Surge protection circuit and switching power supply

Abstract

The utility model provides a surge protection circuit and a switching power supply. The surge protection circuit comprises a rectification module, a protection circuit and a power supply circuit. The rectification module comprises a rectification circuit and a first capacitor, the input end of the rectification circuit is connected with a power supply of the switching power supply, and the output end of the rectification circuit is connected with the first capacitor; the protection circuit comprises a first switch tube and a series circuit composed of at least one resistor, a first pole of the first switch tube and one end of the series circuit are both connected with the rectification circuit, and a second pole of the first switch tube and the other end of the series circuit are both connected with the first capacitor; the power supply circuit is connected with the first capacitor and the controlled end of the first switch tube. According to the utility model, the surge current can be reduced, the circuit is simple, and the cost of the switching power supply can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, and particularly relates to a surge protection circuit and a switching power supply. Background Art

[0002] Surge current refers to the peak current flowing into a power supply device when a switching power supply is plugged into a socket or powered on. Since the input filter capacitor is quickly charged, this peak current is much larger than the steady-state input current and is likely to damage the switching power supply.

[0003] Currently, most switching power supplies are equipped with corresponding protection circuits to reduce the value of surge current and avoid damaging the switching power supply. However, the current protection circuits are relatively complex, increasing the cost of the switching power supply. Summary of the Utility Model

[0004] The utility model provides a surge protection circuit and a switching power supply, aiming to solve the problem that the circuit for protecting the switching power supply against surge current is relatively complex, resulting in a relatively high cost of the switching power supply.

[0005] In a first aspect, the utility model provides a surge protection circuit, which includes a rectification module, a protection circuit, and a power supply circuit; the rectification module includes a rectification circuit and a first capacitor, the input end of the rectification circuit is connected to the power supply of the switching power supply, and the output end of the rectification circuit is connected to the first capacitor; the protection circuit includes a first switching tube and a series circuit composed of at least one resistor, one pole of the first switching tube and one end of the series circuit are both connected to the rectification circuit, and the other pole of the first switching tube and the other end of the series circuit are both connected to the first capacitor; the power supply circuit is respectively connected to the first capacitor and the controlled end of the first switching tube.

[0006] Further, the series circuit includes a first resistor; one end of the first resistor is connected to the first capacitor, and the other end of the first resistor is connected to the rectification circuit.

[0007] Further, the protection circuit further includes a first diode; the positive pole of the first diode is connected to the controlled end of the first switching tube, and the negative pole of the first diode is connected to the power supply circuit.

[0008] Further, the protection circuit further includes a second resistor, a third resistor, and a second diode; one end of the second resistor and the positive pole of the second diode are both connected to the rectification circuit, the other end of the second resistor and the negative pole of the second diode are both connected to the positive pole of the first diode, one end of the third resistor is connected to the negative pole of the first diode, and the other end of the third resistor is connected to the power supply circuit.

[0009] Further, the power supply circuit includes a second capacitor; one end of the second capacitor is respectively connected to the negative electrode of the first diode and the first capacitor, the other end of the second capacitor is grounded, and the second capacitor is also connected to the power supply module of the switching power supply.

[0010] Further, the power supply circuit further includes a third diode and a fourth resistor; one end of the fourth resistor is connected to the power supply module, the other end of the fourth resistor is connected to the positive electrode of the third diode, and the negative electrode of the third diode is respectively connected to the second capacitor and the negative electrode of the first diode.

[0011] Further, a starting circuit is further included, one end of the starting circuit is connected to the first capacitor, and the other end of the starting circuit is connected to the power supply circuit.

[0012] Further, the starting circuit includes a fifth resistor and a sixth resistor; one end of the fifth resistor is connected to the first capacitor, the other end of the fifth resistor is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the power supply circuit.

[0013] Further, the first switching tube is a MOS tube, the gate of the MOS tube is connected to the power supply circuit, the source of the MOS tube is connected to the rectifying circuit, and the drain of the MOS tube is connected to the first capacitor.

[0014] In a second aspect, the present invention further provides a switching power supply, and the switching power supply includes the surge protection circuit described in any one of the above.

[0015] The switching power supply disclosed by the present utility model includes a surge protection circuit. The surge protection circuit includes a rectification module, a protection circuit, and a power supply circuit. The rectification module includes a rectification circuit and a first capacitor. The protection circuit includes a first switching tube and a series circuit. The first pole of the first switching tube is connected to the rectification module, the second pole of the first switching tube is connected to the first capacitor, and the controlled terminal of the first switching tube is connected to the power supply circuit. The series circuit includes at least one resistor for increasing the resistance value of the loop formed by the rectification circuit and the first capacitor. When the first switching tube is not conducting, the rectification circuit can normally charge the first capacitor and the power supply circuit, and due to the high resistance value of the series circuit, the loop current is small. When the voltage of the power supply circuit reaches the conduction voltage of the first switching tube, the first switching tube conducts. At this time, the connection impedance between the rectification circuit and the first capacitor is at the minimum value. When the power supply is disconnected, the voltage of the power supply circuit drops, and the first switching tube can quickly turn off. When the switching power supply is started next time, the first switching tube is still in the off state, and the loop current formed by the rectification circuit and the first capacitor will not be too large, so that the generated surge current is also small. This can not only avoid damage to the switching power supply, but also the entire circuit structure is simple, reducing the cost of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 is a block diagram of a surge protection circuit provided by an embodiment of the present utility model;

[0018] Figure 2 is a block diagram of a surge protection circuit provided by another embodiment of the present utility model;

[0019] Figure 3 is a circuit diagram of a surge protection circuit provided by an embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0021] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, operations, elements, components, and / or their combinations.

[0022] It should also be understood that the terms used in this specification of the present utility model are merely for the purpose of describing specific embodiments and are not intended to limit the present utility model. As used in this specification of the present utility model and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms. It should be further understood that the term "and / or" used in this specification of the present utility model 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.

[0023] In addition, the directional terms mentioned in the present utility model, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", etc., are only references to the directions of the attached drawings and the usage state of the product. Therefore, the directional terms used are for explaining and understanding the present utility model, rather than for limiting the present utility model. In addition, in the drawings, structures that are similar or the same are denoted by the same reference numerals.

[0024] See Figures 1 to 3 , Figure 1 is a block diagram of a surge protection circuit 100 provided by an embodiment of the present utility model; Figure 2 is a block diagram of a surge protection circuit 100 provided by another embodiment of the present utility model; Figure 3 is a circuit diagram of a surge protection circuit 100 provided by an embodiment of the present utility model. As Figure 1 shown, the surge protection circuit 100 includes a rectification module 10, a protection circuit 20, and a power supply circuit 30; the rectification module 10 includes a rectification circuit 11 and a first capacitor C1, the input end of the rectification circuit 11 is connected to the power supply 200 of the switching power supply 200, and the output end of the rectification circuit 11 is connected to the first capacitor C1; the protection circuit 20 includes a first switching transistor Q1 and a series circuit 21 composed of at least one resistor, a first pole of the first switching transistor Q1 and one end of the series circuit 21 are both connected to the rectification circuit 11, a second pole of the first switching transistor Q1 and the other end of the series circuit 21 are both connected to the first capacitor C1; the power supply circuit 30 is respectively connected to the first capacitor C1 and the controlled end of the first switching transistor Q1.

[0025] Specifically, the surge protection circuit 100 includes a rectification module 10, a protection circuit 20, and a power supply circuit 30. The rectification module 10 includes a rectification circuit 11 and a first capacitor C1. The rectification circuit 11 may include a rectifier bridge, which may be composed of four diodes connected end to end. The rectification circuit 11 may also be a rectification circuit 11 commonly used in the art, and the specific circuit is not limited here.

[0026] The input end of the rectification circuit 11 is connected to the power supply 200, which may be a power supply grid. The output end of the rectification circuit 11 is connected to the first capacitor C1, and after rectifying the input current, it charges the first capacitor C1. The first capacitor C1 is also connected to the power supply circuit 30, that is, the rectification circuit 11 can also charge the power supply circuit 30.

[0027] The protection circuit 20 includes a first switching transistor Q1 and a series circuit 21 composed of at least one resistor. The first pole of the first switching transistor Q1 is connected to the rectification circuit 11, the second pole of the first switching transistor Q1 is connected to the first capacitor C1, and the controlled end of the first switching transistor Q1 is connected to the power supply circuit 30. The series circuit 21 may include a large-value resistor or multiple small-value resistors, and the series circuit 21 is connected in parallel with the first switching transistor Q1. After the switching power supply 200 is connected to the power supply grid, the rectification circuit 11 and the first capacitor C1 can form a loop, and while the rectification circuit 11 charges the first capacitor C1, it also increases the impedance of the loop formed by the rectification circuit 11 and the first capacitor C1, so that the current in the loop formed by the rectification circuit 11 and the first capacitor C1 will not be too large.

[0028] The power supply circuit 30 is respectively connected to the first capacitor C1 and the controlled end of the first switching transistor Q1, and is used to provide a supply voltage for the first switching transistor Q1. When the supply voltage is greater than the conduction voltage of the first switching transistor Q1, the first switching transistor Q1 conducts. After the first switching transistor Q1 conducts, the connection impedance between the rectification circuit 11 and the negative electrode of the first capacitor C1 is at the minimum value. When the connection to the power supply grid is disconnected, the power supply circuit 30 loses power supply, and the first switching transistor Q1 can be cut off in a short time, thereby ensuring that the surge current generated when reconnecting to the power supply grid next time will not be too large.

[0029] In addition, the power supply circuit 30 can also be connected to the power supply module 300 of the switching power supply 200. The power supply module 300 may be the power supply winding of the transformer of the switching power supply 200. After the first switching transistor Q1 conducts, the power supply module 300 is used to continuously supply power to the first switching transistor Q1. At the same time, the power supply circuit 30 can also be connected to the drive module 400 of the switching power supply, and is used to supply power to the drive module 400.

[0030] As a further embodiment, the series circuit 21 includes a first resistor R1; one end of the first resistor R1 is connected to the first capacitor C1, and the other end of the first resistor R1 is connected to the rectifier circuit 11.

[0031] Wherein, the series circuit 21 may include a first resistor R1, and the first resistor R1 is connected in parallel with the first switching transistor Q1, that is, one end of the first resistor R1 is connected to the first capacitor C1, and the other end of the first resistor R1 is connected to the rectifier circuit 11. The first resistor R1 may be a resistor with a large resistance value. After the switching power supply 200 is powered on, while not affecting the rectifier circuit 11 to charge the first capacitor C1, it can also ensure that the loop current formed by the rectifier circuit 11 and the first capacitor C1 will not be too large.

[0032] As a further embodiment, the protection circuit 20 further includes a first diode ZD1; the positive electrode of the first diode ZD1 is connected to the controlled end of the first switching transistor Q1, and the negative electrode of the first diode ZD1 is connected to the power supply circuit 30.

[0033] Wherein, the positive electrode of the first diode ZD1 is connected to the controlled end of the first switching transistor Q1, the negative electrode of the first diode ZD1 is connected to the power supply circuit 30, and the first diode ZD1 may be a voltage stabilizing diode, which is used to ensure that the first switching transistor Q1 can be quickly cut off after the switching power supply 200 is powered off.

[0034] As a further embodiment, the protection circuit 20 further includes a second resistor R2, a third resistor R3, and a second diode ZD2; one end of the second resistor R2 and the positive electrode of the second diode ZD2 are both connected to the rectifier circuit 11, the other end of the second resistor R2 and the negative electrode of the second diode ZD2 are both connected to the positive electrode of the first diode ZD1, one end of the third resistor R3 is connected to the negative electrode of the first diode ZD1, and the other end of the third resistor R3 is connected to the power supply circuit 30.

[0035] Wherein, one end of the second resistor R2 and the positive electrode of the second diode ZD2 are both connected to the rectifier circuit 11, the other end of the second resistor R2 and the negative electrode of the second diode ZD2 are both connected to the positive electrode of the first diode ZD1, one end of the third resistor R3 is connected to the negative electrode of the first diode ZD1, and the other end of the third resistor R3 is connected to the power supply circuit 30.

[0036] As a further embodiment, the power supply circuit 30 includes a second capacitor C2; one end of the second capacitor C2 is respectively connected to the negative electrode of the first diode ZD1 and the first capacitor C1, the other end of the second capacitor C2 is grounded, and the second capacitor C2 is also connected to the power supply module 300 of the switching power supply 200.

[0037] As a further embodiment, the power supply circuit 30 further includes a third diode D1 and a fourth resistor R4; one end of the fourth resistor R4 is connected to the power supply module 300, the other end of the fourth resistor R4 is connected to the positive electrode of the third diode D1, and the negative electrode of the third diode D1 is respectively connected to the second capacitor C2 and the negative electrode of the first diode ZD1.

[0038] Wherein, one end of the second capacitor C2 is connected to the negative electrode of the first diode ZD1 and the first capacitor C1, the other end of the second capacitor C2 is grounded, and at the same time, the second capacitor C2 is also connected to the power supply module 300 of the switching power supply 200, and this power supply module 300 can be the power supply winding of a transformer. The second capacitor C2 is a VCC capacitor and is used to supply power to the first switching transistor Q1.

[0039] As a further embodiment, a startup circuit 40 is further included, one end of the startup circuit 40 is connected to the first capacitor C1, and the other end of the startup circuit 40 is connected to the power supply circuit 30.

[0040] Wherein, the startup circuit 40 is connected between the first capacitor C1 and the power supply circuit 30. The first capacitor C1 can charge the power supply circuit 30 through the startup circuit 40. When the voltage of the power supply circuit 30 reaches the conduction voltage of the first switching transistor Q1, the first switching transistor Q1 conducts.

[0041] As a further embodiment, the startup circuit 40 includes a fifth resistor R5 and a sixth resistor R6; one end of the fifth resistor R5 is connected to the first capacitor C1, the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is connected to the power supply circuit 30.

[0042] As a further embodiment, the first switching transistor Q1 is a MOS transistor. The gate of the MOS transistor is connected to the power supply circuit 30, the source of the MOS transistor is connected to the rectification circuit 11, and the drain of the MOS transistor is connected to the first capacitor C1.

[0043] Wherein, the first switching transistor Q1 can be a switching device such as a triode, a MOS transistor, a relay, a thyristor, etc., and can be adjusted according to actual requirements. Taking the first switching transistor Q1 as a MOS transistor as an example, the gate of the MOS transistor is connected to the power supply circuit 30, the source of the MOS transistor is connected to the rectification circuit 11, and the drain of the MOS transistor is connected to the first capacitor C1. When the voltage of the power supply circuit 30 reaches the conduction voltage of the MOS transistor, the MOS transistor conducts.

[0044] The present utility model further provides a switching power supply 200, which includes the surge protection circuit 100 described in any one of the above embodiments. The surge protection circuit 100 includes a rectification module 10, a protection circuit 20, and a power supply circuit 30. The rectification module 10 includes a rectification circuit 11 and a first capacitor C1. The input end of the rectification circuit 11 is connected to the power supply 200 of the switching power supply 200, and the output end of the rectification circuit 11 is connected to the first capacitor C1. The protection circuit 20 includes a first switching tube Q1 and a series circuit 21 composed of at least one resistor. The first pole of the first switching tube Q1 and one end of the series circuit 21 are both connected to the rectification circuit 11, and the second pole of the first switching tube Q1 and the other end of the series circuit 21 are both connected to the first capacitor C1. The power supply circuit 30 is respectively connected to the first capacitor C1 and the controlled end of the first switching tube Q1.

[0045] Specifically, the surge protection circuit 100 includes a rectification module 10, a protection circuit 20, and a power supply circuit 30. The rectification module 10 includes a rectification circuit 11 and a first capacitor C1. The rectification circuit 11 may include a rectifier bridge, which may be composed of four diodes connected end to end. The rectification circuit 11 may also be a rectification circuit 11 commonly used in the art, and the specific circuit is not limited here.

[0046] The input end of the rectification circuit 11 is connected to the power supply 200, which may be a power supply grid. The output end of the rectification circuit 11 is connected to the first capacitor C1, and the first capacitor C1 is charged after rectifying the input current. The first capacitor C1 is also connected to the power supply circuit 30, that is, the rectification circuit 11 can also charge the power supply circuit 30.

[0047] The protection circuit 20 includes a first switching tube Q1 and a series circuit 21 composed of at least one resistor. The first pole of the first switching tube Q1 is connected to the rectification circuit 11, the second pole of the first switching tube Q1 is connected to the first capacitor C1, the controlled end of the first switching tube Q1 is connected to the power supply circuit 30. The series circuit 21 may include a large-value resistor or multiple small-value resistors, and the series circuit 21 is in parallel with the first switching tube Q1. After the switching power supply 200 is connected to the power supply grid, the rectification circuit 11 and the first capacitor C1 can form a loop, and while the rectification circuit 11 charges the first capacitor C1, the impedance of the loop formed by the rectification circuit 11 and the first capacitor C1 is also increased, so that the current in the loop formed by the rectification circuit 11 and the first capacitor C1 will not be too large.

[0048] The power supply circuit 30 is respectively connected to the first capacitor C1 and the controlled terminal of the first switching transistor Q1, and is used to provide a power supply voltage for the first switching transistor Q1. When the power supply voltage is greater than the conduction voltage of the first switching transistor Q1, the first switching transistor Q1 conducts. After the first switching transistor Q1 conducts, the connection impedance between the rectification circuit 11 and the negative electrode of the first capacitor C1 is at a minimum value. When the connection to the power grid is disconnected, the power supply circuit 30 loses power supply, and the first switching transistor Q1 can be cut off in a short time, thereby ensuring that the inrush current generated when reconnecting to the power grid next time will not be too large.

[0049] In addition, the power supply circuit 30 can also be connected to the power supply module 300 of the switching power supply 200. The power supply module 300 can be the power supply winding of the transformer of the switching power supply 200. After the first switching transistor Q1 conducts, the power supply module 300 is used to continuously supply power to the first switching transistor Q1.

[0050] The surge protection circuit disclosed by the present utility model is provided with a first switching transistor and a series circuit. The series circuit increases the impedance when the first switching transistor is not conducting, ensuring that the generated inrush current will not be too large. It can not only avoid damage to the switching power supply, but also has a simple circuit and low cost.

[0051] The above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claims.

Claims

1. A surge protection circuit, characterized in that: Applied to switching power supplies, including: A rectifier module, the rectifier module comprising a rectifier circuit and a first capacitor, an input end of the rectifier circuit is connected to a power supply of the switching power supply, and an output end of the rectifier circuit is connected to the first capacitor; a protection circuit, the protection circuit comprising a first switch tube and a series circuit consisting of at least one resistor, a first electrode of the first switch tube and one end of the series circuit are both connected to the rectifier circuit, and a second electrode of the first switch tube and the other end of the series circuit are both connected to the first capacitor; A power supply circuit is connected to the first capacitor and the controlled end of the first switch tube respectively.

2. The surge protection circuit according to claim 1, characterized in that: The series circuit includes a first resistor; One end of the first resistor is connected to the first capacitor, and the other end of the first resistor is connected to the rectifier circuit.

3. The surge protection circuit according to claim 2, characterized in that: The protection circuit also includes a first diode; The anode of the first diode is connected to the controlled end of the first switch tube, and the cathode of the first diode is connected to the power supply circuit.

4. The surge protection circuit according to claim 3, characterized in that: The protection circuit also includes a second resistor, a third resistor and a second diode; One end of the second resistor and the anode of the second diode are both connected to the rectifier circuit, the other end of the second resistor and the cathode of the second diode are both connected to the anode of the first diode, one end of the third resistor is connected to the cathode of the first diode, and the other end of the third resistor is connected to the power supply circuit.

5. The surge protection circuit according to claim 3, characterized in that: The power supply circuit includes a second capacitor; One end of the second capacitor is connected to the cathode of the first diode and the first capacitor respectively, the other end of the second capacitor is grounded, and the second capacitor is also connected to the power supply module of the switching power supply.

6. The surge protection circuit according to claim 5, characterized in that: The power supply circuit also includes a third diode and a fourth resistor; One end of the fourth resistor is connected to the power supply module, the other end of the fourth resistor is connected to the anode of the third diode, and the cathode of the third diode is connected to the cathode of the second capacitor and the first diode respectively.

7. The surge protection circuit according to claim 1, characterized in that: It also includes a starting circuit, one end of which is connected to the first capacitor, and the other end of which is connected to the power supply circuit.

8. The surge protection circuit according to claim 7, characterized in that: The startup circuit includes a fifth resistor and a sixth resistor; One end of the fifth resistor is connected to the first capacitor, the other end of the fifth resistor is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the power supply circuit.

9. The surge protection circuit according to claim 1, characterized in that: The first switch tube is a MOS tube, a gate of the MOS tube is connected to the power supply circuit, a source of the MOS tube is connected to the rectifier circuit, and a drain of the MOS tube is connected to the first capacitor.

10. A switching power supply, characterized in that: Comprising a surge protection circuit as described in any one of claims 1-9.

Images