CN109639126B - Surge current prevention circuit and electric equipment - Google Patents
Surge current prevention circuit and electric equipment Download PDFInfo
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- CN109639126B CN109639126B CN201910087758.6A CN201910087758A CN109639126B CN 109639126 B CN109639126 B CN 109639126B CN 201910087758 A CN201910087758 A CN 201910087758A CN 109639126 B CN109639126 B CN 109639126B
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- 230000002265 prevention Effects 0.000 title description 3
- 239000003990 capacitor Substances 0.000 claims abstract description 77
- 238000004146 energy storage Methods 0.000 claims abstract description 53
- 238000006243 chemical reaction Methods 0.000 claims abstract description 40
- 238000001914 filtration Methods 0.000 claims description 33
- 230000000087 stabilizing effect Effects 0.000 claims description 16
- 238000004804 winding Methods 0.000 claims description 14
- 238000004880 explosion Methods 0.000 abstract description 5
- 230000005611 electricity Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000000670 limiting effect Effects 0.000 description 5
- 230000002401 inhibitory effect Effects 0.000 description 3
- 230000001629 suppression Effects 0.000 description 3
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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Abstract
The invention discloses an anti-surge current circuit and electric equipment, wherein the anti-surge current circuit comprises: the power conversion circuit comprises a rectifying circuit, an energy storage capacitor, a power conversion circuit, a bypass resistor, a switching tube and a switching tube control circuit; the positive electrode output end of the rectifying circuit is connected with the positive electrode of the energy storage capacitor, and the negative electrode output end is grounded; one end of the bypass resistor is connected with the negative electrode of the energy storage capacitor, and the other end of the bypass resistor is grounded; the input end of the switching tube is connected with the negative electrode of the energy storage capacitor, the output end of the switching tube is grounded, and the control end of the switching tube is connected with the output end of the switching tube control circuit; the power input end of the switching tube control circuit is connected with the power conversion circuit. According to the technical scheme of the invention, surge current in the AC-DC power supply circuit can be effectively restrained, so that phenomena such as spark or explosion sound and the like of the socket spring sheet during plug-in are effectively prevented, the electricity utilization safety, reliability and the like are greatly improved, the service life of the power supply and the use experience of users can be also improved.
Description
Technical Field
The invention relates to the technical field of power supplies, in particular to an anti-surge current circuit and electric equipment.
Background
When various electric equipment is actually used, particularly at the moment of plugging and unplugging of a power plug, the phenomena of sparking and even explosion of the plug can occur frequently. This is due to the arcing effect that occurs when two conductors are momentarily in contact, as a result of the occurrence of large inrush currents that are not effectively suppressed. Obviously, for consumers, the phenomena of sparking and even explosion of the plug occur, the use feeling of the consumers is greatly influenced, the gold-plated layer of the hardware of the plug is damaged after a long time, and the contact failure occurs to cause serious heating, so that the potential safety hazard is increased. In addition, noise of the power grid can be instantaneously fluctuated, and nearby electricity utilization facilities are seriously interfered.
Disclosure of Invention
In view of the above problems, the invention provides an anti-surge current circuit and electric equipment, which can realize active suppression of surge current by inserting a switching tube and a bypass resistor at the negative side of an energy storage capacitor and performing switching control, and can solve the problems that the surge current of a power supply system of the existing electric equipment cannot be effectively suppressed.
An embodiment of the present invention provides an anti-surge current circuit, including: the power conversion circuit comprises a rectifying circuit, an energy storage capacitor, a power conversion circuit, a bypass resistor, a switching tube and a switching tube control circuit;
The input end of the rectifying circuit is used for being connected with an alternating current power supply, the output end of the positive electrode is connected with the positive electrode of the energy storage capacitor, and the output end of the negative electrode is grounded;
one end of the bypass resistor is connected with the negative electrode of the energy storage capacitor, and the other end of the bypass resistor is grounded;
The input end of the switching tube is connected with the negative electrode of the energy storage capacitor, the output end of the switching tube is grounded, and the control end of the switching tube is connected with the output end of the switching tube control circuit;
the power input end of the switching tube control circuit is connected with the power conversion circuit; the power conversion circuit is connected with the energy storage capacitor and is used for carrying out power conversion and output on the rectified direct current.
In the above-described anti-inrush current circuit, optionally, further comprising: and one end of the bypass capacitor is connected with the negative electrode of the energy storage capacitor, and the other end of the bypass capacitor is grounded.
In the above-mentioned anti-surge current circuit, optionally, the switching tube control circuit includes an MCU controller, a driving circuit, and a power supply circuit, the power conversion circuit includes a switching transformer,
The MCU controller is connected with the driving circuit, and the driving circuit is connected with the control end of the switching tube;
And the input end of the power supply circuit is connected with the secondary winding of the switching transformer, and the output end of the power supply circuit is connected with the MCU controller and the driving circuit.
In the above-mentioned anti-surge current circuit, optionally, the power supply circuit includes a rectifying and filtering unit and a step-down voltage stabilizing unit connected in sequence,
The rectification filter unit is connected with the secondary winding of the switching transformer, and the step-down voltage stabilizing unit is connected with the MCU controller and the driving circuit.
In the above-mentioned anti-surge current circuit, optionally, the power supply circuit includes a step-down voltage stabilizing unit, and the power conversion circuit includes a rectifying and filtering unit and a PWM controller for controlling a power tube connected to the switching transformer;
the input end of the rectifying and filtering unit is connected with the secondary winding of the switching transformer, the output end of the rectifying and filtering unit is connected with the input end of the step-down voltage stabilizing unit, and the output end of the rectifying and filtering unit is also connected with the power input end of the PWM controller through a diode.
In the above anti-surge current circuit, optionally, the step-down voltage stabilizing unit is a low dropout linear voltage regulator or a dc-dc converter.
In the above anti-surge current circuit, optionally, the switching tube is a thyristor, a triode or a MOS tube.
In the above-described anti-inrush current circuit, optionally, further comprising: and the input end of the EMI circuit is used for being connected with the alternating current, and the output end of the EMI circuit is connected with the input end of the rectifying circuit.
In the above-described anti-inrush current circuit, optionally, further comprising: and the input end of the secondary rectifying and filtering circuit is connected with the power conversion circuit, and the output end of the secondary rectifying and filtering circuit is used for being connected with a load.
Another embodiment of the present invention provides an electrical apparatus, including the above-mentioned anti-surge current circuit.
According to the technical scheme, the switching tube and the bypass resistor are inserted into the negative side of the energy storage capacitor behind the rectifying circuit, and the switching tube is correspondingly controlled, so that surge current generated in the moment of plugging and unplugging the plug of the power supply can be effectively restrained, further, phenomena such as spark or explosion of the socket spring sheet can be effectively prevented, the electricity utilization safety, the reliability and the like are greatly improved, the service life of the power supply can be prolonged, and the use experience of a user can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that are required for the embodiments will be briefly described, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope of the present invention.
FIG. 1 is a schematic diagram of a typical prior art AC-DC power input section;
FIG. 2 is a schematic diagram of a first structure of an anti-inrush current circuit according to an embodiment of the invention;
FIG. 3 is a schematic diagram of a second structure of an anti-inrush current circuit according to an embodiment of the invention;
FIG. 4 is a schematic diagram of a third configuration of an anti-inrush current circuit according to an embodiment of the invention;
FIG. 5 is a schematic diagram of a fourth configuration of an anti-inrush current circuit according to an embodiment of the invention;
FIG. 6 is a charging curve of an energy storage capacitor of a conventional power supply circuit;
Fig. 7 is a charge curve of a storage capacitor of a power supply circuit using the anti-inrush current circuit of the present invention.
Description of main reference numerals:
1. A 1' -anti-surge current circuit; 10-rectifying circuit; a 20-power conversion circuit; 30-a switching tube control circuit; a 40-EMI circuit; 50-a secondary rectifying and filtering circuit; 210-a switching transformer; 220-PWM controller; 310-MCU controller; 320-a driving circuit; 330-a power supply circuit; 331-rectifying and filtering unit; 332-a step-down voltage stabilizing unit; c1-an energy storage capacitor; q1-a switching tube; r0-shunt resistance; a C2-bypass capacitor; q2-a power tube; d1-a first diode; d2—a second diode; r1-a first resistor; z1-a voltage stabilizing tube; c3-a first filter capacitor; and C4-a second filter capacitor.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description presented herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
In the conventional power supply system for converting AC to DC, in order to suppress the surge current, an input part of an AC-DC power supply as shown in fig. 1 is generally adopted, that is, an AC zero-live wire input sequentially passes through a conventional fuse, an NTC resistor, an EMI filter, a rectifier and then reaches an energy storage capacitor. Although this input circuit considers the surge current and adds the NTC resistor of the passive anti-surge clicking current, the following disadvantages still exist in the passive anti-surge current by utilizing the NTC resistor:
the insertion loss of the NTC resistor is inversely proportional to the effect of suppressing the surge current, namely, in order to achieve an obvious effect of suppressing the surge current, the NTC resistor needs to keep a higher resistance value at normal temperature and recover to an extremely low resistance value at high temperature so as to reduce the insertion loss. However, this balance is not ideal in the characteristics of the existing NTC resistive materials, and many commonly used NTC resistors are not effective in suppressing the surge current, and even burst due to the extreme power consumption in the process, resulting in early rejection of the entire power supply system.
And secondly, under high temperature, for example, when a full-load working power supply is continuously plugged and unplugged, the high temperature in the power supply is not eliminated at the moment, and the NTC resistor is in a low-resistance state at the moment, so that the effect of inhibiting surge current cannot be timely achieved.
In view of the above-mentioned disadvantage of adopting an NTC resistor to passively prevent the surge current, the inventors propose an active anti-surge current circuit, which can effectively solve the problem of suppressing the surge current in the prior art by inserting a switching tube and a shunt resistor at the negative side of an energy storage capacitor after a rectifier.
The present invention will be described in detail with reference to specific examples.
Example 1
Referring to fig. 2, the present embodiment provides an anti-surge current circuit 1, which can be applied to various power systems or power circuits for converting alternating current into direct current (AC-DC), electric devices including the AC-DC power circuits, and the like. The respective components of the inrush current protection circuit 1 will be described below.
As shown in fig. 2, the anti-inrush current circuit 1 includes a rectifying circuit 10, an energy storage capacitor C1, a power conversion circuit 20, a shunt resistor R0, a switching transistor Q1, and a switching transistor control circuit 30.
The input end of the rectifying circuit 10 is used for being connected with an alternating current power supply, the output end of the positive electrode is connected with the positive electrode of the energy storage capacitor C1, and the output end of the negative electrode is grounded.
One end of the bypass resistor R0 is connected with the negative electrode of the energy storage capacitor C1, and the other end of the bypass resistor R0 is grounded.
The input end of the switching tube Q1 is connected with the negative electrode of the energy storage capacitor C1, the output end of the switching tube Q1 is grounded, and the control end of the switching tube Q1 is connected with the output end of the switching tube control circuit 30.
The power input end of the switching tube control circuit 30 is connected with the power conversion circuit 20, and the power conversion circuit 20 is connected with the energy storage capacitor C1 and is used for carrying out power conversion and output on the rectified direct current.
In this embodiment, the rectifying circuit 10 may use an integrated rectifying bridge or a rectifier formed by a plurality of discrete devices, and may be used to perform synchronous rectification output on the ac power. It should be understood that references to "ground" in the various embodiments herein are not meant to be connected to actual ground (ground zero potential), but rather to a low potential reference terminal of the circuit. For example, if the power supply negative electrode is used as the low potential reference terminal, the "ground" refers to the power supply negative electrode.
The energy storage capacitor C1 is located at the output side of the rectifying circuit 10, and can be used for storing energy and filtering direct current after rectification. The storage capacitor C1 may be an electrolytic capacitor having a high voltage resistance value, or the like.
The shunt resistor R0 is connected in series with the energy storage capacitor C1 to form an RC differential circuit, where the time constant is t=r×c, where R is the resistance value of the shunt resistor R0, and C is the capacity of the energy storage capacitor C1. Because of the current limiting function of the resistor, the energy storage capacitor C1 can be charged smoothly, so that the aim of reliably inhibiting instant surge current generated during power-on can be fulfilled.
Considering the influence of the bypass resistor R0 on the circuit performance after the whole circuit starts to work normally, the bypass resistor R0 can be bypassed at a proper time by controlling the switching tube Q1 arranged on the negative side of the energy storage capacitor C1, so that the purpose of effectively inhibiting the surge current can be achieved, and the circuit performance is not influenced.
It can be understood that if the current-limiting precharge of the shunt resistor R0 does not exist, the energy storage capacitor C1 will be charged instantaneously, and if the switching tube Q1 is directly turned on at this time, the switching tube Q1 will be most likely to be burned due to the generated surge current of hundred amperes level, so that not only the suppression of the surge current cannot be performed, but also the inefficiency of the whole circuit may occur, resulting in poor system reliability and the like.
In this embodiment, the shunt resistor R0 may be a resistor with better anti-overload capability, such as a carbon film resistor, a wire-wound resistor, or the like. The resistance value can be selected according to the power of the actual circuit and the capacity of the energy storage capacitor C1. The value of the resistance should satisfy that the time constant t is less than the system start time, preferably t is greater than 200ms and less than the system start time. In this embodiment, the switching tube Q1 is configured to be turned on or turned off according to a control instruction of the switching tube control circuit 30. Illustratively, the switching transistor Q1 may be a transistor with a controllable switching characteristic, such as a thyristor, a triode, or an insulated gate field effect transistor (i.e., MOS transistor), where the MOS transistor is further divided into an N-channel MOS transistor and a P-channel MOS transistor.
For example, when a thyristor is used, the control terminal of the thyristor is connected to the switching tube control circuit 30, the input terminal thereof is connected to the negative terminal of the energy storage capacitor C1, and the output terminal thereof is grounded. Or if an N-channel MOS transistor is adopted, the gate of the switching transistor Q1 is connected to the switching transistor control circuit 30, the drain thereof is connected to the negative terminal of the storage capacitor C1, and the source thereof is grounded. It can be understood that the type and model of the switching tube Q1 can be specifically selected according to the actual circuit requirements during the operation.
In this embodiment, the switching tube control circuit 30 is mainly configured to determine whether the energy storage capacitor C1 is fully charged after power-up and detect whether the supply voltage from the power conversion circuit 20 is stable, and control to open the switching tube Q1 when it is determined that the energy storage capacitor C1 is fully charged and the supply voltage is stable, so that the switching tube Q1 is connected into the charge-discharge path of the capacitor and bypasses the bypass resistor R0.
For example, if the switching tube control circuit 30 detects that the power supply voltage has no trough or is kept fluctuating within a certain amplitude range, that is, it is logically ensured that the external plug is in place with the socket, and no phenomena such as rapid voltage drop or excessive up-and-down floating repeatedly occur, so that it can be determined that the power supply voltage is stable. Meanwhile, if the charging time of the capacitor C1 to be stored is not less than the time constant t, the switching tube Q1 is controlled to be turned on.
It can be understood that by logic judgment before the switching tube Q1 is turned on, the switching tube Q1 is prevented from being turned on by mistake, entering class a or being in a frequent switching state, etc. due to interference, the switching tube Q1 can be damaged greatly, and even broken down, etc. under high voltage and high current. Therefore, the logic processing of the switching tube control circuit 30 can greatly improve the system reliability, and ensure the effective working state of the switching tube Q1.
In this embodiment, the power conversion circuit is mainly used for performing corresponding power conversion on the rectified dc power and outputting the dc power to the load. Illustratively, the power conversion circuit may include, but is not limited to being, a flyback power converter, a forward power converter, a push-pull power converter, a full-bridge power converter, a half-bridge power converter, or the like. The operation of the inrush current protection circuit 1 will be described below.
When ac power is supplied (i.e., when power is supplied), the rectifying circuit 10 rectifies the supplied ac power, and the rectified ac power passes through the energy storage capacitor C1 to charge the energy storage capacitor C1, and then returns to the negative electrode of the power supply through the shunt resistor R0. It can be seen that the instantaneous surge current is effectively suppressed due to the current limiting effect of the shunt resistor R0. After the time constant t passes, the energy storage capacitor C1 is fully charged, and after the power conversion circuit 20 starts to operate, the switching tube control circuit 30 starts to operate normally after obtaining the supply voltage. The switching tube control circuit 30 determines that the energy storage capacitor C1 is fully charged, and when detecting that the power supply voltage is stable, opens the switching tube Q1, thereby bypassing the bypass resistor R0, so that the energy storage capacitor C1 is inserted into the charge-discharge path in a low internal resistance state, and performs normal functions such as energy storage filtering, thereby completing the power-on logic. Then, the power conversion circuit 20 performs power conversion, and thus an operating voltage or the like can be supplied to the connected load.
When the alternating current is disconnected (i.e. when the power is turned off), the switching tube control circuit 30 immediately turns off the switching tube Q1 according to the power-down condition of the power supply voltage, so that the switching tube Q1 can be in a turned-off state before the next power-up, and thus, the surge current generated at the moment of power-up can be effectively inhibited through the energy storage capacitor C1 and the bypass resistor R0. This ensures that the anti-surge current circuit 1 will not fail even when the alternating current is manually and continuously switched on and off, i.e. when the plug is continuously plugged in and plugged out.
Preferably, as shown in fig. 2, the anti-surge current circuit 1 further includes a bypass capacitor C2, wherein one end of the bypass capacitor C2 is connected to the negative electrode of the energy storage capacitor C1, and the other end is grounded. The bypass capacitor C2 is used as a protective element of the switching tube Q1, and can be used to absorb spike voltage to reduce voltage stress of the switching tube Q1, thereby preventing secondary breakdown of the switching tube Q1.
According to the anti-surge current circuit, the switch tube and the bypass resistor are inserted into the negative side of the energy storage capacitor, so that surge current generated in the moment of plugging and unplugging a plug of a switch power supply or electric equipment and the like can be effectively restrained, further, phenomena such as spark or explosion and the like can be effectively prevented from occurring in a socket spring sheet, the electricity utilization safety, the reliability and the like are greatly improved, the service life of a power supply and the use experience of a user can be further improved, and the like.
Example 2
Referring to fig. 3, the present embodiment provides an anti-surge circuit 1', which is different from the above embodiment 1 only in that the switching tube control circuit 30 includes an MCU controller 310, a driving circuit 320 and a power supply circuit 330, and the power conversion circuit 20 mainly includes a switching transformer 210.
Specifically, the MCU controller 310 is connected to the driving circuit 320, and the driving circuit 320 is connected to the control terminal of the switching tube Q1, so as to drive the switching tube Q1 to be turned on or off according to a control command of the MCU controller 310. It is appreciated that the MCU controller 310 may employ different types of MCU chips, such as C51 series, PIC series with reduced instruction set, STM32 series, ARM series, or the like. The driving circuit 320 of the switching tube Q1 is also often different, so those skilled in the art can design the driving circuit 320 according to the actually selected switching tube Q1.
The power supply circuit 330 is configured to provide corresponding operating voltages to the MCU controller 310 and the driving circuit 320. Preferably, the power supply circuit 330 may obtain the supply voltage from the secondary winding terminal of the switching transformer 210 in the power conversion circuit 20. It is understood that the secondary winding may comprise an auxiliary winding of the switching transformer 210.
As an alternative embodiment, the power supply circuit 330 may take power alone from a reserved secondary winding end of the switching transformer 210. Illustratively, as shown in fig. 3, the power supply circuit 330 includes a rectifying and filtering unit 331 and a step-down voltage stabilizing unit 332, which are sequentially connected. It will be appreciated that the rectifying and filtering unit 331 and the step-down voltage stabilizing unit 332 are a separate power supply path formed from the secondary winding output of the switching transformer 210 for providing the MCU controller 310 and the driving circuit 320 with their required operating voltages.
The power conversion circuit 20 further includes a PWM controller 220 and a power transistor Q2 connected to the switching transformer 210. As another alternative embodiment, the power supply circuit 330 includes a buck voltage stabilizing unit 332, and the power conversion circuit 20 includes a rectifying and filtering unit 331. The rectifying and filtering unit 331 is used for rectifying and filtering the operating voltage input to the PWM controller 220, and the like.
Illustratively, as shown in fig. 4, the rectifying and filtering unit 331 has an input terminal connected to the secondary winding of the switching transformer 210, an output terminal connected to the input terminal of the buck voltage stabilizing unit 332, and an output terminal connected to the power input terminal VDD of the PWM controller 220 via a diode. It will be appreciated that by sharing the existing rectifying and filtering unit 331 in the power conversion circuit 20 and isolating the same by the first diode D1, it is ensured that the PWM controller 220 is not affected by the MCU controller 310 and the driving circuit 320 when being powered and started. In addition, by sharing the rectifying and filtering portion, the configuration of the system circuit can be simplified, excessive standby power consumption is not increased, and circuit cost and the like can be reduced.
For example, as shown in fig. 4, the rectifying and filtering unit 331 of the present embodiment may include a second diode D2 and a first filter capacitor C3. Specifically, the anode of the second diode D2 is connected to the secondary winding output of the switching transformer 210, the cathode is connected to one end of the first filter capacitor C3 and the anode of the first diode D1, and the other end of the first filter capacitor C3 is grounded. It is understood that the rectifying and filtering unit 331 is not limited to the circuit structure of fig. 4, but may be other circuits with rectifying and filtering functions.
In this embodiment, the buck regulator 332 is a low dropout linear regulator (i.e. LDO circuit) or a direct current-direct current (DC-DC) converter. Further preferably, the buck regulator 332 may employ a simple LDO circuit to simplify the circuit structure and reduce the cost of the circuit.
As shown in fig. 4, the simple LDO circuit includes a first resistor R1, a regulator Z1, and a second filter capacitor C4. Specifically, one end of the first resistor R1 is connected to the cathode of the second diode D2 in the rectifying and filtering unit 331, and the other end thereof is connected to the power input terminal VCC of the MCU controller 310. The voltage stabilizing tube Z1 and the second filter capacitor C4 are both disposed between the other end of the first resistor R1 and the power input end VCC of the MCU controller 310. Specifically, the cathode of the voltage regulator tube Z1 is connected to the other end of the first resistor R1, the anode is grounded, and one end of the second filter capacitor C4 is connected to the other end of the first resistor R1 and the cathode of the voltage regulator tube Z1, and the other end is grounded.
Optionally, as shown in fig. 5, the anti-surge current circuit 1' further includes an EMI circuit 40, where an input terminal of the EMI circuit 40 is used for accessing an alternating current, and an output terminal of the EMI circuit is connected to an input terminal of the rectifying circuit 10.
Optionally, the anti-surge current circuit 1' further includes a secondary rectifying and filtering circuit 50, where an input end of the secondary rectifying and filtering circuit 50 is connected to the power conversion circuit 20, and an output end of the secondary rectifying and filtering circuit is used to connect to a load.
The anti-surge circuit provided by the embodiment of the invention has the following technical effects:
1. Compared with the prior power supply circuit which adopts the mode of connecting a relay or a controllable silicon on the alternating current side, the invention can better meet the volume requirement by inserting the switching tube and the bypass resistor on the negative side of the energy storage capacitor, is convenient for driving and controlling, and more importantly, also considers the problems of standby power consumption and cost increased for preventing surge, thereby having higher practical value.
2. When the power-on is performed, the MCU controller firstly carries out logic judgment processing and then drives to open the switching tube, so that the switching tube can be ensured not to be interfered and to be switched on by mistake, further, the switching tube can be prevented from entering a class A working state or being in a frequent switching state, the point is particularly important under high-voltage and high-current conditions, the service life of the switching tube can be prolonged, and further the reliability of a system and the like can be improved.
3. The control driving part for controlling the switching tube can further share and isolate the power supply part of the original PWM driver by taking power from the secondary winding of the switching transformer in the power conversion circuit, so that on the basis of ensuring the smooth starting of the original PWM driver and the normal operation of the power tube, the simplicity and the compactness of the system are realized, the cost of the system is saved, and too much standby power consumption is not brought to the system. For actual market product investment, the anti-surge current circuit has higher practical value.
In addition, in order to verify the suppression effect of the surge current of the present invention, fig. 6 and 7 show the charging curve of the storage capacitor in the existing power supply circuit and the charging curve of the storage capacitor in the power supply circuit after the use of the surge current prevention circuit, respectively. As shown in fig. 6, when the anti-surge current circuit of the present invention is not used, the charging curve of the rectified energy storage capacitor is very steep, and it is known that the energy storage capacitor is charged instantly, so that the generated large surge current cannot be effectively suppressed during charging. In the power supply circuit after the anti-surge current circuit is adopted, as shown in fig. 7, the charging curve of the energy storage capacitor is relatively gentle, and the generated surge current can be effectively restrained by utilizing the current limiting effect of the bypass resistor. In addition, the charging process of the energy storage capacitor is far less than the starting time of the whole power system, and the power conversion circuit 20 at the later stage does not work normally at this time, so the starting time of the whole power system is not affected.
Another embodiment of the present invention further provides an electrical device, where the electrical device includes the anti-surge current circuit of the foregoing embodiment 1 or 2. It can be appreciated that the anti-surge circuit can be used in applications involving ac rectification and storage of energy in the storage capacitor after the rectification circuit.
Illustratively, the electric device may include, but is not limited to, a charger, a converter, a switching power supply, a power adapter, and small household appliances such as a notebook, a hair dryer, and a hair curler, wherein the power standby part may employ the anti-surge current circuit of the above embodiment.
Those skilled in the art will appreciate that the drawing is merely a schematic illustration of a preferred implementation scenario and that the modules or flows in the drawing are not necessarily required to practice the invention.
Those skilled in the art will appreciate that modules in an apparatus in an implementation scenario may be distributed in an apparatus in an implementation scenario according to an implementation scenario description, or that corresponding changes may be located in one or more apparatuses different from the implementation scenario. The modules of the implementation scenario may be combined into one module, or may be further split into a plurality of sub-modules.
The above-mentioned inventive sequence numbers are merely for description and do not represent advantages or disadvantages of the implementation scenario. The foregoing disclosure is merely illustrative of some embodiments of the invention, and the invention is not limited thereto, as modifications may be made by those skilled in the art without departing from the scope of the invention.
Claims (9)
1. An anti-inrush current circuit, comprising: the power conversion circuit comprises a rectifying circuit, an energy storage capacitor, a power conversion circuit, a bypass resistor, a switching tube and a switching tube control circuit;
the input end of the rectifying circuit is used for accessing alternating current, the output end of the positive electrode is connected with the positive electrode of the energy storage capacitor, and the output end of the negative electrode is grounded;
one end of the bypass resistor is connected with the negative electrode of the energy storage capacitor, and the other end of the bypass resistor is grounded;
The input end of the switching tube is connected with the negative electrode of the energy storage capacitor, the output end of the switching tube is grounded, and the control end of the switching tube is connected with the output end of the switching tube control circuit;
the power input end of the switching tube control circuit is connected with the power conversion circuit;
the power conversion circuit is connected with the energy storage capacitor and is used for carrying out power conversion and output on the rectified direct current;
The switching tube control circuit comprises an MCU controller, a driving circuit and a power supply circuit, the power conversion circuit comprises a switching transformer, the MCU controller is connected with the driving circuit, and the driving circuit is connected with the control end of the switching tube; the input end of the power supply circuit is connected with the secondary winding of the switching transformer, and the output end of the power supply circuit is connected with the MCU controller and the driving circuit;
The switching tube control circuit is used for judging whether the energy storage capacitor is fully charged after power is supplied, detecting whether the power supply voltage from the power conversion circuit is stable, and controlling to open the switching tube when the energy storage capacitor is fully charged and the power supply voltage is stable; the judging whether the power supply voltage is stable or not comprises the following steps: detecting that the power supply voltage has no wave trough or is kept to fluctuate within a certain amplitude range;
The switching tube control circuit is also used for timely closing the switching tube according to the power-down condition of the power supply voltage, so that the switching tube is in a closed state before the next power-up.
2. The anti-inrush current circuit of claim 1, further comprising: and one end of the bypass capacitor is connected with the negative electrode of the energy storage capacitor, and the other end of the bypass capacitor is grounded.
3. The anti-surge current circuit according to claim 1, wherein the power supply circuit comprises a rectifying and filtering unit and a step-down voltage stabilizing unit connected in sequence,
The rectification filter unit is connected with the secondary winding of the switching transformer, and the step-down voltage stabilizing unit is connected with the MCU controller and the driving circuit.
4. The anti-inrush current circuit of claim 1, wherein the power supply circuit comprises a buck voltage stabilizing unit, and the power conversion circuit comprises a rectifying and filtering unit and a PWM controller for controlling a power transistor connected to the switching transformer;
the input end of the rectifying and filtering unit is connected with the secondary winding of the switching transformer, the output end of the rectifying and filtering unit is connected with the input end of the step-down voltage stabilizing unit, and the output end of the rectifying and filtering unit is also connected with the power input end of the PWM controller through a diode.
5. The anti-inrush current circuit of claim 3 or 4, wherein the buck regulator unit is a low dropout linear regulator or a dc-dc converter.
6. The anti-inrush current circuit of claim 1, wherein the switching transistor is a thyristor, a triode, or a MOS transistor.
7. The anti-inrush current circuit of claim 1, further comprising: and the input end of the EMI circuit is used for being connected with the alternating current, and the output end of the EMI circuit is connected with the input end of the rectifying circuit.
8. The anti-inrush current circuit of claim 1, further comprising: and the input end of the secondary rectifying and filtering circuit is connected with the power conversion circuit, and the output end of the secondary rectifying and filtering circuit is used for being connected with a load.
9. A powered device comprising an anti-inrush current circuit as defined in any one of claims 1-8.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910087758.6A CN109639126B (en) | 2019-01-29 | 2019-01-29 | Surge current prevention circuit and electric equipment |
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| CN201910087758.6A CN109639126B (en) | 2019-01-29 | 2019-01-29 | Surge current prevention circuit and electric equipment |
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| CN109639126B true CN109639126B (en) | 2024-05-07 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110429832A (en) * | 2019-08-06 | 2019-11-08 | 深圳创维－Rgb电子有限公司 | A kind of switching power circuit and television set |
| CN110912101B (en) * | 2019-11-26 | 2022-01-04 | 乐清市贝加尔电子科技有限公司 | Non-contact passive SPD backup protection circuit breaker |
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| CN109639126A (en) | 2019-04-16 |
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