CN202374530U

CN202374530U - Efficient white light LED driving circuit

Info

Publication number: CN202374530U
Application number: CN 201120540197
Authority: CN
Inventors: 李秋俊; 吴贵能
Original assignee: WEI WANLAN
Current assignee: Chongqing Bao Wei photoelectric Co., Ltd.
Priority date: 2011-12-21
Filing date: 2011-12-21
Publication date: 2012-08-08
Anticipated expiration: 2021-12-21

Abstract

The utility model discloses an efficient white light LED driving circuit. The driving circuit comprises a rectifier bridge and a filter capacitor C1; the input voltage of the filter capacitor C1 is controlled by a voltage control circuit composed of a diode D5, an NPN (Negative-Positive-Negative) triode Q2 and a comparator A2; and a varistor control circuit composed of the comparator A2 and an NPN triode Q1 and used for improving the efficiency of a driving power supply is connected with the negative pole of an LED lamp set. On one hand, the driving circuit disclosed by the utility model utilizes a varistor to replace a common fixed value dropping resistor, on the other hand, the driving circuit enables a power supply driving circuit to always acquire high power supply efficiency in a 198V to 242V input voltage range via regulating the operation input voltage range of an output rectifier capacitor, so as to achieve a remarkable effect on the energy conversation of an LED lamp.

Description

A kind of efficient white light LEDs drive circuit

Technical field

The utility model relates to the drive circuit of LED, is specially a kind of simple and efficient rate white light LEDs drive circuit that utilizes the separating component design, belongs to electronic technology field.

Background technology

LED is a kind of energy-efficient green light source that meets environmental protection concept, and therefore being had an optimistic view of in following 10 years by industry to become big potentiality commodity that substitute the traditional lighting utensil.Since present high-quality white LED light source with and the market price of driving power generally higher; Caused the price of White-light LED illumination utensil also to be in higher level, this also is the major reason that present White-light LED illumination utensil is difficult to get into common people family.Therefore, in order to accelerate applying of White-light LED illumination utensil, reduce its price and just stand in the breach.

The drive circuit of white light LEDs adopts the high frequency switch power of constant current mostly at present, and this power supply is on the one hand because it has adopted special-purpose control IC to cause price higher, and it also need dispose electromagnetic interface filter on the other hand, and electromagnetic interface filter can increase the cost of power supply greatly.Therefore, for addressing the above problem, reduce the cost of power supply; At present a kind of driving circuit structure that adopts discrete device to come step-down is arranged also, as shown in Figure 1, it comprises rectifier bridge, filter capacitor C1 and LED coupled in series lamp group; The positive and negative electrode correspondence of filter capacitor C1 is connected the positive and negative two ends of rectifier bridge, in circuit, has inserted fixed resistance R1 respectively, R2 realizes step-down, and the sort circuit structure is owing to adopted discrete device; Therefore can not adopt application-specific integrated circuit, also need not electromagnetic interface filter, thereby make with low cost; But its power-efficient is very low, generally can only reach about 50%, makes the energy-saving effect of LED light fixture have a greatly reduced quality like this; In addition, when input voltage range when 198V ~ 242V changes, the input power excursion of its power supply will be greater than 20%, this causes less stable.

The utility model content

To the above-mentioned deficiency that prior art exists, the main purpose of the utility model is to provide a kind of can reduce the driving power cost, can improve LED driving power efficient again, can also reduce the efficient white light LEDs drive circuit of power supply input power fluctuation simultaneously.

The technical scheme of the utility model is following: a kind of efficient white light LEDs drive circuit; Comprise rectifier bridge and filter capacitor C1; LED lamp group is connected the output of said drive circuit, it is characterized in that, filter capacitor C1 is by its input voltage of voltage control circuit control; Said voltage control circuit comprises diode D5, NPN triode Q2 and comparator A2; The collector electrode of the reverse and NPN triode Q2 of diode D5 all is connected to the negative pole of filter capacitor C1, and the emitter of the forward of diode D5 and NPN triode Q2 all is connected to the negative terminal of rectifier bridge, between the positive pole of the collector electrode of NPN triode Q2 and filter capacitor C1, also is connected with resistance R 1; The base stage of NPN triode Q2 connects the output of comparator A2 and is driven by comparator A2; The reverse input end of comparator A2 is connected to emitter and the ground connection of NPN triode Q2 after resistance R 3, between the positive pole of the reverse input end of comparator A2 and filter capacitor C1, also be connected with resistance R 4;

Negative pole in LED lamp group also is connected with the variable resistor control circuit that is used to promote driving power efficient; This variable resistor control circuit comprises comparator A2 and NPN triode Q1; The positive input of comparator A2 is connected with the positive input of comparator A1; The reverse input end of comparator A1 is ground connection after resistance R 6; The base stage of NPN triode Q1 connects the output of comparator A1 and is driven by comparator A1, and the emitter of NPN triode Q1 is connected with the reverse input end of comparator A1, and the collector electrode of NPN triode Q1 is connected to the negative pole of LED lamp group;

The forward of last Light-Emitting Diode also is connected with diode D7, resistance R 5 and diode D6 in turn in LED lamp group; The oppositely ground connection after capacitor C 2 of diode D7; The forward of diode D6 is also connected to the positive input of comparator A2, the reverse ground connection of diode D6.

Further technical characterictic also is connected with resistance R 2 between the base stage of the output of comparator A2 and NPN triode Q2.

Further technical characterictic also is connected with resistance R 7 between the base stage of the output of comparator A1 and NPN triode Q1.

With respect to prior art, the utlity model has following beneficial effect:

1, cost is lower: the white light LEDs driving power of the utility model, and utilize discrete device to realize step-down, need not drive IC and electromagnetic interface filter, thereby reduced the power supply cost.

2, improved driving power efficient: the white light LEDs driving power of the utility model is because the dropping resistor that defaulted, thus can obtain very high efficient, when input voltage is 198V; Power-efficient is greater than 95%; When input voltage was 220V, power-efficient was greater than 90%, when input voltage is 242V; Power-efficient is greater than 85%, and its energy-saving effect is very obvious.

3, input power changes less: the white light LEDs driving power of the utility model is through the variation of variable resistor control circuit control power supply input power, when input voltage range when 198V ~ 242V changes, the excursion of input power can be less than 15%.

Description of drawings

Fig. 1 is existing resistance drop pressure type white light LEDs driving power circuit schematic diagram;

Fig. 2 is the schematic diagram of the efficient white light LEDs drive circuit of the utility model.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

As shown in Figure 2; A kind of efficient white light LEDs drive circuit comprises rectifier bridge and filter capacitor C1, and LED lamp group is connected the output of drive circuit; Said rectifier bridge is to be made up of four diode D1, D2, D3, D4; The input of rectifier bridge connects the 220V alternating current, the corresponding respectively positive and negative end that is connected rectifier bridge of the positive and negative electrode of filter capacitor C1, and LED lamp group is to be connected to form by several light-emitting diode series connection.In the utility model; Filter capacitor C1 is by its input voltage of voltage control circuit control; Said voltage control circuit comprises diode D5, NPN triode Q2 and comparator A2; The collector electrode of the reverse and NPN triode Q2 of diode D5 all is connected to the negative pole of filter capacitor C1, and the emitter of the forward of diode D5 and NPN triode Q2 all is connected to the negative terminal of rectifier bridge, between the positive pole of the collector electrode of NPN triode Q2 and filter capacitor C1, also is connected with resistance R 1; The base stage of NPN triode Q2 connects the output of comparator A2 and is driven by comparator A2; The reverse input end of comparator A2 is connected to emitter and the ground connection of NPN triode Q2 after resistance R 3, between the positive pole of the reverse input end of comparator A2 and filter capacitor C1, also be connected with resistance R 4.

Referring to Fig. 2; Negative pole in LED lamp group also is connected with the variable resistor control circuit that is used to promote driving power efficient; This variable resistor control circuit comprises comparator A2 and NPN triode Q1; The positive input of comparator A2 is connected with the positive input of comparator A1, and the reverse input end of comparator A1 is ground connection after resistance R 6, and the base stage of NPN triode Q1 connects the output of comparator A1 and driven by comparator A1; The emitter of NPN triode Q1 is connected with the reverse input end of comparator A1, and the collector electrode of NPN triode Q1 is connected to the negative pole of LED lamp group.

Referring to Fig. 2; The forward of last Light-Emitting Diode also is connected with diode D7, resistance R 5 and diode D6 in turn in LED lamp group; The oppositely ground connection after capacitor C 2 of diode D7, the forward of diode D6 is also connected to the positive input of comparator A2, the reverse ground connection of diode D6.

Referring to Fig. 2, between the base stage of the output of comparator A2 and NPN triode Q2, also be connected with resistance R 2, between the base stage of the output of comparator A1 and NPN triode Q1, also be connected with resistance R 7.

Operation principle:

In the circuit of the utility model, through the size of reasonable adjusting resistance R 3 and resistance R 4, when input voltage < during 230V; The voltage at resistance R 3 two ends is less than the voltage at diode D6 two ends; Comparator A2 output this moment high potential, triode Q2 conducting, filter capacitor C1 can operate as normal.

When input voltage was low to moderate 198V, the voltage charging at filter capacitor C1 two ends was to its peak value 280V, and when input voltage was lower than 280V, filter capacitor C1 gave the power supply of LED lamp group through diode D5, because the voltage on this moment resistance R 6 is a little less than design load VD6/R6Comparator A1 exports high potential at this moment, and triode Q1 saturation conduction, the voltage at the collector and emitter two ends of triode Q1 are saturation voltage Vces ≈ 0.3V; Show as a very low resistance this moment; The voltage at filter capacitor C1 two ends almost all drops on the LED lamp group of series connection, so the time power-efficient very high, can reach more than 95%.

Along with the rising gradually of input voltage, output current slightly rises, and this moment, the voltage at resistance R 6 two ends rose, and comparator A1 gets into the linear amplification state, and output current does VD6/R6, triode Q1 also is operated in magnifying state, and its VCE voltage rises; Equivalent resistance between triode Q1 base stage and the emitter increases; This moment, the voltage overwhelming majority at filter capacitor C1 two ends dropped on the LED lamp group, so the time power-efficient still higher, can reach more than 90%.

Along with the continuation of input voltage is risen; The voltage at resistance R 3 two ends increases gradually, and when surpassing VD6 (this moment, the input voltage design load was about 230V), comparator A2 exports electronegative potential; Triode Q2 ends; The voltage at filter capacitor C1 two ends is clamped at about 320V, and when input voltage during greater than 320V, power supply is directly given the power supply of LED lamp group; When less than 320V, LED lamp group is by filter capacitor C1 power supply, and this moment, the VCE of triode Q1 further increased, and the equivalent resistance between triode Q1 base stage and the emitter also further increases, but efficient still can reach more than 85%.

Need to prove at last; Above embodiment is only in order to technical scheme but not the restriction technologies scheme of explanation the utility model; Although the applicant specifies the utility model with reference to preferred embodiment, those of ordinary skill in the art should be appreciated that those modifications that technical scheme of the utility model is carried out perhaps are equal to replacement; And do not break away from the aim and the scope of present technique scheme, all should be encompassed in the middle of the claim scope of the utility model.

Claims

1. efficient white light LEDs drive circuit; Comprise rectifier bridge and filter capacitor C1; LED lamp group is connected the output of said drive circuit, it is characterized in that, filter capacitor C1 is by its input voltage of voltage control circuit control; Said voltage control circuit comprises diode D5, NPN triode Q2 and comparator A2; The collector electrode of the reverse and NPN triode Q2 of diode D5 all is connected to the negative pole of filter capacitor C1, and the emitter of the forward of diode D5 and NPN triode Q2 all is connected to the negative terminal of rectifier bridge, between the positive pole of the collector electrode of NPN triode Q2 and filter capacitor C1, also is connected with resistance R 1; The base stage of NPN triode Q2 connects the output of comparator A2 and is driven by comparator A2; The reverse input end of comparator A2 is connected to emitter and the ground connection of NPN triode Q2 after resistance R 3, between the positive pole of the reverse input end of comparator A2 and filter capacitor C1, also be connected with resistance R 4;

2. efficient white light LEDs drive circuit according to claim 1 is characterized in that, between the base stage of the output of comparator A2 and NPN triode Q2, also is connected with resistance R 2.

3. efficient white light LEDs drive circuit according to claim 1 is characterized in that, between the base stage of the output of comparator A1 and NPN triode Q1, also is connected with resistance R 7.