Double-end flyback circuit and power supply

Abstract

The utility model provides a double-end flyback circuit and a power supply. The double-end flyback circuit comprises a first absorption unit, a second absorption unit and a transformer, the transformer comprises a secondary winding, a first primary winding and a second primary winding, wherein the first primary winding and the second primary winding are connected in series. The second end of the first absorption unit is in one-way conduction with the first end of the first absorption unit and is used for freewheeling of the first primary winding when the path is disconnected; the second end of the second absorption unit is unidirectionally conducted to the first end of the second absorption unit and is used for freewheeling the second primary winding when the path is disconnected; the first absorption unit and the second absorption unit are further used for being connected in series when the access is disconnected and jointly form follow current for the first primary winding and the second primary winding. Three follow current loops can be formed when the access is disconnected, the peak voltage of the transformer can be well absorbed through the three follow current loops, the difference of the number of turns of the two primary windings does not affect the absorption of the peak voltage, and the performance of the circuit is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply, in particular to a double-end flyback circuit and a power supply. Background Art

[0002] Flyback circuits are widely used in various fields due to their small size and low cost. When the input voltage level of a single-ended flyback circuit is high, the voltage stress on the internal power tube is large and it is easy to be broken down. In contrast, the double-ended flyback circuit overcomes this disadvantage and is therefore widely used in high-voltage, low-power applications.

[0003] In the prior art, an absorption loop is usually set for the two windings of a double-ended flyback circuit. However, due to the difference in the number of turns of the two windings and the difference in the magnetic flux of the two windings, the absorption loop cannot absorb the peak voltage well. The peak voltage of the power tube is large and there is a risk of breakdown, which affects the performance of the double-ended flyback circuit. Utility Model Content

[0004] The embodiment of the utility model provides a double-terminal flyback circuit and a power supply to solve the problem in the prior art that when there are differences between two windings, the absorption circuit cannot effectively absorb the peak voltage.

[0005] In a first aspect, an embodiment of the utility model provides a double-ended flyback circuit, comprising: a first absorption unit, a second absorption unit, and a transformer; wherein the transformer comprises: a secondary winding, and a first primary winding and a second primary winding connected in series

[0006] The first end of the first absorption unit is respectively connected to the first end of the first primary winding and the positive DC bus, the second end of the first absorption unit is respectively connected to the first end of the second absorption unit, the second end of the first primary winding and the first end of the second primary winding; the second end of the second absorption unit is respectively connected to the second end of the second primary winding and the negative DC bus;

[0007] A switch tube is also connected in series in the passage where the first primary winding and the second primary winding are located, for controlling the on and off of the passage;

[0008] Among them, the second end of the first absorption unit is unidirectionally conducted to the first end of the first absorption unit, and is used for continuing the current of the first primary winding when the passage is disconnected; the second end of the second absorption unit is unidirectionally conducted to the first end of the second absorption unit, and is used for continuing the current of the second primary winding when the passage is disconnected; the first absorption unit and the second absorption unit are also used to be connected in series when the passage is disconnected, and jointly continue the current of the first primary winding and the second primary winding.

[0009] Optionally, the above circuit further includes: a first capacitor;

[0010] The first end of the first capacitor is connected to the second end of the first primary winding and the first end of the second primary winding respectively, and the second end of the first capacitor is connected to the second end of the first absorption unit and the first end of the second absorption unit respectively.

[0011] Optionally, the first absorption unit includes: a first unidirectional conducting subunit and a first RC absorption subunit;

[0012] The anode of the first unidirectional conductive subunit is connected to the second end of the first absorption unit, the cathode of the first unidirectional conductive subunit is connected to the second end of the first RC absorption subunit; the second end of the first RC absorption subunit is connected to the first end of the first absorption unit; or

[0013] The cathode of the first unidirectional conductive subunit is connected to the first end of the first absorption unit, the anode of the first unidirectional conductive subunit is connected to the first end of the first RC absorption subunit; and the second end of the first RC absorption subunit is connected to the second end of the first absorption unit.

[0014] Optionally, the first RC absorption subunit includes: a first resistor and a second capacitor;

[0015] The first resistor and the second capacitor are connected in parallel between the first end and the second end of the first RC absorption subunit.

[0016] Optionally, the first unidirectional conducting subunit includes: a diode.

[0017] Optionally, the second absorption unit includes: a second unidirectional conductive subunit and a second RC absorption subunit;

[0018] The anode of the second unidirectional conductive subunit is connected to the second end of the second absorption unit, the cathode of the second unidirectional conductive subunit is connected to the second end of the second RC absorption subunit; the second end of the second RC absorption subunit is connected to the first end of the second absorption unit; or

[0019] The cathode of the second unidirectional conductive subunit is connected to the first end of the second absorption unit, the anode of the second unidirectional conductive subunit is connected to the first end of the second RC absorption subunit; the second end of the second RC absorption subunit is connected to the second end of the first absorption unit.

[0020] Optionally, the circuit structure of the second RC absorption subunit is the same as that of the first RC absorption subunit.

[0021] Optionally, the first end of the first primary winding is a terminal of opposite name, and the second end of the first primary winding is a terminal of the same name;

[0022] The first end of the second primary winding is an opposite-name end, and the second end of the second primary winding is a like-name end.

[0023] Optionally, the number of switch tubes is two;

[0024] The first switch tube is connected in series between the intersection of the first end of the first absorption unit and the first end of the first primary winding and the positive DC bus;

[0025] The second switch tube is connected in series between the intersection of the second end of the second absorption unit and the second end of the second primary winding and the negative DC bus.

[0026] In a second aspect, an embodiment of the utility model provides a power supply, including a double-ended flyback circuit as provided in the first aspect of the embodiment of the utility model.

[0027] The utility model provides a double-end flyback circuit and power supply; the double-end flyback circuit comprises: a first absorption unit, a second absorption unit, and a transformer; wherein the transformer comprises: a secondary winding, and a first primary winding and a second primary winding connected in series; the first end of the first absorption unit is respectively connected to the first end of the first primary winding and the positive DC bus, and the second end of the first absorption unit is respectively connected to the first end of the second absorption unit, the second end of the first primary winding and the first end of the second primary winding; the second end of the second absorption unit is respectively connected to the second end of the second primary winding and the negative DC bus; a switch tube is also connected in series in the passage where the first primary winding and the second primary winding are located, for controlling the on-off of the passage; wherein the second end of the first absorption unit is unidirectionally connected to the first end of the first absorption unit, for continuous current for the first primary winding when the passage is disconnected; the second end of the second absorption unit is unidirectionally connected to the first end of the second absorption unit, for continuous current for the second primary winding when the passage is disconnected; the first absorption unit and the second absorption unit are also used to be connected in series when the passage is disconnected, and jointly continuous current for the first primary winding and the second primary winding. In the embodiment of the utility model, an absorption unit is respectively provided for the first primary winding and the second primary winding. The two absorption units can be connected in series to form an absorption unit, and together they continue the current for the first primary winding and the second primary winding to absorb the peak energy. The two absorption units can also continue the current for the first primary winding and the second primary winding respectively, and effectively absorb the energy of the difference between the two windings, thereby effectively reducing the peak voltage, reducing the voltage stress borne by the switching tube, effectively avoiding the breakdown of the switching tube, and improving the reliability and stability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1It is a circuit structure diagram of a double-terminal flyback circuit provided by an embodiment of the utility model;

[0030] Figure 2 It is a schematic diagram of the circuit structure of a first absorption unit provided in an embodiment of the utility model;

[0031] Figure 3 This is a schematic diagram of the circuit structure of another first absorption unit provided in an embodiment of the utility model;

[0032] Figure 4 The utility model provides a circuit schematic diagram of a double-terminal flyback circuit. DETAILED DESCRIPTION

[0033] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0034] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0035] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0036] Figure 1 A schematic diagram of the circuit structure of a double-ended flyback circuit provided by an embodiment of the utility model. Figure 1 The double-ended flyback circuit includes: a first absorption unit 11, a second absorption unit 12, and a transformer T1; wherein the transformer T1 includes: a secondary winding, and a first primary winding L1 and a second primary winding L2 connected in series;

[0037] The first end of the first absorption unit 11 is respectively connected to the first end of the first primary winding L1 and the positive DC bus BUS+, and the second end of the first absorption unit 11 is respectively connected to the first end of the second absorption unit 12, the second end of the first primary winding L1 and the first end of the second primary winding L2; the second end of the second absorption unit 12 is respectively connected to the second end of the second primary winding L2 and the negative DC bus BUS-;

[0038] A switch tube (Q1 and / or Q2) is also connected in series in the path where the first primary winding L1 and the second primary winding L2 are located, for controlling the on and off of the path;

[0039] Among them, the second end of the first absorption unit 11 is unidirectionally conducted to the first end of the first absorption unit 11, and is used for continuing the current of the first primary winding L1 when the passage is disconnected; the second end of the second absorption unit 12 is unidirectionally conducted to the first end of the second absorption unit 12, and is used for continuing the current of the second primary winding L2 when the passage is disconnected; the first absorption unit 11 and the second absorption unit 12 are also used to be connected in series when the passage is disconnected, and jointly continue the current of the first primary winding L1 and the second primary winding L2.

[0040] In the embodiment of the present utility model, two absorption units (a first absorption unit 11 and a second absorption unit 12) are provided. Figure 1 , the first absorption unit 11 and the second absorption unit 12 can be connected in series to jointly provide current for the first primary winding L1 and the second primary winding L2. At the same time, the first absorption unit 11 can also provide current for the first primary winding L1 alone, and the second absorption unit 12 can also provide current for the second primary winding L2 alone. When the number of turns of the first primary winding L1 and the second primary winding L2 are different, the difference in energy can be absorbed by their respective corresponding absorption units (the first absorption unit 11 and the second absorption unit 12), thereby effectively reducing the peak voltage and the voltage stress on the switch tube, which can effectively prevent the switch tube from being broken down, and improve the reliability and stability of the circuit. At the same time, the switch tube can use a switch tube with a lower withstand voltage, reducing the circuit cost.

[0041] In one possible implementation, reference Figure 4 , the above circuit may further include: a first capacitor C1;

[0042] The first end of the first capacitor C1 is connected to the second end of the first primary winding L1 and the first end of the second primary winding L2 respectively, and the second end of the first capacitor C1 is connected to the second end of the first absorption unit 11 and the first end of the second absorption unit 12 respectively.

[0043] In the present utility model embodiment, reference Figure 4 A first capacitor C1 is provided between the midpoint of the two primary windings and the intersection of the two absorption units for coupling to form a freewheeling loop between the first absorption unit 11 and the first primary winding L1, and a freewheeling loop between the second absorption unit 12 and the second primary winding L2.

[0044] In one possible implementation, reference Figure 2 and Figure 3 , the first absorption unit 11 may include: a first unidirectional conduction subunit 111 and a first RC absorption subunit 112;

[0045] The anode of the first unidirectional conductive subunit 111 is connected to the second end of the first absorption unit 11, the cathode of the first unidirectional conductive subunit 111 is connected to the second end of the first RC absorption subunit 112; the second end of the first RC absorption subunit 112 is connected to the first end of the first absorption unit 11; or

[0046] The cathode of the first unidirectional conductive subunit 111 is connected to the first end of the first absorption unit 11 , the anode of the first unidirectional conductive subunit 111 is connected to the first end of the first RC absorption subunit 112 ; the second end of the first RC absorption subunit 112 is connected to the second end of the first absorption unit 11 .

[0047] Based on the principle of the double-ended flyback circuit, when the switch tube is turned on, the first unidirectional conduction subunit 111 is reversely cut off, and the first RC absorption subunit 112 releases energy. When the switch tube is turned off, the first unidirectional conduction subunit 111 is forwardly conducted, and the first RC absorption subunit 112 forms a freewheeling path of the first primary winding L1, absorbs the peak voltage generated by the leakage inductance of the transformer T1 on the switch tube, and reduces the stress of the switch tube.

[0048] In one possible implementation, reference Figure 2 and Figure 3 , the first RC absorption subunit 112 may include: a first resistor R1 and a second capacitor C2;

[0049] The first resistor R1 and the second capacitor C2 are connected in parallel between the first end and the second end of the first RC absorption subunit 112 .

[0050] In the embodiment of the utility model, the first resistor R1 and the second capacitor C2 are connected in parallel to absorb energy, and the circuit structure is simple, the number of components is small, and the cost is low.

[0051] In one possible implementation, reference Figure 2 and Figure 3 The first unidirectional conducting subunit 111 may include: a diode D1.

[0052] In the embodiment of the utility model, a diode D1 is used to achieve unidirectional conduction, which has a simple structure and low device cost.

[0053] As above, in a possible implementation, the second absorption unit 12 may include: a second unidirectional conduction subunit and a second RC absorption subunit;

[0054] The anode of the second unidirectional conductive subunit is connected to the second end of the second absorption unit 12, the cathode of the second unidirectional conductive subunit is connected to the second end of the second RC absorption subunit; the second end of the second RC absorption subunit is connected to the first end of the second absorption unit 12; or

[0055] The cathode of the second unidirectional conductive subunit is connected to the first end of the second absorption unit 12 , the anode of the second unidirectional conductive subunit is connected to the first end of the second RC absorption subunit; the second end of the second RC absorption subunit is connected to the second end of the first absorption unit 11 .

[0056] As above, the second absorption unit 12 also uses the second unidirectional conduction sub-unit and the second RC absorption sub-unit to form a freewheeling path of the second primary winding L2 to absorb the peak voltage.

[0057] In one possible implementation, reference Figure 4 , the circuit structure of the second RC absorption subunit and the first RC absorption subunit 112 can be the same.

[0058] In the present utility model embodiment, reference Figure 4 The circuit structure of the first RC absorption subunit 112 and the second RC absorption subunit is the same. When the switch tube (Q1 and Q2) is turned on, the two second capacitors C2 are charged and energy is stored; when the switch tube is turned off, the first unidirectional conduction subunit 111 and the second unidirectional conduction subunit are both turned on, and the first primary winding L1 and the second primary winding L2 are connected in series through the path formed by the first RC absorption subunit 112 and the second RC absorption subunit; at the same time, the first primary winding L1 can form a path with the first RC absorption subunit 112, or the second primary winding L2 can form a path with the second RC absorption subunit, which effectively improves the absorption capacity of the circuit and reduces the peak pulse of the switch tube. At the same time, the first RC absorption subunit 112 and the second RC absorption subunit are connected in series to form an absorption loop, which also reduces the voltage stress of the first resistor R1 and the second capacitor C2, reduces the device stress requirements, and reduces the circuit cost.

[0059] In one possible implementation, reference Figure 4 , the first end of the first primary winding L1 is an opposite-name end, and the second end of the first primary winding L1 is a like-name end;

[0060] The first end of the second primary winding L2 is an opposite-name end, and the second end of the second primary winding L2 is a like-name end.

[0061] Transformer T1 winding connection method reference Figure 4 , so that the circuit can achieve double-ended flyback.

[0062] In one possible implementation, reference Figure 4 , the number of switch tubes can be two;

[0063] The first switch tube Q1 is connected in series between the intersection of the first end of the first absorption unit 11 and the first end of the first primary winding L1, and the positive DC bus BUS+;

[0064] The second switch tube Q2 is connected in series between the intersection of the second end of the second absorption unit 12 and the second end of the second primary winding L2 and the negative DC bus BUS-.

[0065] To maintain circuit balance, two switching tubes are used. The two switching tubes are turned on or off at the same time to control the on / off of the path where the primary side of the transformer (L1 and L2) is located.

[0066] For further reference, Figure 4 The above circuit may further include a positive bus capacitor and a negative bus capacitor, wherein the intersection BUS_GND of the positive bus capacitor and the negative bus capacitor is connected to the intersection of the first primary winding L1 and the second primary winding L2. Figure 4 , I will not go into details here.

[0067] The circuit structure of the secondary winding can also be referred to Figure 4 , I will not go into details.

[0068] Corresponding to the above embodiments, the embodiments of the utility model further provide a power supply, including any one of the two-terminal flyback circuits provided in the above embodiments, and having the advantages of the two-terminal flyback circuits, which will not be described in detail here.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-ended flyback circuit, characterized in that: include: A first absorption unit, a second absorption unit, and a transformer; wherein the transformer comprises: a secondary winding, and a first primary winding and a second primary winding connected in series; The first end of the first absorption unit is respectively connected to the first end of the first primary winding and the positive DC bus, the second end of the first absorption unit is respectively connected to the first end of the second absorption unit, the second end of the first primary winding and the first end of the second primary winding; the second end of the second absorption unit is respectively connected to the second end of the second primary winding and the negative DC bus; A switch tube is also connected in series in the path where the first primary winding and the second primary winding are located, for controlling the on and off of the path; Among them, the second end of the first absorption unit is unidirectionally conducted to the first end of the first absorption unit, and is used for continuing the current of the first primary winding when the path is disconnected; the second end of the second absorption unit is unidirectionally conducted to the first end of the second absorption unit, and is used for continuing the current of the second primary winding when the path is disconnected; the first absorption unit and the second absorption unit are also used to be connected in series when the path is disconnected, and jointly continue the current of the first primary winding and the second primary winding.

2. The double-ended flyback circuit according to claim 1, characterized in that: Also included: a first capacitor; The first end of the first capacitor is connected to the second end of the first primary winding and the first end of the second primary winding respectively, and the second end of the first capacitor is connected to the second end of the first absorption unit and the first end of the second absorption unit respectively.

3. The double-ended flyback circuit according to claim 1, characterized in that: The first absorption unit includes: a first unidirectional conductive subunit and a first RC absorption subunit; The anode of the first unidirectional conductive subunit is connected to the second end of the first absorption unit, the cathode of the first unidirectional conductive subunit is connected to the second end of the first RC absorption subunit; the second end of the first RC absorption subunit is connected to the first end of the first absorption unit; or The cathode of the first unidirectional conductive subunit is connected to the first end of the first absorption unit, the anode of the first unidirectional conductive subunit is connected to the first end of the first RC absorption subunit; and the second end of the first RC absorption subunit is connected to the second end of the first absorption unit.

4. The double-ended flyback circuit according to claim 3, characterized in that: The first RC absorption subunit includes: a first resistor and a second capacitor; The first resistor and the second capacitor are connected in parallel between a first end and a second end of the first RC absorption subunit.

5. The double-ended flyback circuit according to claim 3, characterized in that: The first unidirectional conducting subunit includes: a diode.

6. The double-ended flyback circuit according to any one of claims 3 to 5, characterized in that: The second absorption unit includes: a second unidirectional conductive subunit and a second RC absorption subunit; The anode of the second unidirectional conductive subunit is connected to the second end of the second absorption unit, the cathode of the second unidirectional conductive subunit is connected to the second end of the second RC absorption subunit; the second end of the second RC absorption subunit is connected to the first end of the second absorption unit; or The cathode of the second unidirectional conductive subunit is connected to the first end of the second absorption unit, the anode of the second unidirectional conductive subunit is connected to the first end of the second RC absorption subunit; and the second end of the second RC absorption subunit is connected to the second end of the first absorption unit.

7. The double-ended flyback circuit according to claim 6, characterized in that: The circuit structure of the second RC absorption subunit is the same as that of the first RC absorption subunit.

8. The double-ended flyback circuit according to any one of claims 1 to 5, characterized in that: The first end of the first primary winding is an opposite-name end, and the second end of the first primary winding is a like-name end; The first end of the second primary winding is an opposite-name end, and the second end of the second primary winding is a like-name end.

9. The double-ended flyback circuit according to any one of claims 1 to 5, characterized in that: The number of the switch tubes is two; A first switch tube is connected in series between an intersection of a first end of the first absorption unit and a first end of the first primary winding and the positive DC bus; The second switch tube is connected in series between the intersection of the second end of the second absorption unit and the second end of the second primary winding and the negative DC bus.

10. A power supply, characterized in that: The invention comprises a double-terminal flyback circuit as claimed in any one of claims 1 to 9.

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