Peak voltage lossless absorption circuit of LED flyback switching power supply

Abstract

The utility model discloses a peak voltage lossless absorption circuit of an LED flyback switching power supply, comprising a voltage lossless absorption module, a main power conversion module and a voltage stabilization feedback module, the voltage lossless absorption module is respectively connected with a power supply and the main power conversion module; the output end of the main power conversion module is connected with the input end of the voltage stabilization feedback module; the voltage lossless absorption module comprises a first electrolytic capacitor, a first MOS tube, a first diode and a second diode, the source electrode of the first MOS tube is connected with the positive electrode of the power supply, the drain electrode of the first MOS tube is connected with the positive electrode of the first electrolytic capacitor, and the negative electrode of the first electrolytic capacitor is connected with the negative electrode of the power supply; the grid electrode of the first MOS tube is connected with the negative electrode of the first diode, and the positive electrode of the first diode is connected with the main power conversion module; the cathode of the second diode is connected with the anode of the first electrolytic capacitor, and the anode of the second diode is connected with the main power conversion module.

Description

Technical Field

[0001] The utility model belongs to the technical field of LEDs, and in particular relates to a peak voltage lossless absorption circuit of an LED flyback switching power supply. Background Art

[0002] like Figure 1 In the prior art, when the main power tube of the flyback switching power supply is turned off, the primary winding of the transformer will generate a peak voltage (also called reverse induced voltage) passing through the MOS tube Q'. The voltage is also superimposed with the power input voltage and the secondary reflected voltage. The superimposed voltage greatly exceeds the withstand voltage of the MOS tube Q'. If the voltage is not absorbed, the voltage will break down and damage the MOS tube.

[0003] In the prior art, in order to prevent the peak voltage and the voltage after superposition from damaging the MOS tube, a clamping network is usually set to absorb the energy generated by the primary winding of the transformer to prevent the MOS tube from being broken down. An RCD absorption circuit is usually used to convert the leakage inductance energy into heat through a resistor, but the power loss of the RCD is too large, which limits the efficiency of the flyback switching power supply. Utility Model Content

[0004] In order to overcome one or more of the above technical defects, the utility model provides a peak voltage lossless absorption circuit for an LED flyback switching power supply.

[0005] In order to solve the above problems, the utility model is implemented according to the following technical solutions:

[0006] A peak voltage lossless absorption circuit of an LED flyback switching power supply comprises a voltage lossless absorption module, a main power conversion module and a voltage stabilization feedback module, wherein the voltage lossless absorption module is connected to the power supply and the main power conversion module respectively, and the output end of the main power conversion module is connected to the input end of the voltage stabilization feedback module;

[0007] The voltage lossless absorption module includes a first electrolytic capacitor, a first MOS tube, a first diode and a second diode.

[0008] The source of the first MOS tube is connected to the positive electrode of the power supply, the drain of the first MOS tube is connected to the positive electrode of the first electrolytic capacitor, and the negative electrode of the first electrolytic capacitor is connected to the negative electrode of the power supply; the gate of the first MOS tube is connected to the negative electrode of the first diode, and the positive electrode of the first diode is connected to the main power conversion module;

[0009] The cathode of the second diode is connected to the anode of the first electrolytic capacitor, and the anode of the second diode is connected to the main power conversion module.

[0010] Optionally, the voltage lossless absorption module further includes a third diode and a resistor, and two ends of the third diode are respectively connected to the power supply.

[0011] The first diode is connected to the main power conversion module through a resistor.

[0012] Optionally, the main power conversion module includes a control chip, a second MOS tube and a transformer, the drain of the second MOS tube is connected to the anode of the second diode, the gate of the second MOS tube is connected to the control chip, and the source of the second MOS tube is grounded through a sampling resistor;

[0013] Two ends of the primary winding of the transformer are respectively connected to the positive electrode of the second diode and the first auxiliary winding, the other end of the first auxiliary winding is connected to the resistor, and the primary winding of the transformer is also connected to the drain of the first MOS tube.

[0014] Optionally, a control chip power supply module is also included, and the control chip power supply module is connected to the power supply and the main power conversion module respectively.

[0015] Optionally, a filter module is further included, wherein the input end of the filter module is connected to the power supply, and the output end is connected to the voltage lossless absorption module.

[0016] Optionally, an input rectifier module is further included, wherein the input end of the input rectifier module is connected to the power supply, and the output end is connected to the filter module.

[0017] Optionally, an output rectification and filtering module is also included, and the output rectification and filtering module is connected to the voltage stabilization feedback module.

[0018] Compared with the prior art, the utility model has the following beneficial effects:

[0019] The utility model discloses a peak voltage lossless absorption circuit of an LED flyback switching power supply. The circuit comprises a voltage lossless absorption module, a main power conversion module and a voltage stabilization feedback module. The voltage lossless absorption module is respectively connected to the power supply and the main power conversion module, and the output end of the main power conversion module is connected to the input end of the voltage stabilization feedback module. The voltage lossless absorption module comprises a first electrolytic capacitor, a first MOS tube, a first diode and a second diode. By adding the voltage lossless absorption module comprising the first electrolytic capacitor, the first MOS tube, the first diode and the second diode in the circuit, the reverse induced voltage generated by the transformer when the MOS tube is cut off can be absorbed and stored, and the voltage is returned, so as to realize the lossless absorption and reuse of the peak voltage, realize the lossless clamping process, and improve the efficiency and reliability of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The specific implementation of the utility model is further described in detail below with reference to the accompanying drawings, wherein:

[0021] Figure 1 A circuit diagram of the prior art;

[0022] Figure 2 A circuit diagram of a peak voltage lossless absorption circuit of an LED flyback switching power supply according to Example 1;

[0023] Marking description: 1. Voltage lossless absorption module; 2. Main power conversion module; 3. Voltage stabilization feedback module; 4. Control chip power supply module; 5. Filter module; 6. Input rectifier module; 7. Output rectifier filter module. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0025] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0027] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0028] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, in this specification, the term "and / or" includes any and all combinations of the relevant listed items.

[0029] Example 1

[0030] This embodiment discloses a peak voltage lossless absorption circuit of an LED flyback switching power supply. Figure 2 , including a voltage lossless absorption module 1, a main power conversion module 2 and a voltage stabilization feedback module 3. The voltage lossless absorption module 1 is connected to the power supply and the main power conversion module 2 respectively, and the output end of the main power conversion module 2 is connected to the input end of the voltage stabilization feedback module 3.

[0031] The voltage lossless absorption module 1 includes a first electrolytic capacitor EC1, a first MOS tube Q1, a first diode D6 and a second diode D7. The source of the first MOS tube Q1 is connected to the positive electrode of the power supply, the drain of the first MOS tube Q1 is connected to the positive electrode of the first electrolytic capacitor EC1, and the negative electrode of the first electrolytic capacitor EC1 is connected to the negative electrode of the power supply; the gate of the first MOS tube Q1 is connected to the negative electrode of the first diode D6, and the positive electrode of the first diode D6 is connected to the main power conversion module 2; the negative electrode of the second diode D7 is connected to the positive electrode of the first electrolytic capacitor EC1, and the positive electrode of the second diode D7 is connected to the main power conversion module 2.

[0032] Specifically, the voltage lossless absorption module 1 further includes a third diode D5 and a resistor R4 , two ends of the third diode D5 are respectively connected to the power supply, and the first diode D6 is connected to the main power conversion module 2 through the resistor R4 .

[0033] Specifically, the main power conversion module 2 includes a control chip U1, a second MOS transistor Q2 and a transformer T1, the drain of the second MOS transistor Q2 is connected to the anode of the second diode D7, the gate of the second MOS transistor Q2 is connected to the control chip U1, and the source of the second MOS transistor Q2 is grounded through a sampling resistor R7;

[0034] Two ends of the primary winding N1 of the transformer T1 are connected to the anode of the second diode D7 and the first auxiliary winding N2 respectively. The other end of the first auxiliary winding N2 is connected to the resistor R4. The primary winding N1 of the transformer T1 is also connected to the drain of the first MOS transistor Q1.

[0035] Specifically, it also includes a control chip power supply module 4, which is connected to the power supply and the main power conversion module 2 respectively.

[0036] In one embodiment, the control chip power supply module 4 includes resistors R1 , R2 , R3 , a diode D8 and an electrolytic capacitor EC2 .

[0037] Specifically, it also includes a filter module 5 , the input end of the filter module 5 is connected to the power supply, and the output end is connected to the voltage lossless absorption module 1 .

[0038] In one embodiment, the filtering module 5 includes a capacitor C1.

[0039] Specifically, it also includes an input rectifier module 6 , the input end of the input rectifier module 6 is connected to the power supply, and the output end is connected to the filter module 5 .

[0040] In one embodiment, the input rectifier module 6 includes a rectifier bridge composed of diodes D1 , D2 , D3 , and D4 .

[0041] In one embodiment, the voltage stabilization feedback module 3 includes resistors R8, R9, R10, R11, and R12, an optical coupler U2, a three-terminal voltage regulator U3, and capacitors C2, C3, and C4.

[0042] Specifically, it also includes an output rectification and filtering module 7, which is connected to the voltage stabilization feedback module 3 to convert the output voltage into a smooth DC low-voltage output.

[0043] In one embodiment, the output rectification and filtering module 7 includes a diode D9 and an electrolytic capacitor EC3.

[0044] When the circuit is just powered on, the second MOS tube Q2 is in the cut-off state, the AC mains is rectified into DC by the input rectifier module 6, and then the high-frequency ripple voltage is filtered out by the filter module 5, and then the main power conversion module 2 is powered by the control chip power supply module 4. The control chip U1 in the main power conversion module 2 is powered on and works, and the output PWM voltage drives the second MOS tube Q2 to turn on. At this time, the power supply current flows through the primary winding N1 of the transformer T1 to store energy in the transformer core. The output end of the transformer is in reverse phase with the same-name end of the output winding N4 and the primary winding N1, and the diode D9 is turned off. The first auxiliary winding N2 is in phase with the same-name end of the primary winding N1, and the diode D6 is turned on. The current of the first auxiliary winding N2 is limited by the resistor R4 and rectified by the first diode D6, and then drives the first MOS tube Q1 to turn on. The voltage of the first electrolytic capacitor EC1 is released to the primary winding N1 and the second MOS tube Q2 through the first MOS tube Q1.

[0045] When the second MOS transistor Q2 is turned off, each winding on the transformer T1 generates a reverse induced voltage. At this time, the induced voltage of the output winding N4 of the transformer T1 is positive at the top and negative at the bottom, and the diode D9 is turned on to output current to the load; the induced voltage of the first auxiliary winding N2 is negative at the top and positive at the bottom, the diode D6 is turned off, and the first MOS transistor Q1 is turned off. At this time, the primary winding N1 generates a reverse induced voltage (specifically Figure 2 The circuit in the circuit generates a voltage that is positive at the bottom and negative at the top), which charges the first electrolytic capacitor EC1 through the second diode D7 and returns to the primary winding N1 of the transformer T1 through the third diode D5, returning the peak voltage generated by the transformer winding to the power supply to achieve lossless absorption.

[0046] The utility model adds a voltage lossless absorption module including a first electrolytic capacitor, a first MOS tube, a first diode and a second diode in the circuit, absorbs and stores the reverse induced voltage (i.e., peak voltage) generated by the primary winding of the transformer when the MOS tube is turned off on the electrolytic capacitor, and returns the voltage to the power supply, thereby realizing lossless absorption and reuse of the peak voltage and lossless clamping process; at the same time, it can also solve the heat dissipation problem related to the dissipated leakage energy in the circuit, and improve the efficiency and reliability of the power supply.

[0047] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Therefore, any modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A peak voltage lossless absorption circuit for an LED flyback switching power supply, characterized in that: It includes a voltage lossless absorption module, a main power conversion module and a voltage stabilization feedback module, wherein the voltage lossless absorption module is connected to the power supply and the main power conversion module respectively, and the output end of the main power conversion module is connected to the input end of the voltage stabilization feedback module; The voltage lossless absorption module includes a first electrolytic capacitor, a first MOS tube, a first diode and a second diode. The source of the first MOS tube is connected to the positive electrode of the power supply, the drain of the first MOS tube is connected to the positive electrode of the first electrolytic capacitor, and the negative electrode of the first electrolytic capacitor is connected to the negative electrode of the power supply; the gate of the first MOS tube is connected to the negative electrode of the first diode, and the positive electrode of the first diode is connected to the main power conversion module; The cathode of the second diode is connected to the anode of the first electrolytic capacitor, and the anode of the second diode is connected to the main power conversion module.

2. The spike voltage lossless absorption circuit according to claim 1, characterized in that: The voltage lossless absorption module also includes a third diode and a resistor, and two ends of the third diode are respectively connected to the power supply. The first diode is connected to the main power conversion module through a resistor.

3. The spike voltage lossless absorption circuit according to claim 1, characterized in that: The main power conversion module includes a control chip, a second MOS tube and a transformer, the drain of the second MOS tube is connected to the anode of the second diode, the gate of the second MOS tube is connected to the control chip, and the source of the second MOS tube is grounded through a sampling resistor; Two ends of the primary winding of the transformer are respectively connected to the positive electrode of the second diode and the first auxiliary winding, the other end of the first auxiliary winding is connected to the resistor, and the primary winding of the transformer is also connected to the drain of the first MOS tube.

4. The spike voltage lossless absorption circuit according to claim 1, characterized in that: It also includes a control chip power supply module, which is connected to the power supply and the main power conversion module respectively.

5. The spike voltage lossless absorption circuit according to claim 1, characterized in that: It also includes a filter module, the input end of the filter module is connected to the power supply, and the output end is connected to the voltage lossless absorption module.

6. The spike voltage lossless absorption circuit according to claim 5, characterized in that: It also includes an input rectifier module, the input end of which is connected to the power supply, and the output end of which is connected to the filter module.

7. The spike voltage lossless absorption circuit according to claim 1, characterized in that: It also includes an output rectification and filtering module, and the output rectification and filtering module is connected to the voltage stabilization feedback module.

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