CN211606870U

CN211606870U - Capacitive coupling type LED current-sharing circuit

Info

Publication number: CN211606870U
Application number: CN202020520715.0U
Authority: CN
Inventors: 孟子钧
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2020-09-29
Anticipated expiration: 2030-04-10

Abstract

The utility model relates to a capacitive coupling formula LED circuit that flow equalizes, it includes a plurality of LED cluster, a plurality of field effect transistor and pulse width modulator P, field effect transistor S₁And field effect transistor S₂Is connected with a coupling capacitor C₁₂Field effect transistor S₂And field effect transistor S₃Is connected with a coupling capacitor C₂₃And so on, the field effect transistor S_nAnd field effect transistor S₁Is connected with a coupling capacitor C_n1. The circuit has the advantages of simple structure, low cost, low loss, small output current deviation, high precision and strong expansibility. It not only overcomes the activeThe current-sharing mode has the defects of high universal cost and great loss, overcomes the defects of poor expansibility and complex circuit of the passive current-sharing mode, has the characteristics of reliable work and flexibility of the active current-sharing circuit of the passive current-sharing circuit, and can realize the optimized current-sharing effect.

Description

Capacitive coupling type LED current-sharing circuit

Technical Field

The utility model relates to a LED control technology, concretely relates to LED circuit that flow equalizes.

Background

The LED is a solid semiconductor light-emitting device, belongs to a green light source, and does not contain substances harmful to human bodies and the environment. In recent years, the development and application range of LED technology is wider and more, and the number of LED technology is more and more, and there is a trend of replacing the traditional adaptive light source in the applications of decoration, exhibition and public lighting. In the application of the high-power LED lamp, the number of LEDs required to be connected by a load LED module is large, and usually, the LED lamp beads with the same number are firstly connected in series, and then a plurality of LED lamp beads are connected in parallel. If the current of a plurality of parallel-connected LED strings is uneven, the LED strings can cause uneven light emission and uneven heat generation, the service life of the LED can be seriously influenced when the LED strings work under the condition for a long time, the work of an LED system is very unfavorable, and therefore, a reliable LED load current sharing measure is indispensable.

At present, current LED load current sharing measures are mainly divided into a passive current sharing mode and an active current sharing mode, and the two current sharing modes respectively have advantages and disadvantages. The active current equalizing mode is generally higher in cost and very large in loss, but the output current deviation is smaller, the precision is high, and the expansibility is stronger. The passive current sharing mode is low in cost and loss, but the deviation of each output current is not ideal in an active current sharing scheme under most conditions, the expansibility is poor, and the complexity of the circuit can be greatly improved.

Disclosure of Invention

The utility model aims at the general cost of the mode of flow equalizing that is active higher, and the loss is very big, and passive flow equalizing mode each way output current deviation does not have the active scheme ideal of flow equalizing, and expansibility is relatively poor, and the defect that the circuit is complicated provides a circuit structure simple, and is with low costs, and the loss is little, and the output current deviation is little, and the precision is high, the capacitive coupling formula LED circuit that flow equalizes that expansibility is strong.

The technical solution of the utility model is that: it comprises a plurality of LED strings formed by a plurality of LEDs connected in series_s1、LED_s2、LED_s3、……LED_snA plurality of field effect transistors S₁、S₂、S₃、……S_nAnd a pulse width modulator P, each LED string LED_s1、LED_s2、LED_s3、……LED_snThe positive terminals are respectively connected with the current output end of the current source, and the LED strings are LED_s1And the negative terminal of the field effect transistor S₁Connected with the drain electrode D of the LED string_s2And the negative terminal of the field effect transistor S₂Are connected to the drain electrode D of the transistor,by analogy, LED string LED_snAnd the negative terminal of the field effect transistor S_nAre connected to each other, each field effect transistor S₁、S₂、S₃、……S_nAre respectively connected with the current input end of the current source, each field effect transistor S₁、S₂、S₃、……S_nRespectively connected to a pulse width output terminal of the pulse width modulator P, a field effect transistor S₁And field effect transistor S₂Is connected with a coupling capacitor C₁₂Field effect transistor S₂And field effect transistor S₃Is connected with a coupling capacitor C₂₃And so on, the field effect transistor S_nAnd field effect transistor S₁Is connected with a coupling capacitor C_n1。

The technical effects of the utility model are that: the circuit has the advantages of simple structure, low cost, low loss, small output current deviation, high precision and strong expansibility. The passive current sharing circuit overcomes the defects of high cost and high loss of an active current sharing mode generally, overcomes the defects of poor expansibility and complex circuit of a passive current sharing mode, has the characteristics of reliable work of the passive current sharing circuit and flexibility of the active current sharing circuit, and can realize the optimized current sharing effect.

Drawings

Fig. 1 is a schematic circuit diagram according to an embodiment of the present invention.

Detailed Description

As shown in FIG. 1, it comprises a plurality of LED strings formed by a plurality of LEDs connected in series_s1、LED_s2、LED_s3、……LED_snA plurality of field effect transistors S₁、S₂、S₃、……S_nAnd a pulse width modulator P, each LED string LED_s1、LED_s2、LED_s3、……LED_snRespectively connected with the current output end of the current source Idc, and LED strings_s1And the negative terminal of the field effect transistor S₁Connected with the drain electrode D of the LED string_s2And field effectTransistor S₂The drain electrodes D are connected, and the analogy is repeated, so that the LEDs are connected in series_snAnd the negative terminal of the field effect transistor S_nAre connected to each other, each field effect transistor S₁、S₂、S₃、……S_nAre connected to the current input of a current source Idc, respectively, each field effect transistor S₁、S₂、S₃、……S_nRespectively connected to a pulse width output terminal of the pulse width modulator P, a field effect transistor S₁And field effect transistor S₂Is connected with a coupling capacitor C₁₂Field effect transistor S₂And field effect transistor S₃Is connected with a coupling capacitor C₂₃And so on, the field effect transistor S_nAnd field effect transistor S₁Is connected with a coupling capacitor C_n1。

The utility model discloses a circuit that flow equalizes based on capacitive coupling's mixture, coupling capacitance plays the balanced effect of electric current between the LED cluster.

Active switching MOSFET field effect transistor S₁、S₂、S₃、……S_nMay operate in a fixed frequency mode, but the duty cycle may operate in other ways. Different switches can adopt different duty ratios and different phases, so that the coupling capacitor provides more flexible current balance control capability.

The LED drive circuit works in a fixed-frequency fixed-duty-ratio mode, each pulse width output end of the pulse width modulator P is in the fixed-frequency fixed-duty-ratio mode, each pulse width output of the pulse width modulator P is 1/n, and n is the number of LED strings. The pulse width modulator P is provided with a certain dead time before each field effect transistor is turned on to prevent the LED strings of each channel from having a slight common on-time.

Working in a fixed-frequency and fixed-duty-ratio mode, each LED string is provided with LEDs_s1、LED_s2、LED_s3、……LED_snThe number of LEDs is completely equal, and each LED string is LED_s1、LED_s2、LED_s3、……LED_snCoupling capacitance C between₁₂、C₂₃、 C₃₄、…… C_n1The capacities are identical.

When the LED drive circuit works in a mode of fixed frequency and fixed duty ratio, the load currents of all paths of LED strings are completely equal, and the current balance of the LEDs can be conveniently realized. The structure is very simple, and the expandability is very strong. For a field effect transistor MOSFET, the pulse width modulator P can realize the current sharing function only by using a driving signal with a fixed duty ratio, so that a driving circuit and a control circuit are easy to realize.

Active switching MOSFET field effect transistor S₁、S₂、S₃、……S_nThe LED drive circuit can also work in other duty ratio modes, for example, 3 LED strings, the duty ratios of all pulse width output ends of the pulse width modulator P are 1/2, and the phase difference between the switches is 1/3 cycles. Each pulse width output of the pulse width modulator P adopts different duty ratios, different current sharing control capacities are realized, the pulse width modulator can be conveniently used for different LED string structures, and a more flexible control effect can be realized.

Operating in other duty cycle modes, each LED string LED_s1、LED_s2、LED_s3、……LED_snThe number of the LEDs can be not completely equal, and the corresponding LEDs in each LED string are_s1、LED_s2、LED_s3、……LED_snCoupling capacitance C between₁₂、C₂₃、 C₃₄、……C_n1The capacities of the two capacitors can be not completely the same, and the effect of mixing and equalizing the flow can be achieved.

To summarize: the capacitive coupling type LED current equalizing circuit introduces a small amount of switching elements and simultaneously adopts a simple control working mode. The coupling capacitors among all the branches can adopt the same capacity or different capacities, and the MOSFET switch of the field effect transistor generally adopts a fixed-frequency working mode, but the duty ratio can also work in other modes. Different switches can adopt different duty ratios and different phases, so that the coupling capacitor provides more flexible current balance control capability.

Claims

1. The capacitive coupling type LED current equalizing circuit comprises a current equalizing circuitSeveral LED strings formed by connecting several LEDs in series_s1、LED_s2、LED_s3、……LED_snA plurality of field effect transistors S₁、S₂、S₃、……S_nAnd a pulse width modulator P, each LED string LED_s1、LED_s2、LED_s3、……LED_snThe positive terminals are respectively connected with the current output end of the current source, and the LED strings are LED_s1And the negative terminal of the field effect transistor S₁Connected with the drain electrode D of the LED string_s2And the negative terminal of the field effect transistor S₂The drain electrodes D are connected, and the analogy is repeated, so that the LEDs are connected in series_snAnd the negative terminal of the field effect transistor S_nAre connected to each other, each field effect transistor S₁、S₂、S₃、……S_nAre respectively connected with the current input end of the current source, each field effect transistor S₁、S₂、S₃、……S_nThe grid G of the pulse width modulator P is respectively connected with a pulse width output end of the pulse width modulator P, and the pulse width modulator P is characterized in that: field effect transistor S₁And field effect transistor S₂Is connected with a coupling capacitor C₁₂Field effect transistor S₂And field effect transistor S₃Is connected with a coupling capacitor C₂₃And so on, the field effect transistor S_nAnd field effect transistor S₁Is connected with a coupling capacitor C_n1。

2. The capacitively coupled LED current sharing circuit of claim 1 wherein each of the LED strings LED is a string of LEDs_s1、LED_s2、LED_s3、……LED_snAre substantially equal in number.

3. The capacitively coupled LED current sharing circuit of claim 2 wherein each of the LED strings LED is a string of LEDs_s1、LED_s2、LED_s3、……LED_snCoupling capacitance C between₁₂、C₂₃、 C₃₄、…… C_n1Phase of capacity completionThe same is true.

4. The capacitively coupled LED current sharing circuit of claim 1 wherein each of the LED strings LED_s1、LED_s2、LED_s3、……LED_snThe number of LEDs of (a) is not exactly equal.

5. The capacitively coupled LED current sharing circuit of claim 4 wherein each of the LED strings LED_s1、LED_s2、LED_s3、……LED_snCorresponding coupling capacitors C₁₂、C₂₃、 C₃₄、…… C_n1Are not exactly the same.