CN202587529U - Pulse width modulation (PWM) dimming circuit for high-voltage direct current centralized power supply light emitting diode (LED) constant current source - Google Patents

Pulse width modulation (PWM) dimming circuit for high-voltage direct current centralized power supply light emitting diode (LED) constant current source Download PDF

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CN202587529U
CN202587529U CN 201220211508 CN201220211508U CN202587529U CN 202587529 U CN202587529 U CN 202587529U CN 201220211508 CN201220211508 CN 201220211508 CN 201220211508 U CN201220211508 U CN 201220211508U CN 202587529 U CN202587529 U CN 202587529U
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circuit
power supply
voltage
constant
led
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张波
张雪霁
肖文勋
丘东元
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South China University of Technology SCUT
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South China University of Technology SCUT
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Abstract

The utility model provides a pulse width modulation (PWM) dimming circuit for a high-voltage direct current centralized power supply light emitting diode (LED) constant current source. The dimming circuit comprises a direct current power supply module and N constant current dimming modules, wherein each constant current dimming module comprises a switch voltage stabilization control circuit, a power supply circuit, a switch step-down circuit, a constant current feedback circuit and a PWM dimming circuit; a terminal voltage of a sampling resistor keeps constant under the control of each switch voltage stabilization control circuit, and constant current of LED loads can be provided; a PWM signal controls an enable pin of each switch voltage stabilization control circuit, an average value of the current flowing through LED lamps in a cycle is changed by adjusting a duty ratio of PWM waves, so that the brightness of the LED lamps is changed; and besides, by the power supply circuit, an input voltage is used for starting the whole dimming circuit, and an output voltage is used for supplying power to the whole dimming circuit, so that the matching of the high input voltage and the voltage withstanding performance of the switch voltage stabilization control circuit is realized. The PWM dimming circuit is simple in structure and convenient to adjust, illumination chromatic aberration is avoided, and the LEDs are stable in emitting and long in service life.

Description

HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit
Technical field
The utility model belongs to the semiconductor lighting application, relates to a kind of PWM light-dimming method of HVDC centrally connected power supply LED constant-current source.
Background technology
Advantages such as LED is high, low in energy consumption with its efficient, energy-conserving and environment-protective and long service life have received the attention of countries in the world day by day, are applied to various illumination occasions more and more widely, are expected to replace in the near future traditional lighting light fixtures such as incandescent lamp, fluorescent lamp.
The luminous flux of LED lamp is directly proportional with forward current through LED, and when low luminosity, the electric current that flows through the LED lamp can reduce, and luminous efficiency can improve, and therefore in the LED illumination, adds dimming function, and energy-saving effect is more obvious, and application prospect is boundless.
The resistance that linearity light adjusting is perhaps regulated sampling resistor through linear regulation sampled voltage reference value, and then change the current value size that flows through LED, realizing light modulation, CN201805598U is said like the Chinese patent document.The shortcoming of this dimming mode is that LED lamp colour stability is bad, because the colour developing of LED lamp is relevant with size of current.In addition,, cause the antijamming capability under the linearity light adjusting mode relatively poor, can produce flicker because the sampled voltage reference value generally can be provided with lowlyer.In addition, to the centrally connected power supply system, the linearity light adjusting mode of regulating input voltage or electric current can only realize the unified light modulation of each LED lamp; Difference light modulation to each LED lamp; If the mechanical light modulation method through changing the sampling resistor value can be cumbersome, workload is bigger, and accuracy is not high.
The utility model content
The purpose of the utility model is to overcome the deficiency of above-mentioned prior art, need not to change the hardware circuit resistance value, and HVDC centrally connected power supply LED constant-current source PWM is provided light adjusting circuit.The utility model flows through constant current when the LED light modulation is stablized; Guarantee that LED is luminous stable, guarantee the LED long-life, change the average current value that flows through the LED lamp in the one-period through the duty ratio of regulating PWM; Thereby realize dimming function to the LED lamp; Because when having electric current to pass through on the LED lamp, the electric current that flows through is a rated current, so can not produce the illumination aberration.Enabling of the direct control switch voltage stabilizing of this PWM dimming mode chip, implementation is simple, concentrates DC power-supply system more suitable to 100V to the high pressure of 800V.
The utility model is realized through following technical scheme: HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit; Comprise dc power supply module and N the constant-current dimming module that is connected with the dc power supply module respectively; The output of each constant-current dimming module is used to connect load; The structure of said N constant-current dimming module is identical but parameter wherein each element is definite by load; Its input links to each other with the positive output end of dc power supply module, the negative output terminal ground connection of dc power supply module.
Above-mentioned constant-current dimming module comprises switch voltage-stabilizing control circuit, power supply circuits, switch reduction voltage circuit, constant current feedback circuit and light adjusting circuit.Said power supply circuits comprise the second diode D 2, first resistance R 1With second resistance R 2, first resistance R 1Be connected between the supply power voltage port VCC of positive output end and switch voltage-stabilizing control circuit of dc power supply modules A the second diode D 2Negative electrode through second resistance R 2Supply power voltage port V with the switch voltage-stabilizing control circuit CCConnect, its anode links to each other with the anode of LED load.Said switch reduction voltage circuit comprises switching tube Q, inductance L and the first diode D 1, the gate pole of switching tube Q links to each other with the drive end PG of switch voltage-stabilizing control circuit, and its drain electrode links to each other with the positive output end of dc power supply module, and its source electrode links to each other through the anode of inductance L with the LED load, the first diode D 1Negative electrode also link to each other its plus earth with the source electrode of switching tube Q.The sampling resistor R of said constant current feedback circuit 3One end links to each other other end ground connection with the feedback end FB of switch voltage-stabilizing control circuit.The 3rd diode D in the said light adjusting circuit 3Negative electrode link to each other with the Enable Pin EN of switch voltage-stabilizing control circuit, its anode connects and is used for the PWM ripple of light modulation.
Above-mentioned switch voltage-stabilizing control circuit comprises a switch voltage-stabilizing chip and simple peripheral circuit thereof, compares with internal reference voltage through the voltage of feedback port FB, in the required drive signal of drive end PG output switching tube, realizes stablizing the purpose of feedback voltage.
The light-dimming method of HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit keeps constant current feedback circuit (sampling resistor R through the switch voltage-stabilizing control circuit 3) terminal voltage constant, realize and sampling resistor R 3The constant current of the LED load of series connection.The control end EN end that enables through at the switch voltage-stabilizing control circuit is imported pwm signal; Make chip be interrupted sex work; To change the current average of LED lamp in the single cycle; Thereby change the brightness of LED lamp, the output current mean value that the PWM ripple of different duty is corresponding different, promptly different LED lamp brightness.
Being used for the PWM ripple of light modulation is provided with the high-low level size according to the parameter request of switch voltage-stabilizing control circuit Enable Pin EN; This PWM wave frequency should be than the switching frequency of switch voltage-stabilizing control circuit more than the little one magnitude, and greater than human eye maximum identification frequency 200Hz.The operating switch state of the direct control switch controlling circuit of voltage regulation of the high-low level of PWM ripple; Thereby controlling the on off state of LED supply current; Changed the mean value of LED supply current, therefore can recently change the current average of LED lamp through the duty that changes the PWM ripple.
Compared with prior art; The utlity model has following advantage: the utility model need not to regulate hardware circuit resistance value and input voltage size, and implementation is simple, and is easy to adjust and unglazed according to aberration; Can also guarantee LED current constant after the light modulation; Guaranteed the luminous stable and long-life of LED, and be suitable for the concentrated DC power-supply system application of 100V, be convenient to the brightness of a plurality of LED lamps of control of system to the 800V high pressure; And control mode is flexible, and the convenient communication system follow procedure that combines is with an automatic light meter.In addition, power supply circuits start through input voltage and two parts of output voltage power supply, have solved input high pressure and the withstand voltage matching problem of switch voltage-stabilizing control circuit.
Description of drawings
Fig. 1 is a HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit block diagram.
Fig. 2 is the direct current supply LED constant-current dimming circuit figure based on IRS2541 switch voltage-stabilizing chip.
Input, output voltage and output current wave figure when Fig. 3 is the no pwm signal input in the utility model execution mode.
Fig. 4 in the utility model execution mode the pwm signal input is arranged the time input PWM and output current wave figure.
Specific embodiments
Further describe below in conjunction with the practical implementation of accompanying drawing, but enforcement of the utility model and protection are not limited thereto the utility model.
HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit block diagram is as shown in Figure 1; Comprising dc power supply module and N the constant-current dimming module (N >=1) that is connected with the dc power supply module respectively; The output of each constant-current dimming module is used to connect load; The input of constant-current dimming module all links to each other with the positive output end of dc power supply module, the negative output terminal ground connection of dc power supply module.The structure of N constant-current dimming module is identical but parameter wherein each element is definite by load; After definite load size; Selection meets the constant current control chip of load request; Confirm resistance (R1, R2, R3) among the figure, the value of inductance L, and the model of diode (D1, D2, D3) and power switch pipe Q according to the parameter of chip and load then.According to I LED=V FB/ R 3The calculating sampling resistance R 3, I wherein LEDBe the required constant current value of load, V FBGiven standard value for the chip internal feedback voltage; First resistance R 1Current-limiting resistance during for chip enable is tried to achieve according to chip enable voltage and input voltage maximum,, V wherein CCBe chip enable voltage, P 1It is first resistance R 1Rated power; During operate as normal, the power supply of chip is changeed is provided second resistance R by output voltage after the chip enable 2Be used for trying to achieve according to chip enable voltage and output voltage maximum to output voltage power supply circuits current limliting,, P wherein 2It is second resistance R 2Rated power.Diode (D1, D2, D3) and power switch pipe Q according to them maximum withstand voltage, the anti-flow valuve in each comfortable circuit choose.Switching regulator among Fig. 1 is made up of chip and peripheral circuit thereof.
Circuit as shown in Figure 2 is the constant-current dimming circuit figure of this light-dimming method based on IRS2541 switch voltage-stabilizing chip.IRS2541 be a kind of can be the highest the switch voltage-stabilizing chip of tolerance 600V high pressure.This programme is implemented according to circuit diagram shown in Figure 2.Comprise chip I RS2541 in the circuit, resistance (R 1~ R 9), electric capacity (C 1~ C 6), diode (D 1~ D 4), voltage-stabiliser tube (D 5And D 6), inductance L and power switch pipe Q, their connection is as shown in Figure 2.
The basic parameter of this example circuit is following:
Input voltage: V IN=311VDC (rectified value of 220VAC);
Load: 12 (1W, 350Ma) LED series connection.
The feedback voltage benchmark V of chip internal IFBTHBe 500mV.According to the required current value 350mA of load, sampling resistor R 3Value can try to achieve by following formula:
Figure 2012202115082100002DEST_PATH_IMAGE001
（1）
Experiment input, output voltage and the output current wave of this instance when no pwm signal is imported is as shown in Figure 3, and < 1>is input voltage signal, and < 2>are output current signal, and < 3>are output voltage signal.Can verify that through experimental waveform when input voltage was about 310V, output current remained near the 350mA size,, can guarantee the operate as normal of LED lamp the constant current conversion of high input direct voltage.Fig. 4 is the light modulation experimental waveform, and < 1>is the PWM dim signal of input, and < 2>are output current wave; This figure has verified the dimming capability of circuit, and during PWM wave height level, chip blocks; Output current is 0, when the PWM ripple is extremely zero, and the 350mA rated current when output current is normal power supply.

Claims (3)

1. HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit is characterized in that comprising dc power supply module (A) and N the constant-current dimming module (B that is connected with dc power supply module (A) respectively 1~ B n), the output of each constant-current dimming module is used to connect load, said N constant-current dimming module (B 1~ B n) the identical but parameter wherein each element of structure confirm that by load its input links to each other with the positive output end of dc power supply module (A), the negative output terminal ground connection of dc power supply module (A); Said constant-current dimming module comprises switch voltage-stabilizing control circuit (1) and the power supply circuits (2) that are connected with switch voltage-stabilizing control circuit (1) respectively, switch reduction voltage circuit (3), constant current feedback circuit (4) and light adjusting circuit (5).
2. HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit as claimed in claim 1 is characterized in that said power supply circuits (2) comprise the second diode (D 2), the first resistance (R 1) and the second resistance (R 2), the first resistance (R 1) be connected between the supply power voltage port VCC of positive output end and switch voltage-stabilizing control circuit (1) of dc power supply module (A); Second diode (the D 2) negative electrode through the second resistance (R 2) with the supply power voltage port V of switch voltage-stabilizing control circuit (1) CCConnect, its anode links to each other with the anode of LED load; Said switch reduction voltage circuit (3) comprises switching tube (Q), inductance (L) and the first diode (D 1); The gate pole of switching tube (Q) links to each other with the drive end PG of switch voltage-stabilizing control circuit (1), and its drain electrode links to each other with the positive output end of dc power supply module (A), and its source electrode links to each other with the anode of LED load through inductance (L); First diode (the D 1) negative electrode also link to each other its plus earth with the source electrode of switching tube (Q); Said constant current feedback circuit (4) comprises sampling resistor (R 3), sampling resistor (R 3) end links to each other other end ground connection with the feedback end FB of switch voltage-stabilizing control circuit (1); The 3rd diode (D in the said light adjusting circuit (5) 3) negative electrode link to each other with the Enable Pin EN of switch voltage-stabilizing control circuit (1), its anode connects and is used for the PWM ripple of light modulation.
3. HVDC centrally connected power supply LED constant-current source PWM light adjusting circuit as claimed in claim 2 is characterized in that switch voltage-stabilizing control circuit (1) comprises a switch voltage-stabilizing chip and peripheral circuit thereof.
CN 201220211508 2012-05-11 2012-05-11 Pulse width modulation (PWM) dimming circuit for high-voltage direct current centralized power supply light emitting diode (LED) constant current source Expired - Lifetime CN202587529U (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102685989A (en) * 2012-05-11 2012-09-19 华南理工大学 PWM (Pulse-Width modulation) dimming method and circuit of LED constant-current source concentratively powered by high-voltage direct current
CN107426874A (en) * 2017-08-25 2017-12-01 赛尔富电子有限公司 A kind of brightness adjustment control power supply for LED

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102685989A (en) * 2012-05-11 2012-09-19 华南理工大学 PWM (Pulse-Width modulation) dimming method and circuit of LED constant-current source concentratively powered by high-voltage direct current
CN107426874A (en) * 2017-08-25 2017-12-01 赛尔富电子有限公司 A kind of brightness adjustment control power supply for LED
CN107426874B (en) * 2017-08-25 2024-03-15 赛尔富电子有限公司 Dimming control power supply for LED lamp

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