TWM449335U - High effective dual output dimming circuit for LED - Google Patents

Description

LED high efficiency dual output dimming circuit

This creation is about an LED driver circuit, especially an LED high efficiency dual output dimming circuit with a dual bus-to-bus (Twin-Bus) circuit.

Light-emitting diodes (LEDs) are currently common lighting components. Compared with traditional incandescent bulbs, LED bulbs have the advantages of high luminous efficiency and energy saving. However, since the LED itself can only be unidirectionally connected, it cannot be directly electrically connected to the AC outlet of the wall, and for this reason, the LED driving circuit is thus developed. The basic LED driving circuit is divided into a linear driving circuit and a switching driving circuit, wherein the switching driving circuit usually has a power factor correction circuit.

Please refer to the first figure, which is a schematic diagram of a conventional switched LED driving circuit. As shown in the first figure, the conventional switching LED driving circuit 1' includes: a rectifying unit 11' and a power factor correcting unit 12 ', a DC/DC conversion unit 13', an output unit 14', a PFC control unit 15', and a converter control unit 16'. Wherein, the power factor correction unit 12' of the first stage is usually a boost type power converter or a buck converter; a second stage DC/ The DC conversion unit 13' is used to adjust the magnitude of the output voltage.

The aforementioned switching type LED driving circuit 1' has a high effect on power correction, and can quickly adjust the output voltage and make the input current not high. Subharmonic; however, as shown in the first figure, the power factor correction unit 12' of the first stage and the DC/DC conversion unit 13' of the second stage are respectively composed of the PFC control unit 15' and the converter Controlled by the control unit 16', the two sets of independent control units cause the complexity of the overall circuit of the switched LED driving circuit 1', and the overall area of the circuit cannot be effectively reduced. In addition, the power loss of the two-stage circuit is also caused. Power conversion efficiency is low. Therefore, through the above, we can know that the conventional switched LED driving circuit still has many shortcomings and disadvantages. In view of this, the creators of this case tried their best to study and create a high-efficiency dual-output dimming circuit for LEDs.

The main purpose of this creation is to provide a high-efficiency dual-output dimming circuit for LEDs, which mainly adopts a single-stage reverse-chirping power factor corrector, and thereby achieves the purpose of reducing the circuit components of the LED lamp control circuit, and at the same time Improve power conversion efficiency; in addition, Twin-Bus dimming architecture, this Twin-Bus dimming architecture not only reduces the withstand voltage of the switching (power) switch of the downstream DC/DC converter, but also performs LED lighting High-frequency dimming operation and low-frequency dimming operation; since the withstand voltage of the switching (power) switch of the rear-stage DC/DC converter has been reduced, it is possible to select a switch with a small withstand voltage and a smaller R _ds (on) Component; in this way, not only can the switching speed be increased, but also the power loss during switching can be reduced.

Therefore, in order to achieve the main purpose of this creation, the creator of this case is A high-efficiency dual-output dimming circuit for an LED is provided, comprising: a single-stage reverse-chieving power factor corrector coupled to an AC input voltage and capable of outputting a first LED voltage and a second LED voltage A Twin-Bus output is achieved; wherein the first LED voltage is slightly greater than the second LED voltage; the DC/DC converter is coupled to the single-stage flyback power factor corrector to receive The first LED voltage and the second LED voltage; an LED module coupled to the DC/DC converter and the single-stage reverse power factor corrector; and a dimmer switch coupled to the The LED module and the single-stage reverse power factor corrector are configured to receive the first LED voltage, thereby performing a high frequency dimming operation and a low frequency dimming operation on the LED module.

In order to more clearly describe the high-efficiency dual-output dimming circuit of the LED proposed by the present invention, the embodiment of the present invention will be described in detail below with reference to the drawings.

Before describing the high-efficiency dual-output dimming circuit of the LED proposed by this creation, a single-stage flyback DC converter with a power factor corrector will be introduced. Please refer to the second figure, which is a circuit block diagram of a single-stage flyback DC converter with a power factor corrector. As shown in the second figure, the single-stage flyback DC converter with a power factor corrector includes: a bridge rectifier unit 11", a plurality of voltage dividing resistors R _vd ", a multiplier 12", and a comparator. 13", a trigger circuit 14", a zero current detection circuit 15", a switch S _P ", a switch resistor RS", a transformer T", an output diode D _O ", an output capacitor C _O ", a load resistor R _L ", and an error amplifier 16". wherein the transformer T" has a leakage inductance L _leak " and a magnetizing inductance L _m ", and the turns ratio of the coil is N ₁ : N ₂ :N ₃ .

As shown in the second figure, the input AC voltage V _ac passes through the bridge rectifier unit 11 ′′ to generate a full-wave rectified AC voltage V _in (V _in is the voltage indication symbol required by the circuit, not belonging to the component symbol), and then passes through The voltage resistor R _vd " obtains the input sinusoidal voltage signal V _m synchronized with the input (V _m is the voltage indication symbol required by the circuit, not belonging to the component symbol); on the other hand, the output voltage V _{O is} via the voltage dividing resistor R _vd " Obtaining the output reference voltage V ₊ (V _O and V ₊ are the voltage indication symbols required by the circuit, not belonging to the component symbol), and the output reference voltage V _{+ is} compared with the error amplifier 16 ′ to generate a reference signal V _r (V _r is The voltage sign required by the circuit is not a component symbol; further, the reference signal V _r and the input sine wave voltage signal V _m are multiplied by the multiplier 12" to generate a sine wave control voltage V _c , and the input current It is converted into a current detection signal V _s via the switch resistor R _S ” (V _c and V _s are voltage indication symbols required by the circuit, and are not part of the component symbol).

This creation is based on the above-mentioned single-stage flyback DC converter with power factor corrector, and the Twin-Bus circuit design with PWM dimming control is added. Please refer to the third figure, which is the architecture diagram of a high efficiency dual output dimming circuit of LED. As shown in the third figure, the LED high efficiency dual output dimming circuit of the present invention mainly includes: a single stage Flyback power factor The corrector 10, the DC/DC converter 11, and an LED module 12.

Please continue to refer to the third figure, and please refer to the fourth figure, which is the circuit diagram of the LED high efficiency dual output dimming circuit. As shown in the third and fourth figures, the single-stage reverse power factor corrector 10 is a power control IC numbered L6561, which is coupled to an input AC voltage V _ac and can output a first LED voltage. V _LED1 and a second LED voltage V _LED2 to achieve a Twin-Bus output; wherein the first LED voltage V _LED1 is slightly larger than the second LED voltage V _LED2 . Moreover, the DC/DC converter 11 is coupled to the single-stage flyback power factor corrector 10 to receive the first LED voltage V _LED1 and the second LED voltage V _LED2 . The LED module 12 is coupled to the DC/DC converter 11 and the single-stage reverse power factor corrector 10. Here, the LED module 12 is composed of a plurality of LED components, and is mainly subjected to The LED voltage V _LED1 is driven to emit light. In order to control the LED 12 of the light emitting module, as shown in FIG. Fourth, a dimmer switch Q _d based LED module 12 is coupled to the single stage flyback power factor correction between 10 to receive a first LED voltage V _LED1 ; Here, the dimming switch Q _d is a metal oxide half field effect transistor (MOSFET) for performing a high frequency dimming operation and a low frequency dimming operation on the LED module 12.

In the high efficiency dual output dimming circuit of the LED of the present invention, the DC/DC converter 11 is composed of an inductor L, a switch Q ₁ , a switching resistor R _S1 , and a first diode D ₁ ; L system coupled to the LED module 12; switch Q ₁ is coupled to the inductor L, and which is a metal-oxide-semiconductor field-effect transistor (mOSFET), based as a DC / DC converter 11 of the power switch. The switching resistor R _S1 is coupled to the switching switch Q ₁ ; the first diode D ₁ is coupled between the LED module 12 and the switching resistor R _S1 , and the first diode D1 is Conducted during the high frequency dimming operation. In particular, since the switching voltage of the first LED voltage V _LED1 is tolerated when the switch Q _{1 is} turned off, a second LED voltage V _LED2 slightly smaller than the first LED voltage V _LED1 is added to the circuit of the present invention. Thereby reducing the withstand voltage of the switch Q ₁ ; furthermore, a second diode D ₂ is disposed between the dimming switch Q _d and the inductor L, and the second diode D ₂ is configured to perform the low frequency Turns on during dimming operation.

Thus, the above system has completely explained the circuit architecture of the high-efficiency dual-output dimming circuit of the LED of the present invention and all its circuit components; and then, the four main functions of the high-efficiency dual-output dimming circuit of the LED of the present invention will be further explained. Circuit action mode. Please refer to the fifth figure, which is the theoretical waveform diagram of the LED high efficiency dual output dimming circuit. As shown in the fifth figure, the four main circuit operation modes are respectively applied to the following four time intervals: t ₁ <t< t ₂ , t ₂ <t<t ₃ , t ₄ <t<t ₅ , and t ₅ <t<t ₆ .

Please refer to the sixth to ninth diagrams, which are circuit diagrams of mode 1, mode 2, mode 3, and mode 4. As shown in the sixth figure, when the time interval t ₁ <t<t ₂ , the high-efficiency dual-output dimming circuit of the LED of the present invention acts on the circuit operation of the mode 1; the condition of the mode is the low-frequency dimmer switch Q _d and the high frequency DC / DC converter 11 to switch the switch Q ₁ is turned on at the same time, this time, current flowing through the dimmer switch Q _d LED module 12 and the energy storage inductance L. Continuing, as shown in the seventh figure, when the time interval t ₂ <t<t ₃ , the high-efficiency dual-output dimming circuit of the LED of the present invention acts on the circuit operation of the mode 2; the condition of the mode is low frequency. The dimming switch Q _{d is} turned on and the switching switch Q _{1 of the} high frequency DC/DC converter 11 is turned off. At this time, the inductor L is released to the LED module 12 via the second diode D ₂ and the dimming switch Q _{d .} can.

Moreover, as shown in the eighth figure, when the time interval t ₄ <t<t ₅ , the high-efficiency dual-output dimming circuit of the LED of the present invention acts on the circuit operation of the mode three; the condition of the mode is the low frequency adjustment. Q _d and the optical switch is turned off frequency of the DC / DC converter 11 to switch the switch Q ₁ turns on, then, the inductance L system switch Q ₁ via a first diode D1 and the LED module 12 can be released. Finally, as shown in the ninth figure, in the time interval t ₅ <t<t ₆ , the high-efficiency dual-output dimming circuit of the LED of the present invention acts on the circuit operation of the mode four; the condition of this mode is the low frequency adjustment. switching of the optical switch Q _d and the high frequency DC / DC converter 11 while the switch Q ₁ is turned off, the inductance L based second diode D ₂ and the first diode D ₁ of the LED module 12 via the discharging.

The four main circuit operation modes of the high-efficiency dual-output dimming circuit of the LED of the present invention have been clearly described above through the sixth to the ninth diagrams; then, the following will be proved by the presentation of experimental data. The feasibility and performance of the high efficiency dual output dimming circuit of the created LED. Please refer to the tenth figure, which is the waveform diagram of the input voltage and the input current; wherein the input voltage V _in the figure (a) and (b) of the tenth figure are 110V and 220V, respectively, and, obviously, from the figure It can be observed that the input voltage V _{in is} approximately in phase with the input current Iin for power factor correction purposes (in particular, V _in and I _{in are} not component symbols, but are required for the circuit).

Continuously, please refer to FIG eleventh, based switch control signal Q ₁ of the waveform diagram. Among them, the figure (a) and the figure (b) of the eleventh figure are the V _gs control signal and the V _ds control signal of the switch Q ₁ of the input voltage V _in 110V, respectively. It can be observed from the figure that the peak value of the V _ds control signal of the switch Q ₁ is about 590 V; in addition, the current signal I _{Do of the} first diode D ₁ has dropped before the V _gs control signal of the switch Q ₁ is turned on. To zero, the phenomenon that the first diode D ₁ has zero current switching (ZCS) is displayed. Another, see FIG twelfth, based switch control signal Q of FIG. ₁ and a waveform of the LED current signal I _LED (specifically stated, I _Do not I _LED elements and symbols, and the desired circuit lines marked symbols). It can be observed from the figure that the withstand voltage of the switch Q ₁ is only 4~5 V, which is the biggest purpose of the Twin-Bus architecture. The pressure resistance of the switch Q ₁ is reduced due to the switch. Therefore, it is possible to select a switching element having a small withstand voltage and a smaller R _ds (on); thus, not only the switching speed can be increased, but also the power loss at the time of switching can be reduced.

Please refer to the thirteenth figure, which is the waveform of the control signal of the dimmer switch Q _d and the LED current signal I _LED . Among them, the graphs (a), (b), (c), and (d) of the thirteenth graph are signal waveforms when the dimming is 100%, 75%, 50%, and 25%, respectively. Thus, the switch from the Q signal waveform diagram shown in FIG twelfth eleventh switch of _{FIG. 1} and FIG thirteenth signal waveforms of the dimmer switch Q _D, an LED-based high this may prove Creation The feasibility and efficiency of an efficiency dual output dimming circuit.

Thus, the above description has completely and clearly disclosed all embodiments of the high efficiency dual output dimming circuit of the LED of the present invention; and, through the above, it can be seen that the present authoring system has the following advantages:

1. This creation uses a single-stage reverse-chirping power factor corrector, and in this way achieves the purpose of reducing the circuit components of the LED lamp control circuit, and at the same time can improve the power conversion efficiency.

2. In addition, this creation is also added to the Twin-Bus dimming architecture. This Twin-Bus dimming architecture not only reduces the withstand voltage of the switching (power) switch of the DC/DC converter of the latter stage, but also performs the high-frequency adjustment of the LED lamp. Light work and low frequency dimming.

3. In accordance with point 2 above, further, since the withstand voltage of the switching (power) switch of the rear-stage DC/DC converter has been reduced, it is possible to select a switching element having a small withstand voltage and a smaller R _ds (on). In this way, not only can the switching speed be increased, but also the power loss during switching can be reduced.

The detailed description of the present invention is intended to be limited to the specific scope of the present invention, and is not intended to limit the scope of the present invention. Changes should be included in the scope of the patent in this case.

1'‧‧‧Switching LED Driver Circuit

11'‧‧‧Rectifier unit

12’‧‧‧Power Factor Correction Unit

13’‧‧‧DC/DC conversion unit

14’‧‧‧Output unit

15’‧‧‧PFC Control Unit

16’‧‧‧Converter Control Unit

11"‧‧‧Bridge rectifier unit

R _vd ”‧‧‧voltage resistor

12"‧‧‧ Multiplier

13"‧‧‧ Comparator

14”‧‧‧Trigger circuit

S _P ‧‧‧Toggle switch

15”‧‧‧ Zero current detection circuit

R _S ‧‧‧Switching switch resistance

T”‧‧‧Transformer

D _O ”‧‧‧ Output diode

C _O ”‧‧‧ Output Capacitor

R _L ”‧‧‧ load resistor

16”‧‧‧Error amplifier

L _leak ‧‧‧ leakage inductance

L _m ”‧‧‧Magnetic inductance

V _ac ‧‧‧Input AC voltage

10‧‧‧Single-stage reverse power factor corrector

11‧‧‧DC/DC Converter

12‧‧‧LED module

V _LED1 ‧‧‧First LED voltage

V _LED2 ‧‧‧second LED voltage

Q _d ‧‧‧ dimming switch

L‧‧‧Inductance

Q ₁ ‧‧‧Toggle switch

R _S1 ‧‧‧Switching resistor

D ₁ ‧‧‧First Diode

D ₂ ‧‧‧Secondary

The first figure is an architectural diagram of a switched LED driver circuit; the second figure is a circuit block diagram of a single-stage flyback DC converter with a power factor corrector; The architecture diagram of the high efficiency dual output dimming circuit of LED; the fourth figure is the circuit diagram of the high efficiency dual output dimming circuit of LED; the fifth figure is the theoretical waveform diagram of the high efficiency dual output dimming circuit of LED; Schematic diagram of circuit operation of mode one; seventh diagram of circuit operation of mode two; eighth diagram of circuit operation of mode three; ninth diagram of circuit operation of mode four; tenth diagram of input voltage and input current waveform diagram; FIG eleventh switch-based control of _a Q switch signal waveforms; FIG twelfth line waveform diagram of the switch control signal Q _1, and the LED current I _LED switching signal; and thirteenth lines of the dimmer switch of FIG. The control signal of Q _d and the waveform diagram of LED current signal I _LED .

12‧‧‧LED module

V _LED1 ‧‧‧First LED voltage

V _LED2 ‧‧‧second LED voltage

Q _d ‧‧‧ dimming switch

L‧‧‧Inductance

Q1‧‧‧Toggle switch

R _S1 ‧‧‧Switching resistor

D ₁ ‧‧‧First Diode

D ₂ ‧‧‧Secondary

Claims (7)

An LED high-efficiency dual-output dimming circuit includes: a single-stage reverse-chieving power factor corrector coupled to an AC input voltage and capable of outputting a first LED voltage and a second LED voltage to achieve a Twin-Bus output; wherein the first LED voltage is slightly greater than the second LED voltage; the DC/DC converter is coupled to the single-stage flyback power factor corrector to receive the a first LED voltage and the second LED voltage; an LED module coupled to the DC/DC converter and the single-stage reverse power factor corrector; and a dimmer switch coupled to the LED The module and the single-stage reverse-chirping power factor corrector receive the first LED voltage, thereby performing a high-frequency dimming operation and a low-frequency dimming operation on the LED module. The high efficiency dual output dimming circuit of the LED of claim 1, wherein the DC/DC converter comprises: an inductor coupled to the LED module; and a switch coupled to The switching resistor is coupled to the switching switch; and a first diode is coupled between the LED module and the switching resistor, wherein the first diode system is configured to perform the Conducted during high frequency dimming operation. The high efficiency dual output dimming circuit of the LED of claim 2, further comprising: a second diode coupled between the dimmer switch and the inductor, wherein the second The pole system is turned on during the low frequency dimming operation. The high efficiency dual output dimming circuit of the LED according to claim 1, wherein the LED module is composed of a plurality of LED elements. The high efficiency dual output dimming circuit of the LED according to claim 1, wherein the single stage reverse power factor corrector is a power control IC numbered L6561. The high efficiency dual output dimming circuit of the LED according to claim 1, wherein the dimming switch is a metal oxide half field effect transistor (MOSFET). The high efficiency dual output dimming circuit of the LED according to claim 2, wherein the switch is a metal oxide half field effect transistor (MOSFET).