CN202396044U

CN202396044U - LED (light-emitting diode) driving circuit and LED light fitting

Info

Publication number: CN202396044U
Application number: CN2011205232613U
Authority: CN
Inventors: 谢素芳; 梁禹
Original assignee: Changzhou Honghuanggu Electronic Science & Technology Co Ltd
Current assignee: Changzhou Honghuanggu Electronic Science & Technology Co Ltd
Priority date: 2011-12-14
Filing date: 2011-12-14
Publication date: 2012-08-22
Anticipated expiration: 2021-12-14

Abstract

The utility model belongs to the field of LED (light-emitting diode) driving, and provides an LED driving circuit and an LED light fitting. According to the utility model, through adopting a filtering unit, a voltage transformation unit, a first rectification filtering unit, a current mutual inductance unit and a second rectification filtering unit in the LED driving circuit, the accurate sampling of output current is realized, the current sampling efficiency is improved, stable constant-current driving control on LED load is realized, and the problems in the prior art that accurate sampling is difficult to be carried out on the output current, and the stability is poor are solved.

Description

A kind of led drive circuit and LED light fixture

Technical field

The utility model belongs to LED and drives the field, relates in particular to a kind of led drive circuit and LED light fixture.

Background technology

At present, drive the field, generally adopt constant-current drive circuit to make the constant operating current of LED maintenance when work to reach luminous stability of LED and the useful life that prolongs LED at LED.The LED constant-current drive circuit that prior art adopted is to carry out voltage sample through the voltage sample resistance of connecting in the LED load, thereby judges the size of current that flows through the LED load, and regulates to obtain correct output current through feedback control loop.Yet; Because extra stray inductance and resistance can be introduced in the two poles of the earth of voltage sample resistance and LED self; And the uncertainty of circuit package and intrinsic temperature coefficient can cause above-mentioned additional parasitic inductance and resistance to be distinguished exactly; And then cause and accurately to sample to output current, and influence the stability of whole LED constant-current drive circuit.Therefore, prior art exists and can't accurately sample to output current, and the problem of poor stability.

The utility model content

The purpose of the utility model is to provide a kind of led drive circuit, and it is existing as can't accurately to sample to output current to be intended to solve prior art, and the problem of poor stability.

The utility model is achieved in that a kind of led drive circuit, and load is connected with LED with DC power supply, comprises the PWM control unit, and said led drive circuit also comprises:

Side joint is in the output of said DC power supply, the filter unit that the direct current of said DC power supply output is carried out filtering;

Import first end of the said DC power supply of termination, control the pulse width control end of the said PWM control unit of termination, the direct current through said filtering unit filters is carried out the voltage transformation unit of voltage transitions;

The output of the said voltage transformation unit of input termination, output is connected with output with the input of said LED load respectively with the loop end, the direct current of said voltage transformation unit output is carried out first rectification filtering unit of rectifying and wave-filtering;

The loop end of input termination said first rectification filtering unit, the loop end of the said voltage transformation unit of elementary termination, secondary termination equipotential ground is to the electric current mutual inductance unit of sampling from the electric current of the loop end output of said first rectification filtering unit;

Import the output of the said electric current mutual inductance of termination unit, export the feedback end of the said PWM control unit of termination, the sampling couple current of the output from said electric current mutual inductance unit is carried out second rectification filtering unit of rectifying and wave-filtering.

Another purpose of the utility model also is to provide a kind of LED light fixture that comprises said led drive circuit.

In the utility model; Through in led drive circuit, adopting said filter unit, said voltage transformation unit, said first rectification filtering unit, said electric current mutual inductance unit and said second rectification filtering unit; Realized accurate sampling, improved current sample efficient, the LED load has been realized stable constant-current driving control output current; It is existing as can't accurately to sample to output current to have solved prior art, and the problem of poor stability.

Description of drawings

Fig. 1 is the modular structure figure of the led drive circuit that provides of the utility model embodiment;

Fig. 2 is the exemplary circuit structure chart of the led drive circuit that provides of the utility model embodiment.

Embodiment

For the purpose, technical scheme and the advantage that make the utility model is clearer,, the utility model is further elaborated below in conjunction with accompanying drawing and embodiment.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.

In the utility model embodiment; Through in led drive circuit, adopting filter unit, voltage transformation unit, first rectification filtering unit, electric current mutual inductance unit and second rectification filtering unit; Realized accurate sampling to output current; Improved the efficient of current sample, the LED load has been realized stable constant-current driving control.

Fig. 1 shows the modular structure of the led drive circuit that the utility model embodiment provides, and for the ease of explanation, only shows the part relevant with the utility model embodiment, and details are as follows:

Led drive circuit 100 is connected with LED load 300 with DC power supply 200, comprises PWM control unit 106, and this led drive circuit 100 also comprises:

Side joint is in the output of DC power supply 200, the filter unit 101 that the direct current of DC power supply 200 outputs is carried out filtering.

Import first end of termination DC power supply 200, control the pulse width control end PM of termination PWM control unit 106, the direct current through filter unit 101 filtering is carried out the voltage transformation unit of exporting after the voltage transitions 102.

The output of input termination voltage transformation unit 102, output is connected with output with the input of LED load 300 respectively with the loop end, the direct current of voltage transformation unit 102 outputs is carried out first rectification filtering unit 103 of rectifying and wave-filtering.

The loop end of input termination first rectification filtering unit 103, the loop end of elementary termination voltage transformation unit 102, secondary termination equipotential ground is to the electric current mutual inductance unit 104 of sampling from the electric current of the loop end output of first rectification filtering unit 103.

Import the output of termination electric current mutual inductance unit 104, export the feedback end FB of termination PWM control unit 106, the sampling couple current of 104 outputs from electric current mutual inductance unit is carried out second rectification filtering unit 105 of rectifying and wave-filtering.

Fig. 2 shows the exemplary circuit structure of the led drive circuit that the utility model embodiment provides, and for the ease of explanation, only shows the part relevant with the utility model embodiment, and details are as follows:

As the utility model one embodiment, filter unit 101 is a filter capacitor C1, the output of the first termination DC power supply 200 of filter capacitor C1, the second termination equipotential ground of filter capacitor C1.

As the utility model one embodiment; Voltage transformation unit 102 is a transformer T1; First end 1 of the primary coil of transformer T1 and second end 2 are respectively the input and the control end of voltage transformation unit 102, and first end 3 of the secondary coil of transformer T1 and second end 4 are respectively the output and the loop end of voltage transformation unit 102.

As the utility model one embodiment; First rectification filtering unit 103 comprises rectifier diode D1 and filter capacitor C2; The anode of rectifier diode D1 and negative electrode are respectively the input and the output of first rectification filtering unit 103; The negative electrode of the first termination rectifier diode D1 of filter capacitor C2, second end of filter capacitor C2 are the loop end of first rectification filtering unit 103, and the second end ground connection of filter capacitor C2.

As the utility model one embodiment; Electric current mutual inductance unit 104 is a current transformer T2; First end 1 of the primary coil of current transformer T2 and second end 2 are respectively the input and the primary side of electric current mutual inductance unit 104, and first end 3 of the secondary coil of current transformer T2 and second end 4 are respectively the output and the secondary end of electric current mutual inductance unit 104.

As the utility model one embodiment; Second rectification filtering unit 105 comprises rectifier diode D2, filter capacitor C3 and resistance R 1; The anode of rectifier diode D2 and negative electrode are respectively the input and the output of second rectification filtering unit 105; First end of filter capacitor C3 is connected with the negative electrode of rectifier diode D2 and first end of resistance R 1 simultaneously, and second end of filter capacitor C3 is connected with second end and the equipotential ground of resistance R 1 simultaneously.

In the utility model embodiment, PWM control unit 106 is judged the amplitude of pulse-width modulation through the sampling couple current that obtains 105 outputs of second rectification filtering unit, and then guarantees that the output current of transformer T1 maintains in the stable current range.

In the utility model embodiment, PWM control unit 106 comprises constant current control IC and switching tube commonly used, is used for through pulse-width modulation the output current of transformer T1 being adjusted; LED load 300 comprises LED 1 and LED 2; The input of the just very LED load 300 of LED 1; The negative pole of the anodal sending and receiving optical diode LED1 of LED 2, the negative pole of LED 2 is the output of LED load 300.

Below in conjunction with operation principle led drive circuit 100 is described in detail:

DC power supply 200 output DCs; Get into first end 1 of the primary coil of transformer T1 after this direct current process filter capacitor C1 filtering; By transformer T1 this direct current is carried out exporting rectifier diode D2 rectification to after the transformation; Subsequently via after the filter capacitor C2 filtering being LED 1 power supply; First end 1 of the primary coil of current transformer T2 is sampled to output current at the negative pole of LED 2 and the common contact of filter capacitor C2, and this output current is carried out mutual inductance coupling back export the anode of sampling couple currents to rectifier diode D2, the rectification through rectifier diode D2 from first end 3 of its secondary coil; Export the feedback end FB of PWM control unit 106 after filter capacitor C3 and resistance R 1 filtering to; So PWM control unit 106 through the sampling couple current that rectifying and wave-filtering is handled, is adjusted the output current of transformer T1 according to this in real time through pulse-width modulation; The output current of transformer T1 is remained in the stable current range, thereby reach constant-current driving control the LED load.

In the utility model embodiment; Through the loop end at first rectification filtering unit 103 current transformer T2 being set samples to the output end current of LED load 300; Realized electric current is accurately sampled; Compare with the prior art that adds sampling resistor at the output of LED load, led drive circuit 100 had both reduced power loss, had saved circuit cost again.

Another purpose of the utility model embodiment also is to provide a kind of LED light fixture that comprises above-mentioned led drive circuit 100.

In the utility model embodiment; Through in led drive circuit 100, adopting filter unit 101, voltage transformation unit 102, first rectification filtering unit 103, electric current mutual inductance unit 104 and second rectification filtering unit 105; Realized accurate sampling, improved current sample efficient, the LED load has been realized stable constant-current driving control output current; It is existing as can't accurately to sample to output current to have solved prior art, and the problem of poor stability.

The above is merely the preferred embodiment of the utility model; Not in order to restriction the utility model; Any modification of being done within all spirit and principles at the utility model, be equal to replacement and improvement etc., all should be included within the protection range of the utility model.

Claims

1. led drive circuit, load is connected with LED with DC power supply, comprises the PWM control unit, it is characterized in that said led drive circuit also comprises:

2. led drive circuit as claimed in claim 1 is characterized in that, said filter unit is a filter capacitor C1, the output of the said DC power supply of first termination of said filter capacitor C1, the second termination equipotential ground of said filter capacitor C1.

3. led drive circuit as claimed in claim 1; It is characterized in that; Said voltage transformation unit is a transformer T1; First end of the primary coil of said transformer T1 and second end are respectively the input and the control end of said voltage transformation unit, and first end of the secondary coil of said transformer T1 and second end are respectively the output and the loop end of said voltage transformation unit.

4. led drive circuit as claimed in claim 1; It is characterized in that; Said first rectification filtering unit comprises rectifier diode D1 and filter capacitor C2, and the anode of said rectifier diode D1 and negative electrode are respectively the input and the output of said first rectification filtering unit, the negative electrode of the first termination rectifier diode D1 of said filter capacitor C2; Second end of said filter capacitor C2 is the loop end of said first rectification filtering unit, and the second end ground connection of said filter capacitor C2.

5. led drive circuit as claimed in claim 1; It is characterized in that; Said electric current mutual inductance unit is a current transformer T2; First end of the primary coil of said current transformer T2 and second end are respectively the input and the primary side of said electric current mutual inductance unit, and first end of the secondary coil of said current transformer T2 and second end are respectively the output and the secondary end of said electric current mutual inductance unit.

6. led drive circuit as claimed in claim 1; It is characterized in that; Said second rectification filtering unit comprises rectifier diode D2, filter capacitor C3 and resistance R 1; The anode of said rectifier diode D2 and negative electrode are respectively the input and the output of said second rectification filtering unit; First end of said filter capacitor C3 is connected with the negative electrode of said rectifier diode D2 and first end of said resistance R 1 simultaneously, and second end of said filter capacitor C3 is connected with second end and the equipotential ground of said resistance R 1 simultaneously.

7. a LED light fixture is characterized in that, said LED light fixture comprises any described led drive circuit like claim 1-6.