CN201995171U

CN201995171U - LED driving power supply with load tracking and frequency reducing functions

Info

Publication number: CN201995171U
Application number: CN2011200130327U
Authority: CN
Inventors: 覃增豪; 柏子江
Original assignee: NINGBO JIANGBEI HWZ ELECTRONIC Co Ltd
Current assignee: NINGBO JIANGBEI HWZ ELECTRONIC Co Ltd
Priority date: 2011-01-17
Filing date: 2011-01-17
Publication date: 2011-09-28
Anticipated expiration: 2021-01-17

Abstract

The utility model discloses an LED driving power supply with load tracking and frequency reducing functions, which belongs to the technical field of power supply. The LED driving power supply comprises a transformer, an electronic switch A, a PWM controller and a PWM frequency setting unit, wherein a coil at the input terminal of the transformer is connected with the electronic switch A in series and then grounded; the control port of the electronic switch A is connected with the output port of the of the PWM controller; the LED driving power supply is characterized in that the LED driving power supply also comprises an inductance coil and a comparator; the inductance coil is wound on the transformer; the inductance coil is connected with the comparator; threshold voltage is also arranged on the comparator; the comparator is connected on the PWM frequency setting unit; and an electronic switch B is connected on the PWM controller. When an LED is operated at a low light mode, the PWM frequency setting unit can receive signals and automatically trace load and reduce frequency, so that the PWM controller is operated at a low frequency mode, and lost energy is greatly reduced.

Description

LED driving power with load tracking frequency-dropping function

Technical field

The utility model belongs to field of power supplies, is used to have the LED driving power of load tracking frequency-dropping function specifically.

Background technology

Along with the fast development of electronic technology, because LED has the luminous efficiency height, advantages such as energy savings, reaching its maturity of LED lighting technology begins to be widely used in various fields, as the indicator light of display screen, various instruments, home lighting or the like field.And LED uses is low-voltage DC, so must there be a LED driving power to come to its power supply, driving power can convert the alternating current of high pressure to low-voltage DC and supply with LED.

Traditional driving power has an input and output, the AC power of input termination family expenses, output termination LED, the AC power that input enters enters later input coil on the transformer through an AC/DC change-over circuit conversion, the input coil connects ground connection behind the electronic switch, the control utmost point of electronic switch links to each other with the delivery outlet of PWM controller, and the PWM controller is used for switching on and off of switch, also comprises a PWM frequency configuration unit of modulating wave being provided for the PWM controller.The two ends of the output coil of transformer are the output of driving power, also are parallel with an electrochemical capacitor on the output.The delivery outlet of PWM controller can come switching on and off of control switch according to the control signal that the modulation wave frequency is exported certain duty ratio, thereby reach galvanic the switching on and off of control, make the magnetic field that in transformer, changes, feasible output coil on transformer produces induced potential, the induced potential of output coil outputs to output, thereby realize driving LED work, electrochemical capacitor plays the effect of a stable output end voltage.

Described electronic switch second is optocoupler, and the positive pole of optocoupler and the negative pole of optocoupler are the control mouth of optocoupler, and the base stage of optocoupler links to each other with the PWM controller with the emitter of optocoupler.

Described electronic switch first is a field effect transistor, and the control utmost point of field effect transistor links to each other with the delivery outlet of PWM controller.

One end of induction coil be divided into two-way after coil, resistance are connected successively, the one tunnel with ground connection after resistance links to each other, another road links to each other with comparator.

For more energy savings, can be adjusted to low brightness at a lot of application LED, when traditional driving power is transferred to low-light level at the LED lamp, PWM frequency configuration unit is still at the modulation signal that sends same frequency to PWM, the full speed operation of PWM speed regulator, expend very much power supply, reduced the useful life of power supply simultaneously.

Summary of the invention

The utility model provides a kind of LED driving power with load tracking frequency-dropping function at deficiency of the prior art, can be adjusted to low-light level work at LED and follow the trail of load realization frequency reducing automatically, reduces the loss of power supply.

In order to solve the problems of the technologies described above, the utility model is solved by following technical proposals: the LED driving power with load tracking frequency-dropping function, comprise transformer, the electronic switch first, PWM controller and PWM frequency configuration unit, ground connection after the input coil of described transformer and the series connection of described electronic switch first, the control mouth of described electronic switch first links to each other with described PWM controller delivery outlet, it is characterized in that: also comprise an induction coil and a comparator, induction coil is on transformer, described induction coil links to each other with described comparator, also be provided with a threshold voltage on the described comparator, described comparator is received on the described PWM frequency configuration unit, and described electronic switch second is received on the PWM controller.

During use, output is that the output coil of transformer meets LED.During the LED operate as normal, the induced electromotive force on the induction coil is higher than the threshold voltage that comparator is set than higher.

When LED when low-light level is worked, induced electromotive force on the induction coil is very little, be transferred on the comparator, threshold voltage less than the comparator setting, comparator is delivered to PWM frequency configuration unit with regard to the level signal of exporting a variation, after PWM frequency configuration unit received signal, the modulation wave signal frequency of PWM frequency configuration unit reduced.The PWM controller is worked under low frequency, has significantly reduced the loss of energy.

Also comprise an electronic switch second, described electronic switch second is optocoupler, and the positive pole of described optocoupler and the negative pole of described optocoupler are the control mouth of described optocoupler, and the base stage of described optocoupler links to each other with described PWM controller with the emitter of described optocoupler.

Described electronic switch first is a field effect transistor, and the control utmost point of described field effect transistor links to each other with the delivery outlet of described PWM controller.

The beneficial effects of the utility model are: when LED was in low-light level work, PWM frequency configuration unit can receive signal, followed load automatically and reduced frequency, thereby make the PWM controller work under low frequency, had significantly reduced the loss of energy.

Description of drawings

Fig. 1 is the line map with LED driving power when work of load tracking frequency-dropping function.

Embodiment

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

Referring to Fig. 1, LED driving power with load tracking frequency-dropping function, comprise input and output, two AC mouths of input and bridge rectifier B1 link to each other, " V+ " of bridge rectifier B1 mouthful, " V-" mouthful electrochemical capacitor C1 in parallel, " V just " mouth successively with transformer T1 on input coil N1, field effect transistor M1 and resistance R 1 connect after ground connection

PWM frequency configuration unit links to each other with the PWM controller, and the delivery outlet of PWM controller extremely links to each other with the control of field effect transistor M1.

Also be wound with induction coil N2 on the transformer T1, diode D3 of end series connection of induction coil coil N2 links to each other with the power supply port of PWM later.The end of described induction coil N2 links to each other with described comparator U1 by a sampling loop.Sampling loop comprises coil N3, resistance first R2 and resistance second R3, induction coil N2 be divided into two-way after coil N3 and resistance R 2 connect, one the tunnel with ground connection after resistance R 3 links to each other, negative mouthful of another road and comparator U1 links to each other, electrochemical capacitor C3 is in parallel with resistance first R2 and resistance second R3.

Positive mouthful of comparator U1 meets a threshold voltage Vref, and the Ui mouth of comparator U1 links to each other with PWM frequency configuration unit,

Also be wound with output coil N4 on the transformer T1, the later and electrochemical capacitor C2 parallel connection of diode D2 of output coil N4 series connection, the two ends of electrochemical capacitor C2 are exactly output.

The negative pole of the positive pole of optocoupler U2, optocoupler U2 and electrochemical capacitor C2 parallel connection, the emitter of the base stage of optocoupler U2 and optocoupler U2 links to each other with the PWM controller.

During use, have the input of LED driving power of load tracking frequency-dropping function and the AC power of family expenses and link to each other, output links to each other with LED or other load.The alternating current of input is changed into direct current by bridge rectifier B1, enters the input coil N1 in the transformer T1 then.

LED is when operate as normal, PWM frequency configuration unit is to the modulating wave of PWM controller input certain frequency, the delivery outlet of PWM controller can be controlled switching on and off of field effect transistor M1 according to the control signal that the modulation wave frequency is exported certain duty ratio, thereby reach galvanic the switching on and off of control, make the magnetic field that in transformer T1, changes, feasible induction coil N2 and output coil N4 on transformer T1 produces induced potential, the induced potential of coil N4 outputs to output, thereby realizes driving LED work.Electrochemical capacitor C1 and electrochemical capacitor C2 play pressure stabilization function in the process.

After the voltage process diode D4 rectification at induction coil N2 two ends and resistance first R2, the resistance second R3 dividing potential drop, compare with the threshold voltage Vref on the comparator U1, the later voltage of the voltage dividing potential drop at induction coil N2 two ends is greater than threshold voltage Vref, then the Ui mouth of comparator U1 keeps low level, and the modulating wave of PWM frequency configuration unit output remains on normal frequency work.

When LED when low-light level is worked, the voltage at induction coil N2 two ends reduces greatly, cause the later voltage of the voltage dividing potential drop at induction coil N2 two ends less than threshold voltage Vref, then the Ui mouth of comparator U1 is exported a low level, PWM frequency configuration unit detects after the level variation, the modulating wave of output low frequency rate, the PWM controller is worked under low frequency.

Claims

1. the LED driving power that has the load tracking frequency-dropping function, comprise transformer, the electronic switch first, PWM controller and PWM frequency configuration unit, ground connection after the input coil of described transformer and the series connection of described electronic switch first, the control mouth of described electronic switch first links to each other with described PWM controller delivery outlet, it is characterized in that: also comprise an induction coil and a comparator, induction coil is on transformer, described induction coil links to each other with described comparator, also be provided with a threshold voltage on the described comparator, described comparator is received on the described PWM frequency configuration unit, and described electronic switch second is received on the PWM controller.

2. the LED driving power with load tracking frequency-dropping function according to claim 1, it is characterized in that: also comprise an electronic switch second, described electronic switch second is optocoupler, the positive pole of described optocoupler and the negative pole of described optocoupler are the control mouth of described optocoupler, and the base stage of described optocoupler links to each other with described PWM controller with the emitter of described optocoupler.

3. the LED driving power with load tracking frequency-dropping function according to claim 1 and 2 is characterized in that: described electronic switch first is a field effect transistor, and the control utmost point of described field effect transistor links to each other with the delivery outlet of described PWM controller.

4. the LED driving power with load tracking frequency-dropping function according to claim 1 and 2 is characterized in that: an end of described induction coil links to each other with described comparator by a sampling loop.

5. the LED driving power with load tracking frequency-dropping function according to claim 3 is characterized in that: an end of described induction coil links to each other with described comparator by a sampling loop.