CN211267157U

CN211267157U - High-efficiency LED drive circuit

Info

Publication number: CN211267157U
Application number: CN201921990489.6U
Authority: CN
Inventors: 毛昭祺; 王纪周; 柯乃泉
Original assignee: Hangzhou Upowertek Power Supply Co ltd
Current assignee: Hangzhou Upowertek Power Supply Co ltd
Priority date: 2019-11-18
Filing date: 2019-11-18
Publication date: 2020-08-14
Anticipated expiration: 2029-11-18

Abstract

The utility model discloses a high-efficiency LED drive circuit, which comprises a Boost main circuit, a Boost control circuit, a Flyback main circuit, a Flyback control circuit, an LED load and a voltage-multiplying rectification circuit, wherein the input end of the Boost main circuit is connected with a power supply, the output end of the Boost main circuit is used as the input end of the Flyback main circuit, the output positive end of the Flyback main circuit is used as the input positive end of the LED load, the input end of the Boost control circuit is electrically connected with the output end of the Boost main circuit, the output end of the Boost control circuit is used as the control end of the Boost main circuit, the input end of the voltage-multiplying rectification circuit is electrically connected with the coupling end of the Boost main circuit, the output positive end of the voltage-multiplying rectification circuit is electrically connected with the output negative end of the Flyback main circuit, the output negative end of the voltage-multiplying rectification circuit is used as the input negative end of the LED load, the input end of the Flyback control circuit is electrically connected with the output negative end of the voltage-multiplying rectification circuit, and the output end of the Flyback control circuit is used as the control end of the Flyback main circuit. The technical scheme obviously improves the energy conversion efficiency of the driving circuit.

Description

High-efficiency LED drive circuit

Technical Field

The utility model relates to an electronic circuit technical field, it is specific, relate to a high efficiency LED drive circuit.

Background

The LED has the advantages of energy conservation, environmental protection, long service life, high conversion efficiency and the like, and is widely applied to the field of illumination. The LED, as a unidirectional conductive semiconductor device, needs a direct current for driving, so that research on the LED driving circuit becomes a key link for development of the LED lighting industry.

Some LED driving circuits on the market adopt a two-stage scheme, as shown in fig. 1, and include a Boost PFC circuit and a Flyback DC-DC circuit, where the Boost PFC circuit realizes a power factor correction function, outputs a DC voltage Vbus with a stable amplitude, and supplies the DC voltage Vbus to a post-stage DC-DC circuit; the DC-DC circuit of the later stage is realized by a Flyback circuit, and the DC-DC conversion is carried out to output the DC current with stable amplitude. In this two-stage circuit scheme, assuming that the efficiency of the Boost circuit is η 1 and the efficiency of the DC-DC circuit is η 2, the total efficiency of the LED driving circuit is η = η 1 × η 2, that is, the total efficiency of the LED driving circuit is lower than the efficiency of each stage of the circuit.

Chinese patent, publication No.: CN203193973U, published: in 2013, 9 and 11, a high-efficiency LED driving circuit comprises a direct-current power supply VIN, an LED control circuit, an overvoltage protection circuit and an LED electric appliance set. The LED control circuit comprises a driving chip and an inductor L, the driving chip comprises a power supply end VIN, a power switch end SW, an overvoltage protection end OVP, a feedback input end FB, an enabling end EN and a grounding end GND, the overvoltage protection circuit comprises the overvoltage protection end OVP and a Schottky diode SBD, and the LED power consumption group comprises series-connection LEDs with the number of integer values from 3 to 8. The output end of the direct-current power supply VIN is electrically connected with the power supply end VIN packaging pin, and the power supply end VIN packaging pin is electrically connected with the power supply end VIN through more than 2 gold wires. This scheme adopts driver chip to carry out the control of LED lamp, increases manufacturing cost.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the problem that traditional LED drive circuit drive efficiency is low, designed a high efficiency LED drive circuit, the LED drive circuit's of this scheme design output current is stable, is showing and is improving energy conversion efficiency.

In order to achieve the technical purpose, the utility model provides a pair of technical scheme is, a high efficiency LED drive circuit, including Boost main circuit, Boost control circuit, Flyback main circuit, Flyback control circuit and voltage doubling rectifier circuit, the Boost main circuit includes inductance L, the input of Boost main circuit is connected with the power, the output of Boost main circuit is as the input of Flyback main circuit, the output positive end of Flyback main circuit is as the output positive end of LED drive circuit, the input of Boost control circuit is connected with the output electricity of Boost main circuit, the output of Boost control circuit is as the control end of Boost main circuit, Boost control circuit is used for controlling the Boost main circuit makes its output voltage's amplitude stable; the inductor L comprises a primary winding M1 serving as a Boost main circuit inductor and a secondary winding M2 coupled with the primary winding M1, two ends of the secondary winding M2 serve as input ends of the voltage-multiplying rectifying circuit, an output positive end of the voltage-multiplying rectifying circuit is electrically connected with an output negative end of the Flyback main circuit, the output negative end of the voltage-multiplying rectifying circuit serves as an output negative end of the LED driving circuit, an input end of the Flyback control circuit is electrically connected with the output negative end of the voltage-multiplying rectifying circuit, an output end of the Flyback control circuit serves as a control end of the Flyback main circuit, and the Flyback control circuit is used for controlling the Flyback main circuit to enable the amplitude of output current of the LED driving circuit to be stable.

In the scheme, the inductance of the Boost main circuit is coupled with the secondary winding, the voltage of the secondary winding is subjected to voltage doubling rectification, the rectified output voltage Vo2 is connected in series with the output voltage Vo1 of the Flyback circuit, and the voltage after the series connection is used as the output voltage of the LED driving circuit; therefore, a part of the output energy of the LED driving circuit is directly converted by the Boost circuit, and the part of the output energy is not converted for the second time by the Flyback circuit, so that the efficiency is higher compared with the two-stage circuit scheme in the prior art. Meanwhile, the Boost main circuit can also realize a PFC (power factor correction) function for the LED driving circuit; in order to stabilize the output current of the LED driving circuit, the output current is detected by a control circuit of the Flyback circuit, and the second switching tube of the Flyback main circuit is controlled by the feedback of the current loop circuit, so that the output current of the LED driving circuit is stabilized.

Preferably, the loop speed of the Flyback control circuit is faster than the loop speed of the Boost control circuit.

Preferably, the Boost main circuit further includes a switching tube S1 and a diode D1, a first end of the primary winding M1 is electrically connected to a first end of a power supply, a second end of the primary winding M1 is electrically connected to an anode end of the diode D1, a cathode end of the diode D1 is electrically connected to an input end of the Flyback main circuit, a first end of the switching tube S1 is electrically connected to an anode end of the diode D1, a second end of the switching tube S1 is grounded, and a control end of the switching tube S1 is electrically connected to an output end of the Boost control circuit.

Preferably, the Flyback main circuit includes a transformer T, a switching tube S2, a diode D2, and a capacitor C1, the transformer includes a primary winding M3 and a secondary winding M4, a first end of the primary winding M3 is electrically connected to a cathode end of the diode D2, a second end of the primary winding M3 is electrically connected to a first end of the switching tube S2, a second end of the switching tube S2 is electrically connected to a second end of the power supply, a control end of the switching tube S2 is electrically connected to an output end of the Flyback control circuit, a first end of the secondary winding M4 is electrically connected to an anode end of the diode D2, a cathode end of the diode D2 is electrically connected to a first end of the capacitor C1, a second end of the capacitor C1 is electrically connected to a second end of the secondary winding M4 of the transformer T, and a cathode end of the diode D2 is electrically connected to an anode end of the LED load.

Preferably, the voltage-doubling rectifying circuit comprises a capacitor C3, a capacitor C4, a diode D3 and a diode D4, wherein a first end of the capacitor C3 is electrically connected with a first end of the secondary winding M2, a second end of the capacitor C3 is electrically connected with an anode end of the diode D4, a cathode end of the diode D4 is electrically connected with a first end of the capacitor C4, a second end of the capacitor C4 is electrically connected with an anode end of the diode D3, a cathode end of the diode D3 is electrically connected with an anode end of the diode D4, an anode end of the diode D3 is electrically connected with a second end of the secondary winding M3, a cathode end of the diode D4 is electrically connected with a second end of the capacitor C1, and an anode end of the diode D3 is electrically connected with a cathode end of the LED load through a.

Preferably, the voltage-doubling rectifying circuit comprises a capacitor C5, a capacitor C6, a diode D5 and a diode D6, wherein an anode terminal of the diode D5 is electrically connected with a first terminal of the secondary winding M2, a cathode terminal of the diode D5 is electrically connected with a first terminal of the capacitor C5, a second terminal of the capacitor C5 is electrically connected with a first terminal of the capacitor C6, a first terminal of the capacitor C6 is electrically connected with a second terminal of the secondary winding M2, a second terminal of the capacitor C6 is electrically connected with an anode terminal of the diode D6, a cathode terminal of the diode D6 is electrically connected with an anode terminal of the diode D5, a first terminal of the capacitor C5 is electrically connected with a second terminal of the capacitor C1, and an anode terminal of the diode D5 is electrically connected with a cathode terminal of the LED load through a.

Preferably, the Boost control circuit comprises a voltage loop circuit and a first drive control circuit, an input end of the voltage loop circuit is electrically connected with a cathode end of the diode D1, an output end of the voltage loop circuit is electrically connected with an input end of the first drive control circuit, and an output end of the first drive control circuit is electrically connected with a control end of the switching tube S1; the voltage loop circuit is used for detecting an output voltage Vbus of a Boost main circuit or detecting an output voltage Vo2 of the voltage-multiplying rectification circuit and comparing the output voltage with a voltage reference signal to output a voltage difference value, the voltage difference value is amplified to serve as a first control signal of the first drive control circuit, the first drive control circuit generates a first drive signal according to the first control signal, and the first drive signal is used for controlling the switching tube S1 to enable the amplitude of the output voltage of the Boost main circuit to be stable.

Preferably, the voltage loop circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C7, and an amplifier U1, a first end of the resistor R1 is electrically connected to a cathode end of the diode D1, a second end of the resistor R2 is electrically connected to a first end of the resistor R2, a second end of the resistor R2 is grounded, a first end of the resistor R2 is electrically connected to a negative input end of the amplifier U1, a positive input end of the amplifier U1 is connected to a reference voltage terminal Vref, and an output end of the amplifier U1 is electrically connected to an input end of the first drive control circuit.

Preferably, the Flyback control circuit includes a current loop circuit and a second driving control circuit, an input end of the current loop circuit is electrically connected to a negative end of the LED load, an output end of the current loop circuit is electrically connected to an input end of the second driving control circuit, and an output end of the second driving control circuit is electrically connected to a control end of the switching tube S2; the current loop circuit is used for detecting the output current of the LED drive circuit and comparing the output current with a current reference signal to output a current difference value, the current difference value is amplified to serve as a second control signal of a second drive control circuit, the second drive control circuit generates a second drive signal according to the second control signal, and the second drive signal is used for controlling the switch tube S2 to enable the amplitude of the output current of the LED drive circuit to be stable.

Preferably, the current loop circuit includes a resistor R4, a capacitor C8, and an amplifier U2, a first end of the resistor R4 is electrically connected to an output end of the amplifier U2, an output end of the amplifier U2 and a second end of the resistor R4 are electrically connected to a first end of the capacitor C8, a second end of the capacitor C8 is electrically connected to a negative input end of the amplifier U2, a positive input end of the amplifier U2 is connected to the reference current terminal Iref, an output end of the amplifier U2 is electrically connected to an input end of the second drive control circuit, and a negative input end of the amplifier U2 is electrically connected to a negative terminal of the LED load.

The utility model has the advantages that: the utility model relates to a high efficiency LED drive circuit, through the inductance coupling secondary winding with the Boost circuit to carry out voltage doubling rectification with the voltage of secondary winding, output voltage Vo2 after the rectification is established ties with Flyback circuit's output voltage Vo1, and the voltage after establishing ties is as LED drive circuit's output voltage; therefore, a part of the output energy of the LED driving circuit is directly converted by the Boost circuit, and the part of the output energy is not converted for the second time by the Flyback circuit, so that the efficiency is higher compared with the two-stage circuit scheme in the prior art. Meanwhile, the Boost main circuit can also realize a PFC function for the LED driving circuit; in order to stabilize the output current of the LED driving circuit, the output current is detected by a control circuit of the Flyback circuit, and the second switching tube of the Flyback main circuit is controlled by the feedback of the current loop circuit, so that the output current of the LED driving circuit is stabilized.

Drawings

Fig. 1 is a schematic diagram of an LED driving circuit employing a two-stage scheme.

Fig. 2 is a structural diagram of a high efficiency LED driving circuit of the present invention.

Fig. 3 is a schematic diagram of a voltage loop circuit of a high-efficiency LED driving circuit according to the present invention.

Fig. 4 is a schematic diagram of a current loop circuit of a high-efficiency LED driving circuit according to the present invention.

Fig. 5 is a schematic diagram of a voltage-doubling rectifying circuit of a high-efficiency LED driving circuit according to the present invention.

Fig. 6 is a schematic diagram of a voltage-doubling rectifying circuit of a high-efficiency LED driving circuit according to the present invention.

The notation in the figure is: the LED driving circuit comprises a 1-Boost main circuit, a 2-Boost control circuit, a 3-Flyback main circuit, a 4-Flyback control circuit, a 5-voltage-multiplying rectification circuit, a 6-LED load component, a 21-voltage loop circuit, a 22-first driving control circuit, a 41-current loop circuit and a 42-second driving control circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail with reference to the accompanying drawings and examples, it should be understood that the specific embodiment described herein is only a preferred embodiment of the present invention, and is only used for explaining the present invention, and does not limit the protection scope of the present invention, and all other embodiments obtained by a person of ordinary skill in the art without creative work belong to the protection scope of the present invention.

Example (b): as shown in fig. 2, a high-efficiency LED driving circuit includes a Boost main circuit 1, a Boost control circuit 2, a Flyback main circuit 3, a Flyback control circuit 4, a voltage-doubler rectification circuit 5, and an LED load 6.

The Boost main circuit 1 comprises an inductor L, a switching tube S1 and a diode D1; the inductor L comprises a primary winding M1 and a secondary winding M2, the primary winding M1 is used as the inductor of the main Boost circuit 1, one end of the primary winding M1 is connected with one end of a switching tube S1 and the anode of a diode D1, the other end of the primary winding M1 is used as the input positive end of the main Boost circuit 1, the other end of the switching tube S1 is used as the input negative end and the output negative end of the main Boost circuit 1, and the cathode of the diode D1 is used as the output positive end of the main Boost circuit 1.

A primary winding M3 of a transformer T of the Flyback main circuit 3 is connected with two output ends of the Boost main circuit 1 after being connected with a switching tube S2 in series, a secondary winding M4 of the transformer T is connected with an output capacitor C1 after being connected with a diode D2, and two ends of the output capacitor C1 are used as an output positive end and an output negative end of the Flyback main circuit 3.

The two ends of a secondary winding M2 of an inductor L of the Boost main circuit 1 are connected with the input end of the voltage-multiplying rectifying circuit 5, the output positive end of the voltage-multiplying rectifying circuit 5 is connected with the output negative end of the Flyback main circuit 3, and the output positive end of the Flyback main circuit 3 and the output negative end of the voltage-multiplying rectifying circuit 5 are respectively used as the output positive end and the output negative end of the LED driving circuit.

The Boost control circuit 2 is composed of a voltage loop circuit and a first drive control circuit 22, the voltage loop circuit is used for detecting the output voltage Vbus of the Boost main circuit 1 or detecting the output voltage Vo2 of the voltage-multiplying rectifying circuit 5, the voltage loop circuit is compared with a voltage reference signal, the difference value of the two is amplified, and then a signal is output to the first drive control circuit 22, the first drive control circuit 22 is used for generating a first drive signal according to the output signal of the voltage loop circuit, the first drive signal is output to the control end of the switch tube S1, and the amplitude of the output voltage of the Boost main circuit 1 is stabilized by controlling the switch tube S1.

Specifically, as shown in fig. 3, the voltage loop circuit 21 includes a resistor R1, a resistor R2, a resistor R3, a capacitor C7, and an amplifier U1, wherein a first end of the resistor R1 is electrically connected to a cathode end of the diode D1, a second end of the resistor R2 is electrically connected to a first end of the resistor R2, a second end of the resistor R2 is grounded, a first end of the resistor R2 is electrically connected to a negative input end of the amplifier U1, a positive input end of the amplifier U1 is connected to the reference voltage terminal Vref, and an output end of the amplifier U1 is electrically connected to an input end of the first drive control circuit 22. In this embodiment, the voltage loop circuit is implemented by an integrated operational amplifier and a peripheral circuit thereof, a negative phase input end of the integrated operational amplifier is connected with a voltage sampling signal (obtained by a divided voltage connected to two output ends of the Boost main circuit 1), a positive phase input end of the integrated operational amplifier is a voltage reference signal Vref, and after a difference between the voltage sampling signal and the divided voltage is amplified, an output end of the operational amplifier is used as an output end of the voltage loop circuit and is connected with the first drive control circuit 22; and a resistor and a capacitor are connected between the negative phase input end and the output end of the operational amplifier to form negative feedback regulation for the operational amplifier.

The Flyback control circuit 4 is composed of a current loop circuit and a second drive control circuit 42, the current loop circuit is used for detecting the output current of the LED drive circuit, comparing the output current with a current voltage reference signal, amplifying the difference value of the two signals and outputting the amplified signal to the second drive control circuit 42, the second drive control circuit 42 is used for generating a second drive signal according to the output signal of the current loop circuit, outputting the second drive signal to the control end of the switch tube S2, and controlling the switch tube S2 to stabilize the amplitude of the output current of the LED drive circuit.

Specifically, as shown in fig. 4, the current loop circuit 41 includes a resistor R4, a capacitor C8, and an amplifier U2, a first end of the resistor R4 is electrically connected to an output end of the amplifier U2, an output end of the amplifier U2 and a second end of the resistor R4 are electrically connected to a first end of the capacitor C8, a second end of the capacitor C8 is electrically connected to a negative input end of the amplifier U2, a positive input end of the amplifier U2 is connected to the reference current terminal Iref, an output end of the amplifier U2 is electrically connected to an input end of the second drive control circuit 42, and a negative input end of the amplifier U2 is electrically connected to a negative end of the LED load. In this embodiment, the current loop circuit is implemented by an integrated operational amplifier and its peripheral circuit, a negative phase input terminal of the integrated operational amplifier is connected to a current sampling signal (obtained by connecting to a Rs terminal of a sampling resistor, see fig. 2), a positive phase input terminal of the integrated operational amplifier is a current reference signal Iref, and after a difference between the current sampling signal and the current reference signal Iref is amplified, an output terminal of the operational amplifier is used as an output terminal of the current loop circuit and is connected to the second driving control circuit 42; and a resistor and a capacitor are connected between the negative phase input end and the output end of the operational amplifier to form negative feedback regulation for the operational amplifier.

In practical use, the Boost circuit can handle most of the output power of the LED driving circuit, and the Flyback circuit can handle as little power as possible, so that the overall efficiency of the LED driving circuit is higher. As shown in fig. 5, the voltage doubler rectifier circuit 5 outputs the input voltage Vr and the output voltage Vo 2. The voltage-doubling rectifying circuit 5 comprises a capacitor C3, a capacitor C4, a diode D3 and a diode D4, wherein a first end of the capacitor C3 is electrically connected with a first end of the secondary winding M2, a second end of the capacitor C3 is electrically connected with an anode end of the diode D4, a cathode end of the diode D4 is electrically connected with a first end of the capacitor C4, a second end of the capacitor C4 is electrically connected with an anode end of the diode D3, a cathode end of the diode D3 is electrically connected with an anode end of the diode D4, an anode end of the diode D3 is electrically connected with a second end of the secondary winding M2, a cathode end of the diode D4 is electrically connected with a negative end of the capacitor C1, and an anode end of the diode D3 is electrically connected with a negative end of the LED load. In this embodiment, it is assumed that the input voltage of the main Boost circuit 1 is Vin and the output voltage is Vbus, the inductor voltage of the main Boost circuit is positive and negative, one of the voltages is Vin, and the other voltage is Vbus-Vin, so that the voltage of the secondary winding of the inductor L in this application is also the same, and has a positive voltage and a negative voltage, and the amplitudes are Vin and Vbus-Vin, respectively. After the secondary winding is subjected to voltage doubling rectification, the voltage doubling rectification circuit 5 superposes two voltages, the rectified output voltage Vo2 is proportional to the sum of the two voltages, and the sum of the two voltages is Vin + (Vbus-Vin), namely Vbus. Therefore, the output voltage Vo2 of the voltage-doubler rectification circuit 5 in the present application is proportional to the output voltage Vbus of the Boost circuit; therefore, in the Boost control circuit 2, the voltage loop circuit may detect the output voltage of the Boost main circuit 1, or may detect the output voltage Vo2 of the voltage-doubler rectifier circuit 5.

Example 2: embodiment 2 is basically the same as the circuit configuration and connection relationship described in embodiment 1, except that the voltage doubler rectifier circuit 5 has a different configuration, as shown in fig. 6, the input voltage Vr, the output voltage Vo2 of the voltage doubler rectifier circuit 5; the voltage-multiplying rectifying circuit 5 comprises a capacitor C5, a capacitor C6, a diode D5 and a diode D6, wherein an anode end of the diode D5 is electrically connected with a first end of the secondary winding M2, a cathode end of the diode D5 is electrically connected with a first end of the capacitor C5, a second end of the capacitor C5 is electrically connected with a first end of the capacitor C6, a first end of the capacitor C6 is electrically connected with a second end of the secondary winding M2, a second end of the capacitor C6 is electrically connected with an anode end of the diode D6, a cathode end of the diode D6 is electrically connected with an anode end of the diode D5, a first end of the capacitor C5 is electrically connected with a second end of the capacitor C1, and an anode end of the diode D5 is electrically connected with a cathode end of the LED load through.

The above-mentioned embodiment does the utility model relates to a high efficiency LED drive circuit's preferred embodiment does not limit with this the utility model discloses a concrete implementation scope, the utility model discloses a scope includes and is not limited to this embodiment, and the all equivalent changes that do according to the utility model discloses a shape, structure are all in the protection scope of the utility model.

Claims

1. A high efficiency LED drive circuit characterized by: the LED driving circuit comprises a Boost main circuit, a Boost control circuit, a Flyback main circuit, a Flyback control circuit and a voltage-multiplying rectification circuit, wherein the Boost main circuit comprises an inductor L, the input end of the Boost main circuit is connected with a power supply, the output end of the Boost main circuit is used as the input end of the Flyback main circuit, the output positive end of the Flyback main circuit is used as the output positive end of the LED driving circuit, the input end of the Boost control circuit is electrically connected with the output end of the Boost main circuit, the output end of the Boost control circuit is used as the control end of the Boost main circuit, and the Boost control circuit is used for controlling the Boost main circuit to enable the amplitude of the output voltage of the Boost main circuit to be stable; the inductor L comprises a primary winding M1 serving as a Boost main circuit inductor and a secondary winding M2 coupled with the primary winding M1, two ends of the secondary winding M2 serve as input ends of the voltage-multiplying rectifying circuit, an output positive end of the voltage-multiplying rectifying circuit is electrically connected with an output negative end of the Flyback main circuit, the output negative end of the voltage-multiplying rectifying circuit serves as an output negative end of the LED driving circuit, an input end of the Flyback control circuit is electrically connected with the output negative end of the voltage-multiplying rectifying circuit, an output end of the Flyback control circuit serves as a control end of the Flyback main circuit, and the Flyback control circuit is used for controlling the Flyback main circuit to enable the amplitude of output current of the LED driving circuit to be stable.

2. A high efficiency LED driver circuit as claimed in claim 1, wherein: the loop speed of the Flyback control circuit is faster than the loop speed of the Boost control circuit.

3. A high efficiency LED driver circuit as claimed in claim 1, wherein:

the Boost main circuit further comprises a switch tube S1 and a diode D1, the first end of the primary winding M1 is electrically connected with the first end of a power supply, the second end of the primary winding M1 is electrically connected with the anode end of the diode D1, the cathode end of the diode D1 is electrically connected with the input end of the Flyback main circuit, the first end of the switch tube S1 is electrically connected with the anode end of the diode D1, the second end of the switch tube S1 is grounded, and the control end of the switch tube S1 is electrically connected with the output end of the Boost control circuit.

4. A high efficiency LED driver circuit as claimed in claim 3, wherein:

the Flyback main circuit comprises a transformer T, a switching tube S2, a diode D2 and a capacitor C1, wherein the transformer comprises a primary winding M3 and a secondary winding M4, the first end of the primary winding M3 is electrically connected with the cathode end of the diode D2, the second end of the primary winding M3 is electrically connected with the first end of the switching tube S2, the second end of the switching tube S2 is electrically connected with the second end of a power supply, the control end of the switching tube S2 is electrically connected with the output end of a Flyback control circuit, the first end of the secondary winding M4 is electrically connected with the anode end of the diode D2, the cathode end of the diode D2 is electrically connected with the first end of the capacitor C1, the second end of the capacitor C1 is electrically connected with the second end of the secondary winding M4 of the transformer T, and the cathode end of the diode D2 is electrically connected with the anode end of an LED load.

5. A high efficiency LED drive circuit as claimed in claim 4, wherein:

the voltage-multiplying rectification circuit comprises a capacitor C3, a capacitor C4, a diode D3 and a diode D4, wherein a first end of the capacitor C3 is electrically connected with a first end of a secondary winding M2, a second end of the capacitor C3 is electrically connected with an anode end of the diode D4, a cathode end of the diode D4 is electrically connected with a first end of a capacitor C4, a second end of the capacitor C4 is electrically connected with an anode end of a diode D3, a cathode end of the diode D3 is electrically connected with an anode end of a diode D4, an anode end of the diode D3 is electrically connected with a second end of the secondary winding M3, a cathode end of the diode D4 is electrically connected with a second end of the capacitor C1, and an anode end of the diode D3 is electrically connected with a cathode end of an LED load through.

6. A high efficiency LED drive circuit as claimed in claim 4, wherein:

the voltage-multiplying rectification circuit comprises a capacitor C5, a capacitor C6, a diode D5 and a diode D6, wherein an anode end of the diode D5 is electrically connected with a first end of a secondary winding M2, a cathode end of the diode D5 is electrically connected with a first end of a capacitor C5, a second end of the capacitor C5 is electrically connected with a first end of a capacitor C6, a first end of the capacitor C6 is electrically connected with a second end of a secondary winding M2, a second end of the capacitor C6 is electrically connected with an anode end of a diode D6, a cathode end of the diode D6 is electrically connected with an anode end of a diode D5, a first end of the capacitor C5 is electrically connected with a second end of the capacitor C1, and an anode end of the diode D5 is electrically connected with a cathode end of an LED load through.

7. A high efficiency LED drive circuit as claimed in claim 3 or 4, wherein:

the Boost control circuit comprises a voltage loop circuit and a first drive control circuit, wherein the input end of the voltage loop circuit is electrically connected with the cathode end of the diode D1, the output end of the voltage loop circuit is electrically connected with the input end of the first drive control circuit, and the output end of the first drive control circuit is electrically connected with the control end of the switch tube S1; the voltage loop circuit is used for detecting an output voltage Vbus of a Boost main circuit or detecting an output voltage Vo2 of the voltage-multiplying rectification circuit and comparing the output voltage with a voltage reference signal to output a voltage difference value, the voltage difference value is amplified to serve as a first control signal of the first drive control circuit, the first drive control circuit generates a first drive signal according to the first control signal, and the first drive signal is used for controlling the switching tube S1 to enable the amplitude of the output voltage of the Boost main circuit to be stable.

8. A high efficiency LED driver circuit as claimed in claim 7, wherein:

the voltage loop circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C7 and an amplifier U1, wherein a first end of the resistor R1 is electrically connected with a cathode end of a diode D1, a second end of the resistor R2 is electrically connected with a first end of the resistor R2, a second end of the resistor R2 is grounded, a first end of the resistor R2 is electrically connected with a negative input end of an amplifier U1, a positive input end of the amplifier U1 is connected with a reference voltage end Vref, and an output end of the amplifier U1 is electrically connected with an input end of a first drive control circuit.

9. A high efficiency LED drive circuit as claimed in claim 4, wherein:

the Flyback control circuit comprises a current loop circuit and a second drive control circuit, wherein the input end of the current loop circuit is electrically connected with the negative end of the LED load, the output end of the current loop circuit is electrically connected with the input end of the second drive control circuit, and the output end of the second drive control circuit is electrically connected with the control end of the switch tube S2; the current loop circuit is used for detecting the output current of the LED drive circuit and comparing the output current with a current reference signal to output a current difference value, the current difference value is amplified to serve as a second control signal of a second drive control circuit, the second drive control circuit generates a second drive signal according to the second control signal, and the second drive signal is used for controlling the switch tube S2 to enable the amplitude of the output current of the LED drive circuit to be stable.

10. A high efficiency LED driver circuit as claimed in claim 9, wherein:

the current loop circuit comprises a resistor R4, a capacitor C8 and an amplifier U2, wherein a first end of the resistor R4 is electrically connected with an output end of the amplifier U2, an output end of the amplifier U2 and a second end of the resistor R4 are electrically connected with a first end of the capacitor C8, a second end of the capacitor C8 is electrically connected with a negative input end of the amplifier U2, a positive input end of the amplifier U2 is connected with a reference current end Iref, an output end of the amplifier U2 is electrically connected with an input end of a second drive control circuit, and a negative input end of the amplifier U2 is electrically connected with a negative end of an LED load.