On-line real-time monitoring circuit for insulation of switching power supply output to earth and switching power supply

Abstract

The present invention discloses an online real-time monitoring circuit for the insulation of a switching power supply output to the earth and a switching power supply. The circuit includes a transformer induction winding circuit, an output voltage insulation monitoring circuit to the earth, and an alarm circuit. The present invention determines in real time whether the output of the switching power supply is short-circuited to the earth by the alarm signal voltage at the alarm signal output end, and can send an alarm signal, thereby quickly eliminating safety hazards of the equipment and ensuring reliable operation of the equipment. The present invention realizes online real-time monitoring of the insulation of the switching power supply output to the earth, and the power supply can know whether the positive or negative output pole of the power supply is short-circuited to the earth without the need for a withstand voltage test. The present invention can not only monitor the insulation function of the switching power supply output to the earth in real time, but also realize intelligent management of whether the output voltage of the switching power supply is insulated from the earth by collecting the alarm signal voltage on the power supply and writing it into the single-chip computer program by the matching terminal equipment. Moreover, the present invention has a simple structure, is reliable and sensitive, and has low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to an online real-time monitoring circuit for the insulation of a switching power supply output to the earth and a switching power supply. Background Art

[0002] In order to comply with safety regulations and technical indicators such as electromagnetic compatibility, smart grid equipment requires that the output voltage of the supporting switching power supply has electrical isolation and insulation function to the ground. This can not only make the supporting equipment comply with relevant industry safety regulations and EMC standards, but also make the equipment work reliably. The existing solution for the insulation function of the output voltage of the switching power supply to the ground is as follows: Figure 1 The circuit shown in the figure has the following shortcomings: 1. Whether the output voltage of the switching power supply is isolated from the ground must be determined through a withstand voltage test, resulting in a low level of intelligence. 2. Whether the output voltage of the switching power supply is isolated from the ground cannot be monitored in real time. If the output voltage of the power supply shorts to the ground during operation and this cannot be detected immediately, the operating equipment will be at risk, significantly reducing its reliability. Furthermore, with the development of smart grid technology, the switching power supplies supporting smart grid equipment are also required to be increasingly intelligent. Currently, the switching power supplies supporting a new type of smart grid equipment (primary and secondary integrated pole-mounted circuit breakers and ring main units) are required to have online, real-time monitoring of the DC output voltage's insulation from the ground. Clearly, the existing solutions for monitoring the output voltage of the switching power supply do not meet the intelligent requirements of the switching power supply, and this problem needs to be addressed urgently. Summary of the Invention

[0003] The present invention provides an online real-time monitoring circuit for the insulation of a switching power supply output to the ground and a switching power supply to solve the problems mentioned in the above background technology section.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A circuit for online real-time monitoring of the insulation of a switching power supply output to earth, comprising a transformer induction winding circuit, an output voltage insulation monitoring circuit to earth, and an alarm circuit; the transformer induction winding circuit is connected to the output voltage insulation monitoring circuit to input an alternating voltage to the output voltage insulation monitoring circuit to earth; the output voltage insulation monitoring circuit is connected to the alarm circuit to input a high-potential DC voltage to the alarm circuit when the positive or negative output electrode of the switching power supply is short-circuited to earth; the alarm circuit is used to convert the high-potential DC voltage into a low-potential DC alarm voltage to determine whether the positive or negative output electrode of the switching power supply is short-circuited to earth.

[0006] Furthermore, the transformer induction winding circuit includes a transformer winding NS1 and a Y safety capacitor CY1; one end of the transformer winding NS1 is connected to the output voltage to earth insulation monitoring circuit, the other end of the transformer winding NS1 is connected to one end of the Y safety capacitor CY1, and the other end of the Y safety capacitor CY1 is connected to the ground.

[0007] Furthermore, the output voltage to earth insulation monitoring circuit includes a rectifier diode D1, a current limiting resistor R1, an energy storage electrolytic capacitor CD1, a discharge diode D2, an energy storage electrolytic capacitor CD2 and a discharge diode D3; the anode of the rectifier diode D1 is connected to the transformer winding NS1, the cathode of the rectifier diode D1 is connected to one end of the current limiting resistor R1, the other end of the current limiting resistor R1 is connected to the positive electrode of the energy storage electrolytic capacitor CD1, the negative electrode of the energy storage electrolytic capacitor CD1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the anode of the discharge diode D2 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the cathode of the discharge diode D2 is connected to the anode of the rectifier diode D1, the positive electrode of the energy storage electrolytic capacitor CD2 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the negative electrode of the energy storage electrolytic capacitor CD2 is connected to the output voltage negative terminal VOUT- of the switching power supply, the anode of the discharge diode D3 is connected to the output voltage negative terminal VOUT- of the switching power supply, and the cathode of the discharge diode D3 is connected to the anode of the rectifier diode D1.

[0008] Furthermore, the alarm circuit includes a current limiting resistor R2, an optocoupler PC1 and a current limiting resistor R3, one end of the current limiting resistor R2 is connected to the positive electrode of the energy storage electrolytic capacitor CD1, the other end of the current limiting resistor R2 is connected to the anode of the light-emitting diode at the input end of the optocoupler PC1, the cathode of the light-emitting diode at the input end of the optocoupler PC1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the collector of the output transistor of the optocoupler PC1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the emitter of the output transistor of the optocoupler PC1 is connected to the alarm signal output terminal VS1 and one end of the current limiting resistor R3, and the other end of the current limiting resistor R3 is connected to the output voltage negative terminal VOUT- of the switching power supply.

[0009] Based on the above-mentioned online real-time monitoring circuit for the insulation of the switching power supply output to the earth, the present invention further discloses a switching power supply, which includes the above-mentioned online real-time monitoring circuit for the insulation of the switching power supply output to the earth.

[0010] Compared with the prior art, the online real-time monitoring circuit for the insulation of the switching power supply output to the earth and the switching power supply proposed in the present invention can determine in real time whether the switching power supply output is short-circuited to the earth through the alarm signal voltage at the alarm signal output end, and can send an alarm signal, thereby quickly eliminating equipment safety hazards and ensuring the reliable operation of the equipment. The present invention realizes online real-time monitoring of the insulation of the switching power supply output to the earth, and the power supply can know whether the positive or negative output pole of the power supply is short-circuited to the earth without undergoing a withstand voltage test. The present invention can not only monitor the insulation function of the switching power supply output to the earth in real time, but also realize intelligent management of whether the switching power supply output voltage is insulated from the earth if the matching terminal equipment collects the alarm signal voltage on the power supply and writes it into the single-chip computer program. In addition, the present invention has a simple structure, is reliable and sensitive, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the insulation isolation principle of the output voltage of an existing switching power supply from the ground;

[0012] Figure 2 This is a functional block diagram of a circuit for online real-time monitoring of the insulation of a switching power supply output to the ground, as proposed in an embodiment of the present invention;

[0013] Figure 3 This is an electrical schematic diagram of an online real-time monitoring circuit for the insulation of a switching power supply output to the ground proposed in an embodiment of the present invention;

[0014] Figure 4 This is an equivalent diagram of the online real-time monitoring circuit for the insulation of the switching power supply output to the ground proposed in an embodiment of the present invention when the positive output electrode of the switching power supply is short-circuited to the ground;

[0015] Figure 5 This is an equivalent diagram of the online real-time monitoring circuit for the insulation of the switching power supply output to the ground proposed in an embodiment of the present invention when the output negative electrode of the switching power supply is short-circuited to the ground;

[0016] Figure 6 This is a waveform diagram of the alarm signal voltage measured by the online real-time monitoring circuit for the insulation between the switching power supply output and the ground proposed in an embodiment of the present invention during a continuous on-off test of the positive electrode output of the switching power supply to the ground. DETAILED DESCRIPTION

[0017] In order to facilitate the understanding of the present invention, the present invention will be described in more detail below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood. It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0018] Example 1

[0019] like Figure 2 As shown, Figure 2 This is a principle block diagram of a circuit for online real-time monitoring of the insulation of a switching power supply output to the earth proposed in an embodiment of the present invention.

[0020] This embodiment provides an online, real-time monitoring circuit 200 for the insulation of a switching power supply output from ground. The circuit includes a transformer inductive winding circuit 201, an output voltage insulation monitoring circuit 202, and an alarm circuit 203. Specifically, in this embodiment, the transformer inductive winding circuit 201 is connected to the output voltage insulation monitoring circuit 202 for inputting an alternating voltage to the output voltage insulation monitoring circuit 202. The output voltage insulation monitoring circuit 202 is connected to the alarm circuit 203 for inputting a high-voltage DC voltage to the alarm circuit 203 when the positive or negative output terminal of the switching power supply is short-circuited to ground. The alarm circuit 203 is configured to convert the high-voltage DC voltage into a low-voltage DC alarm voltage to determine whether the positive or negative output terminal of the switching power supply is short-circuited to ground.

[0021] Specifically, in this embodiment, the transformer inductive winding circuit 201 includes a port with alternating input and output. The output voltage to earth insulation monitoring circuit 202 is composed of an output voltage positive electrode to earth insulation monitoring function circuit and an output voltage negative electrode to earth insulation monitoring function circuit. The output voltage positive electrode to earth insulation monitoring function circuit includes a port with alternating input and output, an output terminal, and a monitoring terminal; the output voltage negative electrode to earth insulation monitoring function circuit includes a port with alternating input and output, an output terminal, and a monitoring terminal shared with the output voltage positive electrode to earth insulation monitoring function circuit. The alarm circuit 203 includes a potential conversion function circuit and an alarm signal generation function circuit. The potential conversion function circuit includes an input terminal and an output terminal; the alarm signal generation function circuit includes an input terminal and an output terminal. The input and output ports of the transformer induction winding circuit 201, which alternately change, are commonly connected to the input and output ports of the output voltage positive pole to earth insulation monitoring function circuit and the output voltage negative pole to earth insulation monitoring function circuit; the output ends of the output voltage positive pole to earth insulation monitoring function circuit and the output voltage negative pole to earth insulation monitoring function circuit are the same output end connected to the input end of the potential conversion circuit; the monitoring end of the output voltage positive pole to earth insulation monitoring function circuit or the output voltage negative pole to earth insulation monitoring function circuit monitors in real time whether the output positive pole or negative pole is short-circuited with the earth; the output end of the potential conversion circuit is connected to the input end of the alarm signal generating circuit, and the output end of the alarm signal generating circuit is the output end of the alarm signal voltage that monitors in real time whether the power supply output voltage is short-circuited with the earth.

[0022] The online real-time monitoring circuit 200 for the insulation of the switching power supply output to the earth proposed in this embodiment realizes online real-time monitoring of the insulation of the switching power supply output to the earth. It is possible to know whether the positive or negative output of the power supply is short-circuited to the earth without performing a withstand voltage test on the power supply.

[0023] Example 2

[0024] like Figure 3 As shown, Figure 3 This is the electrical schematic diagram of the online real-time monitoring circuit for the insulation of the switching power supply output to the earth proposed in an embodiment of the present invention.

[0025] This embodiment provides an online, real-time monitoring circuit for the insulation of a switching power supply output from ground. The circuit includes a transformer induction winding circuit, an output voltage insulation monitoring circuit from ground, and an alarm circuit. Specifically, in this embodiment, the transformer induction winding circuit is connected to the output voltage insulation monitoring circuit for inputting an alternating voltage to the output voltage insulation monitoring circuit. The output voltage insulation monitoring circuit is connected to the alarm circuit for inputting a high-voltage DC voltage to the alarm circuit when the positive or negative output terminal of the switching power supply is short-circuited to ground. The alarm circuit is configured to convert the high-voltage DC voltage into a low-voltage DC alarm voltage to determine whether the positive or negative output terminal of the switching power supply is short-circuited to ground.

[0026] Specifically, in this embodiment, the transformer induction winding circuit includes a port with alternating input and output. The output voltage to earth insulation monitoring circuit is composed of an output voltage positive pole to earth insulation monitoring function circuit and an output voltage negative pole to earth insulation monitoring function circuit. The output voltage positive pole to earth insulation monitoring function circuit includes an input and output alternating port, an output terminal, and a monitoring terminal; the output voltage negative pole to earth insulation monitoring function circuit includes an input and output alternating port, an output terminal, and a monitoring terminal shared with the output voltage positive pole to earth insulation monitoring function circuit. The alarm circuit includes a potential conversion function circuit and an alarm signal generation function circuit. The potential conversion function circuit includes an input terminal and an output terminal; the alarm signal generation function circuit includes an input terminal and an output terminal. The ports of the transformer induction winding circuit with alternating input and output are commonly connected to the ports of the output voltage positive pole to earth insulation monitoring function circuit and the output voltage negative pole to earth insulation monitoring function circuit with alternating input and output; the output ends of the output voltage positive pole to earth insulation monitoring function circuit and the output voltage negative pole to earth insulation monitoring function circuit are the same output end connected to the input end of the potential conversion circuit; the monitoring end of the output voltage positive pole to earth insulation monitoring function circuit or the output voltage negative pole to earth insulation monitoring function circuit monitors in real time whether the output positive pole or negative pole is short-circuited with the ground; the output end of the potential conversion circuit is connected to the input end of the alarm signal generating circuit, and the output end of the alarm signal generating circuit is the output end of the alarm signal voltage that monitors in real time whether the power supply output voltage is short-circuited with the ground.

[0027] Specifically, in this embodiment, the transformer inductive winding circuit includes a transformer winding NS1 and a Y-safety capacitor CY1. One end of the transformer winding NS1 is connected to the output voltage-to-ground insulation monitoring circuit, and the other end of the transformer winding NS1 is connected to one end of the Y-safety capacitor CY1. The other end of the Y-safety capacitor CY1 is connected to ground.

[0028] Specifically, the output voltage-to-earth insulation monitoring circuit in this embodiment includes a rectifier diode D1, a current-limiting resistor R1, an energy storage electrolytic capacitor CD1, a discharge diode D2, an energy storage electrolytic capacitor CD2, and a discharge diode D3. The output voltage positive electrode-to-earth insulation monitoring circuit comprises the rectifier diode D1, current-limiting resistor R1, energy storage electrolytic capacitor CD1, and discharge diode D2; the output voltage negative electrode-to-earth insulation monitoring circuit comprises the rectifier diode D1, current-limiting resistor R1, energy storage electrolytic capacitor CD1, energy storage electrolytic capacitor CD2, and discharge diode D3, which are shared with the output voltage positive electrode-to-earth insulation monitoring circuit. Among them, the anode of the rectifier diode D1 is connected to the transformer winding NS1, the cathode of the rectifier diode D1 is connected to one end of the current limiting resistor R1, the other end of the current limiting resistor R1 is connected to the positive electrode of the energy storage electrolytic capacitor CD1, and the negative electrode of the energy storage electrolytic capacitor CD1 is connected to the output voltage positive terminal VOUT+ of the switching power supply. The anode of the discharge diode D2 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the cathode of the discharge diode D2 is connected to the anode of the rectifier diode D1, the positive electrode of the energy storage electrolytic capacitor CD2 is connected to the output voltage positive terminal VOUT+ of the switching power supply, and the negative electrode of the energy storage electrolytic capacitor CD2 is connected to the output voltage negative terminal VOUT- of the switching power supply. The anode of the discharge diode D3 is connected to the output voltage negative terminal VOUT- of the switching power supply, and the cathode of the discharge diode D3 is connected to the anode of the rectifier diode D1.

[0029] Specifically, in this embodiment, the alarm circuit includes a current-limiting resistor R2, an optocoupler PC1, and a current-limiting resistor R3. The potential conversion function circuit is composed of the current-limiting resistor R2 and the input end of the optocoupler PC1; the alarm signal generation function circuit is composed of the output transistor of the optocoupler PC1 and the current-limiting resistor R3. Among them, one end of the current-limiting resistor R2 is connected to the positive electrode of the energy storage electrolytic capacitor CD1, the other end of the current-limiting resistor R2 is connected to the anode of the light-emitting diode at the input end of the optocoupler PC1, the cathode of the light-emitting diode at the input end of the optocoupler PC1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the collector of the output transistor of the optocoupler PC1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the emitter of the output transistor of the optocoupler PC1 is connected to the alarm signal output terminal VS1 and one end of the current-limiting resistor R3, and the other end of the current-limiting resistor R3 is connected to the output voltage negative terminal VOUT- of the switching power supply.

[0030] In this embodiment, the output of the switching power supply is connected to ground only by the Y-type safety capacitor CY1. When the positive and negative poles of the output voltage are short-circuited to ground, the alternating voltage induced on the transformer winding NS1 forms a closed charge-discharge loop with the Y-type safety capacitor CY1, generating a DC alarm voltage. Based on the level of this DC alarm voltage, it is possible to determine in real time whether the positive and negative poles of the output voltage are short-circuited to ground. Specifically, in this embodiment, when the monitoring terminals of the output voltage positive pole-to-ground insulation monitoring circuit or the output voltage negative pole-to-ground insulation monitoring circuit do not detect a short-circuit between the positive and negative poles of the switching power supply output and ground, the alternating voltage induced on the transformer winding NS1 in the transformer induction winding circuit, because it does not form a charge-discharge loop with the Y-type safety capacitor CY1, remains suspended. Consequently, no voltage VC1 is generated on the energy storage electrolytic capacitor CD1, the potential conversion circuit does not operate, and the alarm signal output terminal VS1 of the alarm signal generating circuit does not output an alarm voltage. At this point, the low level at the alarm signal output terminal VS1 indicates that the positive and negative poles of the switching power supply output are insulated from ground.

[0031] Assuming that the output voltage positive electrode insulation monitoring function circuit detects that the power supply output positive electrode is short-circuited with the ground, its circuit equivalent schematic diagram is as follows: Figure 4 As shown below, combined Figure 4 Detailed introduction to the principle of alarm voltage generation:

[0032] Figure 4When the positive pole of the output voltage of the switching power supply is short-circuited with the ground, a closed loop of charging and discharging of the Y safety capacitor CY1 is formed. The specific principle is that the forward voltage induced by the transformer winding NS1 charges the Y safety capacitor CY1 through the rectifier diode D1, the current limiting resistor R1 and the energy storage electrolytic capacitor CD1. When the transformer winding NS1 induces a reverse voltage, the Y safety capacitor CY1 forms a closed discharge loop through the discharge diode D2 and the transformer winding NS1. The voltage on the Y safety capacitor CY1 will decrease through the discharge loop. When the next pulse width comes, the above process is repeated to charge and discharge the Y safety capacitor CY1. Therefore, within each pulse width, when the Y safety capacitor CY1 is charged, a voltage VC1 will be generated on the energy storage electrolytic capacitor CD1. VC1 supplies power to the input stage of the optocoupler PC1 through the current limiting resistor R2, and the output stage transistor of the optocoupler PC1 will also be turned on. Since the collector of the output transistor of the optocoupler PC1 is connected to the positive output voltage terminal VOU of the switching power supply. T+, a voltage level equal to the voltage at the positive output voltage terminal VOUT+ of the switching power supply will be generated on the current-limiting resistor R3 connected to the emitter of the output transistor of the optocoupler PC1. This voltage level is the voltage level at the alarm signal output terminal VS1. Therefore, when the output transistor of the optocoupler PC1 is turned on, the voltage level at its emitter becomes high, that is, the voltage level at the alarm signal output terminal VS1 becomes high. When the positive terminal of the switching power supply output voltage is not shorted to ground, the Y safety capacitor CY1 does not have a closed charge and discharge circuit, there is no voltage on the energy storage electrolytic CD1, and no current flows through the input terminal of the optocoupler PC1. Its output transistor is in the disconnected state, and the voltage level at the emitter of the optocoupler transistor becomes low, that is, the voltage level at the alarm signal output terminal VS1 becomes low. Therefore, based on the voltage level at the emitter of the output transistor of the optocoupler PC1, that is, the alarm signal output terminal VS1, it can be determined whether the positive output voltage terminal of the switching power supply is shorted to ground.

[0033] Assuming that the output voltage negative electrode insulation monitoring function circuit detects that the output negative electrode of the switching power supply is short-circuited with the ground, the circuit equivalent schematic diagram is as follows: Figure 5 As shown below, combined Figure 5 Detailed introduction to the principle of alarm voltage generation:

[0034] Figure 5When the negative pole of the output voltage of the switching power supply is short-circuited to the ground, a closed loop for charging and discharging the Y safety capacitor CY1 is formed. The specific principle is that the forward voltage induced by the transformer winding NS1 passes through the rectifier diode D1, the current limiting resistor R1, the energy storage electrolytic capacitor CD1, and the energy storage electrolytic capacitor CD2 to charge the Y safety capacitor CY1. When the transformer winding NS1 induces a reverse voltage within a pulse width, the Y safety capacitor CY1 is discharged through the discharge diode D3, and the transformer winding NS1 forms a discharge loop again. The voltage on the Y safety capacitor CY1 will decrease through the discharge loop. After the next pulse width comes, the above process is repeated to charge and discharge the Y safety capacitor CY1. Therefore, when the Y safety capacitor CY1 is charged, a voltage VC1 will be generated on the energy storage electrolytic CD1. The voltage VC1 is supplied to the input stage of the optocoupler PC1 through the current limiting resistor R2, and the output transistor of the optocoupler PC1 will be turned on. The collector of the output transistor is connected to the positive output voltage terminal VOUT+ of the switching power supply. Then, a voltage level equivalent to the positive output voltage terminal VOUT+ of the switching power supply will be generated on the current-limiting resistor R3 connected to the emitter of the output transistor of the optocoupler PC1. This voltage level is the voltage level at the alarm signal output terminal VS1. When the negative terminal of the switching power supply output voltage is not shorted to the ground, the Y safety capacitor CY1 does not have a closed charge and discharge circuit, and there is no voltage on the energy storage electrolytic capacitor CD1. No current flows through the output terminal of the optocoupler PC1, and its output transistor is in the disconnected state. The voltage level on the emitter of the optocoupler PC1 transistor will become low, that is, the voltage level on the alarm signal output terminal VS1 will become low. Therefore, based on the voltage level on the emitter of the output transistor of the optocoupler PC1, that is, the alarm signal output terminal VS1, it can be determined in real time whether the negative output voltage terminal of the switching power supply is shorted to the ground.

[0035] It is worth mentioning that in the above example, the voltage at the positive terminal VOUT+ of the switching power supply output voltage is 5V+, and the voltage at the negative terminal VOUT- of the switching power supply output voltage is 5V+ reference ground level. When the positive terminal VOUT+ of the switching power supply output voltage is continuously connected to the ground, the level change on the alarm signal output terminal VS1 can be quickly measured, such as Figure 6 As shown, from Figure 6 The waveforms shown indicate that the embodiment of the present invention can quickly detect whether the positive or negative output electrode of the power supply is connected to the ground. As long as the power supply is working, the power supply can monitor in real time whether the power supply output is short-circuited to the ground based on the level change at the alarm signal output terminal VS1.

[0036] The technical solution proposed in this embodiment can determine in real time whether the output of the switching power supply is short-circuited to the ground through the alarm signal voltage at the alarm signal output end, and can send an alarm signal, thereby quickly eliminating safety hazards of the equipment and ensuring reliable operation of the equipment. The technical solution proposed in this embodiment realizes online real-time monitoring of the insulation of the switching power supply output to the ground. The power supply does not need to undergo a withstand voltage test to know whether the positive or negative output pole of the power supply is short-circuited to the ground. The technical solution proposed in this embodiment can not only monitor the insulation function of the switching power supply output to the ground in real time online, but also realize intelligent management of whether the output voltage of the switching power supply is insulated from the ground if the matching terminal equipment collects the alarm signal voltage on the power supply and writes it into the single-chip computer program. In addition, the technical solution proposed in this embodiment is simple in structure, reliable and sensitive, and low in cost.

[0037] Example 3

[0038] An embodiment of the present invention provides a switching power supply, which includes the online real-time monitoring circuit for the insulation of the output of any one of the switching power supply in the first embodiment or the second embodiment from the ground.

[0039] The technical solution proposed in this embodiment can determine in real time whether the output of the switching power supply is short-circuited to the ground, and can send out an alarm signal, thereby quickly eliminating equipment safety hazards and ensuring reliable operation of the equipment.

[0040] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. An online real-time monitoring circuit for the insulation of a switching power supply output to the ground, characterized in that: The circuit includes a transformer induction winding circuit, an output voltage-to-earth insulation monitoring circuit, and an alarm circuit; the transformer induction winding circuit is connected to the output voltage-to-earth insulation monitoring circuit and is used to input an alternating voltage to the output voltage-to-earth insulation monitoring circuit; the output voltage-to-earth insulation monitoring circuit is connected to the alarm circuit and is used to input a high-potential DC voltage to the alarm circuit when the positive or negative output electrode of the switching power supply is short-circuited to the earth; the alarm circuit is used to convert the high-potential DC voltage into a low-potential DC alarm voltage to determine whether the positive or negative output electrode of the switching power supply is short-circuited to the earth; In which, the transformer induction winding circuit includes a port with alternating input and output; the output voltage to earth insulation monitoring circuit is composed of an output voltage positive pole to earth insulation monitoring function circuit and an output voltage negative pole to earth insulation monitoring function circuit; the output voltage positive pole to earth insulation monitoring function circuit includes an input and output alternating port, an output terminal, and a monitoring terminal; the output voltage negative pole to earth insulation monitoring function circuit includes an input and output alternating port, an output terminal, and a monitoring terminal shared with the output voltage positive pole to earth insulation monitoring function circuit; the alarm circuit includes a potential conversion function circuit and an alarm signal generation function circuit; the potential conversion function circuit includes an input terminal and an output terminal; the alarm signal generation function circuit includes an input terminal and an output terminal ; The ports of the transformer induction winding circuit with alternating input and output are commonly connected to the ports of the output voltage positive pole to earth insulation monitoring function circuit and the output voltage negative pole to earth insulation monitoring function circuit with alternating input and output; the output ends of the output voltage positive pole to earth insulation monitoring function circuit and the output voltage negative pole to earth insulation monitoring function circuit are the same output end connected to the input end of the potential conversion circuit; the monitoring end of the output voltage positive pole to earth insulation monitoring function circuit or the output voltage negative pole to earth insulation monitoring function circuit monitors in real time whether the output positive pole or negative pole is short-circuited with the earth; the output end of the potential conversion circuit is connected to the input end of the alarm signal generating circuit, and the output end of the alarm signal generating circuit is the output end of the alarm signal voltage for real-time monitoring whether the power supply output voltage is short-circuited with the earth; Wherein, the transformer induction winding circuit includes a transformer winding NS1 and a Y safety capacitor CY1; one end of the transformer winding NS1 is connected to the output voltage to earth insulation monitoring circuit, the other end of the transformer winding NS1 is connected to one end of the Y safety capacitor CY1, and the other end of the Y safety capacitor CY1 is connected to the earth; the output voltage to earth insulation monitoring circuit includes a rectifier diode D1, a current limiting resistor R1, an energy storage electrolytic capacitor CD1, a discharge diode D2, an energy storage electrolytic capacitor CD2 and a discharge diode D3; the anode of the rectifier diode D1 is connected to the transformer winding NS1, and the cathode of the rectifier diode D1 is connected to one end of the current limiting resistor R1, The other end of the current resistor R1 is connected to the positive electrode of the energy storage electrolytic capacitor CD1, the negative electrode of the energy storage electrolytic capacitor CD1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the anode of the discharge diode D2 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the cathode of the discharge diode D2 is connected to the anode of the rectifier diode D1, the positive electrode of the energy storage electrolytic capacitor CD2 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the negative electrode of the energy storage electrolytic capacitor CD2 is connected to the output voltage negative terminal VOUT- of the switching power supply, the anode of the discharge diode D3 is connected to the output voltage negative terminal VOUT- of the switching power supply, and the cathode of the discharge diode D3 is connected to the anode of the rectifier diode D1; Among them, the alarm circuit includes a current limiting resistor R2, an optocoupler PC1 and a current limiting resistor R3, one end of the current limiting resistor R2 is connected to the positive electrode of the energy storage electrolytic capacitor CD1, the other end of the current limiting resistor R2 is connected to the anode of the light-emitting diode at the input end of the optocoupler PC1, the cathode of the light-emitting diode at the input end of the optocoupler PC1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the collector of the output transistor of the optocoupler PC1 is connected to the output voltage positive terminal VOUT+ of the switching power supply, the emitter of the output transistor of the optocoupler PC1 is connected to the alarm signal output terminal VS1 and one end of the current limiting resistor R3, and the other end of the current limiting resistor R3 is connected to the output voltage negative terminal VOUT- of the switching power supply.

2. A switching power supply, characterized in that: The switching power supply comprises the on-line real-time monitoring circuit for the insulation of the switching power supply output to the ground as claimed in claim 1.

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