CN106413188B - High efficiency LED multi-path drive control method - Google Patents

Abstract

A kind of scheme carrying out independent current or voltage control and independent working state control to LED multi-path or DC load using single DC-DC power converter.The program can substitute the scheme of traditional multiple DC-DC power converters driving LED multi-path in the case where equally realizing LED multi-path electric current independent control, greatly reduce the quantity of the large-scale component such as power electronic switching and inductance, it has saved the cost of product and has occupied space, it is particularly suitable for the wide input voltage ranges such as automotive lighting, spaces compact, the application for needing high efficiency, high-performance, multi-way intelligence to control.

Description

High efficiency LED multi-path drive control method

Background introduction

Field that the present invention belongs to

Present patent application is that one belonged in light emitting diode (LED) drive control field invents, specifically one Kind using switching regulator drive high efficiency, low cost, wide-voltage range LED multi-path drive control scheme.

Relevant field description

LED brings a revolutionary variation to lighting area.High-efficient, small in size, the service life is long, pollution-free, with And the Mechanical Reliability come with solid luminescence characteristic, portability etc. make it become the best of luminescent device in many fields Selection.With the continuous improvement of the light efficiency and power level of LED, also correspondingly performance requirement is higher, luminous intensity for the application of LED Bigger field development, the headlighting of automobile are exactly one of field rapidly developed and grow up.

The lighting headlight of the headlighting of automobile, especially driving at night needs high-intensitive, high power density illumination system System.Its technological challenge includes:

A. efficient LED light emitting device and efficient driving circuit are to keep minimum power consumption.The reduction of power consumption is not Valuable electric energy has only been saved, while having also reduced the heat as caused by power consumption.

B. efficient cooling system is existed because luminous efficiency can decline LED component at high temperature using high efficiency and heat radiation system It is also vital that the temperature of device, which is maintained reasonable level, in limited tight space.

C. automobile lighting system is all to be powered by on-vehicle battery, and the voltage change of battery is usually all very big, with the electricity of 12V For pond, voltage change range is usually between 6V to 14V, and if due to former because of certain during automotive service When disconnecting suddenly because of the load of generator, output voltage may cross the very high level that is flushed to, and the peace configured in automobile Full clamp circuit is typically only capable to this overshoot voltage to clamp in 40V or so, so the work input voltage of automobile lighting system Range is 6V to 40V, and the work input voltage of this wide scope proposes greatly lighting system, especially driving circuit Challenge.

D. it is compared due to the cost of LED illumination System with traditional illumination system still higher, how to reduce system cost pair In the popularization of automobile lighting system and a very crucial factor.

The LED headlamp of automobile is usually larger to be made of three lighting part: (Main Beam is generally also cried big king light Lamp), illumination is provided for night running；Daytime running lamps (Signature), are usually lighted always, both conduct when driving A kind of emergency lighting, also as a kind of mark of automobile and decoration；Turn signal, the steering as automobile indicate.These three illuminations Equipment requires to adapt to the wide operating voltage range of 6V to 40V, and can be in while the car is driving a variety of different Work assembled state.On the other hand, the lighting system of automobile has also introduced more intelligent sexual functions with advances in technology, special If not being that headlight part is distributed LED multi-path according to specific matrix form, when driving can car turn to or Spatial distribution state when climb and fall according to transport condition with luminous matrix automatically regulates light by the control to luminous matrix The direction of beam reaches optimal illuminating effect, so as to saving the illumination servo-system that high-end car headlamp is configured. Another function of intelligent headlight can be automatically adjusted according to travel speed when being driving at night the irradiation of dipped beam and distance light away from From, or the preceding distance shone and angle are adjusted to avoid to the dazzling interference of vehicle etc. that other side is opposite and comes.And turn signal Illumination also due to LED application and there is new display mode, such as from it is intermittent flashing become the right from left to rights such as a row LED or The successively scanning mode etc. on a dextrad left side.

The application characteristic of automotive lighting described above and intelligent sexual function etc. propose the drive system of LED automobile illumination The requirement of series of challenges is gone out.On the one hand due to the input service voltage of wide scope, driving circuit needs use that can rise The circuit framework that pressure can be depressured again, is on the other hand combined due to needing to control LED multi-path device in various different working conditions In the case of co-ordination, it is and another so obviously the LED drive circuit of automotive lighting needs to have very flexible control characteristic On the one hand due to the increase of LED number, the number and complexity of driving circuit are also with increaseing accordingly, and cost is naturally also with increasing Add, how to design in this case high-performance required for existing application, again with cost competitiveness lighting system at For the key that can LED automobile illumination be widelyd popularize, LED driving principle disclosed in present patent application is precisely in order to upper It states and provides the method for novelty a kind of under environment to design and produce and provide the automotive lighting of high-performance and price competitiveness and produce Product push the development in the market and industry, and further genralrlization is into other relevant application fields.

Summary of the invention

In conclusion the invention aims to provide the LED multi-path driving side of a kind of high-performance, high efficiency and low cost Case, and flexible control operation can be realized in the case where width works input voltage.This programme breaches currently on the market The every paths of LEDs generallyd use configures the design method of individual buck switchmode converter, only uses a boosting, drop Pressure or buck-boost converter the wide input voltage the case where under realize independent drive control to LED multi-path.The program is being protected The larger electronic devices such as a large amount of power semiconductor and inductance have been saved while holding high efficiency, high performance operation, have greatly been dropped The low cost of system, while also greatly reducing the space that driving circuit is occupied, increase automobile lighting system can By property and design flexibility.

A kind of Sofe Switch operating method to non-isolated supply convertor is additionally provided in principles of this disclosure, Noise jamming when can further increase the working efficiency of system and reduce switch work, be conducive to communication to surrounding, Control circuit provides a more favorable working environment.

Detailed description of the invention

Fig. 1 show traditional LED multi-path automotive lighting drive scheme.

Textual annotation in attached drawing:

IREF--- current control reference signal

IFB---LED current feedback signal

PWM---PWM pulsewidth dim signal

VIN--- DC input voitage

QA, QB, QC, QD--- converter electronic switch

R--- current sampling resistor

LED--- light emitting diode

L--- inductance

Fig. 2 describes the drive scheme that the present invention carries out current control using buck (Buck) converter to LED multi-path Schematic circuit and relevant work wave.

Textual annotation in attached drawing:

IREF--- current control reference signal

IFB----LED current feedback signal

PWM---PWM pulsewidth dim signal

CTRL--- current controling signal

VIN--- DC input voitage

QA, QB--- converter electronic switch

Q1, Q2, QK---LED control switch

R--- current sampling resistor

LED1, LED2, LEDK--- light emitting diode

L1--- inductance

Fig. 3 describes the driving that boost type of the present invention (Boost) converter carries out current control to LED multi-path The schematic circuit of scheme and relevant work wave.

Textual annotation in attached drawing:

IREF--- current control reference signal

IFB----LED current feedback signal

PWM---PWM pulsewidth dim signal

CTRL--- current controling signal

VIN--- DC input voitage

QC, QD--- converter electronic switch

Q1, Q2, QK---LED control switch

R--- current sampling resistor

LED1, LED2, LEDK--- light emitting diode

L1--- inductance

Fig. 4 describes step-down/up type of the present invention (Buck-Boost) converter and carries out electric current control to LED multi-path The schematic circuit and relevant work wave of the driving scheme processed of system.

Textual annotation in attached drawing:

IREF--- current control reference signal

IFB----LED current feedback signal

PWM---PWM pulsewidth dim signal

CTRL--- current controling signal

VIN--- DC input voitage

QA, QB, QC, QD--- converter electronic switch

Q1, Q2, QK---LED control switch

R--- current sampling resistor

LED1, LED2, LEDK--- light emitting diode

L1--- inductance

Fig. 5 describes the present invention and carries out electricity to LED multi-path using one step-down/up type (Buck-Boost) converter The schematic circuit of the drive scheme of voltage-controlled system and relevant work wave.

Textual annotation in attached drawing:

VREF--- voltage controls reference signal

VFB----LED voltage feedback signal

PWM---PWM pulsewidth dim signal

CTRL--- current controling signal

VIN--- DC input voitage

QA, QB, QC, QD--- converter electronic switch

Q1, Q2, QK---LED control switch

R--- current sampling resistor

LED1, LED2, LEDK--- light emitting diode

L1--- inductance

The detailed description of invention

Fig. 1 show the typical three roads automobile headlamp LED illumination drive circuit structure generallyd use at present.Such as one institute of figure Show, since input voltage range is 6V to 40V, the operating voltage of each paths of LEDs generally all more than more than ten volts to 30 volt between, just It falls within input voltage range well, input voltage all may below and above the situation of LED operation voltage during the work time Occur, so three driving circuits all use buck (Buck-Boost) circuit structure.Step-up/step-down circuit energy shown in figure one Enough allow to output and input circuit altogether, and working efficiency is also higher than other kinds of step-up/step-down circuit, so to other classes Which is not described herein again for the step-up/step-down circuit of type.Simultaneously because there are many different work shapes for headlight, daytime running lamps and turn signal State combination, in order to guarantee that illumination can accurately and reliably work on the road combination Xia Ge of various working conditions, the illumination of three tunnels is used Completely self-contained driving circuit.From figure one, it is not difficult to find out that, such drive system has used 12 device for power switching, three electricity Sense and three filter capacitors.The cost of these devices is relatively high, and volume is also bigger, so corresponding system cost can also compare Higher, occupied space is also bigger.

The central principle of invention is to drive LED multi-path lighting circuit using a switch-mode power converter, And each paths of LEDs can be operating independently in the case where wide input voltage range and various working conditions combine.In order to by letter Enter the entire principle of numerous elaboration, is first talked about here from the working principle of buck.Figure two is shown using a buck circuit Come the circuit theory for driving LED multi-path to work independently.As shown in Figure 2, LED1, LED2 ... ..LEDK is that the road K needs independent drive Dynamic LED string, each LED string respectively have a capacitor C1, C2 ... the CK electric current in parallel gone here and there with smooth LED therewith, each LED string again respectively have a diode D1, D2 ... ..DK is connected in series therewith to prevent energy mutual between each smoothing capacity Mutually flow, the anode of the LED branch formed in this way is connected in parallel, negative terminal again an each and control switch Q1, Q2 ... ..QK is connected in series to control the guiding path of each string LED current, and the negative terminal of each control switch is respectively examined with an electric current Survey element R1, R2 ... .RK is connected to ground after being connected in series, form the LED operation branch for capableing of independent control；In the circuit In the operating voltage of each LED string be below the minimum of input voltage, so power supply conversion is with by main switch QA, auxiliary switch Buck conversion circuit composed by QB and L1 realizes that in figure the source electrode of QA is connected to form switching node with the drain electrode of QB The drain electrode of SW, QA are connected with Input voltage terminal, and the source electrode of QB is connected with ground, the first port and switching node SW phase of inductance L1 Even, the anode sys node that the second port of inductance is connected to each LED branch is acted in collusion to make each other's confessions electric to each LED.

Each paths of LEDs as shown in Figure 2, LED1, LED2 ... ..LEDK has respective individual control loop COTROL LOOP 1, CONTROL LOOP2 ... .CONTROL LOOPK controls its electric current and operation, and each control loop is from corresponding Current measuring element reading current feedback signal IFB1, IFB2 of LED branch ... ..IFBK, further according to corresponding LED current Control signal IREF1, IREF2 ... processing of the .IREFK Jing Guo control loop generate control accordingly signal CTRL1, CTRL2,.....CTRLK.These control signals from control distribution logic CONTROL STEERING LOGIC again by being distributed Buck converter and control switch is controlled to switch periods to be operated in the switch of respective cycle to control corresponding LED branch Electric current.

The basic operation waveform of circuit is as shown in figure two, each operation cycle of buck converter and the control of each paths of LEDs System switch simultaneously operating, is successively grasped according to the control signal of each paths of LEDs control loop under the control of control distribution logic Make to meet the needs of each paths of LEDs current control.Signal is controlled in the operation cycle CYCLE 1 of buck converter as shown in the figure VG1 makes the Q1 conducting for controlling LED1 current path, and the control switch Q2-QK of other each paths of LEDs is all in off state, decompression The current direction LED1 and corresponding smoothing capacity C1 that converter is exported, control distributes logic CONTROL during this period STEERING LOGIC also correspondingly control signal CTRL1 caused by control loop CONTROL LOOP1 be connected to QA and QB driving circuit generates the gate electrode drive signals VGA and VGB of QA and QB.In this operating process when QA is connected, and QB is turned off The electric current IL1 of inductance L1 rises, and electric current flows to LED1 by L1 from input terminal VIN；The electricity of inductance L1 when QA is turned off, and QB is connected It flows IL1 and afterflow is carried out by QB, electric current continues to flow through LED1 until decaying to zero.Signal is controlled caused by the control loop Control under LED1 just meet it from the electric current that inductance L1 is obtained in this switch periods and maintain institute in whole work process It is required that average current needs.In the current waveform such as figure two of IL1 shown in IL1 (1).Next switch operation cycle is in IL1 When decaying to zero, Q2 is connected in VG2, the current direction LED2 of buck converter, while controlling distribution logic corresponding Control loop CONTROL LOOP2 caused by control signal CTRL2 be sent to the gate drive circuit of QA and QB control drop The operation of buckling parallel operation.The rest may be inferred, and control distribution logic successively distributes to each switch operation cycle of buck converter Each paths of LEDs uses, and carries out operation control to the switch periods being assigned to by the control loop of each paths of LEDs, thus reaches The effect being independently controlled to LED multi-path is realized using a buck converter.It needs exist for illustrating, in actual operation There is a dead time when QA and QB alteration switch state, namely after a switch-off signal issues, another is opened The Continuity signal of pass is issuing after the delay time of dead zone, occurs to avoid two switches in alteration switch state of short duration While the situation that is connected.In order to enable waveform working principle to be described is clearly understandable, shown in figure two and all attached drawings Waveform in without display dead time.

In inductive current waveform described above, next operation cycle is the inductance electricity in upper a cycle always When stream decays to zero, such way is easier so that being conveyed to the electricity of corresponding LED string in each operation cycle Stream energy is precisely controlled, and the control of the current control in each period namely each paths of LEDs electric current can be realized completely solely It is vertical, simultaneously because smoothing capacity C1, C2 ... the presence of .CK, the electric current of each paths of LEDs are able to maintain that continuously.Each paths of LEDs electric current Ripple can also be met by selecting the smoothing capacity of suitable capacity.On the other hand the working condition of each paths of LEDs is upper It states and also can be realized independent control in method, to meet the requirement of a variety of different working condition combinations.It is each in figure two Control signal PWM1, PWM2 that control loop is received ... corresponding each paths of LEDs can be placed in work or non-work by ..PWMK Make state.When a certain paths of LEDs is placed in off working state, control distribution logic can be according to the state of corresponding control signal The paths of LEDs is removed from work sequence, when carrying out operation cycle distribution for the in running order circuit LED successively into Row distribution.Such as when LED2 is placed in off working state by PWM2, the operation of LED2 can remove in the sequence of operation, in LED1 Operation at the end of, next operation cycle will skip LED2, distribute in running order LED3.In this way using a drop Buckling parallel operation can not only realize the independent control of the electric current of each paths of LEDs, and the working condition of each paths of LEDs also can be realized independent control System.It needs exist for illustrating, operation when each paths of LEDs carries out current control is corresponding with the switching operating frequency of buck converter , generally in tens kilo hertzs to several hundred kilo hertzs of range, and the variation of each paths of LEDs working condition be another more slowly Time and frequency range in, function is the concept of ' ON ' and ' OFF ', so both in the above description in working principle It is independent of each other.

Implementation of the invention can also be realized with other methods other than method described above.Institute in figure two The current practice waveform IL1 (2) of the inductance L1 shown can realize the electric current of each paths of LEDs is independently controlled, the road You Duige While the working condition of LED also realizes independent control, the Sofe Switch operation of buck converter is realized, its working principles are as follows:

As shown in IL1 (2) in Fig. 2, by taking first operation cycle as an example, when main switch QA is turned off in moment t1B, auxiliary is opened After closing QB conducting, the electric current of inductance L1 is begun to decline until decaying to zero and the difference of operating method shown in current waveform IL1 (1) , operating method QB when IL1 decays to zero shown in current waveform IL1 (2) still maintains on state, and QA is still cut Only, in the case where QB continues conducting, IL1 changes after decaying to zero due to the presence of the parasitic capacitance energy storage of each paths of LEDs in this way Become flow direction, begin setting up the negative direction electric current flowed from right to left, QB is established in the negative direction electric current of IL1 to close to peak value When turn off, at this moment IL1 is put because the shutdown of QB changes flow path by the parasitic capacitance of the charging of parasitic capacitance to QB and QA Electricity maintains continuity, and the charge and discharge rising of switching node SW pressed with QB and QA parasitic capacitance, works as SW in this course Voltage when rising towards or being equal to input voltage VIN QA be connected, at this moment since the source and drain both end voltage VDS of QA is close or waits Zero-voltage soft switch operation is realized in the switch operation of zero, QA.Such operating method has still maintained the electricity to each paths of LEDs The independent control of the working condition of stream and each paths of LEDs, while the Sofe Switch operation of buck converter is realized again.As previously mentioned, In order to enable waveform working principle to be described is clearly understandable, without display dead time in waveform shown in the drawings.

In the above described two methods, the operation of each paths of LEDs and the switch operation of buck converter are synchronous and inductance L1 Electric current drops to zero in each switch periods.If come using the inductive current of buck converter as a continuous current source It uses, current value adjusts the levels of current required for meeting whole system and working by control distribution logic, and each paths of LEDs is in institute Quickly energy can be obtained from inductive current when starting work in duty cycle for being assigned to, and and buck converter The independent control of electric current and working condition that can be realized under switch operation is synchronous or nonsynchronous situation to each road.? Buck converter is controlled as current source in system work institute by the electric current of switch operation handlebar inductance L1 under this operational circumstances The current value needed, rather than IL1 will be made to decay in each switch periods as [0012] to [0014] trifle is described Zero.The adjusting of the working value of inductive current can be set according to different rules according to the needs of practical application, one of Method is that inductive current is adjusted in the electricity for being equal to the in running order LED in each road according to the instantaneous operating conditions of each paths of LEDs The summation of flow valuve, each paths of LEDs is needed according to itself current control through its corresponding control loop and control in operation The control of system distribution logic successively obtains electric current from the IL1 as current source.Such operating method and electricity of each operation cycle The start from scratch method of foundation of inducing current compares, and the response speed of the current control of each paths of LEDs can be than very fast.In He Gelu Can permit two-way in principle when LED cooperating or LED multi-path simultaneously turn on, but if the operating voltage of each paths of LEDs not Equally, electric current can only flow to operating voltage it is minimum LED string, even if LED higher to operating voltage go here and there its accordingly control open It closes the electric current in the conductive state that there will not be to flow through, so in the control for the LED for using each road in running order in actual work The operating method that system switch sequentially turns in order is relatively good.Such operating method makes control logic fairly simple orderly, The average current value of buck converter then adjusts setting according in running order LED load summation in real time.It leads at work Logical LED string controls the electric current of LED still through its corresponding control loop using pulse-width regulated, but its operating frequency can It, can also be with the asynchronous operation of buck converter with synchronous with the operation of buck converter.When system is from working condition, namely At least state of LED operation all the way, be transferred to all LED all idle state when, due to needing to prevent the electricity of inductance L1 Flow no access afterflow and caused by voltage overshoot, the circuit LED finally turned off not changing with working state control signal Change immediately turns off, but continues to keep work under the control of current controlled circuit, until inductive current IL1 exhausts, thus The access for efficiently avoiding IL1 sudden shut off and caused by voltage overshoot phenomenon.Inductive current energy in practical applications Consumption absorption usually only need several milliseconds or shorter of time, so will not visually have any impact.

The above is equally applicable to using the method that a buck converter carries out drive control to LED multi-path with one Booster converter carries out current control independent and working state control to LED multi-path.With a booster converter to more The principle that paths of LEDs carries out drive control is as shown in Figure 3.In figure three LED1, LED2 ... ..LEDK is that the road K needs independent drive Dynamic LED string, each LED string respectively have a capacitor C1, C2 ... the CK electric current in parallel gone here and there with smooth LED therewith, each LED string again respectively have a diode D1, D2 ... ..DK is connected in series therewith to prevent energy mutual between each smoothing capacity Mutually flow, the anode of the LED branch formed in this way is connected in parallel, negative terminal again an each and control switch Q1, Q2 ... ..QK is connected in series to control the guiding path of each string LED current, and the negative terminal of each control switch is respectively examined with an electric current Survey element R1, R2 ... .RK is connected to ground after being connected in series, form the LED operation branch for capableing of independent control；In foregoing circuit The operating voltage of each LED string is all higher than the peak of input voltage, so power supply conversion is risen with as composed by QC, QD and L1 Pressure type translation circuit realizes that the source electrode of QD is connected to form switching node SW with the drain electrode of QC in figure, the drain electrode of QD is as defeated Outlet is connected to each LED statements based on collusion electricity with the anode sys node of each LED branch, and the source electrode of QC is connected with ground, inductance L1's First port is connected to input voltage VIN, and second port is connected with switching node SW.

Each paths of LEDs shown in Fig. 3, LED1, LED2 ... ..LEDK has respective individual control loop COTROL LOOP 1, CONTROL LOOP2 ... .CONTROL LOOPK controls its electric current and operation, and each control loop is from corresponding Current sense resistor reading current feedback signal IFB1, IFB2 of LED branch ... ..IFBK, further according to corresponding LED current Control signal IREF1, IREF2 ... processing of the .IREFK Jing Guo control loop generate control accordingly signal CTRL1, CTRL2,.....CTRLK.These control signals from control distribution logic CONTROL STEERING LOGIC again by being distributed Buck converter and control switch is controlled to switch periods to be operated in the switch of respective cycle to control corresponding LED branch Electric current.

The work of buck converter driving LED multi-path is used in figure two described in from [0012] trifle to [0015] trifle Principle is equally applicable to the described situation that LED multi-path is driven using booster converter of figure three.Except that in figure two QA is main switch in circuit, and QB is synchronous auxiliary switch, and the electric current of inductance L1 rises during QA conducting, QB be connected during under Drop；And QC is main switch in figure three-circuit, QD is auxiliary switch, and the electric current of inductance L1 rises during QC conducting, QD conducting Period decline.Using the principle work wave of boost converter circuit also as shown in figure three.As the circuit as shown in figure two, Booster converter driving circuit shown in figure three is also able to use working principle described in [0012] trifle to [0014] trifle Realize that switch periods are synchronous with LED operation in the case where boosting inverter using a booster converter, each end cycle When inductive current be zero and using inductance negative current realize Sofe Switch operation in the case of realize LED multi-path electric current independence Control, while also realizing the independent control of the working condition of each paths of LEDs.Principle described in [0015] trifle is equally applicable The booster converter driving circuit shown in figure three uses a booster converter to make using inductive current as continuous current source With, the independent control of the electric current of realization LED multi-path and working condition under the control of control distribution logic, and each paths of LEDs Current control starts in the case where inductive current is close to target current value, obtains faster dynamic responding speed.Because work is former It manages identical and has been described in detail in above-mentioned trifle, so being not repeated herein.

In practical applications, especially in automobile application, often the operating voltage of each paths of LEDs lighting device is widely different, Can even occur some operating voltages simultaneously lower than minimum input voltage, some operating voltages are higher than maximum input voltage, and have A little operating voltages are just needed in this case between minimum input voltage and maximum input voltage using step-down/up type electricity Source converter drives Multi-path LED load, and schematic circuit is as shown in Figure IV.In figure four LED1, LED2 ... ..LEDK is K LED that road needs independently to drive string, each LED string respectively have a capacitor C1, C2 ... CK is in parallel with smooth LED string therewith Electric current, each LED string respectively have again a diode D1, D2 ... ..DK is connected in series therewith to prevent energy in each smooth electricity Mutual flowing between appearance, the anode of the LED branch formed in this way are connected in parallel, negative terminal and an each and control switch Q1, Q2 ... ..QK is connected in series to control the guiding path of each string LED current, and the negative terminal of each control switch is respectively and an electric current Detecting element R1, R2 ... .RK is connected to ground after being connected in series, form the LED operation branch for capableing of independent control；For sake of convenience Assume that the operating voltage of LED1 is higher than input voltage in foregoing circuit, the operating voltage of LED2 is lower than input voltage, LED3's Operating voltage is lower than input voltage, and the operating voltage of LEDK is higher than input voltage, in actual operation due to the change of input voltage The size relation for changing each paths of LEDs operating voltage and input voltage also can be as change, control circuit can be closed according to actual voltage It is situation to determine the voltage transformation mode when work of each paths of LEDs in real time.Power converting circuit is with by QA, QB, QC, QD and L1 Composed step-down/up type translation circuit realizes that QA and QB composition decompression bridge arm in figure four, QA is main switch, and QB is that auxiliary is opened It closes, the source electrode of QA is connected to form switching node SW1 with the drain electrode of QB, and the drain electrode of QA is connected to Input voltage terminal, and the source electrode of QB connects To ground terminal；QC and QD composition boosting bridge arm, QC is main switch, and QD is auxiliary switch, and the source electrode of QD is connected shape with the drain electrode of QC At switching node SW2, the drain electrode of QD is connected as output end with the anode sys node of each LED branch acts in collusion to make each other's confessions to each LED The source electrode of electricity, QC is connected with ground, and the first port of inductance L1 is connected to switching node SW1, and second port is connected to switching node SW2。

Each paths of LEDs shown in Fig. 4, LED1, LED2 ... ..LEDK has respective individual control loop COTROL LOOP 1, CONTROL LOOP2 ... .CONTROL LOOPK controls its electric current and operation, and each control loop is from corresponding Current sense resistor reading current feedback signal IFB1, IFB2 of LED branch ... ..IFBK, further according to corresponding LED current Control signal IREF1, IREF2 ... processing of the .IREFK Jing Guo control loop generate control accordingly signal CTRL1, CTRL2,.....CTRLK.These control signals from control distribution logic CONTROL STEERING LOGIC again by being distributed Buck-boost converter and control switch is controlled to switch periods to be operated in the switch of respective cycle to control the electricity of respective branch Stream.

Circuit in Fig. 4 is equally made of decompression bridge arm QA and QB in input terminal, forms boosting by QC and QD in output end Bridge arm, when circuit carries out decompression transformation operation, QC is in cut-off, and QD is in the conductive state, and QA and QB carry out decompression transformation behaviour Make, operating principle is identical with step-down conversion circuit described in figure two；When circuit carries out boosting inverter operation, QA is on, at QB In off state, QC and QD carry out boosting inverter operation, and operating principle is identical with boost conversion circuit described in figure three.From [0012] Trifle is equally applicable to figure four to the described working principle using single-stage converter driving LED multi-path of [0015] trifle and is retouched That states drives the situation of LED multi-path using buck-boost converter.Except that because circuit described in figure four has simultaneously There are boosting and decompression transformation function, the relationship of operating voltage and input voltage to each paths of LEDs load driven is not any Limitation.Waveform shown in figure four describes the VLED1 > VIN when input voltage is in some particular value as an example, A kind of operation waveform in the case where VLED2 < VIN, VLED3 < VIN, VLEDK > VIN.As shown in figure four, switch periods CYCLE1 circuit provides driving current to LED1, and because of VLED1 > VIN, circuit does boosting inverter operation, is in whole cycle QA Conducting, QB are in off state, and QC and QD carry out boosted switch operation；Driving electricity is provided to LED2 in switch periods CYCLE2 Stream, because of VLED2 < VIN, circuit does decompression transformation operation, is in whole cycle QD, and QC is in off state, QA and QB Carry out step-down switching operation；Driving current, because of VLED3 < VIN, circuit and CYCLE2 are provided to LED3 in switch periods CYCLE3 Equally, decompression transformation operation is done；... driving current is provided to LEDK closing period CYCLEK circuit, because of VLEDK > VIN, Circuit does boosting inverter operation, is in whole cycle QA, and QB is in off state, and QC and QD carry out boosted switch behaviour Make.Control circuit is according to the operating voltage of actual LED and the relationship situation of input voltage come in real time in whole work process Ground determines the voltage transformation mode when work of each paths of LEDs.

Waveform shown in Fig. 4 is that the schematic circuit in figure uses [0012], [0013] and [0014] trifle is described dropping Operating principle in the case that buckling is changed and described in [0018] trifle in the case where boosting inverter, the switch of converter Period is synchronous with LED operation, and inductive current when each end cycle is zero or realizes that Sofe Switch operates using inductance negative current, The independent control to the electric current of LED multi-path is realized using a buck-boost converter, while also realizing the work shape of each paths of LEDs The situation of the independent control of state.[0015] it is used described in trifle using inductive current as continuous current source, passes through decompression Operation, and used described in [0018] trifle using inductive current as continuous current source, by boost operations, realize to more The working principle that paths of LEDs is independently controlled is applied equally to buck driving circuit shown in figure four, is gone up and down using one Buckling parallel operation is used using inductive current as continuous current source, according to voltage relationship situation in actual work come true in real time Voltage transformation mode when fixed each paths of LEDs work realizes the electric current and work shape of LED multi-path under the control of control distribution logic The independent control of state, and the current control of each paths of LEDs starts in the case where inductive current is close to target current value, obtains more Fast dynamic responding speed.

There are one unique advantages for buck driving circuit shown in Fig. 4.As described in [0015] trifle, make Use buck converter using inductive current as continuous current source in use, when system is from working condition, a namely at least paths of LEDs The state of work, be transferred to all LED all idle state when, due to needing the electric current for preventing inductance L1 there is no access afterflow Voltage overshoot caused by and, the circuit LED finally turned off not as the change of working state control signal immediately turns off, but Continue to keep work under the control of current controlled circuit, until inductive current IL1 exhausts.In use booster converter inductance Electric current is also same situation when using as continuous current source, last paths of LEDs is needed to keep when being transferred to off working state Work is exhausted until inductive current.And when using buck driving circuit shown in figure four, when system is transferred to from working condition When off working state, as long as turning off QA and QD, QB and QC maintain conducting, and the residual current of inductance L1 can pass through QB and QC Circulation is kept by the circuit on ground, is gradually exhausted.The LED finally to work all the way in this way can be immediately when off working state arrives Shutdown, exhausts the remaining energy storage of inductance without being utilized to.

Buck-boost converter drive scheme described in Fig. 4 is realized using a boosting bridge arm and a decompression bridge arm Stepping functions.The benefit of such scheme is that LED and corresponding control switch circuit can be with input voltages altogether, output end Polarity of voltage it is identical with input terminal, current detecting and all relatively good processing of control signal etc., and device for power switching is held The voltage stress received is also smaller, and efficiency is relatively high.It also can be realized lifter change using a bridge arm in practical applications Function, because this kind of circuit is it is well known which is not described herein again.The scheme benefit of single bridge arm buck is power device used Few, LED and corresponding control switch circuit can not be with input voltages altogether, although altogether but the voltage pole of output end Property and input terminal on the contrary, current detecting and all not so good processing of control signal etc., and the voltage that device for power switching is born Stress is also bigger, efficiency compare it is lower, so driven for LED multi-path, especially high-grade drives, without advantage, but It is that in some fairly simple applications or can be considered.

One supply convertor of use described above, which is realized, carries out independent control to the electric current of LED multi-path or DC load The principle of system can also be used to realize that the voltage to multi-channel DC load carries out independent control.Specific implementation only need to be figure Two, each LED operation branch in schematic circuit described in figure three and figure four does following change according to schematic diagram shown in figure five: One smoothing capacity is in parallel with needing to carry out voltage-controlled LED string, the negative terminal and ground after parallel connection connect, and one is isolated Diode and a control switch are connected in series, and the negative terminal after series connection is connected with the LED anode gone here and there, and the anode after series connection is as LED The positive input terminal of the positive input terminal of work branch, all LED operation branches is all connected to the output end of boost-buck power converter, Namely the anode of the upper end electronic switch of boosting bridge arm.Every LED branch has the electricity as composed by two voltage detection resistances Detection unit is pressed, the voltage feedback signal VFB detected is fed back to instead of current feedback signal IFB in figure two, figure three and figure four Each corresponding control loop of paths of LEDs branch, control loop control reference signal according to the voltage of each LED branch and are received Voltage feedback signal controls the voltage of each LED branch under the coordination of control distribution logic, controls the principle of operation Just the same with the operating principle of realization LED current control described herein, different is the object for being to control, control Reference signal and feedback signal are all signals corresponding with voltage, rather than signal corresponding with electric current.Pay attention to be shown in figure five Realize that the principle of voltage driving, same principle are also applied for using decompression transformation to LED multi-path using buck-boost converter Device and booster converter to realize LED multi-path voltage driving, and because hereinbefore having had a detailed description, which is not described herein again, simultaneously Be also required to emphasize above-mentioned principle other than it can drive LED, equally can also be used to the other kinds of DC load of multichannel into The independent voltage control of row.

Above statement disclose it is a kind of using single decompression, boosting or boost-buck power converter come to LED multi-path Load carries out the principle of independent electric current and working state control.Need exist for emphasizing, it is set forth above in cited circuit, member Device, functional block diagram etc. are provided to be used to that the principle of the present invention is described as an example, without constituting to of the invention real Apply the limitation of scheme.The working principle of the invention also can be real other than it can be realized the control to the current or voltage of LED Now to the control of the current or voltage of other kinds of DC load；Used in schematic circuit described as an example Component can also be replaced completing same principle sexual function with the component of any other type；It in practical applications can be with Different embodiments working principle according to the present invention is taken to be implemented；The case where not violating the working principle of the invention Under, embodiment can both use analog control circuit, can also be using digital control circuit, analog-digital hybrid control electricity Various functions described in the present invention are completed on road or microprocessor control circuit, computer control circuit etc..

Claims (7)

1. a kind of drive for realizing independent current control and working state control to LED multi-path using a step-down/up type converter Dynamic method a, which is characterized in that direct-current input power supplying, negative voltage side is as ground；One is made of two electronic switches It is depressured bridge arm, the negative terminal of the upper end electronic switch is connected to form switching node 1 with the anode of lower end electronic switch, upper end electronics The positive voltage terminal for just terminating to direct-current input power supplying of switch, the negative terminal of lower end electronic switch are connected to ground；One by two electronics The boosting bridge arm of composition is switched, the negative terminal of the upper end electronic switch is connected to form switching node with the anode of lower end electronic switch 2, output end of the anode of upper end electronic switch as driving load, the negative terminal of lower end electronic switch is connected to ground；One inductance, First port is connected to switching node 1, and second port is connected to switching node 2；More than LED branch all the way, each LED branch includes One LED string at least containing a LED, a smoothing capacity, a diode, a control switch and an electric current inspection Survey element, smoothing capacity and LED string is in parallel, diode and LED string be connected in series, the anode after series connection as LED branch just End, the negative terminal after series connection are connected with the anode of control switch, and the negative terminal of control switch is connected by current measuring element and ground, The anode of all LED branches, which is connected in parallel, is connected to the anode of boosting bridge arm upper end electronic switch, the work of each LED string Voltage allows the voltage higher or lower than direct-current input power supplying during the work time；One control unit, it is each comprising controlling The current control loop of LED string and the control controlled the working condition of each LED branch distribute logic, above-mentioned electric current control Circuit processed according to the current control reference of each LED branch and from corresponding current measuring element acquired by feedback signal pair The electric current of each LED branch is controlled, and control distributes logic according to the current control of each in running order LED branch Needs and the operating voltage of corresponding LED string and the relationship of input voltage sequentially coordinate the control switch of each LED branch Operation with above-mentioned buck-boost converter meets the job requirement of each LED branch, when the operating voltage of LED string is lower than input Converter is in decompression transformation mode when voltage, and when the operating voltage of LED string is higher than input voltage, converter is in boosting and becomes Mold changing formula.

2. driving method according to claim 1, it is characterised in that needing the LED for carrying out current control to exchange into needs The other kinds of DC load of current control is carried out to form corresponding load branch.

3. according to claim 1 or driving method as claimed in claim 2, it is characterised in that control distribution logic is buck Each switch operation cycle of converter distributes to each in running order branch in order, the branch distributed according to Operation of the control signal of its corresponding current control loop to buck-boost converter in corresponding switch periods controls, and makes Within the switch operation cycle being assigned to acquired in the magnitude of current just meet required by it maintains in whole work process Average operating current needs, each switch operation cycle terminates when inductive current drops to zero, next switch operation week And then phase opens.

4. according to claim 1 or driving method as claimed in claim 2, it is characterised in that control distribution logic is buck Each switch operation cycle of converter sequentially distributes to each in running order branch, and the branch distributed is according to it Operation of the control signal of corresponding current control loop to buck-boost converter in corresponding switch periods controls, so that The acquired magnitude of current just meets required by it is maintained in whole work process within the switch operation cycle being assigned to The needs of average operating current, each switch operation cycle auxiliary switch when inductive current drops to zero continue to be connected, directly Auxiliary switch turns off when after changing direction to inductive current close to the peak value of negative direction, corresponding to switch the operation cycle and terminate, under And then one switch operation cycle opens.

5. according to claim 1 or driving method as claimed in claim 2, it is characterised in that go up and down buckling in operation Parallel operation controls the current value required for system work, each branch root as current source by the electric current of switch operation handlebar inductance According to needing through the control of its corresponding control loop and control distribution logic successively from above-mentioned current source for itself current control Electric current required for obtaining, so that the magnitude of current acquired within the operation cycle being assigned to just meets it entire worked The needs of required average operating current are maintained in journey.

6. a kind of drive for realizing independent voltage control and working state control to LED multi-path using a step-down/up type converter Dynamic method a, which is characterized in that direct-current input power supplying, negative voltage side is as ground；One is made of two electronic switches It is depressured bridge arm, the negative terminal of the upper end electronic switch is connected to form switching node 1 with the anode of lower end electronic switch, upper end electronics The positive voltage terminal for just terminating to direct-current input power supplying of switch, the negative terminal of lower end electronic switch are connected to ground；One by two electronics The boosting bridge arm of composition is switched, the negative terminal of the upper end electronic switch is connected to form switching node with the anode of lower end electronic switch 2, output end of the anode of upper end electronic switch as driving load, the negative terminal of lower end electronic switch is connected to ground；One inductance, First port is connected to switching node 1, and second port is connected to switching node 2；More than LED branch all the way, each LED branch includes One LED string at least containing a LED, a smoothing capacity, a diode, a control switch and a voltage inspection Survey unit；Smoothing capacity and LED string are in parallel, negative terminal and ground connection after parallel connection；Diode and control switch are connected in series, series connection Negative terminal afterwards is connected with the LED anode gone here and there, and positive input terminal of the anode after series connection as LED branch is connected to lifting buckling The output end of parallel operation, namely boosting bridge arm upper end electronic switch anode；Voltage detection unit is connected to the both ends inspection of LED string Survey the voltage of LED string；The operating voltage of each LED string allows the electricity higher or lower than direct-current input power supplying during the work time Pressure；One control unit, comprising controlling the voltage control loop of each LED string and being carried out to the working condition of each LED branch The control of control distributes logic, and above-mentioned voltage control loop according to the voltage of each LED branch controls reference value and from corresponding Feedback signal acquired by voltage detection unit controls the voltage of each LED branch, and control distribution logic is according to each The pass of the operating voltage and input voltage of the voltage-controlled needs of in running order LED branch and corresponding LED string The control switch of each LED branch and operating to meet the work of each LED branch for above-mentioned buck-boost converter are sequentially coordinated by system It is required, when the operating voltage of LED string is lower than input voltage, converter is in decompression transformation mode, when the work electricity of LED string Converter is in boosting inverter mode when pressure is higher than input voltage.

7. driving method according to claim 6, it is characterised in that exchange into needs needing to carry out voltage-controlled LED Voltage-controlled other kinds of DC load is carried out to form corresponding load branch.