flyback auxiliary power supply circuit and switching power supply

Abstract

This invention discloses a flyback auxiliary power supply circuit and a switching power supply. The flyback auxiliary power supply circuit includes a transformer, at least one fuse, and multiple voltage output branches. The transformer includes a primary winding and multiple secondary windings. Each secondary winding is connected to at least one voltage output branch. Each fuse corresponds to one voltage output branch. The primary winding is used to connect to the power supply. At least one of the multiple voltage output branches is connected to its corresponding secondary winding through its corresponding fuse. The multiple voltage output branches are used to connect to the circuit to be powered. This invention can ensure the normal output voltage of the secondary windings when a circuit to be powered fails, preventing all secondary windings from failing to output the required voltage.

Description

Technical Field

[0001] This utility model belongs to the field of electronic circuit technology, and in particular relates to a flyback auxiliary power supply circuit and a switching power supply. Background Technology

[0002] In power systems, auxiliary power supplies are typically used to power control circuits, drive circuits, protection circuits, and monitoring circuits. Since different circuits may require different input voltages, auxiliary power supplies can simultaneously output different voltages to power the corresponding circuits.

[0003] However, the inventors have discovered that when using a flyback auxiliary power supply to power multiple circuits with different voltage requirements, if one of the circuits that needs power fails (such as a short circuit), the entire auxiliary power supply will be unable to continue supplying power, causing all the circuits that need power to stop working. Utility Model Content

[0004] This utility model provides a flyback auxiliary power supply circuit and a switching power supply to ensure that the undamaged branch works normally when a circuit requiring power fails.

[0005] A first aspect of this utility model provides a flyback auxiliary power supply circuit, including a transformer, at least one fuse, and multiple voltage output branches; the transformer includes a primary winding and multiple secondary windings; each secondary winding is connected to at least one voltage output branch; each fuse corresponds to one voltage output branch.

[0006] The primary winding is used to connect to the power supply.

[0007] At least one of the multiple voltage output branches is connected to its corresponding secondary winding through its corresponding fuse.

[0008] The multiple voltage output branches are used to connect to the circuit to be powered.

[0009] In one embodiment, the flyback auxiliary power supply circuit includes multiple fuses; each fuse corresponds to a voltage output branch.

[0010] Each voltage output branch is connected to its corresponding secondary winding via its corresponding fuse.

[0011] In one embodiment, the fuse is a resettable fuse.

[0012] In one embodiment, the flyback auxiliary power supply circuit includes a fuse;

[0013] The voltage output branch connected to the fuse is used to connect the drive circuit in the circuit to be powered.

[0014] In one embodiment, the transformer includes a first primary winding and a second primary winding; the auxiliary power supply circuit further includes a first switching transistor and a second switching transistor.

[0015] The first end of the first primary winding is used to connect to the positive terminal of the power supply.

[0016] The second end of the first primary winding is connected to the first end of the first switching transistor;

[0017] The second end of the first switching transistor is connected to the first end of the second primary winding;

[0018] The first end of the second primary winding is also used to connect the neutral line;

[0019] The second end of the second primary winding is connected to the first end of the second switching transistor;

[0020] The second terminal of the second switching transistor is used to connect to the negative terminal of the power supply.

[0021] In one embodiment, the flyback auxiliary power supply circuit further includes a first diode and a second diode; the positive terminal of the power supply includes the positive terminal of the battery, and the negative terminal of the power supply includes the negative terminal of the battery.

[0022] The first end of the first primary winding is connected to the positive terminal of the battery through the first diode;

[0023] The second end of the second primary winding is connected to the negative terminal of the battery through the second diode.

[0024] In one embodiment, the flyback auxiliary power supply circuit further includes a third diode, a fourth diode, a fifth diode, and a sixth diode; the positive terminal of the power supply also includes an AC input terminal, a bypass input terminal, and a positive bus; the negative terminal of the power supply also includes a negative bus.

[0025] The first end of the first primary winding is connected to the AC input terminal through the third diode, to the bypass input terminal through the fourth diode, and to the positive bus through the fifth diode.

[0026] The second end of the second primary winding is connected to the negative busbar through the sixth diode.

[0027] In one embodiment, at least one of the voltage output branches includes a voltage converter;

[0028] At least one of the secondary windings is connected to the circuit to be powered via the voltage converter.

[0029] In one embodiment, at least one of the voltage output branches further includes a voltage regulator;

[0030] At least one of the secondary windings is connected to the circuit to be powered via the voltage regulator;

[0031] Alternatively, at least one of the secondary windings is connected to the circuit to be powered via the voltage converter and the voltage regulator.

[0032] A second aspect of this utility model provides a switching power supply, including the flyback auxiliary power supply circuit described in the first aspect or any embodiment of the first aspect.

[0033] The beneficial effects of this utility model embodiment compared with the prior art are:

[0034] By connecting a fuse in series between the secondary winding of the transformer and the voltage output branch, and with the voltage output branch connected to the circuit to be powered, the fuse can blow when a short circuit fault occurs in the circuit to be powered, generating a large current. This prevents the output voltage of the secondary winding from being pulled down, ensuring that the secondary winding can still maintain a normal voltage, thus allowing the circuit to be powered connected to the secondary winding to continue operating normally. At the same time, in the feedback control, the primary winding of the transformer can still be adjusted according to the output voltage of the secondary winding, ensuring that the branches without faults can operate normally. That is, the normal output voltage of the secondary winding will not trigger the protection of the primary winding due to abnormal output voltage and current of the secondary winding caused by a fault in the circuit to be powered, thus preventing all secondary windings from outputting the required voltage. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a flyback auxiliary power supply circuit provided in an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the structure of a flyback auxiliary power supply circuit provided in another embodiment of this application;

[0038] Figure 3 This is a schematic diagram of the structure of a flyback auxiliary power supply circuit provided in another embodiment of this application;

[0039] Figure 4 This is a schematic diagram of the structure of a flyback auxiliary power supply circuit provided in another embodiment of this application. Detailed Implementation

[0040] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this solution, not all of them. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.

[0041] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.

[0042] The inventors have discovered that when using a flyback auxiliary power supply to power multiple circuits with different voltage requirements, if one of the circuits (circuit A) malfunctions (e.g., a short circuit), the voltage of circuit A will be pulled down. Consequently, the voltage of the secondary winding connected to circuit A will also be pulled down, causing other circuits connected to the same secondary winding to also be unable to receive power normally. Furthermore, a short circuit in circuit A will generate a large current. Because the flyback circuit detects the output voltage and current of the secondary winding and adjusts the primary winding accordingly, when a large current is detected in a secondary winding, the primary winding will be protected, causing all secondary windings to fail to output voltage normally, thus preventing all circuits from operating properly.

[0043] Considering that even if some of the circuits to be powered fail, the control circuit still needs to be able to collect data during the fault, record fault waveforms, or perform safe exit functions, it is necessary to ensure that the branches in the auxiliary power supply circuit that have not failed operate normally. Based on this, in the embodiments of this application, a fuse is connected in series between the secondary winding and the voltage output branch. The large current generated when the circuit to be powered fails will cause the fuse to blow, preventing the circuit to be powered from pulling down the voltage of the secondary winding and ensuring that the secondary winding can still maintain a normal voltage. Simultaneously, in the feedback control of the flyback circuit, the primary winding can still be adjusted according to the output voltage of the secondary winding, ensuring that each secondary winding outputs a normal voltage.

[0044] The implementation of this utility model will be described in detail below with reference to the specific accompanying drawings:

[0045] See Figure 1The flyback auxiliary power supply circuit provided by this utility model includes a transformer T, at least one fuse FSU, and multiple voltage output branches 1i (the value of i can be 1, 2, 3...n, where n is a positive integer, such as...). Figure 1 In the diagram, 11, 12, 13, 14, ..., 1i, ..., 1n represent voltage output branches; the transformer T includes a primary winding TA and multiple secondary windings TBj (j can take values ​​of 1, 2, 3...m, where m is a positive integer and m≤n, e.g., ...). Figure 1 In this context, TB1, TB2, TB3, ..., TBj, ..., TBm represent secondary windings. Each secondary winding TBj is connected to at least one voltage output branch 1i; each fuse FSU corresponds to one voltage output branch 1i.

[0046] Here, each secondary winding TBj can output a different voltage. For example, the first secondary winding TB1 can output +12V, the second secondary winding can output -12V, ..., the j-th secondary winding TBj can output xjV, ..., the m-th secondary winding can output xmV. Each secondary winding TBj can be connected to one or more voltage output branches 1i. For a single secondary winding TBj, when multiple voltage output branches 1i are connected, the input voltage of each voltage output branch 1i is the same, but the output voltages can be the same or different.

[0047] In this embodiment, the primary winding TA is used to connect to the power supply 2; at least one of the multiple voltage output branches 1i is connected to its corresponding secondary winding through its corresponding fuse FSU; the multiple voltage output branches 1i are used to connect to the circuit to be powered 3i (e.g., Figure 1 In this context, 31, 32, 33, 34, ..., 3i, ..., 3n represent the circuit to be powered.

[0048] In this embodiment, the power supply 2 is DC, and the voltage is transformed by transformer T to transfer energy from the primary side to the secondary side. Then, the voltage output branch 1i supplies power to the circuit 3i to be powered. The circuit 3i to be powered may include a drive circuit, a control circuit, a sampling circuit, and a main control board sampling circuit, etc.

[0049] The secondary winding TBj supplies power to the circuit 3i to be powered through the voltage output branch 1i. The voltage output branch 1i can be connected to the corresponding secondary winding through the fuse FSU, or it can be directly connected to the corresponding secondary winding.

[0050] When a fault occurs in the circuit 3i connected to the voltage output branch 1i linked to the fuse FSU, generating a large current, the fuse FSU will blow to prevent the voltage of the secondary winding from dropping, ensuring that other voltage output branches 1i of the same secondary winding TBj can still operate normally. Simultaneously, in the feedback control of the flyback circuit, the primary winding TA of transformer T can still operate normally without triggering the protection, ensuring that other secondary windings TBj of transformer T are also unaffected.

[0051] Considering that some circuits in the circuit to be powered are more prone to failure, the fuse FSU can be set at the voltage output branch 1i connected to the circuit to be powered 3i that is prone to failure, so that the fuse FSU can accurately protect the entire auxiliary power supply circuit.

[0052] In addition, by only installing a fuse FSU at the voltage output branch 1i of the power supply circuit that is prone to failure, the overall size of the auxiliary power supply circuit can be kept small, and the increased cost is also small.

[0053] In some embodiments, the auxiliary power supply circuit can supply power to the drive circuit, enabling the drive circuit to drive the power transistor in the power circuit. However, the power transistor in the power circuit is a high-current device with a high risk of failure, and a failure of the power transistor can easily damage the drive circuit, pulling down the voltage of the drive circuit. Therefore, the voltage output branch 1i connected to the fuse FSU in the auxiliary power supply circuit provided in this embodiment can be used to connect to the drive circuit in the circuit to be powered 3i, so that the fuse FSU will blow in time when the voltage of the drive circuit is pulled down.

[0054] Optionally, when the flyback auxiliary power supply circuit includes a fuse FSU, the voltage output branch 1i connected to the fuse FSU is used to connect the drive circuit in the circuit to be powered 3i. Here, considering the cost and size of the auxiliary power supply circuit, only one fuse FSU can be set. Since the drive circuit is prone to failure, in order to ensure the normal use of the auxiliary power supply circuit, the fuse FSU can be set between the voltage output branch 1i used to connect the drive circuit and the corresponding secondary winding TBj, so as to ensure the effectiveness of the fuse FSU and achieve both cost and performance considerations.

[0055] Further, see Figure 2 To provide more comprehensive protection for each branch and prevent it from affecting the voltage output of the secondary winding TBj, the flyback auxiliary power supply circuit may include multiple fuses FSU; each fuse FSU corresponds one-to-one with a voltage output branch 1i; each voltage output branch 1i is connected to its corresponding secondary winding TBj through its corresponding fuse FSU.

[0056] In this embodiment, each voltage output branch 1i is connected to a fuse FSU. If any of the power supply circuits 3i connected to the voltage output branch 1i fails and generates a large current, the corresponding fuse FSU can blow, ensuring that the other voltage output branches are not affected and can supply power normally.

[0057] Optionally, the fuse FSU can be a resettable fuse.

[0058] When a short circuit or overload occurs in the circuit, the large current flowing through the resettable fuse generates heat, causing the fuse to enter a high-resistance state. This rapidly reduces the operating current, thus limiting and protecting the circuit. After the fault is cleared, the resettable fuse cools down and returns to a low-resistance state, eliminating the need for manual fuse replacement.

[0059] In some embodiments, at least one voltage output branch 1i may include a voltage converter; at least one secondary winding TBj is connected to the circuit to be powered 3i via the voltage converter.

[0060] Here, the voltage converter can boost or buck the voltage output from the connected secondary winding TBj and then supply it to the circuit to be powered 3i to meet the voltage requirements of each circuit to be powered 3i.

[0061] Reference Figure 1 The secondary winding TB1 outputs a +12V voltage, which, after passing through the voltage output branch 12 containing the voltage converter, can output a +7V voltage.

[0062] Optionally, at least one voltage output branch 1i may also include a voltage regulator.

[0063] In this circuit, at least one secondary winding TBj is connected to the circuit to be powered 3i via a voltage regulator; or, at least one secondary winding TBj is connected to the circuit to be powered 3i via a voltage converter and a voltage regulator.

[0064] In this embodiment, a voltage regulator can be provided to maintain the stability of the output voltage. For the circuit to be powered that requires high voltage stability, a voltage regulator can be provided in the voltage output branch 1i to meet the voltage requirements of the circuit to be powered 3i.

[0065] In some embodiments, such as Figure 3 As shown, the transformer T includes a first primary winding TA1 and a second primary winding TA2; the flyback auxiliary power supply circuit also includes a first switching transistor Q1 and a second switching transistor Q2.

[0066] The first end of the first primary winding TA1 is used to connect to the positive terminal of the power supply; the second end of the first primary winding TA1 is connected to the first end of the first switching transistor Q1; the second end of the first switching transistor Q1 is connected to the first end of the second primary winding; the first end of the second primary winding TA2 is also used to connect to the neutral line; the second end of the second primary winding TA2 is connected to the first end of the second switching transistor Q2; the second end of the second switching transistor Q2 is used to connect to the negative terminal of the power supply.

[0067] In this embodiment, the primary side of transformer T can be equipped with two primary windings and connected to two switching transistors to form a two-transistor flyback circuit. The cooperation of the two switching transistors reduces the voltage stress on the main switching transistor, lowers the voltage withstand requirement of the switching transistor, and improves the stability and reliability of the circuit.

[0068] In one embodiment, the flyback auxiliary power supply circuit further includes a first diode D1 and a second diode D2; the positive terminal of the power supply includes the battery positive terminal BAT+, and the negative terminal of the power supply includes the battery negative terminal BAT-. The first end of the first primary winding TA1 is connected to the battery positive terminal BAT+ through the first diode D1; the second end of the second primary winding TA2 is connected to the battery negative terminal BAT- through the second diode D2.

[0069] In this embodiment, the power supply for the auxiliary power circuit can be a battery, and the battery's electrical energy is converted by the auxiliary power circuit and then supplied to the corresponding circuit 3i to be powered.

[0070] For example, the first terminal of the first primary winding TA1 can be a terminal with the same name, and the second terminal of the first primary winding TA1 can be a terminal with a different name; the first terminal of the second primary winding TA2 can be a terminal with the same name, and the second terminal of the second primary winding TA2 can be a terminal with a different name. The above is only an example and can be determined according to the specific design of the circuit.

[0071] In one embodiment, the flyback auxiliary power supply circuit further includes a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6; the positive terminal of the power supply also includes an AC input terminal Line_A, a bypass input terminal BYP_A, and a positive bus BUS+; the negative terminal of the power supply also includes a negative bus BUS-.

[0072] The first end of the first primary winding TA1 is connected to the AC input terminal Line_A via the third diode D3, to the bypass input terminal BYP_A via the fourth diode D4, and to the positive bus BUS+ via the fifth diode D5; the second end of the second primary winding TA2 is connected to the negative bus BUS- via the sixth diode D6.

[0073] In this embodiment, the power supply may further include DC power converted from AC input, DC power converted from bypass input, and positive and negative buses.

[0074] The battery positive terminal BAT+, AC input terminal Line_A, bypass input terminal BYP_A, and positive bus BUS+ are each connected to the first terminal of the first primary winding TA1 via a diode. This allows the auxiliary power supply circuit to draw power from multiple sources; as long as one of these sources is powered, the auxiliary power supply circuit can provide power to the circuit to be powered. Furthermore, by placing a diode in each source, reverse current can be prevented, and the maximum voltage input to the auxiliary power supply circuit can be selected.

[0075] It is important to note that the AC input terminal Line_A and the bypass input terminal BYP_A input direct current (DC), not alternating current (AC). The terms AC input and bypass input merely indicate the source of the electrical energy. AC power can be converted to DC by a rectifier circuit before being input into the auxiliary power supply circuit.

[0076] In some feasible embodiments, such as Figure 4 As shown, the secondary winding TB1 can output a +12V voltage. The secondary winding TB1 is connected to the drive circuit through the fuse FSU. Figure 4 The first circuit to be powered (31) shown in the diagram can be configured as a drive circuit. The secondary winding TB1 is also connected to the first main control board sampling circuit DSP1. The secondary winding TB2 can output a voltage of -12V and is connected to the second main control board sampling circuit DSP2.

[0077] When the drive circuit malfunctions and the voltage is pulled low, the large current generated in the line will cause the fuse FSU to blow, thus not affecting the output voltage of the secondary winding TB1, and the entire auxiliary power supply circuit can continue to operate normally. Meanwhile, since the first main control board sampling circuit DSP1 and the second main control board sampling circuit DSP2 can receive normal voltage and continue to operate, the fault waveform can be collected for subsequent fault analysis.

[0078] In this embodiment, a fuse is connected in series between the secondary winding and the voltage output branch. The voltage output branch is connected to the circuit to be powered. When a short circuit fault occurs in the circuit to be powered, generating a large current, the fuse will blow to prevent the output voltage of the secondary winding from dropping. This ensures that the secondary winding can still maintain a normal voltage, thus allowing the circuit to be powered connected to the secondary winding to continue operating normally. At the same time, in the feedback control, the primary winding of the transformer can still be adjusted according to the output voltage of the secondary winding, ensuring that the branches without faults can operate normally. That is, the secondary winding output voltage is normal, and the abnormal output voltage and current of the secondary winding caused by a fault in the circuit to be powered will not trigger the protection of the primary winding, causing all secondary windings to be unable to output the required voltage.

[0079] This application also provides a switching power supply. For details not described in detail herein, please refer to the corresponding circuit embodiments described above.

[0080] In some embodiments, the switching power supply may include the flyback auxiliary power supply circuit as described in any of the above embodiments.

[0081] Optionally, a feedback regulation circuit for the flyback auxiliary power supply circuit can be set in the switching power supply. The feedback regulation circuit can be used to regulate the flyback auxiliary power supply circuit to ensure that the output voltage of the flyback auxiliary power supply circuit is stable.

[0082] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A flyback auxiliary power supply circuit, characterized in that, It includes a transformer, at least one fuse, and multiple voltage output branches; the transformer includes a primary winding and multiple secondary windings; each secondary winding is connected to at least one voltage output branch; each fuse corresponds to one voltage output branch. The primary winding is used to connect to the power supply. At least one of the multiple voltage output branches is connected to its corresponding secondary winding through its corresponding fuse. The multiple voltage output branches are used to connect to the circuit to be powered.

2. The flyback auxiliary power supply circuit according to claim 1, characterized in that, The flyback auxiliary power supply circuit includes multiple fuses; each fuse corresponds to a voltage output branch. Each voltage output branch is connected to its corresponding secondary winding via its corresponding fuse.

3. The flyback auxiliary power supply circuit according to claim 1 or 2, characterized in that, The fuse is a resettable fuse.

4. The flyback auxiliary power supply circuit according to claim 1, characterized in that, The flyback auxiliary power supply circuit includes a fuse; The voltage output branch connected to the fuse is used to connect the drive circuit in the circuit to be powered.

5. The flyback auxiliary power supply circuit according to claim 1 or 2, characterized in that, The transformer includes a first primary winding and a second primary winding; the auxiliary power supply circuit also includes a first switching transistor and a second switching transistor. The first end of the first primary winding is used to connect to the positive terminal of the power supply. The second end of the first primary winding is connected to the first end of the first switching transistor; The second end of the first switching transistor is connected to the first end of the second primary winding; The first end of the second primary winding is also used to connect the neutral line; The second end of the second primary winding is connected to the first end of the second switching transistor; The second terminal of the second switching transistor is used to connect to the negative terminal of the power supply.

6. The flyback auxiliary power supply circuit according to claim 5, characterized in that, The flyback auxiliary power supply circuit also includes a first diode and a second diode; the positive terminal of the power supply includes the positive terminal of the battery, and the negative terminal of the power supply includes the negative terminal of the battery. The first end of the first primary winding is connected to the positive terminal of the battery through the first diode; The second end of the second primary winding is connected to the negative terminal of the battery through the second diode.

7. The flyback auxiliary power supply circuit according to claim 6, characterized in that, The flyback auxiliary power supply circuit also includes a third diode, a fourth diode, a fifth diode, and a sixth diode; the positive terminal of the power supply also includes an AC input terminal, a bypass input terminal, and a positive bus; the negative terminal of the power supply also includes a negative bus. The first end of the first primary winding is connected to the AC input terminal through the third diode, to the bypass input terminal through the fourth diode, and to the positive bus through the fifth diode. The second end of the second primary winding is connected to the negative busbar through the sixth diode.

8. The flyback auxiliary power supply circuit according to claim 1 or 2, characterized in that, At least one of the voltage output branches includes a voltage converter; At least one of the secondary windings is connected to the circuit to be powered via the voltage converter.

9. The flyback auxiliary power supply circuit according to claim 8, characterized in that, At least one of the voltage output branches further includes a voltage regulator; At least one of the secondary windings is connected to the circuit to be powered via the voltage regulator; Alternatively, at least one of the secondary windings is connected to the circuit to be powered via the voltage converter and the voltage regulator.

10. A switching power supply, characterized in that, Includes the flyback auxiliary power supply circuit as described in any one of claims 1 to 9.

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