DC anti-surge circuit and protection device

Abstract

The invention discloses a direct-current anti-surge circuit and protection equipment, and relates to the technical field of direct-current anti-surge circuits, and the circuit is characterized in that the first end of a charging capacitor is connected to the first end of a first divider resistor and the cathode of a first diode, and the second end of the charging capacitor is connected to the second end of the first divider resistor and the anode of the first diode; the current-limiting resistor and the first end of the first switch element are jointly connected to the anode of the first diode, and the control end of the first switch element is connected to the cathode of the first diode; the current-limiting resistor and the second end of the first switch element are jointly connected to an output voltage negative electrode; the first divider resistor is connected to the cathode of the second diode through the second divider resistor, the cathode of the second diode is connected to the output voltage anode, and the anode of the second diode is connected to the first end of the charging capacitor. In this way, at the moment of power-on, current flows to the negative electrode of the input voltage through the current-limiting resistor, so that the direct-current power supply is not subjected to overlarge impact current.

Description

Technical Field

[0001] The present application relates to the technical field of DC surge protection circuits, and in particular to a DC surge protection circuit and protection equipment. Background Art

[0002] At present, according to the power supply system of aviation airborne platforms, protective equipment is still the main power source for airborne equipment. Since airborne platforms carry a large number of airborne equipment, the normal function of protective equipment is particularly important for airborne equipment. Therefore, protective equipment will be equipped with an anti-reverse connection circuit to prevent the occurrence of circuit failures caused by reverse connection or thunderstorms when the protective equipment is in use. In actual application scenarios, the anti-reverse connection protection circuits are mainly diode anti-reverse connection circuits and relay anti-reverse connection circuits; among them, the diode anti-reverse connection circuit has a large voltage drop, and the number of relay contact actions in the relay anti-reverse connection circuit is limited, and long-term use of the contacts may cause sparking and burning and contact adhesion, which is not suitable for frequent working occasions; the switch tube anti-reverse connection circuit, although the circuit has a small voltage drop, no mechanical contacts, and no life span of the contacts.

[0003] In the back-end circuit of the above-mentioned anti-reverse connection circuit, there is a capacitor connected in parallel with the DC power supply and other airborne electrical equipment. It is impossible to avoid the damage caused by the surge current generated by the back-end circuit at the moment of power-on, which in turn affects the normal power supply of the DC power supply to other airborne electrical equipment in the back-end circuit.

[0004] Therefore, the existing anti-reverse connection circuit cannot avoid the situation where the DC power supply is damaged by the surge current generated at the moment of power-on, which is a problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a DC surge protection circuit and protection equipment to solve the above-mentioned problem and avoid the damage of the DC power supply caused by the surge current generated at the moment of power-on.

[0006] In a first aspect, the present application provides a DC surge protection circuit, which is applied to a protection device, and the circuit includes: a charging capacitor, a current limiting resistor, and a first switching element; The first end of the charging capacitor is connected to the first end of the first voltage-dividing resistor and the cathode of the first diode respectively, and the second end is connected to the second end of the first voltage-dividing resistor and the anode of the first diode respectively; The current limiting resistor and the first end of the first switch element are commonly connected to the anode of the first diode, and the control end of the first switch element is connected to the cathode of the first diode; The second end of the current limiting resistor and the first switch element are commonly connected to the negative electrode of the output voltage; The first voltage-dividing resistor is connected to the cathode of the second diode through the second voltage-dividing resistor, the cathode of the second diode is connected to the positive electrode of the output voltage, and the anode of the second diode is connected to the first end of the charging capacitor; If the voltage at the control terminal of the first switch element is less than the turn-on threshold, the first switch element is turned off.

[0007] Preferably, if the voltage at the control terminal of the first switch element is greater than or equal to a turn-on threshold, the first switch element is turned on.

[0008] Preferably, the circuit further comprises a second switching element; The first end of the second switch element is respectively connected to the first end of the third voltage-dividing resistor, the first end of the first filter element, the anode of the third diode and the second end of the first voltage-dividing resistor, and the control end is respectively connected to the second end of the third voltage-dividing resistor, the second end of the first filter element, the cathode of the third diode and the first end of the fourth voltage-dividing resistor; The second end of the fourth voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor.

[0009] Preferably, the circuit further comprises a second filtering element; The first end of the second filter element is connected to the second end of the fourth voltage-dividing resistor, and the second end of the second filter element is connected to the second end of the second switch element.

[0010] Preferably, the circuit further comprises a fourth diode; The first end of the fourth diode is respectively connected to the third end of the second filter element and the negative electrode of the input voltage, and the second end is respectively connected to the fourth end of the second filter element and the positive electrode of the input voltage.

[0011] Preferably, the first filter element is a filter capacitor.

[0012] Preferably, the second filtering element is a common mode filtering inductor.

[0013] Preferably, the fourth diode is a transient voltage suppressor TVS.

[0014] Preferably, both the first switch element and the second switch element are MOS tubes.

[0015] It can be seen from the above technical solution that the present application has at least the following beneficial effects: In the DC surge protection circuit provided in the present application, the charging capacitor is used to delay the conduction time of the first switching element. Before the first switching element is turned on, the current flowing back to the DC power supply is within a normal range due to the current limiting effect of the current limiting resistor, and the DC power supply will not be subjected to excessive current shocks that affect the power supply quality, thereby ensuring the normal power supply of the DC power supply.

[0016] In a second aspect, the present application provides a protection device, the protection device comprising: a charging capacitor, a current limiting resistor and a first switching element; The first end of the charging capacitor is connected to the first end of the first voltage-dividing resistor and the cathode of the first diode respectively, and the second end is connected to the second end of the first voltage-dividing resistor and the anode of the first diode respectively; The current limiting resistor and the first end of the first switch element are commonly connected to the anode of the first diode, and the control end of the first switch element is connected to the cathode of the first diode; The second end of the current limiting resistor and the first switch element are commonly connected to the negative electrode of the output voltage; The first voltage-dividing resistor is connected to the cathode of the second diode through the second voltage-dividing resistor, the cathode of the second diode is connected to the positive electrode of the output voltage, and the anode of the second diode is connected to the first end of the charging capacitor; If the voltage at the control terminal of the first switch element is less than the turn-on threshold, the first switch element is turned off.

[0017] The protection device provided in the present application has the same technical features as the above-mentioned DC surge protection circuit, so it can also solve the same technical problems and achieve the same technical effects.

[0018] It should be understood that the description of technical features, technical solutions, beneficial effects or similar language in this application does not imply that all features and advantages can be realized in any single embodiment. On the contrary, it is understood that the description of features or beneficial effects means that specific technical features, technical solutions or beneficial effects are included in at least one embodiment. Therefore, the description of technical features, technical solutions or beneficial effects in this specification does not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions and beneficial effects described in the present embodiment can also be combined in any appropriate manner. Those skilled in the art will understand that the embodiment can be realized without one or more specific technical features, technical solutions or beneficial effects of a specific embodiment. In other embodiments, additional technical features and beneficial effects can also be identified in a specific embodiment that does not embody all embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of current flow when a first switch element in a DC surge protection circuit provided in an embodiment of the present application is turned off; Figure 2 A schematic diagram of current flow when a first switch element in a DC surge protection circuit provided by an embodiment of the present application is turned on; Figure 3A schematic diagram of the current flow direction when the protective device provided in the embodiment of the present application is connected in a forward direction; Figure 4 A schematic diagram of the current flow when the protective device provided in an embodiment of the present application is reversely connected. DETAILED DESCRIPTION

[0020] The terms "first", "second", "third", etc. in the specification of this application and the accompanying drawings are used to distinguish different objects rather than to limit a specific order.

[0021] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0022] In order to make the description of the following embodiments clear and concise, a brief introduction to the related technology is first given: The embodiment of the present invention provides a DC surge protection circuit, which is applied to protection equipment, such as Figure 1 As shown, Figure 1 A schematic diagram of current flow when a first switch element V3 is turned off in a DC surge protection circuit provided in an embodiment of the present application. The circuit includes: a charging capacitor C2, a current limiting resistor R5 and a first switch element V3; the first end of the charging capacitor C2 is respectively connected to the first end of the first voltage-dividing resistor R3 and the cathode of the first diode V5, and the second end is respectively connected to the second end of the first voltage-dividing resistor R3 and the anode of the first diode V5; the current limiting resistor R5 and the first end of the first switch element V3 are commonly connected to the anode of the first diode V5, and the control end of the first switch element V3 is connected to the cathode of the first diode V5; the current limiting resistor R5 and the second end of the first switch element V3 are commonly connected to the negative electrode of the output voltage; the first voltage-dividing resistor R3 is connected to the cathode of the second diode V6 through the second voltage-dividing resistor R4, the cathode of the second diode V6 is connected to the positive electrode of the output voltage, and the anode of the second diode V6 is connected to the first end of the charging capacitor C2; if the control end voltage of the first switch element V3 is less than the conduction threshold, the first switch element V3 is turned off; if the control end voltage of the first switch element V3 is greater than or equal to the conduction threshold, the first switch element V3 is turned on. Wherein, the first switch element V3 is a MOS tube.

[0023] Specifically, at the moment of power-on, the 28V voltage is not directly applied to the control end (gate) and the first end (source) of the first switch element V3, but is applied to both ends of the charging capacitor C2 to charge the charging capacitor C2. At this time, the first end (source) and the second end (drain) of the first switch element V3 are in the cut-off state, and the parasitic diode of the first switch element V3 also cuts off the current flowing in from the negative electrode of the output voltage (DC28V_PGND_out). The current can only flow back to the negative electrode of the input voltage (not shown in the figure) from the negative electrode of the output voltage (DC28V_PGND_out) (not shown in the figure) through the current limiting resistor R5. When the charging capacitor C2 is fully charged, it slowly discharges to the first end and the control end of the first switch element V3. Figure 2 As shown, Figure 2 A schematic diagram of the current flow when the first switch element in a DC surge protection circuit is turned on is provided in an embodiment of the present application. The voltage between the first end and the control end of the first switch element V3 gradually increases. When the voltage between the first end and the control end of the first switch element V3 exceeds the turn-on threshold (10V), the first end and the second end of the first switch element V3 are turned on, and the circuit enters a steady-state working state. At this time, the current limiting resistor R5 is equivalent to being short-circuited by the first end and the second end of the first switch element V3, and the current flows from the second end of the first switch element V3 to the first end, and then flows to the negative electrode of the input voltage, that is, the second end and the first end of the switch element V3 form a loop with the negative electrode of the output voltage.

[0024] In this arrangement, since there is a capacitor in the back-end circuit of the circuit in parallel with the DC power supply and other onboard electrical equipment, at the moment of power-on, the current flows to the negative electrode of the input voltage through the current limiting resistor R5, so the DC power supply will not be subjected to excessive impact current. In the prior art, at the moment of power-on, the DC power supply will be directly impacted by the sudden increase in current, causing the DC power supply to be damaged, thereby affecting the normal power supply of other onboard electrical equipment.

[0025] Compared with the prior art, in this circuit, the charging capacitor C2 is used to delay the turn-on time of the first switching element V3. Before the first switching element V3 is turned on, the current flowing back to the DC power supply is within a normal range due to the current limiting effect of the current limiting resistor R5, and the DC power supply will not be subjected to excessive current shock to affect the power supply quality; after the first switching element V3 is turned on, that is, the circuit maintains a voltage-stabilizing state, and there is no sudden change in the current. The first switching element V3 can short-circuit the current limiting resistor R5, and the current flows back to the DC power supply through the first switching element V3, thereby ensuring the normal power supply of the DC power supply.

[0026] In addition, when the power is turned off, the second diode V6 can accelerate the discharge of the charging capacitor C2, so that the first switch element V3 is quickly turned off, avoiding the first switch element V3 from being damaged by heat accumulation due to slow shutdown. When the power is on, the first diode V5 can control the voltage UGS1 (not shown in the figure) between the first end and the control end of the first switch element V3 within a range of less than or equal to 15V, avoiding the situation where the first switch element V3 is broken down and damaged due to overvoltage between the first end and the control end of the first switch element V3. The MOS tube is used as the first switch element V3 in this circuit because the MOS tube has the advantages of high power, high rated current, low on-resistance, low on-voltage drop and low heat generation, and has a long service life. Compared with the triode, it can better suppress the surge current generated by the back-end circuit capacitor of the circuit.

[0027] The following is an introduction to the anti-reverse connection module of this circuit. Figure 3 As shown, Figure 3 A schematic diagram of the current flow when the protective device provided in the embodiment of the present application is positively connected. The above-mentioned DC surge protection circuit also includes a second switch element V2; the first end of the second switch element V2 is respectively connected to the first end of the third voltage-dividing resistor R2, the first end of the first filter element C2, the anode of the third diode V4 and the second end of the first voltage-dividing resistor R3, and the control end is respectively connected to the second end of the third voltage-dividing resistor R2, the second end of the first filter element C2, the cathode of the third diode V4 and the first end of the fourth voltage-dividing resistor R1; the second end of the fourth voltage-dividing resistor R1 is connected to the first end of the second voltage-dividing resistor R4; wherein the second switch element V2 is a MOS tube, and the first filter element C2 is a filter capacitor.

[0028] Specifically, when the protection device is positively connected, the voltage between the control end (gate) and the first end (source) of the second switching element V2 (MOS tube) is greater than or equal to the conduction threshold (10V). At this time, the first end (source) and the second end (drain) of the second switching element V2 are in the on state, and the current forms a loop through the second switching element V2 and the back-end circuit.

[0029] like Figure 4 As shown, Figure 4 A schematic diagram of the current flow when the protection device is reversely connected provided in an embodiment of the present application. When the protection device is reversely connected, the voltage between the control end and the first end of the second switch element V2 (MOS tube) is less than the turn-on threshold (10V). At this time, the first end (source) and the second end (drain) of the second switch element V2 are in the cut-off state, and the parasitic diode of the second switch power supply also cuts off the current, so that the current cannot form a loop with the back-end circuit through the second switch element V2. With such a configuration, when the user reversely connects the protective device, the second switch element V2 can cut off the reverse current in time to prevent the reverse current from flowing into the back-end circuit, thereby causing the back-end circuit to be broken down by the reverse current and causing functional damage, thereby protecting the safety of the back-end circuit and extending the service life of the back-end circuit.

[0030] In addition, the first filter element C2, i.e., the filter capacitor, can filter out the peak voltage between the control end (gate) and the first end (source) of the first switch element V3 at the moment when the second switch element V2 is turned on and off. The third diode V4 is a voltage regulator diode, which can control the voltage UGS2 between the control end (gate) and the first end (source) of the second switch element V2 to be less than or equal to 15V, thereby preventing the control end (gate) and the first end (source) of the second switch element V2 from being over-voltage-broken and damaged. The MOS tube is used as the second switch element V2 in this circuit because the MOS tube has the advantages of small conduction voltage drop and small heat generation, and has a long service life. Compared with the triode, it can better protect the back-end circuit when the protective equipment is reversely connected.

[0031] The filter module of the circuit is introduced below. The DC surge protection circuit also includes a second filter element L1; the first end of the second filter element L1 is connected to the second end of the fourth voltage-dividing resistor R1, and the second end is connected to the second end of the second switch element V2; wherein the second filter element L1 is a common-mode filter inductor.

[0032] Specifically, the common-mode filter inductor uses ferrite as the magnetic core and suppresses the interference of common-mode signals by vertical coupling of mutual inductance. The common-mode filter inductor (the second filter element L1) can filter out common-mode interference signals, noise signals and power conversion spike signals in the current. The larger the inductance of the common-mode filter inductor, the better the filtering and surge suppression effects will be. The selection of the common-mode filter inductor needs to be comprehensively considered based on load current, PCB space, etc. Among them, the selection of the common-mode filter inductor mainly considers the inductance, rated current and DC resistance. Since the common-mode filter inductor in the embodiment of the present application is 1.2mH.

[0033] Such a setting can filter out the common-mode interference signal in the DC surge protection circuit. Since the common-mode filter inductor actually produced is asymmetric, it also has a certain inhibitory effect on the differential-mode interference signal, so that the current in the circuit can be output stably, the electromagnetic compatibility of the circuit can be improved, and the stability and reliability of the circuit can be improved.

[0034] The protection module of the circuit is introduced below. The above-mentioned DC surge protection circuit also includes a fourth diode V1; the first end of the fourth diode V1 is respectively connected to the third end of the second filter element L1 and the negative electrode of the input voltage, and the second end is respectively connected to the fourth end of the second filter element L1 and the positive electrode of the input voltage. Among them, the fourth diode V1 is a TVS (Transient Voltage Suppressor).

[0035] Specifically, the selection principle of transient voltage suppressor is that the breakdown voltage VBR should generally be greater than 1.2 times the rated voltage of the DC power supply, the clamping voltage VC is generally about 1.5 times the breakdown voltage VBR, and the pulse power of the transient voltage suppressor is calculated based on the source impedance of different levels of waveforms in DO-160G. If a transient overvoltage occurs in the circuit, the transient voltage suppressor will quickly turn on and guide the transient overvoltage to the ground line, thereby protecting other components in the circuit from damage.

[0036] In this way, the transient voltage suppressor can improve the surge protection effect of the DC surge protection circuit. In addition, in extreme weather, such as thunderstorms, or in scenes prone to static electricity, the transient voltage suppressor can also guide the high voltage to the bottom line to ensure the normal operation of the back-end circuit and ensure the safety of the back-end circuit.

[0037] On the basis of the above method embodiment, the embodiment of the present invention further provides a protection device, the protection device comprises: a charging capacitor C2, a current limiting resistor R5 and a first switch element V3; The first end of the charging capacitor C2 is respectively connected to the first end of the first voltage-dividing resistor R3 and the cathode of the first diode V5, and the second end is respectively connected to the second end of the first voltage-dividing resistor R3 and the anode of the first diode V5; The current limiting resistor R5 and the first end of the first switch element V3 are commonly connected to the anode of the first diode V5, and the control end of the first switch element V3 is connected to the cathode of the first diode V5; The current limiting resistor R5 and the second end of the first switch element V3 are commonly connected to the negative electrode of the output voltage; The first voltage-dividing resistor R3 is connected to the cathode of the second diode V6 through the second voltage-dividing resistor R4, the cathode of the second diode V6 is connected to the positive electrode of the output voltage, and the anode of the second diode V6 is connected to the first end of the charging capacitor C2; If the voltage at the control terminal of the first switch element V3 is less than the turn-on threshold, the first switch element V3 is turned off.

[0038] The protection device provided in the embodiment of the present invention has the same technical features as the DC surge protection circuit provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0039] The descriptions of the structures corresponding to the above-mentioned figures have different emphases. For parts not described in detail in a certain structure, reference can be made to the relevant descriptions of other structures.

[0040] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application.

Claims

1. A DC surge protection circuit, characterized in that: Applied to protection equipment, the circuit comprises: a charging capacitor, a current limiting resistor and a first switching element; The first end of the charging capacitor is connected to the first end of the first voltage-dividing resistor and the cathode of the first diode respectively, and the second end is connected to the second end of the first voltage-dividing resistor and the anode of the first diode respectively; The current limiting resistor and the first end of the first switch element are commonly connected to the anode of the first diode, and the control end of the first switch element is connected to the cathode of the first diode; The second end of the current limiting resistor and the first switch element are commonly connected to the negative electrode of the output voltage; The first voltage-dividing resistor is connected to the cathode of the second diode through the second voltage-dividing resistor, the cathode of the second diode is connected to the positive electrode of the output voltage, and the anode of the second diode is connected to the first end of the charging capacitor; If the voltage at the control terminal of the first switch element is less than the turn-on threshold, the first switch element is turned off.

2. The DC surge protection circuit according to claim 1, characterized in that: If the voltage at the control terminal of the first switch element is greater than or equal to the turn-on threshold, the first switch element is turned on.

3. The DC surge protection circuit according to claim 1, characterized in that: The circuit further comprises a second switching element; The first end of the second switch element is respectively connected to the first end of the third voltage-dividing resistor, the first end of the first filter element, the anode of the third diode and the second end of the first voltage-dividing resistor, and the control end is respectively connected to the second end of the third voltage-dividing resistor, the second end of the first filter element, the cathode of the third diode and the first end of the fourth voltage-dividing resistor; The second end of the fourth voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor.

4. The DC surge protection circuit according to claim 3, characterized in that: The circuit also includes a second filtering element; The first end of the second filter element is connected to the second end of the fourth voltage-dividing resistor, and the second end of the second filter element is connected to the second end of the second switch element.

5. The DC surge protection circuit according to claim 4, characterized in that: The circuit also includes a fourth diode; The first end of the fourth diode is respectively connected to the third end of the second filter element and the negative electrode of the input voltage, and the second end is respectively connected to the fourth end of the second filter element and the positive electrode of the input voltage.

6. The DC surge protection circuit according to claim 3, characterized in that: The first filter element is a filter capacitor.

7. The DC surge protection circuit according to claim 4, characterized in that: The second filtering element is a common mode filtering inductor.

8. The DC surge protection circuit according to claim 5, characterized in that: The fourth diode is a transient voltage suppressor TVS.

9. The DC surge protection circuit according to claim 1 or 3, characterized in that: The first switch element and the second switch element are both MOS tubes.

10. A protective device, characterized in that: The protection device comprises: a charging capacitor, a current limiting resistor and a first switching element; The first end of the charging capacitor is connected to the first end of the first voltage-dividing resistor and the cathode of the first diode respectively, and the second end is connected to the second end of the first voltage-dividing resistor and the anode of the first diode respectively; The current limiting resistor and the first end of the first switch element are commonly connected to the anode of the first diode, and the control end of the first switch element is connected to the cathode of the first diode; The second end of the current limiting resistor and the first switch element are commonly connected to the negative electrode of the output voltage; The first voltage-dividing resistor is connected to the cathode of the second diode through the second voltage-dividing resistor, the cathode of the second diode is connected to the positive electrode of the output voltage, and the anode of the second diode is connected to the first end of the charging capacitor; If the voltage at the control terminal of the first switch element is less than the turn-on threshold, the first switch element is turned off.

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