CN109038503B

CN109038503B - Hiccup type protection circuit of direct current power supply

Info

Publication number: CN109038503B
Application number: CN201811060359.2A
Authority: CN
Inventors: 不公告发明人
Original assignee: Shenzhen Core Light Testing Technology Co Ltd
Current assignee: Shenzhen core light Testing Technology Co., Ltd
Priority date: 2015-03-09
Filing date: 2015-03-09
Publication date: 2020-10-23
Anticipated expiration: 2035-03-09
Also published as: CN106033880B; CN109038504A; CN109038504B; CN109038503A; CN106033880A

Abstract

The invention discloses two hiccup type protection circuits for a direct current power supply, belongs to the technical field of power supplies, and is suitable for being used for overcurrent protection in the direct current power supply. The protection circuit of the existing power supply product has a lot of defects, or needs to be manually restarted, or the protection has larger time lag to damage the power supply, and the like. The invention relates to two new circuit designs, wherein the circuit is a four-terminal network, the input end of the four-terminal network is connected with the positive pole and the negative pole of a protected direct current power supply, and the output end of the four-terminal network is connected with a load. It does "hiccup formula" protection to being protected DC power supply, and this kind of "hiccup formula" protection, the action is fast, and automatic recovery is also fast, and the time length of protection can be adjusted, and ambient temperature's influence is little, and the consumption is very low, and whole circuit is simple, and the cost is also low, and practice proves can overcome the shortcoming of the protection circuit of current power supply product completely.

Description

Hiccup type protection circuit of direct current power supply

Technical Field

The invention discloses a hiccup type protection circuit for two direct current power supplies, and belongs to the technical field of power supplies. It is suitable for the use of overcurrent protection in DC power supply, no matter the DC power supply adopts switching power supply technology or power frequency transformer step-down technology.

Background

When a direct current power supply works, load aggravation or output end short circuit is often caused due to load change, careless use and the like, so that output current is overlarge and damaged, and the addition of a protection circuit is an important ring for designing the power supply.

At present, a direct current power supply generally has three protection modes of a current interception type, a current limiting type and an overheating type. 1, closure type: when the output of the direct current power supply is overloaded or short-circuited, the power supply is cut off, and the load is not supplied with power any more. The power supply can be recovered only by restarting the power supply, and the power supply can be turned off again if overload or short circuit conditions still exist after the power supply is restarted. That is to say, the power supply can not be recovered by self, and the manual restart is needed, which causes inconvenience to the application. 2, current limiting type: a maximum value of the output current is set, and once the load current reaches the maximum value, the current is not increased any more, and the output voltage is decreased, thereby causing an increase in internal power consumption of the power supply, an increase in heat generation, a decrease in energy efficiency, and a decrease in reliability. 3, overheating type: a temperature sensor, such as a commonly used 78 and 79 series integrated three-terminal voltage regulator, is embedded in a circuit of a power supply, when the output is overloaded or short-circuited, the temperature of a device rises due to the increase of current, the temperature sensor senses the corresponding action to shut down the power supply without current output, and when the temperature of the device drops, the circuit can be automatically restarted. The defect is that the sensing temperature changes have larger time lag, and the temperature sensor is likely to have no time to generate corresponding actions, so that the power supply is damaged; or the automatic restart is delayed, and the load requirement cannot be met; and is greatly affected by the ambient temperature.

The three power protection modes have defects, cannot adapt to certain loads with special requirements, cannot adapt to scientific and technological development requirements, and need to be developed.

Disclosure of Invention

The invention provides a new circuit design aiming at the defects of the popular power supply protection mode, and the new circuit design is a four-terminal network, the input end of the four-terminal network is connected with the positive pole and the negative pole of a protected direct-current power supply, and the output end of the four-terminal network is connected with a load. The protection circuit performs hiccup type protection on a protected direct current power supply, and a specific circuit is detailed later. The hiccup type protection has the advantages of quick action, quick automatic recovery, adjustable protection time, small influence of environmental temperature, low power consumption, simple whole circuit and low cost. Practice proves that the defects of the three power protection modes can be completely overcome.

Drawings

Fig. 1 is a design of a hiccup-type protection circuit, in which a power adjusting transistor adopts a P-channel field effect transistor and is connected to the anode of a direct-current power supply. Fig. 2 is another design of the hiccup-type protection circuit, in which the power adjusting transistor is an N-channel fet and is connected to the negative electrode of the dc power supply.

Detailed Description

The figures and the description of the invention are further explained below with reference to examples.

Fig. 1 shows an embodiment of the hiccup protection circuit of the present invention, which can be regarded as a four-terminal network, and the input terminals of the four-terminal network are (a1), (B1), (a1) is connected to the positive terminal of the protected dc power supply, and (B1) is connected to the negative terminal of the protected dc power supply, and is used as the reference zero potential of the circuit. The output ends of the four-terminal network are (A2), (B2), wherein the (A2) end is the positive pole of the output, and the (B2) end is the negative pole of the output. The load is connected to both ends of (A2) and (B2).

The specific design of the circuit of FIG. 1 is described first. The N1 and N2 elements in fig. 1 are model TL431, which are three-terminal adjustable precision voltage references, and have three pins, cathode K, anode a and reference R.

One end of a resistor R1 is connected with the anode (A1) of a protected direct current power supply, the other end of a resistor R1 is connected with the cathode of an N1 element, the anode of the N1 element is connected with the cathode (B1) of the protected direct current power supply, then the cathode K of an N1 element is in short circuit with two pins of a reference R, 2.5V precision reference voltage output can be obtained from the cathode of the N1 element, the method is used in the embodiment, and one end of the resistor R4 is connected with the cathode of an N1 element.

One end of a resistor R2 is connected with the anode (A1) of the protected direct current power supply, one end of the resistor R3 is connected with the anode (A1) of the protected direct current power supply after being connected with a capacitor C1 in parallel, the other end of the resistor R3 is connected with the anode of a diode VD1 and the grid of a P-channel field effect tube V1, and the source of the field effect tube V1 is connected with the anode (A1) of the protected direct current power supply; the cathode of the diode VD1 is simultaneously connected with the other end of the resistor R2 and the cathode of the N2 element; the anode of the N2 element is connected with the negative pole (B1) of the protected direct current power supply; a reference pin of the N2 element is connected with the other end of the resistor R4, one end of the capacitor C2 and one end of the resistor R6; the other end of the capacitor C2 is connected with the negative pole (B1) of the protected DC power supply and one end of the resistor R5, the other end of the resistor R5 is connected with the output negative pole end (B2), and the other end of the resistor R6 is also connected with the output negative pole end (B2).

The source electrode of the P-channel field effect transistor V2 is connected with the positive electrode (A1) of the protected direct-current power supply, the negative electrode of the voltage regulator tube VD2 is connected with the source electrode of the field effect transistor V2, the grid electrode of the field effect transistor V2 is connected with the drain electrode of the field effect transistor V1, the positive electrode of the voltage regulator tube VD2 and one end of the resistor R7, the other end of the resistor R7 is connected with the output negative electrode end (B2), and the drain electrode of the field effect transistor V2 is the output positive electrode end (A2).

The working principle of the circuit of fig. 1 is as follows: after the current is switched on, the current is limited by the resistor R1, the N1 element is electrified, 2.5V precision reference voltage is output from the cathode of the N1 element, the 2.5V precision reference voltage is added to a series branch consisting of the resistor R4 and the resistor R6, and the voltage division on the resistor R6 is designed to be 2.4V. Resistor R2 is the current limiting resistor of the N2 element. When the two ends of the resistor R5 (a2) and the resistor B2) are not loaded or lightly loaded, no load current or a small load current flows through the resistor R5, and thus no voltage drop or a small voltage drop (less than 0.1V) flows through the resistor R5, so that the reference pin of the N2 device has a voltage of only 2.4V or less than 2.5V, so that the N2 device is in an off state, the gate of the pmos fet V1 obtains a high level through the resistor R3, the fet V1 is also in an off state, the gate of the pmos fet V2 obtains a low level through the resistor R7, the fet V2 is in an on state, and the load is allowed to output a current and can normally operate. The voltage regulator VD2 limits the over-high voltage between the grid electrode and the source electrode of the field effect transistor V2, and plays a role in protecting the field effect transistor V2.

When the two ends (a2) and (B2) carry heavy loads or are short-circuited, a large load current or a large short-circuit current flows through the resistor R5, so that the voltage drop across the resistor R5 reaches or exceeds 0.1V, the voltage across the reference pin of the N2 element reaches or exceeds 2.5V, the N2 element is in a conducting state, the gate level of the fet V1 is lowered, the fet V1 is in a conducting state, the drain output high level of the fet V1 is applied to the gate of the fet V2, the fet V2 is in a blocking state, the output current is cut off, and the dc power source is protected. Because no output current exists, no voltage drop exists on the resistor R5, the voltage on the reference pin of the N2 element does not reach 2.5V, the N2 element is in an off state again, the gate of the field-effect tube V1 obtains a high level again through the resistor R3, the field-effect tube V1 also is in an off state again, at the moment, the gate of the field-effect tube V2 obtains a low level again through the resistor R7, the field-effect tube V2 is in an on state again to allow the output current, if the load is still heavy or the short circuit phenomenon is not eliminated, the field-effect tube V1 is also continuously and alternately switched on and off, and the field-effect tube V2 is continuously and alternately switched off and on to perform 'hiccup' protection on the direct-current power supply.

When fet V1 is off, fet V2 is on, and when fet V1 is on, fet V2 is off, which is microscopically transient. When the N2 element is turned on, the capacitor C1 and the interelectrode capacitance between the source and the gate of the fet V1 are charged through the diodes VD1 and N2, so that the fet V1 is turned on for a delay time, and the turn-off of the fet V2 is delayed; similarly, when the N2 element is turned off, the capacitor C1 and the interpolar capacitor between the source and the gate of fet V1 are charged to discharge through resistor R3, and there is a delay time for fet V1 to turn off, and thus turn on fet V2 is delayed. The sum of these two delay times is the period of hiccups. The inter-electrode capacitance between the source and the gate of the fet V1 is negligible compared to the capacitance C1, and the "hiccup" period can be adjusted by properly selecting the values of the capacitance C1 and the resistance R3, and is usually adjusted to a millisecond level. The capacitor C2 is connected between the reference pin of the N2 element and the negative pole (B1) of the protected direct current power supply, and plays a role in filtering.

The resistance of the resistor R5 determines the threshold value of the output current to be protected, and the threshold value is io (a), and the resistance of R5 is determined by the formula R5 ═ 0.1(V)/io (a). For example, if the critical value of the output current to be protected is 10 amperes, the resistance of R5 should be 0.1/10 to 0.01 ohms.

The circuit of fig. 2 is another embodiment of the hiccup protection circuit of the present invention, and also can be regarded as a four-terminal network, and the input terminals of the four-terminal network are (a01), (B01), (a01) is connected to the positive pole of the protected dc power supply, and (B01) is connected to the negative pole of the protected dc power supply and is used as the reference zero potential of the circuit. The output ends of the four-terminal network are (A02), (B02), wherein the (A02) end is the positive pole of the output, and the (B02) end is the negative pole of the output. The load is connected at two ends of (A02) and (B02), and the anode (A01) of the protected direct current power supply and the anode (A02) of the output of the circuit in the figure 2 are in through short circuit. The power adjusting tube of the circuit in fig. 2 adopts an N-channel field effect tube and is connected to the negative electrode of the direct current power supply. The N-channel field effect transistor is relatively cheap and easily available. The model of the N01 and N02 elements is TL431, and the three-end adjustable precision voltage reference is provided.

One end of a resistor R01 is connected with the anode (A01) of a protected direct current power supply, the other end of a resistor R01 is connected with the cathode of an N01 element, the anode of the N01 element is connected with the cathode (B01) of the protected direct current power supply, then the cathode K of an N01 element is in short circuit with two pins of a reference R, and 2.5V precision reference voltage output can be obtained from the cathode of the N01 element. And one end of the resistor R04 is connected to the cathode of the N01 element.

One end of a resistor R02 is connected with the anode (A01) of the protected direct current power supply, and the other end of a resistor R02 is connected with one end of a resistor R03 and the base electrode of a PNP triode V01; the other end of the resistor R03 is connected with the cathode of the N02 element; the anode of the N02 element is connected with the negative pole (B01) of the protected direct current power supply; a reference pin of the N02 element is connected with the other end of the resistor R04 and one end of the resistor R06, the other end of the resistor R06 is connected with one end of the resistor R05 and the source electrode of the N-channel field effect transistor V03, and the other end of the resistor R05 is connected with the negative electrode (B01) of the protected direct-current power supply; the drain of the field effect transistor V03 is the negative output terminal (B02).

The emitter of the triode V01 is connected with the anode (A01) of the protected direct current power supply, the collector of the triode V01 is connected with one end of a resistor R07 and one end of a resistor R08, and the other end of the resistor R07 is connected with the source of a field effect transistor V03; the other end of the resistor R08 is connected with the anode of a diode VD01, and the cathode of the diode VD01 is connected with one end of a capacitor C01, one end of a resistor R09 and the grid of an N-channel field effect transistor V02; the other end of the capacitor C01 and the other end of the resistor R09 are connected to the source electrode of the field effect transistor V03; the source of fet V02 is also connected to the source of fet V03.

One end of a resistor R010 is connected with the anode (A01) of a protected direct current power supply, the other end of the resistor R010 is connected with the drain electrode of a field effect tube V02, the grid electrode of the field effect tube V03 and the cathode of a voltage regulator tube VD02, and the anode of the voltage regulator tube VD02 is connected with the source electrode of a field effect tube V03.

The working principle of the circuit of fig. 2 is that: after the current is switched on, the current is limited by the resistor R01, the N01 element is electrified, 2.5V precision reference voltage is output from the cathode of the N01 element, the 2.5V precision reference voltage is added to a series branch consisting of the resistor R04 and the resistor R06, and the voltage division on the resistor R06 is designed to be 2.4V. The resistor R02 and the resistor R03 are current limiting resistors of the N02 element. When no load or light load is applied to the two ends of the resistor R05 (a02) and the resistor B02), no load current or small load current flows through the resistor R05, so that no voltage drop or small voltage drop (less than 0.1V) occurs on the resistor R05, and therefore, the voltage of the reference pin of the N02 device is only 2.4V or less than 2.5V, so that the N02 device is in an off state, the base of the PNP triode V01 is connected to the series node of the resistor R02 and the resistor R03, at this time, a high level is obtained, the triode V01 is in an off state, the gate of the N-channel fet V02 is also in a low level and cannot be turned on, the gate of the N-channel fet V02 is in an off state, the gate of the N-channel fet V03 is in a high level through the resistor R010, the fet V03 is in an on state, so that the output current is. The voltage regulator VD02 limits the over-high voltage between the grid electrode and the source electrode of the field effect transistor V03, and plays a role in protecting the field effect transistor V03.

When the two ends (a02) and (B02) carry heavy loads or are short-circuited, a large load current or a large short-circuit current flows through the resistor R05, so that the voltage drop across the resistor R05 reaches or exceeds 0.1V, the voltage across the reference pin of the N02 element reaches or exceeds 2.5V, the N02 element is in a conducting state, the base potential of the triode V01 is reduced, the triode V01 is in a conducting state, the gate of the fet V02 is conducted at a high level through the resistor R08 and the diode VD01, the driving voltage across the gate of the fet V03 is short-circuited, the fet V03 is in a blocking state, the output current is cut off, and the dc power supply is protected. Because no output current exists, no voltage drop exists on the resistor R05, the voltage on the reference pin of the N02 element does not reach 2.5V, the N02 element is in a cut-off state again, the base of the triode V01 obtains a high level again, the field-effect tube V02 is also in a cut-off state again, at the moment, the gate of the field-effect tube V03 obtains a high level again through the resistor R010, the field-effect tube V03 is in a conducting state again, the output current is allowed, if the load is still heavy or the short circuit phenomenon is not eliminated, the triode V01 and the field-effect tube V02 of the circuit in the figure 2 are also continuously and alternately conducted, and the field-effect tube V03 is continuously and alternately conducted, so that the DC power supply is protected in a hiccup mode.

Similar to the embodiment of fig. 1, fet V03 is on when fet V02 is off, and fet V03 is off when fet V02 is on, which is microscopically transitional. When the N2 element is turned on, the triode V01 is also turned on, the capacitor C01 and the interelectrode capacitor between the source and the gate of the field-effect transistor V02 are charged through the diode VD01 and the resistor R05, so that the field-effect transistor V02 is turned on for a delay time, and then the turn-off of the field-effect transistor V03 is delayed; similarly, when the N2 element is turned off, the transistor V01 is also turned off, the capacitor C01 and the interpolar capacitor between the source and the gate of the fet V02 are charged to discharge through the resistor R09, and there is a delay time when the fet V02 is turned off, and the turn-on of the fet V03 is delayed accordingly. The sum of these two delay times is the period of hiccups. The inter-electrode capacitance between the source and the gate of the fet V02 is negligible compared to the capacitance C01, and the "hiccup" period can be adjusted by properly selecting the values of the capacitance C01 and the resistance R09, and is usually adjusted to a millisecond level.

The resistance of the resistor R05 determines the threshold value of the output current to be protected, and the threshold value is io (a), and the resistance of R05 is determined by the formula R05 ═ 0.1(V)/io (a). For example, if the critical value of the output current to be protected is 10 amperes, the resistance of R05 should be 0.1/10 to 0.01 ohms.

In summary, the hiccup protection circuit for the dc power supply of the invention comprises resistance elements R1-R7, three-terminal adjustable precision voltage reference TL431 elements N1-N2, capacitors C1-C2, a diode VD1, a voltage regulator VD2, and P-channel fets V1-V2, and the specific connection modes of these elements are as follows: one end of a resistor R1 is connected with the anode (A1) of a protected direct current power supply, the other end of a resistor R1 is connected with the cathode of an N1 element, the anode of the N1 element is connected with the cathode (B1) of the protected direct current power supply, the cathode K of the N1 element is in short circuit with two pins of a reference R, and one end of a resistor R4 is connected with the cathode of the N1 element; one end of a resistor R2 is connected with the anode (A1) of the protected direct current power supply, one end of the resistor R3 is connected with the anode (A1) of the protected direct current power supply after being connected with a capacitor C1 in parallel, the other end of the resistor R3 is connected with the anode of a diode VD1 and the grid of a P-channel field effect tube V1, the source of the field effect tube V1 is connected with the anode (A1) of the protected direct current power supply, and the cathode of the diode VD1 is connected with the other end of the resistor R2 and the cathode of the N2 element at the same time; the anode of the N2 element is connected with the negative pole (B1) of the protected direct current power supply, and the reference pin of the N2 element is connected with the other end of the resistor R4, one end of the capacitor C2 and one end of the resistor R6; the other end of the capacitor C2 is connected with the negative pole (B1) of the protected direct-current power supply and one end of the resistor R5, the other end of the resistor R5 is connected with the output negative pole end (B2), and the other end of the resistor R6 is also connected with the output negative pole end (B2); the source electrode of the P-channel field effect transistor V2 is connected with the positive electrode (A1) of the protected direct-current power supply, the negative electrode of the voltage regulator tube VD2 is connected with the source electrode of the field effect transistor V2, the grid electrode of the field effect transistor V2 is connected with the drain electrode of the field effect transistor V1, the positive electrode of the voltage regulator tube VD2 and one end of the resistor R7, the other end of the resistor R7 is connected with the output negative electrode end (B2), and the drain electrode of the field effect transistor V2 is the output positive electrode end (A2).

The hiccup time period can be adjusted by properly selecting the values of the capacitor C1 and the resistor R3, the resistance value of the resistor R5 determines the threshold value of the output current to be protected, and the threshold value is io (a), and the resistance value of R5 is determined by the formula R5 ═ 0.1(V)/io (a).

In summary, the second dc power hiccup type protection circuit of the present invention is composed of resistance elements R01-R010, three-terminal adjustable precision voltage reference TL431 elements N01-N02, a capacitor C01, a diode VD01, a voltage regulator VD02, a PNP triode V01, and N-channel field effect transistors V02-V03, and the specific connection modes of these elements are as follows: one end of a resistor R01 is connected with the anode (A01) of a protected direct current power supply, the other end of a resistor R01 is connected with the cathode of an N01 element, the anode of the N01 element is connected with the cathode (B01) of the protected direct current power supply, the cathode K of the N01 element is in short circuit with two pins of a reference R, and one end of a resistor R04 is connected with the cathode of the N01 element; one end of a resistor R02 is connected with the positive electrode (A01) of the protected direct-current power supply, the other end of a resistor R02 is connected with one end of a resistor R03 and the base electrode of a PNP triode V01, the other end of a resistor R03 is connected with the cathode of an N02 element, the anode of an N02 element is connected with the negative electrode (B01) of the protected direct-current power supply, the reference pin of an N02 element is connected with the other end of a resistor R04 and one end of a resistor R06, the other end of a resistor R06 is connected with one end of a resistor R05 and the source electrode of an N-channel field effect tube V03, the other end of the resistor R05 is connected with the negative electrode (B01) of the protected direct-current power supply, and the drain; the emitter of a triode V01 is connected with the anode (A01) of a protected direct current power supply, the collector of a triode V01 is connected with one end of a resistor R07 and one end of a resistor R08, the other end of the resistor R07 is connected with the source of a field effect transistor V03, the other end of the resistor R08 is connected with the anode of a diode VD01, the cathode of the diode VD01 is connected with one end of a capacitor C01, one end of a resistor R09 and the gate of an N-channel field effect transistor V02, and the other end of a capacitor C01 and the other end of a resistor R09 are connected with the source of a field effect transistor V03; the source of fet V02 is also connected to the source of fet V03; one end of a resistor R010 is connected with an anode (A01) of a protected direct-current power supply, the other end of the resistor R010 is connected with a drain electrode of a field-effect tube V02, a grid electrode of the field-effect tube V03 and a cathode of a voltage-stabilizing tube VD02, and an anode of the voltage-stabilizing tube VD02 is connected with a source electrode of a field-effect tube V03; the positive pole (A01) of the protected DC power supply and the positive pole (A02) of the output are in through short circuit.

The hiccup time period can be adjusted by properly selecting the values of the capacitor C01 and the resistor R09, the resistance value of the resistor R05 determines the threshold value of the output current to be protected, and the threshold value is io (a), and the resistance value of R05 is determined by the formula R05 ═ 0.1(V)/io (a).

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1. The utility model provides a DC power supply hiccup formula protection circuit which characterized in that: the circuit consists of resistance elements R1-R7, three-end adjustable precision voltage reference TL431 elements N1-N2, capacitors C1-C2, a diode VD1, a voltage stabilizing tube VD2 and P-channel field effect tubes V1-V2; the specific connection modes of the elements are as follows: one end of a resistor R1 is connected with the anode (A1) of a protected direct current power supply, the other end of a resistor R1 is connected with the cathode of an N1 element, the anode of the N1 element is connected with the cathode (B1) of the protected direct current power supply, the cathode K of the N1 element is in short circuit with two pins of a reference R, and one end of a resistor R4 is connected with the cathode of the N1 element; one end of a resistor R2 is connected with the anode (A1) of the protected direct current power supply, one end of the resistor R3 is connected with the anode (A1) of the protected direct current power supply after being connected with a capacitor C1 in parallel, the other end of the resistor R3 is connected with the anode of a diode VD1 and the grid of a P-channel field effect tube V1, the source of the field effect tube V1 is connected with the anode (A1) of the protected direct current power supply, and the cathode of the diode VD1 is connected with the other end of the resistor R2 and the cathode of the N2 element at the same time; the anode of the N2 element is connected with the negative pole (B1) of the protected direct current power supply, and the reference pin of the N2 element is connected with the other end of the resistor R4, one end of the capacitor C2 and one end of the resistor R6; the other end of the capacitor C2 is connected with the negative pole (B1) of the protected direct-current power supply and one end of the resistor R5, the other end of the resistor R5 is connected with the output negative pole end (B2), and the other end of the resistor R6 is also connected with the output negative pole end (B2); the source electrode of a P-channel field effect transistor V2 is connected with the anode (A1) of a protected direct-current power supply, the cathode of a voltage regulator tube VD2 is connected with the source electrode of a field effect transistor V2, the grid electrode of the field effect transistor V2 is connected with the drain electrode of a field effect transistor V1, the anode of a voltage regulator tube VD2 and one end of a resistor R7, the other end of the resistor R7 is connected with an output cathode end (B2), and the drain electrode of the field effect transistor V2 is an output anode end (A2); the resistance value of the resistor R5 determines the critical value of the output current to be protected, and if the critical value is IO (A), the resistance value of R5 is 0.01 ohm; when the fet V1 is turned off, the fet V2 is turned on, and when the fet V1 is turned on, the fet V2 is turned off, and when the N2 element is turned on, the capacitor C1 and the inter-electrode capacitor between the source and the gate of the fet V1 are charged through the diodes VD1 and N2, so that the fet V1 is turned on for a delay time, and then the turn-off of the fet V2 is delayed; similarly, when the N2 element is turned off, the capacitor C1 and the inter-electrode capacitor between the source and the gate of the fet V1 are charged to discharge through the resistor R3, so that there is a delay time when the fet V1 is turned off, and the turn-on of the fet V2 is delayed; the sum of these two delay times is the period of hiccup; the hiccup period can be adjusted to millisecond level by adjusting the values of the capacitor C1 and the resistor R3, and the capacitor C2 is connected between the reference pin of the N2 element and the cathode (B1) of the protected direct current power supply and plays a role in filtering.