and valley voltage sample circuit, a flyback input control circuit；Described feedback control unit includes an isolation optocoupler feedback circuit, first, second amplifier unit and for the auxiliary power circuit powered to described isolation optocoupler feedback unit, first, second amplifier unit；The PWM constant current topological structure unit that one is connected with described feedback control unit.