TWI399122B - Single-state led driving circuit with zero voltage switching - Google Patents

Description

Single-stage LED drive circuit with zero voltage switching

The present invention relates to an LED driving circuit, and more particularly to a single-stage LED driving circuit with zero voltage switching.

With the current development trend of LEDs for lighting and display backlights, there have been many patents related to driving circuits for LED characteristics (refer to prior art [1-3]). Among these drive circuit architectures, the main purpose is to improve the performance of driving LEDs. However, in the current industry, due to the overall consideration of the entire electrical products, there will be additional requirements on the drive circuit. The conventional LED driver circuit power supply is taken from the mains input. Because of the safety requirements, the input and output terminals need to be electrically isolated, and sometimes three different voltages are required because different LEDs (R, G, B) must be driven at the same time. Therefore, in order to achieve the requirements of electrical isolation and individual driving, the conventional circuit is designed as a two-stage circuit to drive the LED (refer to the prior art [4]).

Referring to Figure 1, there is shown a block diagram of a conventional LED driver circuit. The conventional LED driving circuit 10 includes a passive filter 11, a pre-stage power factor correction circuit 12, and a post-stage multi-winding output isolation converter 13. The conventional LED driving circuit 10 is used to drive a plurality of sets or multi-color LEDs 14 including a red LED 141, a green LED 142 and a blue LED 143. After the AC power is passed through the passive filter 11, in order to meet the safety requirements, the pre-stage power correction circuit 12 is used to achieve high power efficiency, and the post-stage multi-winding output isolation converter 13 is used, for example, boosting. Converter, buck converter and step-down converter (Buck-boost Converter), to achieve multiple sets of voltage output (refer to prior art [5]).

In the prior art [1], although the effect of high power can be achieved, the problem of electrical isolation cannot be considered. Under these conventional LED driving circuit architectures, since the switching switch cannot be switched to zero voltage, the switching loss is significant, and the circuit efficiency is lowered.

Therefore, it is necessary to provide an innovative and progressive single-stage LED drive circuit with zero voltage switching to solve the above problems.

Prior art:

[1] Republic of China Patent Publication No. 200704284, patent name: Single-stage digital power converter for driving LEDs.

[2] Republic of China Patent Publication No. 200522794, patent name: LED driving circuit.

[3] Republic of China Patent Publication No. 200603183, patent name: LED driving circuit.

[4] S. Muthu and J. Gaines, "Red, Green and Blue LED-Based White Light Source: Implementation Challenges and Control Design", IEEE Industry Applications Conference, 2003, pp. 515-522.

[5] Zhou Zhimin, Zhou Jihai, Ji Aihua, LED Driver Circuit Design and Application , Shanghai Post and Telecommunications Press, 2006.

The invention provides a single-stage LED driving circuit with zero voltage switching, comprising: a power factor correction circuit and an isolated converter with zero voltage switching. The power correction circuit is configured to receive an AC input voltage to correct Cause of merit. The zero-voltage switching isolated converter is connected to the power factor correction circuit, and has at least one switch, the switch-on relationship is zero voltage switching, and the isolated converter is configured to convert the AC input voltage into at least a DC output voltage. To drive at least one LED.

The single-stage LED driving circuit with zero voltage switching of the invention integrates the power correction circuit and the isolated converter, and some components in the isolated converter are identical to some components of the power factor correction circuit. The inductance of the power correction circuit operates in the discontinuous conduction mode (DCM), which makes the power factor close to 1. And the isolated converter operates under inductive load mode, so that all active switches have the advantage of zero voltage switching (ZVS) conduction, reducing the switching loss of the active switch. Therefore, the single-stage LED driving circuit with zero voltage switching of the present invention has high power factor, high circuit efficiency, and has the effects of reducing circuit components and reducing cost.

Referring to Figure 2, there is shown a schematic diagram of a single stage zero voltage switching LED drive circuit of the present invention. The single-stage zero voltage switching LED driving circuit 22 of the present invention comprises: a power factor correction circuit 221 and an isolated converter 222 with zero voltage switching. The power factor correction circuit 221 is configured to receive an AC input voltage to correct the power factor. The zero-voltage switching isolated converter 222 is connected to the power factor correction circuit, and has at least one switch, the switch-on relationship is zero voltage switching, and the isolated converter is configured to convert the AC input voltage into at least a DC output. Voltage to drive at least one LED. In the embodiment of the present invention, the zero-voltage switching isolated converter 222 can be a An isolated converter having multiple winding outputs and zero voltage switching to provide a plurality of DC output voltages for driving a plurality of sets or multi-color LEDs 24, the LED group 24 including a red LED 241, a green LED 242, and a blue LED 243.

The single-stage zero voltage switching LED driving circuit 22 of the present invention further includes a passive filter 21 for filtering high frequency components, and the passive filter 21 is connected between the alternating current input voltage and the power factor correcting circuit 221.

Referring to Figure 3, there is shown a circuit diagram of a first embodiment of a single stage zero voltage switching LED drive circuit of the present invention. In the single-stage zero-voltage switching LED driving circuit 30 of the first embodiment of the present invention, the power factor correcting circuit is a boosting power factor correcting circuit, and the isolated converter is an isolated positive half-bridge resonant converter. . The passive filter includes a filter inductor _Lf and a filter capacitor _Cf.

The power correction circuit includes: a first rectifying diode D _r1 , a second rectifying diode D _r2 , a first inductor L ₁ , a first switching switch Q ₁ , a second switching switch Q ₂ , a first capacitor C ₁ and a second capacitor C ₂ ; wherein the first rectifying diode D _{r1 is} connected to the second rectifying diode D _r2 ; the first switching switch Q ₁ and the second switching switch Q ₂ is connected, and is connected in parallel and the second rectifying diode D _r2 of the first rectifying diode D _R1; the first capacitor C _{1 2} is connected to the second capacitor C and the first switch Q ₁ and the second switch Q ₂ are connected in parallel; the first inductor L _{1 is} connected between the passive filter and the connection point a of the first switch Q ₁ and the second switch Q ₂ .

The isolated converter with zero voltage switching includes: the first switching switch Q ₁ , the second switching switch Q ₂ , the first capacitor C ₁ , the second capacitor C ₂ , a third capacitor C _r , and a The third inductor L _r , a transformer T and a rectifier R. The single-stage LED driving circuit with zero voltage switching of the present invention integrates the power factor correction circuit and the isolated converter, and some components in the isolated converter are identical to some components of the power factor correction circuit, in this embodiment. The first switch Q ₁ , the second switch Q ₂ , the first capacitor C ₁ and the second capacitor C ₂ of the isolated switch with zero voltage switching are connected to the power factor correction circuit The first switch Q ₁ , the second switch Q ₂ , the first capacitor C ₁ and the second capacitor C _{2 are the} same.

In this embodiment, the third capacitor C _r and the third inductor L _r are connected to the connection point a of the first switch Q ₁ and the second switch Q ₂ ; the transformer T is connected to the The third inductor L _r and a connection point b between the first capacitor C ₁ and the second capacitor C ₂ ; the rectifier R is connected to the transformer T. The rectifier R includes four rectifying diodes D _r5 , D _r6 , D _r7 and D _r8 . The transformer T can be a multi-winding output transformer to provide a plurality of DC output voltages to drive a plurality of LEDs.

The following describes the operation mode of the single-stage LED driving circuit with zero voltage switching in the first embodiment of the present invention: (1) Working mode I: When the driving signal V _{gs 2 turns off} the second switching switch Q ₂ , it enters the working mode. I. After a short delay time of idling, the driving of the first switch Q ₁ V _{gs 1} signal from low potential to the high potential, the first switch Q ₁ is not turned on immediately. Since the resonant tank is designed to be inductive, the resonant current i _R will lag behind the voltage, so at the instant when the second switching switch Q _{2 is} turned off, i _R is negative and flows backward through the diode D ₁ (the base of the MOSFET can be utilized) - The diode between the bungee is used as D ₁ and D ₂ , and no additional parallel diodes are required). Once D _{1 is} turned on, the rectified input voltage straddles the first inductor L ₁ , the inductor current i _{L 1} increases linearly from zero, and the speed at which i _{L 1} increases is proportional to the input voltage. Initially, i _{L 1 is} small, and the combined current i _{S 1} of i _{L 1} and i _R is still reversed, and D ₁ continues to conduct. When i _{L 1} rises to turn forward so i _{S 1,} D ₁ is turned off, the first switch Q ₁ is turned on it, into the working mode II. Since the first switch Q ₁ is turned on when switching voltage is equal to zero, with the advantages of zero voltage switching is turned on, the significant reduction in the switching losses.

(2) operating mode II: when the first switch Q ₁ turns on, the voltage across the first inductor L ₁ is still equal to the rectified input voltage, the inductor current i _{L 1} continued to increase linearly, whereas the resonant current i _R It gradually oscillates from a negative value to a positive value. After i _R is a positive value, i _{L 1} and i _R flow together through the first changeover switch Q ₁ . When the first switch Q ₁ is turned off, the inductor current i _{L 1} reaches a peak of this cycle, and then enters the operating mode III.

(3) Operation mode III: When entering the operation mode III, i _R is a positive value, the current path is switched from the first switch Q ₁ to the diode D ₂ , and the second capacitor C _{2 is} charged. On the other hand, the inductor current i _{L 1} flows through D ₂ while charging the first capacitor C ₁ and the second capacitor C ₂ . The voltage ( v _s - V _dc ) across the first inductor L ₁ is negative, and i _{L 1} decreases linearly from the peak. In order for the converter to operate in the DCM, the voltage sum ( V _dc ) between the first capacitor C ₁ and the second capacitor C ₂ must be greater than twice the peak value of the AC input voltage v _s .

Since the peak value of i _{L 1} is proportional to the AC input voltage v _s , the time during which i _{L 1} falls to zero varies with the input voltage. If i _{L 1} falls to zero later than i _R , it enters operating mode IV-a; conversely, when i _{L 1} drops to zero earlier than i _R , it enters operating mode IV-b.

(4) Operating mode IV-a: When the AC input voltage v _{s is} at a higher voltage, i _R oscillates to zero and then reverses. At this time, the inductor current i _{L 1} continues to decrease linearly. When i _R re-oscillates to be larger than i _{L 1} , the second switching switch Q _{2 is} turned on, and the difference between the reversed i _R and i _{L 1} flows through the second switching switch Q ₂ . Before the drive signal V _{gs 2} goes low, the inductor current i _{L 1} drops first to zero and then enters the operating mode V.

(5) Working mode IV-b: When the AC input voltage v _{s is} at a lower voltage, i _{L 1} will first drop to zero, and the power supply stops inputting current. At this time, i _{R is} still a positive value and continues to flow through D ₂ until the i _R oscillation passes through the zero point to become a negative value, and the second switching switch Q _{2 is} switched on with the D ₂ cutoff, and then enters the operating mode V.

(6) Working mode V: At this time, the second switching switch Q _{2 is} turned on, i _R is negative and flows through the second switching switch Q ₂ , and the second capacitor C ₂ supplies energy to the resonant circuit when V _{gs 2} is high When the potential becomes a low potential, the second switching switch Q ₂ is turned off, and the circuit returns to the operating mode I of the next high frequency period.

Therefore, whether it enters mode IV-a in operational mode III or enters mode IV-b and then mode V from operational mode III. Before the second switch Q _{2 is} turned on, i _R is a positive value and flows through D ₂ , and the voltage across Q ₂ is almost zero. Therefore, the second switch Q ₂ can achieve zero voltage switching conduction. It can be found from the above working mode that the first switching switch Q ₁ and the second switching switch Q ₂ have the advantages of zero voltage switching conduction, and the switching loss can be greatly reduced. Therefore, the single-stage LED driving circuit with zero voltage switching of the present invention has high power factor, high circuit efficiency, and has the effects of reducing circuit components and reducing cost.

Referring to Figure 4, there is shown a circuit diagram of a second embodiment of a single stage zero voltage switching LED drive circuit of the present invention. In the LED driving circuit 40 of the single-stage zero voltage switching of the second embodiment of the present invention, the power factor correcting circuit is a boosting power factor correcting circuit, and the isolated converter is an isolated quasi-half bridge resonant converter. . The difference from the first embodiment is that the single-stage zero-voltage switching LED driving circuit 40 of the second embodiment does not have the second capacitance C ₂ . Therefore, the single-stage zero voltage switching LED driving circuit 40 of the second embodiment has the effect of the single-stage LED driving circuit 30 with zero voltage switching of the first embodiment.

Referring to Figure 5, there is shown a circuit diagram of a third embodiment of the LED drive circuit of the single stage with zero voltage switching of the present invention. In the LED driving circuit 50 of the single-stage zero voltage switching of the third embodiment of the present invention, the power factor correcting circuit is a step-down power factor correcting circuit, and the isolated converter is an isolated positive half bridge resonant converter. Device.

The power correction circuit includes: a first rectifying diode D _r1 , a second rectifying diode D _r2 , a third rectifying diode D ₃ , a fourth rectifying diode D ₄ , and a first An inductor L _p1 , a second inductor L _p2 , a first switch Q ₁ , a second switch Q ₂ , a first capacitor C ₁ and a second capacitor C ₂ ; wherein the first rectifier diode D _{R1 is} connected to the second rectifying diode D _r2 ; the first switching switch Q _{1 is} connected to the second switching switch Q ₂ ; the first capacitor C _{1 is} connected to the second capacitor C ₂ , and the first The switch Q ₁ and the second switch Q ₂ are connected in parallel; the first inductor L _{p1 is} connected between the first rectifier diode D _r1 and the first switch Q ₁ ; the second inductor L _{p2 is} connected to Between the second rectifying diode D _r2 and the second switching switch Q ₂ ; the third rectifying diode D _{3 is} connected to the fourth rectifying diode D ₄ and the first rectifying diode D _r1 and the second rectifying diode D _r2 are connected in parallel. .

The isolated converter with zero voltage switching includes: the first switching switch Q ₁ , the second switching switch Q ₂ , the first capacitor C ₁ , the second capacitor C ₂ , a third capacitor C _r , and a The third inductor L _r , the third rectifying diode D ₃ , the fourth rectifying diode D ₄ , a transformer T and a rectifier R. The single-stage LED driving circuit with zero voltage switching of the present invention integrates the power factor correction circuit and the isolated converter, and some components in the isolated converter are identical to some components of the power factor correction circuit, in this embodiment. The first switching switch Q ₁ , the second switching switch Q ₂ , the third rectifying diode D ₃ , the fourth rectifying diode D ₄ , the first switching switch with zero voltage switching a capacitor C ₁ and the second capacitor C ₂ are coupled to the first switch Q ₁ , the second switch Q ₂ , the third rectifier diode D ₃ , and the fourth rectifier ₂ of the power factor correction circuit The pole body D ₄ , the first capacitor C ₁ and the second capacitor C _{2 are the} same.

In this embodiment, the third capacitor C _r and the third inductor L _r are connected to the connection point a of the first switch Q ₁ and the second switch Q ₂ ; the transformer T is connected to the The third inductor L _r and a connection point b between the first capacitor C ₁ and the second capacitor C ₂ ; the rectifier R is connected to the transformer T. The rectifier includes four rectifying diodes D _r5 , D _r6 , D _r7 and D _r8 . The transformer can be a multi-winding output transformer to provide a plurality of DC output voltages to drive a plurality of LEDs.

The following describes the working mode of the single-stage LED driving circuit with zero voltage switching in the third embodiment of the present invention: (1) Working mode I: When the driving signal V _{gs 2 turns off} the second switching switch Q ₂ , it enters the working mode. I. After a short delay time of idling, the driving of the first switch Q ₁ V _{gs 1} signal from low potential to the high potential, the first switch Q ₁ is not turned on immediately. Since the resonant tank is designed to be inductive, the resonant current i _R will lag behind the voltage, so at the instant when the second switching switch Q _{2 is} turned off, i _R is negative and flows backward through the diode D ₁ (the base of the MOSFET can be utilized) - The diode between the bungee is used as D ₁ and D ₂ , and no additional parallel diodes are required). Once D _{1 is} turned on, the rectified input voltage straddles the first inductor L _p1 , the inductor current i _{Lp 1} increases linearly from zero, and the speed at which i _{Lp 1} increases is proportional to the input voltage. Initially, i _{Lp 1 is} small, and the combined current i _S1 of i _{Lp 1} and i _R is still reversed, and D ₁ continues to conduct. When i _{L 1} rises to turn i _S1 into the positive direction, D _{1 is} turned off, and the first switch Q ₁ is turned on to enter the operation mode II. Since the first switch Q ₁ is turned on when switching voltage is equal to zero, with the advantages of zero voltage switching is turned on, the significant reduction in the switching losses.

(2) operating mode II: entering the momentary operating mode II, the first switch Q ₁ turns on, the voltage across the first inductor L _p1 is still equal to the rectified input voltage, the inductor current i _{Lp 1} continued to increase linearly, whereas The resonant current i _R gradually oscillates from a negative value to a positive value. After i _R is a positive value, i _{Lp 1} and i _R flow together through the first changeover switch Q ₁ . When the drive voltage V _{gs 1} into the low level, the first switch Q ₁ is turned off, the inductor current i _{Lp 1} reaches a peak of this cycle, and then enters the operating mode III.

(3) Working mode III: In order for the converter to operate in DCM, the voltage across the first capacitor C ₁ ( V _dc / 2 ) must be designed to be greater than the peak value of the AC input voltage v _s to make the first rectifier diode D _{r1 is} reverse biased. At this time, the first inductor current i _{Lp 1} will no longer flow through the input power source, but will flow through the third rectifying diode D ₃ and charge the first capacitor C ₁ . Since the voltage across the first inductor L _{p 1} is negative ( -V _dc / 2 ) at this time, the first inductor current i _{Lp 1} linearly decreases from the peak value. Also, since the peak value of the first inductor current i _{Lp 1} is proportional to the input voltage v _s , the time during which the first inductor current i _{Lp 1} falls to zero differs as the input voltage v _s changes. If the first inductor current i _{Lp 1} falls to zero later than i _R , it enters the operating mode IV-a; conversely, when the first inductor current i _{Lp 1} drops to zero earlier than i _R , it enters the operating mode IV-b. When entering the operating mode III, i _R is a positive value, and the current path of i _R is converted by the first switching switch Q ₁ to the diode D ₂ and the second capacitor C _{2 is} charged.

(4) Working mode IV-a: The operating mode IV-a occurs when the input voltage is at a higher voltage. At this time, the second switching switch Q _{2 is} turned on, and the second switching switch i _R flows through Q ₂ . The voltage across the first inductor L _{p 1} is still negative ( -V _dc / 2 ), so the first inductor current i _{Lp 1} continues to decrease linearly. Since the design converter operates in the DCM, the first inductor current i _{Lp 1} will first decrement to zero before the drive signal V _{gs 2} goes low, and enter the operating mode V when the first inductor current i _{Lp 1} falls to zero.

(5) Operating mode IV-b: Operating mode IV-b occurs when the input voltage is at a lower voltage. At this time, the first inductor current i _{LP 1} has first dropped to zero in the operating mode III, and i _R is Positive values flow through D ₂ . Therefore, when the i _R oscillation changes to a negative value through the zero point, D _{2 is} turned off, and the second switching switch Q _{2 is} switched on to enter the operation mode V.

(6) Working mode V: At the instant of entering the working mode V, the second switching switch Q _{2 is} turned on, i _R is a negative value and flows through the second switching switch Q ₂ , at which time the resonant circuit draws from the second capacitor C ₂ energy. When V _{gs 2} changes from a high potential to a low potential, the second switching switch Q ₂ is turned off, and the circuit enters the operating mode I of the next high frequency period.

Therefore, whether it enters mode IV-a in operational mode III or enters mode IV-b and then mode V from operational mode III. Before the second switch Q _{2 is} turned on, i _R is a positive value and flows through D ₂ , and the voltage across Q ₂ is almost zero. Therefore, the second switch Q ₂ can achieve zero voltage switching conduction. It can be found from the above working mode that the first switching switch Q ₁ and the second switching switch Q ₂ have the advantages of zero voltage switching conduction, and the switching loss can be greatly reduced. Therefore, the single-stage LED driving circuit with zero voltage switching of the present invention has high power factor, high circuit efficiency, and has the effects of reducing circuit components and reducing cost.

Referring to Figure 6, there is shown a circuit diagram of a fourth embodiment of a single stage zero voltage switching LED drive circuit of the present invention. In the LED driving circuit 60 of the single-stage zero voltage switching of the second embodiment of the present invention, the power factor correcting circuit is a step-down power factor correcting circuit, and the isolated converter is an isolated quasi-half bridge resonant converter. Device. The difference from the third embodiment is that the single-stage zero-voltage switching LED driving circuit 60 of the second embodiment does not have the second capacitance C ₂ . The third rectifying diode D _{3 is} connected between the first rectifying diode D _r1 and the parallel connection point of the second switching switch Q ₂ and the first capacitor C ₁ , the fourth rectifying diode D _{4 is} connected between the second rectifying diode D _r2 and a parallel connection point of the first switching switch Q ₁ and the first capacitor C ₁ . Therefore, the single-stage zero voltage switching LED driving circuit 60 of the fourth embodiment has the effect of the single-stage LED driving circuit 50 with zero voltage switching of the third embodiment.

The single-stage zero voltage switching LED driving circuit of the present invention further includes a control circuit (not shown) for controlling whether the switching switch is turned on or not.

The single-stage LED driving circuit with zero voltage switching of the invention integrates the power correction circuit and the isolated converter, and some components in the isolated converter are identical to some components of the power factor correction circuit. The inductance of the power correction circuit operates in discontinuous conduction mode (DCM), which makes the power factor close to 1. And the isolated converter operates under inductive load mode, so that all active switches have the advantage of zero voltage switching (ZVS) conduction, reducing the switching loss of the active switch. Therefore, the single-stage LED driving circuit with zero voltage switching of the present invention has high power factor, high circuit efficiency, and has the effects of reducing circuit components and reducing cost.

However, the above embodiments are merely illustrative of the principles of the invention and its effects, and are not intended to limit the invention. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the spirit of the invention. The scope of the invention should be as set forth in the appended claims.

10‧‧‧Learning LED driver circuit

11‧‧‧ Passive filter

12‧‧‧Pre-stage power factor correction circuit

13‧‧‧After multi-winding output isolated converter

14‧‧‧LED group

21‧‧‧ Passive filter

22‧‧‧Single-level LED drive circuit with zero voltage switching of the present invention

24‧‧‧LED group

30‧‧‧In the first embodiment of the present invention, a single-stage LED driving circuit with zero voltage switching

40‧‧‧Second embodiment of the present invention, single-stage LED drive circuit with zero voltage switching

50‧‧‧The third embodiment of the present invention has a single-stage LED drive circuit with zero voltage switching

60‧‧‧The fourth embodiment of the present invention has a single stage with zero voltage Switching LED drive circuit

141‧‧‧Red LED

142‧‧‧Green LED

143‧‧‧Blue LED

221‧‧‧Power correction circuit

222‧‧‧Isolated converter with zero voltage switching

241‧‧‧Red LED

242‧‧‧Green LED

243‧‧‧Blue LED

C ₁ ‧‧‧first capacitor

C ₂ ‧‧‧second capacitor

C _r ‧‧‧third capacitor

C _f ‧‧‧Filter capacitor

D _r1 ‧‧‧First Rectifier Diode

D _r2 ‧‧‧second rectifying diode

D ₁ , D ₂ ‧‧‧Base-bungium diode

D ₃ ‧‧‧3rd rectifying diode

D ₄ ‧‧‧fourth rectifier diode

L ₁ ‧‧‧first inductance

L _p1 ‧‧‧first inductance

L _p2 ‧‧‧second inductance

L _r ‧‧‧third inductance

L _f ‧‧‧Filter inductor

Q ₁ ‧‧‧First switch

Q ₂ ‧‧‧Second switch

T‧‧‧Transformer

R‧‧‧Rectifier

D _r5 , D _r6 , D _r7 , D _r8 ‧‧‧ four rectifying diodes

1 is a block diagram showing a conventional LED driving circuit; FIG. 2 is a block diagram showing a single-stage LED driving circuit with zero voltage switching according to the present invention; FIG. 4 is a circuit diagram showing a second embodiment of a single-stage LED driving circuit with zero voltage switching according to the present invention; FIG. 5 is a circuit diagram showing a third embodiment of the LED driving circuit with zero voltage switching of the present invention. FIG. 6 is a circuit diagram showing a fourth embodiment of the LED driving circuit of the single-stage zero voltage switching of the present invention.

21‧‧‧ Passive filter

22‧‧‧Single-level LED drive circuit with zero voltage switching of the present invention

24‧‧‧LED group

221‧‧‧Power correction circuit

222‧‧‧Isolated converter with zero voltage switching

241‧‧‧Red LED

242‧‧‧Green LED

243‧‧‧Blue LED

Claims (18)

A single-stage LED driving circuit with zero voltage switching, comprising: a power factor correction circuit for receiving an AC input voltage to correct a power factor; and an isolated converter with zero voltage switching, connecting the power factor correction The circuit has at least one switch that is zero voltage switching, and the isolated converter is configured to convert the AC input voltage to at least a DC output voltage to drive the at least one LED. The LED driving circuit of claim 1, further comprising a passive filter for filtering high frequency components, wherein the passive filter is connected between the AC input voltage and the power factor correction circuit; wherein the power factor correction circuit is A boosting power factor correction circuit is an isolated positive half bridge resonant converter. The LED driving circuit of claim 2, wherein the power factor correction circuit comprises: a first rectifying diode, a second rectifying diode, a first inductor, a first switching switch, a second switching switch, a first capacitor and a second capacitor; wherein the first rectifying diode is connected to the second rectifying diode; the first switching switch is connected to the second switching switch, and the first rectifying diode And the second rectifying diode is connected in parallel; the first capacitor is connected to the second capacitor, and is connected in parallel with the first switching switch and the second switching switch; the first inductor is connected to the passive filter and the first A switch is connected between the connection point of the second switch. The LED driving circuit of claim 3, wherein the isolated converter with zero voltage switching comprises: the first switching switch, the second switching switch, the a first capacitor, a second capacitor, a third capacitor, a third inductor, a transformer, and a rectifier; wherein the third capacitor and the third inductor are connected to the first switch and the second switch a connection point of the switch; the transformer is connected between the third inductor and a connection point of the first capacitor and the second capacitor; the rectifier is connected to the transformer. The LED drive circuit of claim 4, wherein the transformer is a multi-winding output transformer to provide a plurality of DC output voltages to drive a plurality of LEDs. The LED driving circuit of claim 1, further comprising a passive filter for filtering high frequency components, wherein the passive filter is connected between the AC input voltage and the power factor correction circuit; wherein the power factor correction circuit is A boosting power factor correction circuit is an isolated quasi-half bridge resonant converter. The LED driving circuit of claim 6, wherein the power factor correcting circuit comprises: a first rectifying diode, a second rectifying diode, a first inductor, a first switching switch, and a second switching switch And a first capacitor; wherein the first rectifying diode is connected to the second rectifying diode; the first switching switch is connected to the second switching switch, and the first rectifying diode and the second The rectifier diodes are connected in parallel; the first capacitor is connected in parallel with the first switch and the second switch; the first inductor is connected to the passive filter and the first switch is connected to the second switch Between the points. The LED driving circuit of claim 7, wherein the isolated converter with zero voltage switching comprises: the first switching switch, the second switching switch, the a first capacitor, a third capacitor, a third inductor, a transformer, and a rectifier; wherein the third capacitor and the third inductor are connected to and connected to a connection point between the first switch and the second switch; The transformer is coupled between the third inductor and the first capacitor; the rectifier is coupled to the transformer. The LED drive circuit of claim 8, wherein the transformer is a multi-winding output transformer to provide a plurality of DC output voltages to drive a plurality of LEDs. The LED driving circuit of claim 1, further comprising a passive filter for filtering high frequency components, wherein the passive filter is connected between the AC input voltage and the power factor correction circuit; wherein the power factor correction circuit is A step-down power factor correction circuit is an isolated positive half bridge resonant converter. The LED driving circuit of claim 10, wherein the power factor correcting circuit comprises: a first rectifying diode, a second rectifying diode, a third rectifying diode, a fourth rectifying diode, and a a first inductor, a second inductor, a first switch, a second switch, a first capacitor, and a second capacitor; wherein the first rectifier diode is connected to the second rectifier diode; The first switching switch is connected to the second switching switch, and is connected in parallel with the first rectifying diode and the second rectifying diode; the first capacitor is connected to the second capacitor, and the first switching switch And the second switching switch is connected in parallel; the first inductor is connected between the first rectifying diode and the first switching switch; the second inductor is connected to the second rectifying diode and the second switching switch The third rectifying diode and the The fourth rectifying diode is connected and connected in parallel with the first rectifying diode and the second rectifying diode. The LED driving circuit of claim 11, wherein the isolated converter with zero voltage switching comprises: the first switching switch, the second switching switch, the first capacitor, the second capacitor, a third capacitor, and a a third inductor, a transformer, and a rectifier; wherein the third capacitor and the third inductor are connected to and connected to a connection point between the first switch and the second switch; the transformer is connected to the third inductor and the Between the junction of the first capacitor and the second capacitor; the rectifier is connected to the transformer. The LED drive circuit of claim 12, wherein the transformer is a multi-winding output transformer to provide a plurality of DC output voltages to drive a plurality of LEDs. The LED driving circuit of claim 1, further comprising a passive filter for filtering high frequency components, wherein the passive filter is connected between the AC input voltage and the power factor correction circuit; wherein the power factor correction circuit is A step-down power factor correction circuit is an isolated quasi-half bridge resonant converter. The LED driving circuit of claim 14, wherein the power factor correction circuit comprises: a first rectifying diode, a second rectifying diode, a third rectifying diode, a fourth rectifying diode, and a a first inductor, a second inductor, a first switch, a second switch, and a first capacitor; wherein the first rectifier diode is connected to the second rectifier diode; the first switch The second switching switch is connected and connected in parallel with the first rectifying diode and the second rectifying diode; the first capacitor and the first a switching switch and the second switching switch are connected in parallel; the first inductor is connected between the first rectifying diode and the first switching switch; the second inductor is connected to the second rectifying diode and the second The third rectifying diode is connected between the first rectifying diode and the parallel connection point of the second switching switch and the first capacitor, and the fourth rectifying diode is connected to the first The second rectifier diode is between the first switching switch and the parallel connection point of the first capacitor. The LED driving circuit of claim 15, wherein the isolated converter with zero voltage switching comprises: the first switching switch, the second switching switch, the first capacitor, a third capacitor, a third inductor, and a a transformer and a rectifier; wherein the third capacitor and the third inductor are connected to and connected to a connection point between the first switch and the second switch; the transformer is connected between the third inductor and the first capacitor The rectifier is connected to the transformer. The LED drive circuit of claim 16, wherein the transformer is a multi-winding output transformer to provide a plurality of DC output voltages to drive a plurality of LEDs. The LED driving circuit of claim 1 further includes a control circuit for controlling whether the switching switch is turned on or not.