Leakage inductance recovery circuit and flyback power supply
By designing a leakage inductance recovery circuit in the power supply, the leakage inductance energy of the primary coil of the transformer is recovered and converted into the power supply voltage, the problems of low leakage inductance energy utilization and low working efficiency in the existing power supply are solved, and more efficient power operation is achieved.
Patent Information
- Application Number
- CN202421418871.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-20
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-06-20
AI Technical Summary
Due to the existence of leakage inductance in the existing power supply, the switching device is overvoltage breakdown, and the leakage inductance suppression circuit consumes the leakage energy stored by the transformer, reducing the power efficiency.
A leakage inductance recovery circuit is designed, through the recovery unit, the leakage inductance energy of the transformer primary coil when the voltage is reversed, and converted into a power supply voltage for use by the main control unit.
The utilization rate of leakage inductance energy is improved, the energy loss of the power supply is reduced, and the working efficiency of the power supply is improved.
Smart Images
Figure CN222721355U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electronic circuits, in particular to a leakage inductance recovery circuit and a flyback power supply. Background Art
[0002] In existing small and medium power supplies, due to the existence of transformer leakage inductance, when the switching device is turned off, a back electromotive force will be generated, which can easily cause the switching device (such as a switch MOS or a transistor) to be over-voltage and breakdown. The leakage inductance can also form an oscillation circuit with the distributed capacitance in the circuit and the distributed capacitance of the transformer coil, causing the circuit to oscillate and radiate electromagnetic energy outward, causing electromagnetic interference. Therefore, in order to protect the switching devices in the power supply, a leakage inductance suppression circuit is usually provided in the power supply to suppress the leakage inductance to protect the switching devices in the power supply. However, since the existing leakage inductance suppression circuit usually uses a resistor or a diode for suppression, this leakage inductance suppression circuit will consume the leakage inductance energy stored in the transformer, occupying about 2% of the power supply efficiency, thereby reducing the working efficiency of the power supply.
[0003] Therefore, in order to solve the above problems, the utility model provides a leakage inductance recovery circuit and a flyback power supply which can improve the leakage inductance energy utilization rate and the power supply working efficiency. Utility Model Content
[0004] The utility model provides a leakage inductance recovery circuit and a flyback power supply, aiming to solve the problem that leakage inductance energy utilization rate and working efficiency of the existing power supply are both low.
[0005] In order to solve the above technical problems, the utility model provides a leakage inductance recovery circuit on the one hand, which includes: a main control unit, the main control unit is used to provide a cut-off signal; a switch unit, one end of which is connected to the main control unit, and the other end is used to be connected to the primary coil of the transformer, the switch unit is used to cut off according to the cut-off signal to reverse the voltage of the primary coil of the transformer; a recovery unit, one end of which is connected to the switch unit, and the other end is connected to the main control unit, the recovery unit is used to recover the leakage inductance energy of the primary coil of the transformer when the voltage is reversed, and convert the leakage inductance energy into a supply voltage to supply power to the main control unit.
[0006] Furthermore, the recovery unit includes a recovery module, a voltage drop module and a filtering module, one end of the recovery module is connected to the switch unit, and the other end is connected to one end of the voltage drop module, and the other end of the voltage drop module is connected to the main control unit; one end of the filtering module is connected to the voltage drop module, and the other end is grounded.
[0007] Furthermore, the recovery module includes a first diode, a first capacitor and a first resistor, the positive electrode of the first diode is connected to the switching unit, the negative electrode of the first diode is connected to one end of the first capacitor and the first resistor, the other end of the first capacitor is connected to the voltage drop module, and the other end of the first resistor is used to be connected to the primary coil of the transformer.
[0008] Furthermore, the voltage drop module includes a second diode and a third diode, the anode of the second diode is connected to the first capacitor, the cathode of the second diode is connected to the anode of the third diode and the filter module, and the cathode of the third diode is connected to the main control unit.
[0009] Further, the filtering module includes a second capacitor, one end of the second capacitor is connected to the cathode of the second diode, and the other end of the second capacitor is grounded.
[0010] Furthermore, the recovery unit further includes a current limiting module, one end of which is connected between the anode of the second diode and the first capacitor, and the other end of which is grounded.
[0011] Furthermore, the current limiting module includes a fourth diode, a cathode of the fourth diode is connected between an anode of the second diode and the first capacitor, and an anode of the fourth diode is grounded.
[0012] Furthermore, the main control unit includes an IC chip and a third capacitor, the power supply end of the IC chip is connected to the cathode of the third diode and one end of the third capacitor, the signal output end of the IC chip is connected to the switch unit, and the other end of the third capacitor is grounded.
[0013] Furthermore, the switching unit includes a MOS tube, a second resistor and a third resistor, the gate of the MOS tube is connected to the signal output end of the IC chip, the drain of the MOS tube is connected to the positive electrode of the first diode and the primary coil of the transformer, the source of the MOS tube is connected to one end of the second resistor and the third resistor, and the other end of the second resistor and the third resistor is grounded.
[0014] On the other hand, the utility model also provides a flyback power supply, which includes an anti-interference unit, a rectifier and filter unit and the above-mentioned leakage inductance recovery circuit, wherein one end of the anti-interference unit is used to receive alternating current, and the other end is connected to one end of the rectifier and filter unit, and the other end of the rectifier and filter unit is connected to the leakage inductance recovery circuit and the primary coil of the transformer.
[0015] The leakage inductance recovery circuit and flyback power supply disclosed by the utility model recover the leakage inductance energy when the switch unit is turned off through the recovery unit and convert it into a power supply voltage, and provide the power supply voltage to the main control unit for the main control unit to start and operate, thereby realizing the recovery of leakage inductance energy, improving the utilization rate of leakage inductance energy, and further improving the working efficiency of the power supply. The leakage inductance recovery circuit disclosed by the utility model solves the problem that the leakage inductance energy utilization rate and working efficiency of the existing power supply are both low. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0017] Figure 1 is a circuit schematic diagram of a leakage inductance suppression circuit in the prior art;
[0018] Figure 2 It is a circuit schematic diagram of a flyback power supply provided with a leakage inductance suppression circuit in the prior art;
[0019] Figure 3 It is a structural schematic diagram of a leakage inductance recovery circuit provided by an embodiment of the utility model;
[0020] Figure 4 It is a circuit schematic diagram of a leakage inductance recovery circuit provided by an embodiment of the utility model;
[0021] Figure 5 It is a structural schematic diagram of a flyback power supply provided by an embodiment of the utility model;
[0022] Figure 6 The utility model is provided in an embodiment of the present invention, which is a circuit schematic diagram of a flyback power supply provided with a leakage inductance recovery circuit.
[0023] Reference numerals:
[0024] 10. Leakage inductance recovery circuit; 11. Main control unit; 12. Switch unit; 13. Recovery unit; 131. Recovery module; 132. Voltage drop module; 133. Filter module; 134. Current limiting module; 100. Flyback power supply; 20. Anti-interference unit; 30. Rectification and filtering unit. DETAILED DESCRIPTION
[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0026] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.
[0027] It should also be understood that the terms used in this utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in this utility model specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.
[0028] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.
[0029] See also Figure 1 and Figure 2 , Figure 1 The schematic diagram of the leakage inductance suppression circuit in the existing power supply is shown in FIG. Figure 2The schematic diagram of the flyback power supply with a leakage inductance suppression circuit is shown in FIG. In the existing small and medium power supply, after the AC power is input, the AC current is subjected to EMI interference prevention by capacitors CX3, CX2 and inductor L1, and then rectified by rectifier bridges BD1 and BD2, and filtered by filter capacitors EC1 and EC2 to be a smooth DC voltage to be input into the transformer. When the MOS tube Q3A is turned on, the filtered DC voltage supplies power to the transformer normally; when the MOS tube Q3A is turned off, the voltage of the primary coil of the transformer is reversed, and the energy stored in the leakage inductance of the primary coil of the transformer cannot be transferred to the secondary coil. The leakage inductance of the primary coil of the transformer and the parasitic capacitance of the MOS tube Q3A generate a resonant voltage waveform, and the voltage peak of this resonant voltage waveform is superimposed on the reflected voltage of the secondary coil and the input voltage of the power supply, directly charging the capacitor C2. At this time, the voltage of the capacitor C2 will rise rapidly. After the diode D3 is turned off, the capacitor C2 is discharged through the resistor R45 and the clamping resistor R4. Before the MOS tube Q3A is turned on, the clamping resistor R4 becomes the load of the transformer, thereby consuming the energy stored in the transformer and reducing the working efficiency of the power supply. Therefore, in order to improve the leakage inductance energy utilization rate and the working efficiency of the power supply, the present application provides a leakage inductance recovery circuit that can recover leakage inductance energy.
[0030] Figures 3 to 6 An embodiment of the leakage inductance recovery circuit provided by the utility model is shown. The leakage inductance recovery circuit 10 of this embodiment includes a main control unit 11, a switch unit 12 and a recovery unit 13, wherein the main control unit 11 is used to provide a cut-off signal; one end of the switch unit 12 is connected to the main control unit 11, and the other end is used to connect to the primary coil of the transformer, and the switch unit 12 is used to cut off according to the cut-off signal to reverse the voltage of the primary coil of the transformer; one end of the recovery unit 13 is connected to the switch unit 12, and the other end is connected to the main control unit 11, and the recovery unit 13 is used to recover the leakage inductance energy of the primary coil of the transformer when the voltage is reversed, and convert the leakage inductance energy into a power supply voltage to supply power to the main control unit 11. In this embodiment, the leakage inductance energy when the switch unit 12 is cut off is recovered and converted into a power supply voltage by the recovery unit 13, and the power supply voltage is provided to the main control unit 11 for the main control unit 11 to start and run, thereby realizing the recovery of leakage inductance energy, improving the utilization rate of leakage inductance energy, and thus improving the working efficiency of the power supply.
[0031] In one embodiment, such as this embodiment, Figure 4As shown, the recovery unit 13 includes a recovery module 131, a voltage drop module 132 and a filter module 133, one end of the recovery module 131 is connected to the switch unit 12, and the other end is connected to one end of the voltage drop module 132, and the other end of the voltage drop module 132 is connected to the main control unit 11; one end of the filter module 133 is connected to the voltage drop module 132, and the other end is grounded. Specifically, the recovery module 131 includes a first diode D3, a first capacitor C2 and a first resistor R4, the positive electrode of the first diode D3 is connected to the switch unit 12, the negative electrode of the first diode D3 is connected to one end of the first capacitor C2 and the first resistor R4, the other end of the first capacitor C2 is connected to the voltage drop module 132, and the other end of the first resistor R4 is used to connect to the primary coil of the transformer.
[0032] Furthermore, the voltage drop module 132 includes a second diode D2 and a third diode D5, the anode of the second diode D2 is connected to the first capacitor C2, the cathode of the second diode D2 is connected to the anode of the third diode D5 and the filtering module 133, and the cathode of the third diode D5 is connected to the main control unit 11.
[0033] Furthermore, the filtering module 133 includes a second capacitor C1, one end of the second capacitor C1 is connected to the cathode of the second diode D2, and the other end of the second capacitor C1 is grounded. The voltage spike can be smoothed by the second capacitor C1.
[0034] Further, the recovery unit 13 further includes a current limiting module 134, one end of which is connected between the anode of the second diode and the first capacitor, and the other end is grounded. Specifically, the current limiting module 134 includes a fourth diode D1, a cathode of which is connected between the anode of the second diode D2 and the first capacitor C2, and a cathode of the fourth diode D1 is grounded.
[0035] In one embodiment, such as this embodiment, Figure 4 As shown, the main control unit 11 includes an IC chip U1 and a third capacitor C4, the power supply terminal VDD of the IC chip U1 is connected to the cathode of the third diode D5 and one end of the third capacitor C4, the signal output terminal DRV of the IC chip U1 is connected to the switch unit 12, and the other end of the third capacitor C4 is grounded. It should be noted that in this embodiment, the third capacitor C4 is a small chip capacitor.
[0036] In one embodiment, such as this embodiment, Figure 4As shown, the switch unit 12 includes a MOS tube Q3A, a second resistor R13 and a third resistor R5, the gate of the MOS tube Q3A is connected to the signal output terminal DRV of the IC chip U1, the drain of the MOS tube Q3A is connected to the positive electrode of the first diode D3 and the primary coil of the transformer, the source of the MOS tube Q3A is connected to one end of the second resistor R13 and the third resistor R5, and the other ends of the second resistor R13 and the third resistor R5 are grounded.
[0037] It should be noted that the leakage inductance recovery circuit of this embodiment realizes the process of leakage inductance recovery as follows: when the IC chip U1 sends a cut-off signal to control the MOS tube Q3A to be cut off, the voltage of the primary coil of the transformer is reversed, and the energy stored in the leakage inductance of the primary coil of the transformer is turned on through the first diode D3, and the leakage inductance energy charges the first capacitor C2 to realize energy recovery, and the energy recovered by the first capacitor C2 is reduced in voltage through the second diode D2, and the voltage after the voltage drop is smoothed by the second capacitor C1. The voltage input value is further reduced by the third diode D5 to the power supply terminal VDD of the IC chip U1, thereby supplying power to the IC chip U1. Among them, in the recovery module, the first resistor R4 is used as a clamping resistor, and its resistance value is several hundred K ohms or several megohms, that is, the resistance value of the first resistor R4 is relatively large. When the MOS tube Q3A is turned off, since the impedance of the first resistor R4 is large and it is in a high impedance state, it will cause a circuit similar to being broken, which can prevent energy from flowing through the first resistor R4, so that the energy flows through a low impedance channel, thereby preventing the first resistor R4 from consuming the energy stored in the transformer, and the energy flowing through the low impedance channel can be reused to power the IC chip U1, thereby improving energy utilization and further improving the working efficiency of the power supply.
[0038] It should also be noted that, in this embodiment, the leakage inductance recovery circuit 10 of this embodiment can not only recover the leakage inductance energy to power the IC chip U1, but also can be used for high-voltage startup of the IC chip. Since the energy is added to the IC chip U1, the number of turns of the power supply winding of the primary feedback winding T1D of the transformer can be reduced, for example, Figure 4 In the embodiment, only one small chip capacitor C4 is needed in the primary feedback winding T1D to meet the requirement. Compared with the original circuit which needs one 10uF electrolytic capacitor, it can reduce the cost and recover the leakage inductance energy.
[0039] In an embodiment, such as this embodiment, a flyback power supply 100 is also provided. Figure 5The flyback power supply 100 includes an anti-interference unit 20, a rectifying and filtering unit 30, and a leakage inductance recovery circuit 10 as described above, wherein one end of the anti-interference unit 20 is used to receive AC power, and the other end is connected to one end of the rectifying and filtering unit 30, and the other end of the rectifying and filtering unit 30 is connected to the leakage inductance recovery circuit 10 and the primary coil of the transformer. For details, please refer to Figure 6 , Figure 6 This is a circuit schematic diagram of a flyback power supply with a leakage inductance absorption circuit provided in this embodiment. The anti-interference unit 20 includes a capacitor CX3, a capacitor CX2 and an inductor L1, and the rectifier filter unit 30 includes a rectifier bridge BD1, a rectifier bridge BD2, filter capacitors EC1 and EC2. When the AC power is input, the AC current is anti-EMI interference through the capacitor CX3, the capacitor CX2 and the inductor L1. The AC power after anti-EMI interference is then rectified into a DC voltage through the rectifier bridge BD1 and the rectifier bridge BD2. The DC voltage is filtered into a smooth DC voltage through the filter capacitors EC1 and EC2. Finally, the smooth DC voltage is input into the leakage inductance recovery circuit 10 and the primary coil of the transformer.
[0040] The leakage inductance recovery circuit provided by the utility model recovers the leakage inductance energy when the switch unit is turned off through the recovery unit and converts it into a power supply voltage, and provides the power supply voltage to the main control unit for the main control unit to start and operate, thereby realizing the recovery of leakage inductance energy, improving the utilization rate of leakage inductance energy, and further improving the working efficiency of the power supply. The leakage inductance recovery circuit disclosed by the utility model solves the problem that the leakage inductance energy utilization rate and working efficiency of the existing power supply are both low.
[0041] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.
Claims
1. A leakage inductance recovery circuit, characterized in that: include: A main control unit, the main control unit is used to provide a cutoff signal; a switch unit, one end of which is connected to the main control unit, and the other end of which is used to be connected to the primary coil of the transformer, and the switch unit is used to be cut off according to the cut-off signal to reverse the voltage of the primary coil of the transformer; A recovery unit, one end of which is connected to the switch unit and the other end of which is connected to the main control unit, wherein the recovery unit is used to recover the leakage inductance energy of the primary coil of the transformer when the voltage is reversed, and convert the leakage inductance energy into a supply voltage to supply power to the main control unit.
2. The leakage inductance recovery circuit according to claim 1, characterized in that: The recovery unit includes a recovery module, a voltage drop module and a filter module. One end of the recovery module is connected to the switch unit, and the other end is connected to one end of the voltage drop module. The other end of the voltage drop module is connected to the main control unit; one end of the filter module is connected to the voltage drop module, and the other end is grounded.
3. The leakage inductance recovery circuit according to claim 2, characterized in that: The recovery module includes a first diode, a first capacitor and a first resistor, the positive electrode of the first diode is connected to the switch unit, the negative electrode of the first diode is connected to one end of the first capacitor and the first resistor, the other end of the first capacitor is connected to the voltage drop module, and the other end of the first resistor is used to be connected to the primary coil of the transformer.
4. The leakage inductance recovery circuit according to claim 3, characterized in that: The voltage drop module includes a second diode and a third diode, the anode of the second diode is connected to the first capacitor, the cathode of the second diode is connected to the anode of the third diode and the filter module, and the cathode of the third diode is connected to the main control unit.
5. The leakage inductance recovery circuit according to claim 4, characterized in that: The filtering module includes a second capacitor, one end of the second capacitor is connected to the cathode of the second diode, and the other end of the second capacitor is grounded.
6. The leakage inductance recovery circuit according to claim 4, characterized in that: The recovery unit further includes a current limiting module, one end of which is connected between the anode of the second diode and the first capacitor, and the other end of which is grounded.
7. The leakage inductance recovery circuit according to claim 6, characterized in that: The current limiting module includes a fourth diode, a cathode of the fourth diode is connected between an anode of the second diode and the first capacitor, and an anode of the fourth diode is grounded.
8. The leakage inductance recovery circuit according to claim 4, characterized in that: The main control unit includes an IC chip and a third capacitor, the power supply end of the IC chip is connected to the cathode of the third diode and one end of the third capacitor, the signal output end of the IC chip is connected to the switch unit, and the other end of the third capacitor is grounded.
9. The leakage inductance recovery circuit according to claim 8, characterized in that: The switch unit includes a MOS tube, a second resistor and a third resistor, the gate of the MOS tube is connected to the signal output end of the IC chip, the drain of the MOS tube is connected to the anode of the first diode and the primary coil of the transformer, the source of the MOS tube is connected to one end of the second resistor and the third resistor, and the other end of the second resistor and the third resistor is grounded.
10. A flyback power supply, characterized in that: The flyback power supply includes an anti-interference unit, a rectifier and filter unit, and a leakage inductance recovery circuit as described in any one of claims 1 to 9, wherein one end of the anti-interference unit is used to receive alternating current, and the other end is connected to one end of the rectifier and filter unit, and the other end of the rectifier and filter unit is connected to the leakage inductance recovery circuit and the primary coil of the transformer.