Low-ripple flyback PFC switching power supply

Abstract

The utility model provides a low-ripple flyback PFC switching power supply. A primary side input assembly and a secondary side output assembly are connected through a transformer T1; the first output end of the transformer T1 is connected with the drain electrode of the switching tube Q3; the first output end of the output unit is connected with the source electrode of the switching tube Q3; the ripple reduction unit is respectively connected with the drain electrode, the source electrode and the grid electrode of the switch tube Q3; when flyback conversion occurs and ripples are generated, the first output end of the output unit is boosted, and the ripple reduction unit is used for stabilizing the grid potential of the switch tube Q3, so that the conduction internal resistance of the switch tube Q3 is increased to reduce the ripples. According to the invention, the ripple reduction unit is arranged in the output unit to control the conduction internal resistance of the switching tube, so that the power frequency ripple of the output current is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LED lighting power supply, in particular to a low ripple flyback PFC switching power supply. BACKGROUND

[0002] LED (light-emitting diode) is a commonly used light-emitting device, which emits light based on the principle of electron and hole recombination. Since it can efficiently convert electrical energy into light energy, LED is widely used in display and lighting fields.

[0003] However, the existing LED flickers when lighting, which easily interferes with the occasions requiring high light stability. For example, in an indoor lighting environment, the human eye may perceive the lighting flicker of the LED, thereby being more prone to visual fatigue. CONTENT OF THE INVENTION

[0004] In view of the above problems, the present application is proposed to provide a low ripple flyback PFC switching power supply to overcome the above problems or at least partially solve the above problems.

[0005] The present application discloses a low ripple flyback PFC switching power supply, comprising: a primary input component and a secondary output component; the secondary output component comprises: a wave reduction unit and an output unit;

[0006] The primary input component and the secondary output component are connected through a transformer T1; the first output end of the transformer T1 is connected with the drain of a switch tube Q3; the first output end of the output unit is connected with the source of the switch tube Q3; the wave reduction unit is connected with the drain, the source and the gate of the switch tube Q3, respectively;

[0007] When the wave occurs due to flyback conversion, the first output end of the output unit is boosted, and the wave reduction unit is used to stabilize the gate potential of the switch tube Q3, so that the on-resistance of the switch tube Q3 is increased to reduce the wave.

[0008] Further, the wave reduction unit comprises: a diode BD10, a Schottky diode BD11, a diode BD12, a diode BD13, a resistor BR16, a resistor BR17, a resistor BR18, a resistor BR20, a resistor BR21, a capacitor BC12 and a capacitor BC13;

[0009] The output end of the primary input component is connected with the input end of the transformer T1; the first output end of the transformer T1 is connected with the anode of a diode D13 and one end of a capacitor BC12;

[0010] The drain of the switch tube Q3 is connected with the negative electrode of diode D13 and one end of resistor BR17; the other end of capacitor BC12 is connected with one end of resistor BR20 and one end of resistor BR21; the other end of resistor BR21 is connected with the negative electrode of diode BD10; the other end of resistor BR20 is connected with the positive electrode of diode BD12; the negative electrode of diode BD12 is connected with the other end of resistor BR17 and one end of resistor BR18; the other end of resistor BR18 is connected with the positive electrode of capacitor BC13 and one end of resistor BR16; the negative electrode of capacitor BC13 is connected with the positive electrode of diode BD10 and ground wire;

[0011] The source of the switch tube Q3 is connected with the first input end of the output unit and the negative electrode of diode BD13; the second output end of transformer T1 is connected with the second input end of the output unit and ground wire;

[0012] The gate of the switch tube Q3 is connected with the other end of resistor BR16 and the negative electrode of Schottky diode BD11; the positive electrode of Schottky diode BD11 is connected with the positive electrode of diode BD13.

[0013] Further, the anti-rug unit further comprises diode BD8 and Schottky diode BD9;

[0014] The positive electrode of diode BD8 and the drain of switch tube Q3 are connected; the negative electrode of diode BD8 and the negative electrode of Schottky diode BD9 are connected; the positive electrode of Schottky diode BD9 is connected with the positive electrode of capacitor BC13.

[0015] Further, the negative electrode of diode D13 is connected with the positive electrode of capacitor C21, one end of capacitor C23 and one end of resistor R42;

[0016] The second output end of transformer T1 is connected with the negative electrode of capacitor C21, the other end of capacitor C23 and the other end of resistor R42.

[0017] Further, the positive electrode of diode D13 is connected with one end of resistor R40 and one end of resistor R41; the negative electrode of diode D13 is connected with the other end of resistor R40 and one end of capacitor C33; the other end of capacitor C33 is connected with the other end of resistor R41.

[0018] Further, the primary input assembly comprises input unit, driving unit and control unit;

[0019] The driving unit is connected with the input unit and the control unit; the output end of the driving unit is connected with the input end of transformer T1;

[0020] The current of the input unit is transmitted to the drive unit; and the control signal of the control unit is transmitted to the drive unit.

[0021] Further, the control unit comprises a controller U1; and the drive unit comprises a switch tube Q1.

[0022] The GATE pin of the controller U1 is connected with one end of a resistor R14 and one end of a resistor R15; the gate of the switch tube Q1 is connected with the other end of the resistor R15 and the anode of a diode D4; and the cathode of the diode D4 is connected with the other end of the resistor R14.

[0023] Further, a power supply HV is connected with one end of an inductor L1 and one end of a resistor R36; the other end of the inductor L1 is connected with the first input end of a transformer T1; the other end of the resistor R36 is connected with one end of a resistor R37; and the HV pin of the controller U1 is connected with the other end of the resistor R37.

[0024] Further, the drain of the switch tube Q1 is connected with the second input end of the transformer T1 and one end of a capacitor C4; and the source of the switch tube Q1 is connected with the other end of the capacitor C4.

[0025] Further, the output unit comprises a common-mode inductor T3.

[0026] The source of the switch tube Q3 is connected with the first input end of the common-mode inductor T3; and the second output end of the transformer T1 is connected with the second input end of the common-mode inductor T3.

[0027] The first output end of the common-mode inductor T3 is connected with the anode of an LED lamp; and the second output end of the common-mode inductor T3 is connected with the cathode of the LED lamp.

[0028] The application has the following advantages:

[0029] In the embodiment of the application, in order to solve the problem that the existing LED flickers when lighting and interferes with the occasions requiring high light stability, the application provides a solution of "arranging a ripple reduction unit in the output unit to control the on-resistance of the switch tube", specifically: the primary input assembly and the secondary output assembly are connected through the transformer T1; the first output end of the transformer T1 is connected with the drain of the switch tube Q3; the first output end of the output unit is connected with the source of the switch tube Q3; and the ripple reduction unit is connected with the drain, the source and the gate of the switch tube Q3 respectively; when the ripple is generated by the flyback conversion, the first output end of the output unit is boosted, and the ripple reduction unit is used to stabilize the gate potential of the switch tube Q3, so that the on-resistance of the switch tube Q3 is increased to reduce the ripple. By arranging the ripple reduction unit in the output unit to control the on-resistance of the switch tube, the power frequency ripple of the output current is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the description of the present application will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0031] Figure 1 is a structure block diagram of a low-ripple flyback PFC switching power supply provided by an embodiment of the present application;

[0032] Figure 2 is a circuit structure diagram of a secondary side output component in an embodiment of the present application;

[0033] Figure 3 is a circuit structure diagram of a primary side input component in an embodiment of the present application;

[0034] Figure 4 is a circuit structure diagram of an output rectification and filtering unit in a specific embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the objectives, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative labor fall within the scope of protection of the present application.

[0036] The inventors found through analysis of the prior art that the existing LED flickers when lighting, which easily causes interference in occasions requiring high light stability. The essential reason is that when the LED is driven by a switching power supply, the current frequency ripple output by the power supply circuit to the LED is large. Specifically, the frequency of the frequency ripple is usually low, generally 50Hz or 60Hz. If the capacity of the filter capacitor is not large enough, the process of energy storage and discharge of the capacitor cannot well smooth the output voltage in one frequency cycle, resulting in a large frequency ripple. Since the brightness of the LED is approximately proportional to the current, the frequency ripple will cause the current flowing through the LED to fluctuate. When the ripple current passes through the LED, the brightness of the LED will flicker with the ripple period.

[0037] Based on the above systematic analysis of the prior art, one of the core technical concepts of the present application is to set a ripple reduction unit in the output unit to control the on-resistance of the switching tube, thereby reducing the frequency ripple.

[0038] It should be noted that in any embodiment of the present application, the low-ripple flyback PFC switching power supply can be used for LED, and can also be used for other devices requiring low-ripple output.

[0039] Referring to Figure 1 , a low-ripple flyback PFC switching power supply provided by an embodiment of the present application is shown, which comprises: a primary input component and a secondary output component; the secondary output component comprises: a ripple reduction unit and an output unit;

[0040] The primary input component and the secondary output component are connected through a transformer T1; a first output end of the transformer T1 is connected with a drain of a switch tube Q3; a first output end of the output unit is connected with a source of the switch tube Q3; the ripple reduction unit is connected with the drain, the source and the gate of the switch tube Q3 respectively;

[0041] When the ripple is generated by the flyback conversion, the first output end of the output unit is boosted, and the ripple reduction unit is used to stabilize the gate potential of the switch tube Q3, so that the on-resistance of the switch tube Q3 is increased to reduce the ripple.

[0042] In the embodiment of the present application, in order to solve the problem that the existing LED flickers when lighting and interferes with the occasion requiring high light stability, the present application provides a solution of "providing a ripple reduction unit in the output unit to control the on-resistance of the switch tube", specifically: the primary input component and the secondary output component are connected through a transformer T1; a first output end of the transformer T1 is connected with a drain of a switch tube Q3; a first output end of the output unit is connected with a source of the switch tube Q3; the ripple reduction unit is connected with the drain, the source and the gate of the switch tube Q3 respectively; when the ripple is generated by the flyback conversion, the first output end of the output unit is boosted, and the ripple reduction unit is used to stabilize the gate potential of the switch tube Q3, so that the on-resistance of the switch tube Q3 is increased to reduce the ripple. By providing a ripple reduction unit in the output unit to control the on-resistance of the switch tube, the output current frequency ripple is reduced.

[0043] In the following, a low-ripple flyback PFC switching power supply in the present exemplary embodiment will be further described.

[0044] It should be noted that the working principle of the ripple reduction unit is: when the ripple is superimposed on the direct current, the voltage of the output end (LED+) is raised, and the G-pole voltage of the switch tube Q3 is fixed, so that the voltage of the GS-pole of the switch tube Q3 is reduced, the on-resistance of the switch tube Q3 is increased, and the top of the ripple is cut off.

[0045] Referring to Figure 2In an embodiment of the present application, the ripple reduction unit comprises a diode BD10, a Schottky diode BD11, a diode BD12, a diode BD13, a resistor BR16, a resistor BR17, a resistor BR18, a resistor BR20, a resistor BR21, a capacitor BC12 and a capacitor BC13.

[0046] The output end of the primary input assembly is connected with the input end of the transformer T1; the first output end of the transformer T1 is connected with the anode of the diode D13 and one end of the capacitor BC12;

[0047] The drain of the switch tube Q3 is connected with the cathode of the diode D13 and one end of the resistor BR17; the other end of the capacitor BC12 is connected with one end of the resistor BR20 and one end of the resistor BR21; the other end of the resistor BR21 is connected with the cathode of the diode BD10; the other end of the resistor BR20 is connected with the anode of the diode BD12; the cathode of the diode BD12 is connected with the other end of the resistor BR17 and one end of the resistor BR18; the other end of the resistor BR18 is connected with the anode of the capacitor BC13 and one end of the resistor BR16; the cathode of the capacitor BC13 is connected with the anode of the diode BD10 and the ground wire;

[0048] The source of the switch tube Q3 is connected with the first input end of the output unit and the cathode of the diode BD13; the second output end of the transformer T1 is connected with the second input end of the output unit and the ground wire;

[0049] The gate of the switch tube Q3 is connected with the other end of the resistor BR16 and the cathode of the Schottky diode BD11; the anode of the Schottky diode BD11 is connected with the anode of the diode BD13.

[0050] It should be noted that the ripple reduction unit uses discrete components to build a circuit, that is, the circuit can be built by using common diodes, triodes, resistors and capacitors, without using special IC in the ripple reduction unit, thereby reducing the design cost;

[0051] The specific working principle of the ripple reduction unit in the embodiment is as follows:

[0052] When the transformer T1 is in the negative half cycle, the secondary side current of the transformer T1 charges the capacitor BC12 through the BD10 and the BR21;

[0053] When the transformer T1 is in the positive half cycle, the secondary side current of the transformer T1 charges the capacitor BC13 through the resistor BR20, the diode BD12 rectification and the voltage charged by the capacitor BC12 in the negative half cycle, thereby the voltage of the capacitor BC13 is higher than the voltage of the LED+, so that the switch tube Q3 is half on;

[0054] Since the current passes through the resistor BR20, the resistor BR17, the switch tube Q3 and the LED light source in turn and then returns to the ground, the resistor BR20 and the resistor BR17 in series can reduce the voltage of the capacitor BC13, and then make the on-resistance of the switch tube Q3 larger, thereby reducing the ripple. Meanwhile, reducing the resistance of the resistor BR17 or increasing the resistance of the resistor BR20 can improve the effect of reducing the ripple.

[0055] In the embodiment, the resistor BR16 is used as the driving resistor of the switch tube Q3; and the Schottky diode BD11 and the diode BD13 are used for clamping.

[0056] With reference to Figure 2 In an embodiment of the present application, the ripple reduction unit further comprises a diode BD8 and a Schottky diode BD9.

[0057] The anode of the diode BD8 is connected with the drain of the switch tube Q3; the cathode of the diode BD8 is connected with the cathode of the Schottky diode BD9; and the anode of the Schottky diode BD9 is connected with the anode of the capacitor BC13.

[0058] It should be noted that the diode BD8 and the Schottky diode BD9 are used to charge the capacitor BC13 rapidly in the positive half cycle when the switch is turned on, so as to realize the rapid opening of the switch tube Q3.

[0059] With reference to Figure 2 In an embodiment of the present application, the cathode of the diode D13 is connected with the anode of the capacitor C21, one end of the capacitor C23 and one end of the resistor R42.

[0060] The second output end of the transformer T1 is connected with the cathode of the capacitor C21, the other end of the capacitor C23 and the other end of the resistor R42.

[0061] It should be noted that the capacitor C21, the capacitor C23 and the resistor R42 are used to rectify and filter the current of the output component.

[0062] With reference to Figure 2 In an embodiment of the present application, the anode of the diode D13 is connected with one end of the resistor R40 and one end of the resistor R41; the cathode of the diode D13 is connected with the other end of the resistor R40 and one end of the capacitor C33; and the other end of the capacitor C33 is connected with the other end of the resistor R41.

[0063] It should be noted that the resistor R40, the resistor R41 and the capacitor C33 are used to rectify and filter the current of the output component.

[0064] With reference to Figure 1In an embodiment of the present application, the primary side input assembly comprises an input unit, a driving unit and a control unit.

[0065] The driving unit is connected with the input unit and the control unit; an output end of the driving unit is connected with an input end of the transformer T1.

[0066] The input unit transmits current to the driving unit; the control unit transmits a control signal to the driving unit.

[0067] Referring to Figure 3 In an embodiment of the present application, the control unit comprises a controller U1; the driving unit comprises a switch tube Q1.

[0068] A GATE pin of the controller U1 is connected with one end of a resistor R14 and one end of a resistor R15; a gate of the switch tube Q1 is connected with the other end of the resistor R15 and a positive electrode of a diode D4; a negative electrode of the diode D4 is connected with the other end of the resistor R14.

[0069] Referring to Figure 3 In an embodiment of the present application, a power supply HV is connected with one end of an inductor L1 and one end of a resistor R36; the other end of the inductor L1 is connected with a first input end of the transformer T1; the other end of the resistor R36 is connected with one end of a resistor R37; a HV pin of the controller U1 is connected with the other end of the resistor R37.

[0070] Referring to Figure 3 In an embodiment of the present application, a drain of the switch tube Q1 is connected with a second input end of the transformer T1 and one end of a capacitor C4; a source of the switch tube Q1 is connected with the other end of the capacitor C4.

[0071] Referring to Figure 3 In an embodiment of the present application, the output unit comprises a common mode inductor T3.

[0072] A source of the switch tube Q3 is connected with a first input end of the common mode inductor T3; a second output end of the transformer T1 is connected with a second input end of the common mode inductor T3.

[0073] The first output end of the common mode inductor T3 is connected with a positive electrode of the LED lamp; the second output end of the common mode inductor T3 is connected with a negative electrode of the LED lamp.

[0074] Referring to Figure 3 In a specific embodiment of the present application, the input unit further comprises a lightning surge absorption subunit, an EMC filter subunit and a rectification filter subunit.

[0075] The input end of the lightning surge absorption subunit is connected with an AC power supply; the output end of the lightning surge absorption subunit is connected with the input end of the EMC filtering subunit; the output end of the EMC filtering subunit is connected with the input end of the rectification filtering subunit; and the output end of the rectification filtering subunit is connected with the input end of the fluctuation unit.

[0076] It should be noted that the lightning surge absorption subunit comprises a fuse F1, a voltage-dependent resistor MOV1, a capacitor CY2 and a capacitor CY3; the EMC filtering subunit comprises a common-mode inductor LF1 and a common-mode inductor LF2; and the rectification filtering subunit comprises a capacitor CX2 and a rectification bridge DB1.

[0077] Reference Figure 4 In an embodiment of the present application, the output assembly further comprises an output rectification filtering unit, which is configured to output a DIM signal.

[0078] Although the preferred embodiments of the present application have been described, those skilled in the art who have the benefit of the basic inventive concept can make further changes and modifications to the embodiments. Therefore, the appended claims are intended to cover all changes and modifications falling within the scope of the embodiments of the present application.

[0079] Finally, it should be noted that, in this document, the terms such as first and second are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between the entities or operations. Moreover, the terms "comprise", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or terminal device. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.

[0080] The above has provided a detailed description of a low-ripple flyback PFC switching power supply according to the present application. In this document, specific examples are applied to describe the principles and implementation modes of the present application. The above description of the embodiments is only used to help understand the method and core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation modes and application ranges can be changed; and in view of the above, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A low-ripple flyback PFC switching power supply, characterized in that, The utility model relates to a kind of transformer, including: Primary side input component and secondary side output component; The secondary side output component includes: wavelet reduction unit and output unit; The primary side input component and the secondary side output component are connected by transformer T1;The first output end of the transformer T1 is connected with the drain of switch tube Q3;The first output end of the output unit is connected with the source of the switch tube Q3;The wavelet reduction unit is connected with the drain, source and gate of the switch tube Q3 respectively; When the wavelet of reverse flyback conversion occurs, the first output end of the output unit is boosted, and the wavelet reduction unit is used to stabilize the gate potential of the switch tube Q3, so that the on-resistance of the switch tube Q3 increases to reduce the wavelet.

2. The low-ripple flyback PFC switching power supply of claim 1, wherein, The wavelet reduction unit includes: diode BD10, Schottky diode BD11, diode BD12, diode BD13, resistor BR16, resistor BR17, resistor BR18, resistor BR20, resistor BR21, capacitor BC12 and capacitor BC13; The output end of the primary side input component is connected with the input end of the transformer T1;The first output end of the transformer T1 is connected with the positive electrode of diode D13 and one end of capacitor BC12; The drain of the switch tube Q3 is connected with the negative electrode of diode D13 and one end of resistor BR17;The other end of the capacitor BC12 is connected with one end of resistor BR20 and one end of resistor BR21;The other end of the resistor BR21 is connected with the negative electrode of diode BD10;The other end of the resistor BR20 is connected with the positive electrode of diode BD12;The negative electrode of the diode BD12 is connected with the other end of the resistor BR17 and one end of the resistor BR18;The other end of the resistor BR18 is connected with the positive electrode of the capacitor BC13 and one end of the resistor BR16;The negative electrode of the capacitor BC13 is connected with the positive electrode of the diode BD10 and ground wire; The source of the switch tube Q3 is connected with the first input end of the output unit and the negative electrode of diode BD13;The second output end of the transformer T1 is connected with the second input end of the output unit and ground wire; The gate of the switch tube Q3 is connected with the other end of the resistor BR16 and the negative electrode of the Schottky diode BD11;The positive electrode of the Schottky diode BD11 is connected with the positive electrode of the diode BD13.

3. The low-ripple flyback PFC switching power supply of claim 2, wherein, The wavelet reduction unit further includes: diode BD8 and Schottky diode BD9; The positive electrode of the diode BD8 is connected with the drain of the switch tube Q3;The negative electrode of the diode BD8 is connected with the negative electrode of the Schottky diode BD9;The positive electrode of the Schottky diode BD9 is connected with the positive electrode of the capacitor BC13.

4. The low-ripple flyback PFC switching power supply of claim 2, wherein, The negative electrode of the diode D13 is connected with the positive electrode of the capacitor C21, one end of the capacitor C23 and one end of the resistor R42; The second output end of the transformer T1 is connected with the negative electrode of the capacitor C21, the other end of the capacitor C23 and the other end of the resistor R42.

5. The low-ripple flyback PFC switching power supply of claim 2, wherein, The positive electrode of the diode D13 is connected with one end of the resistor R40 and one end of the resistor R41; the negative electrode of the diode D13 is connected with the other end of the resistor R40 and one end of the capacitor C33; the other end of the capacitor C33 is connected with the other end of the resistor R41.

6. The low-ripple flyback PFC switching power supply of claim 1, wherein, The primary input assembly comprises an input unit, a driving unit and a control unit. The driving unit is connected with the input unit and the control unit; the output end of the driving unit is connected with the input end of the transformer T1; The current of the input unit is transmitted to the driving unit; the control signal of the control unit is transmitted to the driving unit.

7. The low-ripple flyback PFC switching power supply of claim 6, wherein, The control unit comprises a controller U1; the driving unit comprises a switch tube Q1; The GATE pin of the controller U1 is connected with one end of the resistor R14 and one end of the resistor R15; the gate of the switch tube Q1 is connected with the other end of the resistor R15 and the positive electrode of the diode D4; the negative electrode of the diode D4 is connected with the other end of the resistor R14.

8. The low-ripple flyback PFC switching power supply of claim 7, wherein, The power supply HV is connected with one end of the inductor L1 and one end of the resistor R36; the other end of the inductor L1 is connected with the first input end of the transformer T1; the other end of the resistor R36 is connected with one end of the resistor R37; the HV pin of the controller U1 is connected with the other end of the resistor R37.

9. The low-ripple flyback PFC switching power supply of claim 8, wherein, The drain of the switch tube Q1 is connected with the second input end of the transformer T1 and one end of the capacitor C4; the source of the switch tube Q1 is connected with the other end of the capacitor C4.

10. The low-ripple flyback PFC switching power supply of claim 1, wherein, The output unit comprises a common mode inductor T3; The source of the switch tube Q3 is connected with the first input end of the common mode inductor T3; the second output end of the transformer T1 is connected with the second input end of the common mode inductor T3; The first output end of the common mode inductor T3 is connected with the positive electrode of the LED lamp; the second output end of the common mode inductor T3 is connected with the negative electrode of the LED lamp.

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