CN101394699B

CN101394699B - LED driver

Info

Publication number: CN101394699B
Application number: CN2007101530185A
Authority: CN
Inventors: 朱益杉; 赵兴国
Original assignee: Leadtrend Technology Corp
Current assignee: Leadtrend Technology Corp
Priority date: 2007-09-18
Filing date: 2007-09-18
Publication date: 2012-07-11
Anticipated expiration: 2027-09-18
Also published as: CN101394699A

Abstract

The invention discloses a light emitting diode driving device, comprising: the power factor correction circuit, the bridge type switch circuit, the resonance circuit, the transformer and the feedback circuit. The power factor correction circuit adjusts the output signal according to a feedback signal. The bridge type switching circuit switches the output signal of the power factor correction circuit into a pulse signal. The resonant circuit outputs a sine wave signal to the primary side of the transformer according to the pulse wave signal. The feedback circuit can output a feedback signal to a feedback end of the power factor correction circuit corresponding to the primary side current of the transformer. Therefore, the output current can be adjusted by adjusting the feedback circuit.

Description

Light emitting diode drive device

Technical field

The present invention relates to a kind of light emitting diode drive device, relate in particular to a kind of light emitting diode drive device, be applicable to high power output, to drive at least one light-emitting diode (LED) module.

Background technology

Light-emitting diode (LED) is by the made light-emitting component of semi-conducting material; Be different from traditional lighting; It belongs to chemiluminescence, and multiple advantages such as have high brightness, high-luminous-efficiency, drive circuit is simple, power consumption is low, reaction speed is fast replaces traditional lighting at present gradually.

In the design of LED driving circuit, generally take first and second side isolation design for the security consideration meeting.With reference to Fig. 1, input voltage vin produces primary side voltage V1 after via bridge rectifier 110 rectifications.In this,

that primary side voltage V1 is about input voltage vin doubly; For instance; When input voltage vin is about the alternating voltage of 110V (volt), after bridge rectifier 110 rectifications, the primary side voltage V1 of generation is about the direct voltage of 156V; PWM (PWM) controller 120 is through the switching of output pulse width modulating signal Vg power controlling switch Q1; Cause the primary side voltage V1 of transformer 130 to be converted to the secondary side of transformer 130, and produce output voltage V o, to light the LED that is serially connected with on the output.(Flyback Topology) is example with the flyback framework, and when power switch Q1 conducting (on), energy storage is in the magnetizing inductance LP of transformer 130 primary sides, not conducting of secondary side this moment; And when power switch Q1 ended (off), the interior energy of magnetizing inductance LP that is stored in transformer 130 primary sides was released into secondary side, and then produced output voltage V o.In this, output voltage V o is direct current (DC) voltage.

The current signal I of LED flows through _LED, can pass through linear voltage regulator TL and optical coupler (photo coupler) 140, the voltage quasi position of the compensation pin COMP of decision PWM controller 120.PWM controller 120 is adjusted PWM signal Vg according to the voltage quasi position of compensation pin COMP, promptly adjusts responsibility cycle (duty cycle) size of power switch Q1.In other words, will be according to accurate position voltage (Vref) and the resistance (R of linear voltage regulator TL _LED) stabling current signal I _LED, i.e. I _LED=Vref/R _LEDTherefore, when the LED on the output more many time, power output is big more, and then the responsibility cycle of the PWM signal Vg of power controlling switch Q1 can be big more; Vice versa.

When being applied to high power output (promptly; Output connects very a plurality of LEDs) time; In order to satisfy the current harmonics standard, generally can add power factor correction circuit (power factorcorrection (PEC) circuit) 150 in prime, as shown in Figure 2.

Please, after the input voltage vin of interchange is adjusted via bridge rectifier 110 rectifications and power factor correction circuit 150, produce the primary side voltage V2 of direct current with reference to Fig. 2.For instance, if input voltage vin is about 110V (interchange), the primary side voltage V2 of generation is about 200V (direct current); And if input voltage vin is about 220V (interchange), the primary side voltage V2 of generation then is about 400V (direct current).

Have two groups of feedback paths in power factor correction circuit 150 inside.One is electric current feedback path 152, with so that the waveform of input current Iin can follow input voltage vin waveform and with the input voltage vin same-phase, to improve power factor (PF) and then to satisfy the current harmonics standard.Another is a voltage feedback path 154, feedbacks adjustment input current Iin size through primary side voltage V2, and then holds primary side voltage V2.

Yet the design of these a little drive circuits must use linear voltage regulator and optical coupler to do the isolation of first and second side.In addition, when high power was exported the application of (generally greater than 150W), the palpus collocation was suitable for large-sized transformer, thereby caused cost to increase, and took up space, and the incident heat dissipation problem of difficult solution.In addition, be to cooperate the application of high power output, whole drive circuit must use two independently control IC (integrated circuit), i.e. pfc controller and PWM controller, and not only line design is comparatively complicated, and cost is costliness comparatively also.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of light emitting diode drive device, so as to solving the complicated and expensive problem of the existing line design of prior art.

For realizing above-mentioned purpose, the light emitting diode drive device that the present invention disclosed comprises: power factor correction (PFC) circuit, bridge switching circuit, resonant circuit, transformer and feedback circuit.Power factor correction circuit can be according to its output signal of feedback signal adjustment.Bridge switching circuit connects the output of power factor correction circuit, and it can switch to a pulse wave signal with the output signal of power factor correction circuit.Resonant circuit connects the output of bridge switching circuit, and it can vibrate to export a string ripple signal according to pulse wave signal.First end of transformer primary side connects resonant circuit, to receive string ripple signal.Feedback circuit is connected to second end of transformer primary side, the primary side current of its corresponding transformer and the back coupling end of reset signal to power factor correction circuit.

Bridge switching circuit can be half bridge switching circuit, and it comprises the switch element of pair of series.This is connected between the output and ground connection of power factor correction circuit switch element, and the series connection contact between two switch elements is connected to resonant circuit.

In this, the drive control signal of two switch elements of semibridge system switching circuit can be the pulse wave signal of a pair of complementation, inputs to the control end of two switch elements of semibridge system switching circuit respectively.Wherein, this can have 50% responsibility cycle to complementary control signal.

Resonant circuit can comprise the resonant slots that electric capacity-inductance is formed.

Feedback circuit can comprise resistance and rectifier cell.The resistance of feedback circuit is connected between second end and ground connection of transformer primary side.Wherein, the primary side current of transformer is flowed through resistance and is formed an interchange cross-pressure on resistance, and feedback circuit carries out rectification to produce feedback signal with this interchange cross-pressure.

Feedback circuit more can comprise filter element, so that feedback signal is carried out filtering, and filtered feedback signal is offered power factor correction circuit.

The secondary side of transformer also couples at least one light-emitting diode (LED) module, and the resistance of the resistance in the feedback circuit is corresponding to the brightness of light-emitting diode (LED) module.

In light emitting diode drive device according to this case; Utilize the primary side current of transformer to feedback control; Therefore; Need not come the primary side and the secondary side of isolating transformer through linear voltage regulator and optical coupler, the danger of getting an electric shock take place when avoiding changing output light emitting diode, and can reduce cost.In addition, in light emitting diode drive device, through the resistance of adjustment feedback circuit according to this case; For example: the resistance value of adjustment resistance R cs; Adjust output current (that is, the secondary side current of transformer), and then the luminosity of control light-emitting diode (LED) module; Compared to prior art, control mode is comparatively simple.In addition, according to the light emitting diode drive device of this case be applicable to high power output (for example:＞200W).And, in light emitting diode drive device, only using single controller (that is, power factor correction circuit) with feedback function according to this case, its control circuit is comparatively simple and overall price is comparatively cheap.

Description of drawings

Fig. 1 is the sketch map of the light emitting diode drive device of prior art;

Fig. 2 is the sketch map of the light emitting diode drive device of another prior art;

Fig. 3 is the sketch map of light emitting diode drive device according to an embodiment of the invention;

Fig. 4 is the oscillogram of each signal among Fig. 3; And

Fig. 5 is the sketch map of light emitting diode drive device according to another embodiment of the present invention.

Wherein, Reference numeral:

110: bridge rectifier 120: PWM (PWM) controller

130: transformer 140: optical coupler

150: power factor correction circuit 152: the electric current feedback path

154: voltage feedback path 210: bridge rectifier

220: bridge switching circuit 230: transformer

240: resonant circuit 250: power factor correction circuit

252: electric current feedback path 254: the voltage feedback path

260: feedback circuit 280: signal generator

290: 292: the first light-emitting diode (LED) modules of light-emitting diode (LED) module

294: the second light-emitting diode (LED) module V1: primary side voltage

Vin: input voltage Q1: power switch

Vg: PWM signal Vo: output voltage

LP: transformer primary side magnetizing inductance NP: the transformer primary side number of turn

NS: Circuit Fault on Secondary Transformer number of turn I _LED: current signal

TL: linear voltage regulator COMP: compensation pin

Vref: accurate position voltage R _LEDResistance

V2: primary side voltage Iin: input current

CS: the output signal of feedback signal V3:PFC circuit

Sa: pulse wave signal Sb: string ripple signal

Ipri: primary side current Isec: secondary side current

Q2: switch element Q3: switch element

Sc: control signal Sc ': control signal

Cr: electric capacity Lr: inductance

Rcs: resistance Dcs: rectifier cell

Ccs: filter element Vcs: the magnitude of voltage of feedback signal

Embodiment

Please, show light emitting diode drive device according to an embodiment of the invention with reference to Fig. 3.Light emitting diode drive device comprises: bridge switching circuit 220, transformer 230, resonant circuit 240, power factor correction (PFC) circuit 250 and feedback circuit 260 according to an embodiment of the invention.

Power factor correction circuit 250 is coupled between bridge rectifier 210 and the bridge switching circuit 220.Resonant circuit 240 is coupled between first end of bridge switching circuit 220 and transformer 230 primary sides.Feedback circuit 260 is coupled to second end of transformer 230 primary sides and the voltage of power factor correction circuit 250 is feedback between the end.

Input voltage vin inputs to power factor correction circuit 250 after bridge rectifier 210 rectifications.Power factor correction circuit 250 has two groups of feedback paths.Electric current feedback path 252 is connected to bridge switching circuit 220 so that the waveform of input current Iin can follow input voltage vin waveform and with the input voltage vin same-phase.Voltage feedback path 254 receives the feedback signal CS from feedback circuit 260, and according to the size of feedback signal CS adjustment input current Iin, adjusts the output signal V3 of power factor correction circuit 250 according to this.In other words, power factor correction circuit 250 can be according to its output signal of feedback signal CS adjustment V3.

Bridge switching circuit 220 can switch to pulse wave signal Sa with the output signal V3 of power factor correction circuit 250.Pulse wave signal Sa via resonant circuit 240 vibration after, produce a string ripple signal Sb in the primary side of transformer 230, and the primary side current Ipri of transformer 230 also is a string ripple signal.In other words, resonant circuit 240 can vibrate to export a string ripple signal Sb according to pulse wave signal Sa.260 primary side current Ipri of feedback circuit, and reset signal CS corresponding to transformer 230.

Wherein, bridge switching circuit 220 can be full-bridge type switching circuit or semibridge system switching circuit.With the semibridge system switching circuit is example, and bridge switching circuit 220 comprises switch element Q2, the Q3 of pair of series.In this, switch element Q2, Q3 are serially connected with between the output and ground connection of power factor correction circuit 250, and the series connection contact between the two switch element Q2, Q3 is connected to the input of resonant circuit 240.

In this, can control the running of two switch element Q2, Q3 through pair of control signal Sc, Sc '.This is to control signal Sc, the preferable pulse wave signal that can be a pair of complementation of Sc '.This is inputed to the control end of switch element Q2, Q3 respectively to complementary control signal Sc, Sc '; Cause two switch element Q2, Q3 according to this to complementary control signal Sc, Sc ' interleaved switching, switch to pulse wave signal Sa with output signal V3 with power factor correction circuit 250.In this, can adopt responsibility cycle is 50% complementary control signal Sc, Sc '.

In addition, a signal generator 280 can be set in light emitting diode drive device, drive bridge switching circuit 220 to produce control signal.

Resonant circuit 240 can comprise capacitor C r and inductance L r.The end of capacitor C r is connected to bridge switching circuit 220, and the other end then is connected to inductance L r.The end of the relative capacitor C r of inductance L r then is connected to first end of transformer 230 primary sides.In other words, resonant circuit 240 can comprise the resonant slots that electric capacity-inductance is formed.

In an embodiment, capacitor C r is connected between the serial connection contact and inductance L r between two switch element Q2, the Q3, to receive the pulse wave signal Sa that produces via the switching of switch element Q2, Q3.

Feedback circuit 260 can comprise resistance R cs and rectifier cell Dcs.Resistance R cs is coupled between second end and ground connection of transformer 230 primary sides.Rectifier cell Dcs is coupled between the end and power factor correction circuit 250 of the relative ground connection of resistance R cs.

The primary side current Ipri of the transformer 230 resistance R cs that flows through can form one and exchange cross-pressure on resistance R cs, and after the rectification of interchange cross-pressure via rectifier cell Dcs of this resistance R cs, produce feedback signal CS.

In this, feedback circuit 260 also can comprise a filter element Ccs, so after the filtering of the interchange cross-pressure of resistance R cs via rectifier cell Dcs rectification and filter element Ccs, produces feedback signal CS and give power factor correction circuit 250.

In this, transformer 230 can be forward type also or flyback.In addition, in the circuit of the both sides of transformer 230, can adopt different ground connection.

In the output of light emitting diode drive device, i.e. the secondary side of transformer 230 can couple at least one by light-emitting diode (LED) module 290 that one or more LED constituted.And, can promptly adjust the resistance of resistance R cs, the brightness of the light-emitting diode (LED) module 290 of control through adjustment feedback circuit 260.In other words, the resistance of resistance R cs is corresponding to the brightness of light-emitting diode (LED) module 290.

In this, if the resistance of adjustment resistance R cs, correspondingly, the magnitude of voltage Vcs of feedback signal CS can change along with the resistance of resistance R cs.And power factor correction circuit 250 is adjusted its output signal V3 according to feedback signal CS; Therefore the change that its output signal V3 then can corresponding feedback signal CS and being changed; And then influenced the voltage peak of pulse wave signal Sa, and change the voltage peak of string ripple signal Sb.According to the characteristic of transformer 230, the secondary side current Isec of transformer 230 is multiplied by the turn ratio (NP/NS) of the primary side and the secondary side of transformer 230 for primary side current Ipri.Therefore, be equivalent to change the secondary side current Isec of transformer 230 in the primary side current Ipri equivalence of change transformer 230.For instance; If increase the resistance of resistance R cs; The magnitude of voltage Vcs of feedback signal CS can rise thereupon; Cause the magnitude of voltage of the output signal V3 of power factor correction circuit 250 to descend, and then cause the primary side current Ipri of transformer 230 to descend, then can descend thereupon corresponding to the secondary side current Isec of primary side current Ipri.And because of the primary side current Ipri of transformer 230 descends, the magnitude of voltage Vcs of feedback signal CS then can descend thereupon, and the magnitude of voltage Vcs of last feedback signal CS can be stable at certain value.In this, resistance R cs can adopt variable resistor, so that carry out the adjustment of luminosity.

In other words, can regulate and control the luminosity of light-emitting diode (LED) module 290 through the resistance R cs resistance that changes feedback circuit 260.

In addition, because the resonance frequency of resonant circuit 240 is the above frequencies of kHz, therefore concerning human eye, can't experience the phenomenon that light-emitting diode (LED) module 290 has flicker.

With the flyback framework is example, the current signal I of pulse wave signal Sa, feedback signal CS, the light-emitting diode (LED) module of flowing through _LED, and the signal waveform of the primary side current Ipri of transformer 230 and secondary side current Isec as shown in Figure 4, when Fig. 4 is shown in according to the light-emitting diode assembly drive unit running of this case, the relation between each signal.Visible by Fig. 4; Corresponding to pulse wave signal; Primary side in transformer 230 forms primary side current Ipri; Because should be on the flyback framework, form and the reverse secondary side current Isec of primary side current Ipri in the primary side of transformer 230, and then produce current signal I corresponding to secondary side current Isec _LED, the light-emitting diode (LED) module 290 of flowing through is with driven for emitting lights diode (led) module 290.And fixing it is stable that feedback signal CS keeps down in resistance R cs resistance, and with the stable output of output signal V3 that causes power factor correction circuit 250, and then bridge switching circuit 220 is able to the pulse wave signal Sa that provides voltage peak stable according to this.

In another embodiment, with reference to Fig. 5, in the output of light emitting diode drive device, promptly the secondary side of transformer 230 can couple at least one first light-emitting diode (LED) module 292 and at least one second light-emitting diode (LED) module 294.And, first light-emitting diode (LED) module 292 and second light-emitting diode (LED) module, 294 reverse parallel connections, that is, first light-emitting diode (LED) module 292 and second light-emitting diode (LED) module 294 oppositely are coupled to the two ends of the secondary side of transformer 230.In this, transformer 230 is understood according to primary side current Ipri, and in its secondary side one output voltage V o is provided, to drive first light-emitting diode (LED) module 292 and second light-emitting diode (LED) module 294.This output voltage V o is an interchange string ripple, and can drive first light-emitting diode (LED) module 292 in the positive half cycle of output voltage V o, and negative half period then can drive second light-emitting diode (LED) module 294.In other words, transformer 230 can be according to primary side current Ipri driven first light-emitting diode (LED) module 292 and second light-emitting diode (LED) module 294.And the resistance of resistance R cs is corresponding to the brightness of two light-emitting diode (LED) modules (292,294).

In light emitting diode drive device according to this case; Feedback control owing to utilize the primary side current of transformer; Two ends first and second side of transformer is to isolate mutually; Therefore can save the cost and the overall space volume of linear voltage regulator and optical coupler element, the danger of getting an electric shock takes place in the time of also can avoiding changing light-emitting diode.In addition; In light emitting diode drive device, only need adjust the resistance of feedback circuit, for example: the resistance value of adjustment resistance R cs according to this case; Can adjust the secondary side current of transformer; And then the luminosity of control light-emitting diode (LED) module, compared to existent technique, control mode is comparatively simple.In addition, according to the light emitting diode drive device of this case be applicable to high power output (for example:＞200W).And, in light emitting diode drive device, only using single controller (that is, power factor correction circuit) with feedback function according to this case, its control circuit is comparatively simple and overall price is comparatively cheap.

Certainly; The present invention also can have other various embodiments; Under the situation that does not deviate from spirit of the present invention and essence thereof; Being familiar with those of ordinary skill in the art ought can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims

1. A light-emitting diode driving device, characterized in that, comprising:

a power factor correction circuit for adjusting an output signal according to a feedback signal;

a bridge switch circuit connected to the power factor correction circuit to switch the output signal of the power factor correction circuit into a pulse signal;

a resonant circuit, connected to the bridge switch circuit (220), for outputting a sine wave signal according to the pulse wave signal;

A transformer, the first end of the primary side of the transformer is connected to the resonant circuit to receive the sinusoidal signal; and

A feedback circuit is connected to the second end of the primary side of the transformer to output the feedback signal corresponding to the primary side current of the transformer.

2. The light-emitting diode driving device according to claim 1, wherein the bridge switch circuit is a half-bridge switch circuit, comprising a pair of switching elements connected in series, and the pair of switching elements are connected to the power factor correction circuit. between the output terminal and a ground, and the series junction of the pair of switching elements is connected to the resonant circuit.

3. The LED driving device according to claim 2, wherein the pair of switching elements are driven by a pair of complementary control signals.

4. The light emitting diode driving device according to claim 2, further comprising: a signal generator connected to the control terminals of the pair of switching elements to control switching of the pair of switching elements.

5. The LED driving device according to claim 4, wherein the signal generator generates a pair of complementary control signals to control the pair of switching elements.

6. The LED driving device according to claim 5, wherein the pair of complementary control signals has a duty cycle of 50%.

7. The LED driving device according to claim 1, further comprising: a signal generator connected to the bridge switch circuit to drive the bridge switch circuit.

8. The LED driving device according to claim 1, wherein the resonant circuit comprises:

a capacitor, one end of which is connected to the bridge switch circuit to receive the pulse signal; and

An inductor is connected between the other end of the capacitor and the first end of the primary side of the transformer to output the sine wave signal.

9. The LED driving device according to claim 1, wherein the feedback circuit comprises:

a resistor, the resistor is connected between the second end of the primary side of the transformer and a ground, the primary side current flows through the resistor to form an AC voltage across the resistor; and

A rectification element is used to rectify the AC cross voltage of the resistor to generate the feedback signal.

10 . The light emitting diode driving device according to claim 9 , wherein the feedback circuit further comprises a filter element for filtering the feedback signal and providing the filtered signal to the power factor correction circuit. 11 .

11. The LED driving device according to claim 9, wherein the secondary side of the transformer is further coupled to a first LED module, and the resistance value of the resistor corresponds to the brightness of the first LED module .

12. The light emitting diode driving device according to claim 11, wherein the secondary side of the transformer is further coupled to a second light emitting diode module, and the second light emitting diode module is connected in reverse parallel to the first light emitting diode module, And the resistance value of the resistor corresponds to the brightness of the second LED module.

13. The LED driving device according to claim 1, wherein the secondary side of the transformer is further coupled to a first LED module, and the transformer drives the first LED module according to the primary side current.

14. The light emitting diode driving device according to claim 13, wherein the secondary side of the transformer is further coupled to a second light emitting diode module, and the second light emitting diode module is connected in reverse parallel to the first light emitting diode module, And the transformer alternately drives the first LED module and the second LED module according to the primary side current.