Impulse current suppression circuit and switching power supply

Abstract

The utility model relates to an impulse current suppression circuit and a switching power supply, the impulse current suppression circuit comprises a rectification circuit, a first bridge arm comprises a diode D1 and a silicon controlled rectifier SCR1, a cathode of the diode D1 and an anode of the silicon controlled rectifier SCR1 are connected together to form a first input end of the rectification circuit, and the first input end is used for being connected with a first phase input end of the switching power supply; the cathode of the silicon controlled rectifier SCR1 is connected with the positive output end of the rectifying circuit; the anode of the diode D1 is connected with the negative output end of the rectifying circuit; the first silicon controlled rectifier driving circuit is connected between the trigger electrode and the cathode of the silicon controlled rectifier SCR1; the first detection control circuit is used for detecting a voltage difference between an anode and a cathode of the silicon controlled rectifier SCR1, generating a control signal when the voltage difference is smaller than a set voltage, and controlling the silicon controlled rectifier driving circuit to provide a trigger signal for a trigger electrode of the silicon controlled rectifier SCR1; the silicon controlled rectifier is automatically closed when the anode voltage is lower than the cathode voltage. According to the utility model, impact current suppression can be realized without an impact current limiting resistor.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power supply especially relates to an impact current suppression circuit and switching power supply. BACKGROUND

[0002] In the switching power supply starting process, the output gives the energy storage large capacitor charging process and can produce the larger impact current. The front stage rectifier circuit or PFC circuit anti-impact current ability is limited, if not to the impact current and carry out the suppression, very easy to lead to the front stage circuit damage. The conventional impact current suppression circuit adopts the power fixed value resistance or thermistor series connection to the charging loop, such circuit loss is big, only is suitable for small power switching power supply. The medium and large power power supply then adopts the relay or thyristor parallel current limiting resistance scheme, this to the current limiting resistance's power bearing capacity requirement is very high, easy to appear the thermal damage, and the volume is bigger. The prior art still has the scheme that the thyristor phase control technology is used to realize the impact current suppression, these schemes since all adopt the digital control, control difficulty is bigger, cost is higher and program error risk is big. SUMMARY

[0003] In view of this, the technical problem to be solved by the utility model is to provide an impact current suppression circuit and switching power supply, at least one of the technical problems existing in the prior art is solved to some extent.

[0004] As a first aspect of the application, the technical scheme of the impact current suppression circuit embodiment provided is as follows:

[0005] An impact current suppression circuit applied to a switching power supply, the switching power supply comprising an output capacitor, the impact current suppression circuit being used to suppress a large current generated when the output capacitor is charged in the starting process of the switching power supply, characterized in that the impact current suppression circuit comprises:

[0006] a rectifier circuit, wherein a first bridge arm comprises a diode D1 and a thyristor SCR1, the cathode of the diode D1 and the anode of the thyristor SCR1 being connected together as a first input end of the rectifier circuit, used for connecting a first phase input end of the switching power supply, the cathode of the thyristor SCR1 being connected to a positive output end of the rectifier circuit, and the anode of the diode D1 being connected to a negative output end of the rectifier circuit;

[0007] a first thyristor drive circuit connected between the trigger electrode and the cathode of the thyristor SCR1;

[0008] a first detection control circuit used for detecting a voltage difference between the anode and the cathode of the thyristor SCR1 and generating a control signal when the voltage difference is less than a set voltage, the control signal being used to control the first thyristor drive circuit to provide a trigger signal for the trigger electrode of the thyristor SCR1;

[0009] The thyristor is automatically turned off when the anode voltage is lower than the cathode voltage.

[0010] Preferably, the first thyristor driving circuit obtains driving energy from the first phase input terminal of the switching power supply.

[0011] Preferably, the first thyristor driving circuit comprises a diode D3, a capacitor C1, a resistor R1 and an optocoupler OCl, the anode of the diode D3 is connected to the connection point of the cathode of the diode D1 and the anode of the thyristor SCR1, the cathode of the diode D3 is connected to one end of the capacitor C1 and one end of the resistor R1, the other end of the capacitor C1 is connected to the cathode of the thyristor SCR1, the other end of the resistor R1 is connected to the collector of the receiving triode of the optocoupler OCl, the emitter of the receiving triode of the optocoupler OCl is connected to the trigger electrode of the thyristor SCR1, the anode of the emitting diode of the optocoupler OCl inputs the control signal, and the cathode is connected to ground.

[0012] Preferably, the first detection control circuit comprises:

[0013] a first voltage sampling circuit for sampling the voltage of the first input terminal of the rectifier circuit and the voltage of the positive output terminal of the rectifier circuit, and subtracting the two to obtain the voltage difference;

[0014] a first pulse trigger circuit for comparing the voltage difference with a set voltage, and generating the control signal when the voltage difference is less than the set voltage.

[0015] Preferably, the first voltage sampling circuit comprises a resistor R2, a resistor R3, a resistor R4, a resistor R5 and an operational amplifier U1A, one end of the resistor R2 is connected to the connection point of the cathode of the diode D1 and the anode of the thyristor SCR1, the other end of the resistor R2 and one end of the resistor R5 are connected to the non-inverting input terminal of the operational amplifier U1A, the other end of the resistor R5 is connected to ground, one end of the resistor R3 is connected to the cathode of the thyristor SCR1, the other end of the resistor R3 and one end of the resistor R4 are connected to the inverting input terminal of the operational amplifier U1A, and the other end of the resistor R4 and the output terminal of the operational amplifier U1A are connected together to output the voltage difference.

[0016] Preferably, the first pulse trigger circuit comprises an operational amplifier U2A and a capacitor C3, the inverting input terminal of the operational amplifier U2A inputs the voltage difference, the non-inverting input terminal inputs the set voltage, and the output terminal is connected to one end of the capacitor C3, and the other end of the capacitor C3 outputs the control signal.

[0017] Further, the rectifier circuit has the same bridge arm structure as the first bridge arm structure, and the surge current suppression circuit further comprises thyristor drive circuits and control circuits for the thyristors in the other bridge arms, wherein the thyristor drive circuits for the thyristors in the other bridge arms have the same structure as the first thyristor drive circuit, and the detection control circuits for the thyristors in the other bridge arms have the same structure as the first detection control circuit.

[0018] Preferably, the rectifier circuit has two or three bridge arms.

[0019] As a second aspect of the present application, the switching power supply embodiment is provided as follows:

[0020] A switching power supply, characterized in that it comprises an output capacitor and the surge current suppression circuit according to any one of the first aspect, and the surge current suppression circuit is used to suppress the large current generated when charging the output capacitor during the starting process of the switching power supply.

[0021] Preferably, the switching power supply is an AC-DC switching power supply.

[0022] The working principle of the present application will be described in conjunction with specific embodiments, which will not be described here. Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) The first detection control circuit detects the voltage difference before and after the rectifier circuit (i.e. controls the voltage difference between the anode and cathode of the thyristor in the rectifier circuit) to control the opening of the thyristor in the rectifier circuit, thereby controlling the size of the surge current, so that the surge current limiting resistor in the prior art is not needed, heat damage is avoided, and the product size is reduced.

[0024] (2) The first detection control circuit in the embodiment detects and controls, which is an analog circuit detection and control. Compared with the digital control scheme in the prior art, the detection accuracy is higher, the control speed is faster, the control difficulty is small, the cost is low, and the error risk is small. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A schematic diagram of a phase-controlled surge current suppression circuit according to the first embodiment of the present application applied to a switching power supply;

[0026] Figure 2 For Figure 1 A working timing diagram of the circuit. DETAILED DESCRIPTION

[0027] In order to make the utility model's purpose, technical scheme and advantage more clearly, the following will be further detailed in the utility model with the help of the drawings and examples.

[0028] It should be noted that the terms "comprising" and "having" and any variations thereof described in the specification and claims of the present application are intended to cover non-exclusive inclusion, for example, a series of components, unit circuits or control sequences are not necessarily limited to those components, unit circuits or control sequences clearly listed, but can include components, unit circuits or control sequences not clearly listed or inherent to these circuits.

[0029] In addition, the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0030] It should be understood that in the specification and claims, when describing that an element is "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element; when describing that a step is connected to another step, the step can be directly connected to the other step, or connected to the other step through a third step.

[0031] First embodiment

[0032] The embodiment provides a surge current suppression circuit applied to a switching power supply, Figure 1 For the principle diagram of the surge current suppression circuit applied to the switching power supply of the first embodiment of the utility model, please refer to Figure 1 Wherein: the switching power supply comprises an output capacitor C2, the surge current suppression circuit is used for suppressing large current generated when the output capacitor C2 is charged in the starting process of the switching power supply, and the surge current suppression circuit comprises:

[0033] The rectifier circuit, wherein the first bridge arm comprises a diode D1 and a silicon controlled rectifier SCR1, the cathode of the diode D1 and the anode of the silicon controlled rectifier SCR1 are connected together to be the first input end of the rectifier circuit, and are used for connecting the first phase input end of the switching power supply; the cathode of the silicon controlled rectifier SCR1 is connected to the positive output end of the rectifier circuit; and the anode of the diode D1 is connected to the negative output end of the rectifier circuit.

[0034] The first silicon controlled rectifier driving circuit is connected between the trigger electrode and the cathode of the silicon controlled rectifier SCR1.

[0035] The first detection control circuit is used for detecting the voltage difference between the anode and the cathode of the silicon controlled rectifier SCR1, and generating a control signal when the voltage difference is less than a set voltage, so as to control the silicon controlled rectifier driving circuit to provide a trigger signal for the trigger electrode of the silicon controlled rectifier SCR1.

[0036] The thyristor turns itself off when the voltage at its anode falls below the voltage at its cathode.

[0037] Please continue to see Figure 1 , wherein: the first thyristor driving circuit takes power from the first phase input terminal of the switching power supply to obtain driving energy provided by the thyristor SCR1.

[0038] Please continue to see Figure 1 , wherein: the first thyristor drive circuit includes a diode D3, a capacitor C1, a resistor R1 and an optocoupler OC1, the anode of the diode D3 is connected to the connection point of the cathode of the diode D1 and the anode of the thyristor SCR1, the cathode is simultaneously connected to one end of the capacitor C1 and one end of the resistor R1, the other end of the capacitor C1 is connected to the cathode of the thyristor SCR1, the other end of the resistor R1 is connected to the collector of the transistor at the receiving end of the optocoupler OC1, the emitter of the transistor at the receiving end of the optocoupler OC1 is connected to the trigger electrode of the thyristor SCR1, the anode of the diode at the transmitting end of the optocoupler OC1 inputs the control signal, and the cathode is used for grounding.

[0039] Please continue to see Figure 1 , wherein: the first detection control circuit includes:

[0040] a first voltage sampling circuit, configured to sample the voltage at the first input terminal of the rectifier circuit and the voltage at the positive output terminal of the rectifier circuit, and subtract the two to obtain a voltage difference;

[0041] The first pulse trigger circuit is used to compare the voltage difference with a set voltage ΔU, and generate a control signal when the voltage difference is less than the set voltage ΔU.

[0042] Please continue to see Figure 1 , wherein: the first voltage sampling circuit includes a resistor R2, a resistor R3, a resistor R4, a resistor R5 and an operational amplifier U1A, wherein one end of the resistor R2 is connected to the connection point of the cathode of the diode D1 and the anode of the thyristor SCR1, the other end and one end of the resistor R5 are simultaneously connected to the non-inverting input terminal of the operational amplifier U1A, the other end of the resistor R5 is used for grounding, one end of the resistor R3 is connected to the cathode of the thyristor SCR1, the other end and one end of the resistor R4 are simultaneously connected to the inverting input terminal of the operational amplifier U1A, and the other end of the resistor R4 is connected to the output terminal of the operational amplifier U1A to output the voltage difference.

[0043] Please continue to see Figure 1 , wherein: the first pulse trigger circuit includes an operational amplifier U2A and a capacitor C3, the operational amplifier U2A has an inverting input terminal input voltage difference, a non-inverting input terminal input set voltage ΔU, an output terminal connected to one end of the capacitor C3, and the other end of the capacitor C3 outputs a control signal Control.

[0044] Please continue to see Figure 1Wherein: the second bridge arm structure of the rectifier circuit is same as the first bridge arm structure, the second bridge arm comprises a diode D2 and a thyristor SCR2, the impact current suppression circuit further comprises a second thyristor driving circuit and a second control circuit of the thyristor SCR2, the two circuits are not shown in the figure in the Figure 1 second embodiment, and the second thyristor driving circuit is same in structure as the first thyristor driving circuit, and the second detection control circuit is same in structure as the first detection control circuit.

[0045] It should be noted that the number of bridge arms of the rectifier circuit in the embodiment can be 2 or 3: when the number of bridge arms of the rectifier circuit is 2, the input of the switching power supply is two-phase input; when the number of bridge arms of the rectifier circuit is 3, the input of the switching power supply is three-phase input. Figure 2 The circuit is only an example and should not constitute a limitation on the protection scope of the utility model, and the number of bridge arms of the rectifier circuit can be designed by the person skilled in the art according to the needs, when the number of bridge arms of the rectifier circuit is more than 1, the other bridge arm structures are same as the first bridge arm structure, the impact current suppression circuit further comprises a thyristor driving circuit and a control circuit of each thyristor in the other bridge arms, and the thyristor driving circuit of each thyristor in the other bridge arms is same in structure as the first thyristor driving circuit, and the detection control circuit of each thyristor is same in structure as the first detection control circuit.

[0046] Please continue to refer to Figure 1 , and the working timing diagram of Figure 2 , the working principle of the embodiment is explained by taking N line control as an example, and the L line control is the same as the N line control, and details are not repeated.

[0047] The impact current suppression circuit samples the voltage of the N line relative to the reference ground and the voltage of the rectifier output BC+ relative to the reference ground through resistors and compares and subtracts through the operational amplifier U1A, and the voltage output by the operational amplifier U1A is compared with the reference reference source △U through the operational amplifier U2A. When the voltage difference of the N line relative to the reference ground and the voltage of the rectifier output positive BC+ relative to the reference ground is less than the reference reference source △U, the operational amplifier U2A outputs high, a pulse is sent to the A pole of the optocoupler OC1 through the DC blocking capacitor to open the thyristor SCR1, and the thyristor is automatically turned off when the N line voltage is lower than the rectifier output positive BC+ voltage. The reference reference source △U controls the opening angle of the thyristor, and the size of the impact current is controlled. The driving energy of the thyristor SCR1 comes from the rectifier diode D3 when the N line voltage is higher than the rectifier output positive BC+ voltage, and the energy is stored in the driving energy storage capacitor C1.

[0048] Second embodiment

[0049] The switching power supply provided by the embodiment comprises an output capacitor and the inrush current suppression circuit of any one of the first embodiment, and the inrush current suppression circuit is used to suppress the large current generated when the switching power supply charges the output capacitor during the starting process.

[0050] The switching power supply of the embodiment comprises the inrush current suppression circuit of any one of the first embodiment, detects the voltage difference before and after the rectifier circuit through an analog circuit, controls the turn-on of the thyristor of the rectifier circuit, realizes the control of the inrush current size, and thus does not need the inrush current limiting resistor, and can overcome the defects of the prior art.

[0051] Further, the switching power supply is an AC-DC switching power supply.

[0052] The above description of the embodiments is only used to help understand the inventive concept of the application, and does not limit the application. For those skilled in the art, any modification, equivalent replacement, improvement, etc. made without departing from the principle of the application shall be included in the protection scope of the application.

Claims

1. An inrush current suppression circuit, applied to a switching power supply, wherein the switching power supply includes an output capacitor, and the inrush current suppression circuit is used to suppress the high current generated when the output capacitor is charged during the startup of the switching power supply, characterized in that: The inrush current suppression circuit comprises: A rectifier circuit, wherein the first bridge arm includes a diode D1 and a thyristor SCR1, the cathode of the diode D1 and the anode of the thyristor SCR1 are connected together to form a first input terminal of the rectifier circuit, which is used to connect to the first phase input terminal of the switching power supply, the cathode of the thyristor SCR1 is connected to the positive output terminal of the rectifier circuit, and the anode of the diode D1 is connected to the negative output terminal of the rectifier circuit; A first thyristor driving circuit is connected between the trigger electrode and the cathode of the thyristor SCR1; a first detection control circuit, configured to detect a voltage difference between an anode and a cathode of the thyristor SCR1, and generate a control signal when the voltage difference is less than a set voltage, thereby controlling the thyristor drive circuit to provide a trigger signal to a trigger electrode of the thyristor SCR1; The thyristor turns itself off when the voltage at its anode is lower than the voltage at its cathode.

2. The inrush current suppression circuit according to claim 1, wherein: The first thyristor driving circuit obtains power from the first phase input terminal of the switching power supply to obtain driving energy provided by the thyristor SCR1.

3. The inrush current suppression circuit according to claim 2, wherein: The first thyristor drive circuit includes a diode D3, a capacitor C1, a resistor R1 and an optocoupler OC1. The anode of the diode D3 is connected to the connection point of the cathode of the diode D1 and the anode of the thyristor SCR1, and the cathode is simultaneously connected to one end of the capacitor C1 and one end of the resistor R1. The other end of the capacitor C1 is connected to the cathode of the thyristor SCR1. The other end of the resistor R1 is connected to the collector of the transistor at the receiving end of the optocoupler OC1. The emitter of the transistor at the receiving end of the optocoupler OC1 is connected to the trigger electrode of the thyristor SCR1. The anode of the diode at the transmitting end of the optocoupler OC1 inputs the control signal, and the cathode is used for grounding.

4. The inrush current suppression circuit according to claim 1, wherein: The first detection control circuit includes: a first voltage sampling circuit, configured to sample the voltage at the first input terminal of the rectifier circuit and the voltage at the positive output terminal of the rectifier circuit, and subtract the two to obtain the voltage difference; The first pulse trigger circuit is used to compare the voltage difference with a set voltage, and generate a control signal when the voltage difference is less than the set voltage.

5. The inrush current suppression circuit according to claim 4, wherein: The first voltage sampling circuit includes a resistor R2, a resistor R3, a resistor R4, a resistor R5 and an operational amplifier U1A, one end of the resistor R2 is connected to the connection point of the cathode of the diode D1 and the anode of the thyristor SCR1, and the other end and one end of the resistor R5 are simultaneously connected to the non-inverting input terminal of the operational amplifier U1A, the other end of the resistor R5 is used for grounding, one end of the resistor R3 is connected to the cathode of the thyristor SCR1, and the other end and one end of the resistor R4 are simultaneously connected to the inverting input terminal of the operational amplifier U1A, and the other end of the resistor R4 is connected to the output terminal of the operational amplifier U1A to output the voltage difference.

6. The inrush current suppression circuit according to claim 4, wherein: The first pulse trigger circuit includes an operational amplifier U2A and a capacitor C3. The inverting input terminal of the operational amplifier U2A inputs the voltage difference, the non-inverting input terminal inputs the set voltage, the output terminal is connected to one end of the capacitor C3, and the other end of the capacitor C3 outputs the control signal.

7. The inrush current suppression circuit according to claim 1, wherein: The other bridge arm structures of the rectifier circuit are the same as the first bridge arm structure, and the inrush current suppression circuit also includes the thyristor drive circuit and control circuit of each thyristor in the other bridge arms, and the thyristor drive circuit of each thyristor in the other bridge arms is the same as the first thyristor drive circuit structure, and the respective detection control circuit is the same as the first detection control circuit structure.

8. The inrush current suppression circuit according to any one of claims 1 to 7, characterized in that: The number of bridge arms of the rectifier circuit is 2 or 3.

9. A switching power supply, characterized in that: It comprises an output capacitor and the inrush current suppression circuit according to any one of claims 1 to 8, wherein the inrush current suppression circuit is used to suppress the large current generated when the output capacitor is charged during the startup of the switching power supply.

10. The switching power supply according to claim 9, characterized in that: The switching power supply is an AC-DC switching power supply.

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