Power supply protection device and single-phase power supply equipment

Abstract

The utility model discloses a power supply protection device and a single-phase power supply device, comprising a rectifier bridge, two ends of an input side of the rectifier bridge are respectively connected with a live line and a zero line of an AC power supply, and two ends of an output side of the rectifier bridge are respectively connected with a bus capacitor unit and a load; the power supply protection device further comprises a pre-charging module which comprises an NTC pre-charging resistor and a PTC pre-charging resistor. The live wire comprises a first branch connected with the PTC pre-charging resistor and a second branch connected with the NTC pre-charging resistor; a zero sequence current transformer; the zero line and the first branch pass through the zero sequence current transformer and are connected with the rectifier bridge; the zero sequence current transformer is used for generating induced current according to the current conditions of the first branch and the second branch; the tripping protection module is respectively connected with the zero sequence current transformer and the alternating current power supply; the tripping protection module is used for making the live wire in an open-circuit state according to the induction current. Therefore, continuous heating of the PTC pre-charging resistor is prevented, and the situation that the product is burnt and even fire disasters are caused is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to emergency protection circuit device technical field especially relates to a power protection device and single -phase power supply equipment. BACKGROUND

[0002] At present, the common single -phase power supply product, all AC power through rectification again through power electronic conversion obtains the voltage required by load. The rectified DC power generally needs large capacity capacitor to stabilize voltage, due to the existence of the capacitor, the power -on current needs to be limited.

[0003] Therefore, as shown in the accompanying Figure 1 The current limiting scheme of the existing single -phase power supply product is through the pre -charge resistance R0 current limiting, and then the pre -charge resistance R0 is short -circuited through the relay K0 connected in parallel at the two ends of the pre -charge resistance R0, and then the power -on current limiting is completed. However, when the existing scheme has some fault conditions (such as PFC circuit switch tube breakdown short circuit), the positive and negative poles of the output side of the rectifier bridge will be short -circuited, so that only the pre -charge resistance R0 is connected in series in the loop after the product is powered on, which causes the pre -charge resistance R0 to continuously heat, thereby causing the product to burn out and even causing a fire. UTILITY MODEL CONTENTS

[0004] The utility model provides a kind of power protection device and single -phase power supply equipment, for solving the problem of pre -charge resistance overheating caused by circuit short circuit in prior art.

[0005] The technical scheme of the utility model is a kind of power protection device, including rectifier bridge, the input side two ends of the rectifier bridge are connected with the fire line and zero line of AC power respectively, and the output side two ends of the rectifier bridge are connected with bus capacitor unit and load respectively;The power protection device further includes:

[0006] Pre -charge module, including NTC pre -charge resistance and PTC pre -charge resistance;

[0007] The fire line includes the first branch connected with the PTC pre -charge resistance and the second branch connected with the NTC pre -charge resistance;

[0008] Zero sequence current transformer;The zero line and the first branch pass through the zero sequence current transformer and are connected with the rectifier bridge;The zero sequence current transformer is used to generate induced current according to the current condition of the first branch and the second branch;

[0009] Tripping protection module, the tripping protection module is connected with the zero sequence current transformer and the AC power respectively;The tripping protection module is used to make the fire line be in open circuit state according to the induced current.

[0010] Further, the pre -charge module further includes relay K1;

[0011] The NTC pre-charging resistor and the PTC pre-charging resistor are arranged in parallel; one end of an input side of the rectifier bridge is connected with the PTC pre-charging resistor and the NTC pre-charging resistor respectively.

[0012] The PTC pre-charging resistor is connected with a relay K1 in parallel.

[0013] Further, the NTC pre-charging resistor and the PTC pre-charging resistor are arranged closely.

[0014] Further, the power protection device further comprises:

[0015] A sampling processing module, an input end of the sampling processing module is connected with an output winding of the zero sequence current transformer; the sampling processing module is used for rectifying and filtering the induced current to form a voltage signal;

[0016] A signal output module, an input end of the signal output module is connected with an output end of the sampling processing module, and an output end of the signal output module is connected with a first input end of the tripping protection module; the signal output module is used for receiving and comparing the voltage signal, and making the fire line in an open circuit state according to a comparison result.

[0017] Further, the tripping protection module comprises a thyristor SCR, a tripping coil L10, a switching device K2, a rectifier diode D1, a rectifier diode D2, a rectifier diode D3 and a rectifier diode D4.

[0018] The rectifier diode D1 and the rectifier diode D2 are connected in series to form a first bridge arm, and the rectifier diode D3 and the rectifier diode D4 are connected in series to form a second bridge arm.

[0019] A gate of the thyristor SCR is connected with an output end of the signal output module; a cathode and an anode of the thyristor SCR are connected with two ends of the first bridge arm and two ends of the second bridge arm respectively.

[0020] The fire line is connected with the switching device K2 in series, and the switching device K2 is further connected with the tripping coil L10 in magnetic coupling.

[0021] Wherein, a first end of the switching device K2 is connected with an original fire line, a second end of the switching device K2 is connected with a second end of the tripping coil L10, a first end of the tripping coil L10 is connected with a midpoint of the second bridge arm, and a midpoint of the first bridge arm is connected with a zero line which does not pass through the zero sequence current transformer.

[0022] Further, the switching device K2 is a manual reset switch.

[0023] Further, the power protection device further comprises a power processing module, an output end of the power processing module is connected with the sampling processing module and the signal output module respectively, and an input end of the power processing module is connected with the second input end of the tripping protection module.

[0024] Further, the power protection device further comprises a test circuit in series with a key S1, a first end of the test circuit is connected with a zero line not passing through the zero sequence current transformer, and a second end of the test circuit is connected with a first branch passing through the PTC pre-charging resistor.

[0025] The test circuit does not pass through the zero sequence current transformer.

[0026] Further, the power protection device further comprises a housing, and the housing encapsulates the rectifier bridge, the bus capacitor unit, the load and the pre-charging module.

[0027] The utility model also provides a single-phase power supply equipment, the single-phase power supply equipment includes above-mentioned power protection device.

[0028] Compared with the prior art, the utility model has at least the following beneficial effects:

[0029] The utility model discloses a PTC pre-charging resistor heating leads to the resistance value rise, and the resistance value of NTC pre-charging resistor corresponds to drop, and the output winding of zero sequence current transformer produces induced current, and the induced current is output to tripping protection module after processing, and the induced current after processing is received by tripping protection module and makes the fire line be in open circuit state, even if the whole power protection device is in tripping power-off state, prevents PTC pre-charging resistor sustained heating, thereby avoids the situation of burning product even causes fire. BRIEF DESCRIPTION OF DRAWINGS

[0030] Unless otherwise defined, 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 utility model belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit the utility model; the specification, claims and above-mentioned drawing of the utility model and the terms "include" and "have" and any deformation thereof in the specification and claims of the utility model are intended to cover the non-exclusive inclusion; the specification and claims of the utility model or the above-mentioned drawing of the utility model, the terms "first", "second" and the like are used to distinguish different objects, not to describe a specific order.

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of not paying creative labor.

[0032] Figure 1 Circuit schematic diagram of the current limiting scheme of the existing single-phase power supply product in the background art;

[0033] Figure 2 The first module block diagram of the power supply protection device provided by the present application;

[0034] Figure 3 The first circuit schematic diagram of the power supply protection device provided by the present application;

[0035] Figure 4 The second module block diagram of the power supply protection device provided by the present application;

[0036] Figure 5 The second circuit schematic diagram of the power supply protection device provided by the present application.

[0037] Reference signs:

[0038] 10, rectifier bridge;

[0039] 20, AC power supply;

[0040] 30, bus capacitor unit;

[0041] 40, load;

[0042] 50, pre-charge module;

[0043] 60, zero sequence current transformer;

[0044] 70, trip protection module;

[0045] 80, sampling processing module;

[0046] 90, signal output module;

[0047] 100, shell;

[0048] 110, test loop;

[0049] 120, power supply processing module. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects of the utility model clearer, the utility model will be further described in detail in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. Therefore, one feature mentioned in the specification will be used to explain one feature of one embodiment of the utility model, and it is not suggested that each embodiment of the utility model must have the explained feature. In addition, it should be noted that the specification describes many features. Although certain features can be combined together to show possible system designs, these features can also be used in other combinations that are not explicitly explained. Therefore, unless otherwise stated, the explained combination is not intended to be limited.

[0051] The principle and structure of the utility model will be described in detail in combination with the drawings and embodiments.

[0052] Embodiment 1

[0053] Referring to the drawings Figures 2-3 The utility model provides a kind of power protection device, including rectifier bridge 10, the input side both ends of the rectifier bridge 10 are connected with the fire line L and zero line N of alternating current power supply 20 respectively, the output side both ends of the rectifier bridge 10 are connected with bus capacitor unit 30 and load 40 respectively;The power protection device further includes:

[0054] precharge module 50, including NTC precharge resistance and PTC precharge resistance;And the precharge module 50 can also feedback the overheat condition in circuit

[0055] The fire line L includes the first branch L1 connected with the PTC precharge resistance and the second branch L2 connected with the NTC precharge resistance;

[0056] Zero sequence current transformer 60;Only the zero line N and the first branch L1 pass through the zero sequence current transformer 60 and are connected with the rectifier bridge 10;The zero sequence current transformer 60 is used to generate induced current according to the current condition of the first branch L1 and the second branch L2;

[0057] trip protection module 70, the trip protection module 70 is connected with the zero sequence current transformer 60 and the alternating current power supply 20 respectively;The trip protection module 70 is used to make the fire line L be in open circuit state, i.e. fire line L is disconnected according to the induced current.

[0058] It should be noted that the NTC pre-charge resistor in this embodiment is a negative temperature coefficient resistor, and the resistance value of the NTC pre-charge resistor is selected to be megohm level; the PTC pre-charge resistor is a positive temperature coefficient resistor, and the resistance value of the PTC pre-charge resistor is selected according to the size of the power supply allowed power-on current, generally tens to hundreds of ohms. And to be compatible with the leakage protection function, the NTC pre-charge resistor and the PTC pre-charge resistor should meet the following conditions at the same time:

[0059] 1. Under the condition of the maximum voltage allowed by the power grid, the current during the power-on pre-charge time of the circuit on the second branch L2 is much smaller than 30mA (because the leakage protection function needs to be compatible, the value is selected according to the leakage protection standard requirement, and is not limited here).

[0060] 2. Under the condition of the minimum voltage allowed by the power grid, when the internal short circuit of the power supply occurs and the temperature of the PTC pre-charge resistor reaches the set value, the current on the second branch L2 should be greater than 30mA.

[0061] Wherein, when the power supply protected by the power supply protection device works normally, because the resistance value of the NTC pre-charge resistor is extremely large, the current flowing through the second branch L2 is almost zero. When the internal short circuit of the power supply occurs, only the PTC pre-charge resistor is connected in series with the live wire L, so that the PTC pre-charge resistor continuously heats up to cause the resistance value of the PTC pre-charge resistor to rise, which causes the current flowing through the first branch L1 to decrease. At the same time, the NTC pre-charge resistor will cause the resistance value of the NTC pre-charge resistor to decrease due to the continuous heating of the PTC pre-charge resistor, which causes the current flowing through the second branch L2 to increase, thereby causing the output winding of the zero sequence current transformer 60 to generate an induced current. After processing, the induced current is output to the tripping protection module 70, and the tripping protection module 70 receives the processed induced current, so that the live wire L is in an open circuit state, that is, the entire power supply protection device is in a tripped power-off state, preventing the PTC pre-charge resistor from continuously heating up, thereby avoiding the situation of burning the product and even causing a fire.

[0062] And when the power supply protection device is in a tripped power-off state, it needs to be powered on again after the maintenance personnel have completely eliminated the fault. If the maintenance personnel have not completely eliminated the fault, the power supply protection device will repeat the above steps again, and the live wire L will be in an open circuit state again, and the fault will be eliminated again.

[0063] It should be noted that because the second branch L2 does not pass through the zero sequence current transformer 60, the total current sum of the first branch L1 and the second branch L2 (equivalent to the total current of the firewire L) is equal to the total current of the neutral wire N, and the total current of the firewire L is equal in size and opposite in direction to the total current of the neutral wire N. In this way, when the current passing through the second branch L2 is very small, it can be considered that the current passing through the first branch L1 is equal in size to the current of the neutral wire N, at this time the magnetic fields generated by the currents passing through the first branch L1 and the neutral wire N of the zero sequence current transformer 60 cancel each other out, and the zero sequence current transformer 60 has no output. When the current passing through the second branch L2 increases, the current passing through the first branch L1 will decrease accordingly, at this time the current passing through the first branch L1 is not equal in size to the current on the neutral wire N, which will cause the power protection device to have a leakage current, and the leakage current will cause the generation of a zero sequence current, and the zero sequence current transformer 60 can sense this non-zero zero sequence current and convert it into an induced current and output it from the output winding.

[0064] In order to ensure that the output winding of the zero sequence current transformer 60 can generate an induced current according to the current passing through the first branch L1 connected to the PTC pre-charging resistor and the current passing through the second branch L2 connected to the NTC pre-charging resistor, with reference to the accompanying drawings, Figure 3 The pre-charging module 50 further comprises a relay K1.

[0065] The NTC pre-charging resistor and the PTC pre-charging resistor are connected in parallel; one end of the input side of the rectifier bridge 10 is connected to the first branch L1 through the second end of the PTC pre-charging resistor, and the other end of the input side of the rectifier bridge 10 is also connected to the second branch L2 through the second end of the NTC pre-charging resistor.

[0066] The relay K1 is connected in parallel across the PTC pre-charging resistor.

[0067] It should be noted that the connection of the first branch L1 and the second branch L2 on the firewire L which does not pass through the zero sequence current transformer 60 is the P2 node, the connection of the first end of the relay K1 and the first end of the PTC pre-charging resistor is the P4 node (the first end of the PTC pre-charging resistor is the connection with the one end of the input side of the rectifier bridge 10); the connection of the second end of the relay K1 and the second end of the PTC pre-charging resistor is the P3 node.

[0068] In order to ensure that the NTC pre-charging resistor can receive the heat generated by the PTC pre-charging resistor more quickly and rapidly, the NTC pre-charging resistor and the PTC pre-charging resistor are arranged in close proximity.

[0069] In order to ensure that the NTC pre-charging resistor can receive the heat generated by the PTC pre-charging resistor more quickly and rapidly, the NTC pre-charging resistor and the PTC pre-charging resistor are arranged in close proximity. Figure 2 The power protection device further comprises:

[0070] A sampling processing module 80, an input end of the sampling processing module 80 is connected with an output winding of the zero sequence current transformer 60; the sampling processing module 80 is used for rectifying and filtering the induced current to form a voltage signal;

[0071] A signal output module 90, an input end of the signal output module 90 is connected with an output end of the sampling processing module 80, and an output end of the signal output module 90 is connected with a first input end of the tripping protection module 70; the signal output module 90 is used for receiving and comparing the voltage signal, and making the fire line L in an open circuit state according to a comparison condition.

[0072] It should be noted that the signal output module 90 is provided with a comparator and a latch. The comparator can be any circuit or chip that can realize level comparison, which is not limited herein. Similarly, the latch can be any circuit or chip that can realize signal latching, which is not limited herein.

[0073] The induced current generated by the output winding of the zero sequence current transformer 60 is an alternating current signal. The alternating current signal needs to be rectified and filtered by the sampling processing module 80, converted into a voltage signal, and input to the signal output module 90. Then, the comparator compares the input voltage signal with the reference voltage of the comparator. If the input voltage signal is higher than the reference voltage of the comparator, the comparator outputs an effective level to the tripping protection module 70, so that the tripping protection module 70 is turned on. Then, the tripping protection module 70 in the on state makes the fire line L in an open circuit state, so that the entire power protection device is in a tripping and power-off state, the PTC pre-charging resistor is prevented from continuously generating heat, and the situation of burning the product or causing a fire is avoided.

[0074] Meanwhile, the effective level output by the comparator is latched and maintained by the latch. Therefore, the action current (or leakage current) of the entire power protection device can be adjusted by adjusting the reference voltage of the comparator. It should be ensured that the action current is less than 30 mA.

[0075] In order to ensure that the tripping protection module 70 can make the fire line L in an open circuit state according to the effective level output by the signal output module 90, reference is made to the attached Figure 3 The embodiment provides a circuit topology of the tripping protection module 70:

[0076] The tripping protection module 70 includes a thyristor SCR, a tripping coil L10, a switching device K2, a rectifier diode D1, a rectifier diode D2, a rectifier diode D3, and a rectifier diode D4.

[0077] The rectifier diode D1 and the rectifier diode D2 are connected in series to form a first bridge arm, and the rectifier diode D3 and the rectifier diode D4 are connected in series to form a second bridge arm.

[0078] The gate of the thyristor SCR is connected with the output end of the signal output module 90, and the cathode and anode of the thyristor SCR are connected with both ends of the first bridge arm and both ends of the second bridge arm respectively.

[0079] The live wire L is connected in series with the switching device K2, and the switching device K2 is also connected in magnetic coupling with the trip coil L10.

[0080] The first end of the switching device K2 is connected with the original live wire, the second end of the switching device K2 is connected with the second end of the trip coil L10, the first end of the trip coil L10 is connected with the midpoint of the second bridge arm, and the midpoint of the first bridge arm is connected with the neutral wire N which does not pass through the zero sequence current transformer 60.

[0081] It should be noted that the characteristic of the thyristor SCR is that the current between the cathode and the anode must be turned off after conduction in order to turn off the thyristor SCR, and if the thyristor SCR is not turned on before conduction, there is no gate drive signal (i.e. lower than the reference voltage in the thyristor SCR), and the thyristor SCR is not turned on.

[0082] The node P1 is further arranged between the switching device K2 and the node P2, and the node P1 is used to connect the first end of the trip coil L10.

[0083] In this way, the comparator outputs an effective level to the gate of the thyristor SCR, causing the voltage at the gate of the thyristor SCR to be greater than the reference voltage, so that the thyristor SCR is turned on, thereby turning on the circuit where the trip protection module 70 is located, and the trip coil L10 is powered, thereby causing the switching device K2 to be turned off, causing the live wire L to be in an open circuit state, and the entire power supply protection device to be in a tripped and powered-off state, and the thyristor SCR is turned off due to tripping without current flowing through it, and the trip coil L10 is also powered off; and the switching device K2 needs to be manually reset after being turned off to close and be powered on again.

[0084] When the power supply protection device is in a tripped and powered-off state, the switching device K2 needs to be manually reset to close and be powered on again after the maintenance personnel have eliminated the fault. If the maintenance personnel have not completely eliminated the fault, the power supply protection device will trip again, causing the live wire L to be in an open circuit state again, and the fault needs to be eliminated again.

[0085] In order to ensure that the switching device K2 does not automatically reset when the live wire L is in an open circuit state, causing the PTC pre-charge resistor to continuously heat up, thereby avoiding the situation of burning out the product and even causing a fire, the switching device K2 is a manually reset switch.

[0086] In this way, when the switch device K2 is opened due to the energization of the tripping coil L10, even if the switch device K2 is not automatically closed after the tripping coil L10 is de-energized, the maintenance personnel need to manually press the reset again to confirm whether the fault of the power supply protection device is eliminated after the fault is eliminated. If the fault is not completely eliminated, the thyristor SCR will be energized again to open the switch device K2, so that the firewire L is in an open circuit state again, and the fault is eliminated again until the fault is completely eliminated.

[0087] In order to ensure that the sampling processing module 80 and the signal output module 90 can be powered and run, with reference to the attached Figure 2 The power supply protection device further comprises a power supply processing module 120, an output end of the power supply processing module 120 is connected with the sampling processing module 80 and the signal output module 90 respectively, and an input end of the power supply processing module 120 is connected with the second input end of the tripping protection module 70.

[0088] Specifically, the input end of the power supply processing module 120 is connected with the anode of the thyristor SCR, and the cathode of the thyristor SCR is connected with the sampling processing module 80 and the signal output module 90 respectively.

[0089] In this way, the power supply processing module 120 performs voltage step-down processing on the voltage rectified through the first bridge arm and the second bridge arm, and then supplies power to the sampling processing module 80 and the signal output module 90 to make them run.

[0090] In order to realize the leakage protection function of the power supply protection device, with reference to the attached Figure 2 The power supply protection device further comprises a housing 100, and the housing 100 encapsulates the rectifier bridge 10, the bus capacitor unit 30, the load 40 and the pre-charging module 50.

[0091] The housing 100 is grounded through a wire.

[0092] In this way, when the load 40 leaks due to some faults, a part of the current will flow into the ground through the housing 100, resulting in the inequality of the currents of the first branch L1 and the zero line N of the zero sequence current transformer 60, causing the zero sequence current transformer 60 to generate a zero sequence current, so that the output winding of the zero sequence current transformer 60 outputs an induced current. After the induced current is processed by the sampling processing module 80 and the signal output module 90, the thyristor SCR is turned on, so that the tripping coil L10 is energized and the switch device K2 is opened, resulting in the firewire L being in an open circuit state, and the entire power supply protection device being in a tripping and de-energized state, thereby realizing the leakage protection function.

[0093] Therefore, under the premise of realizing the leakage protection function of the power protection device, the power protection device can also make the output winding of the zero sequence current transformer 60 generate an induced current according to the resistance value change of the NTC pre-charging resistor and the PTC pre-charging resistor in the pre-charging module 50. After the induced current is processed by the sampling processing module 80 and the signal output module 90, the thyristor SCR is turned on, so that the trip coil L10 is powered on, the switching device K2 is turned off, the firewire L is in an open circuit state, and then the single-phase power supply equipment is in a tripping power-off state, thereby preventing the PTC pre-charging resistor from continuously heating, and avoiding the situation of burning the product and even causing a fire.

[0094] Embodiment 2

[0095] Based on the embodiment 1, referring to the accompanying drawings Figures 4-5 The power protection device further comprises a test circuit 110 in series with a key S1, a first end of the test circuit 110 is connected with the zero line N which does not pass through the zero sequence current transformer 60, and a second end of the test circuit 110 is connected with the first branch L1 which passes through the PTC pre-charging resistor.

[0096] The test circuit 110 does not pass through the zero sequence current transformer 60.

[0097] It should be noted that the connection between the first end of the test circuit 110 and the zero line N which does not pass through the zero sequence current transformer 60 is a node P5, and the node P5 is also connected with the midpoint of the first bridge arm; and the second end of the test circuit 110 is connected at the node P4.

[0098] In this way, when the power protection device is normally closed, the key S1 is pressed, that is, only the PTC pre-charging resistor is connected in series in the zero fire line loop, so that the current passing through the first branch L1 and the zero line N of the zero sequence current transformer 60 is not equal, the output winding of the zero sequence current transformer 60 outputs an induced current to turn on the thyristor SCR, at this time, the switching device K2 will be immediately turned off, so that the power protection device is tripped and powered off, for testing whether the switching device K2 exists sticking and other abnormalities; meanwhile, the design of the test circuit 110 in series with the key S1 also saves the current limiting resistor in the function of the traditional leakage protection.

[0099] Embodiment 3

[0100] The utility model further provides a single-phase power supply equipment, the single-phase power supply equipment includes above-mentioned power protection device.

[0101] In this way, when the single-phase power supply device is normally closed, because the resistance of the NTC pre-charging resistor is very large, the current through the second branch L2 is almost zero, and the current through the first branch L1 is equal to the current through the neutral line N, so the magnetic field generated by the current through the first branch L1 and the neutral line N of the zero-sequence current transformer 60 is counteracted, and the zero-sequence current transformer 60 has no output.

[0102] When a leakage occurs in the single-phase power supply device, part of the current flows into the ground through the shell 100, so the current through the first branch L1 and the neutral line N of the zero-sequence current transformer 60 is not equal, the zero-sequence current transformer 60 generates a zero-sequence current, and the output winding of the zero-sequence current transformer 60 outputs an induced current, which is processed by the sampling processing module 80 and the signal output module 90, and turns on the thyristor SCR, so that the trip coil L10 is powered, the switching device K2 is turned off, the live wire L is in an open circuit state, and the single-phase power supply device is in a tripped power-off state, thereby realizing the leakage protection function.

[0103] When a short circuit occurs in the single-phase power supply device, only the PTC pre-charging resistor is connected in series with the live wire L, the PTC pre-charging resistor continuously generates heat and increases in resistance, so the current through the first branch L1 decreases, and the NTC pre-charging resistor decreases in resistance due to the continuous heat generated by the PTC pre-charging resistor, so the current through the second branch L2 increases, and the current through the first branch L1 is not equal to the current through the neutral line N, so the output winding of the zero-sequence current transformer 60 generates an induced current, which is processed by the sampling processing module 80 and the signal output module 90, and turns on the thyristor SCR, so that the trip coil L10 is powered, the switching device K2 is turned off, the live wire L is in an open circuit state, and the single-phase power supply device is in a tripped power-off state, thereby preventing the PTC pre-charging resistor from continuously generating heat and avoiding the burning of the single-phase power supply device and even causing a fire.

[0104] Therefore, the power supply protection device or the single-phase power supply device can realize the overheat protection of the pre-charging resistor in the pre-charging module 50 on the basis of the leakage protection function.

[0105] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments, and the preferred embodiments of the present application are given in the drawings, but do not limit the patent scope of the present application. The present application can be realized in many different forms, and conversely, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing specific embodiments, or equivalently replace some of the technical features. Any equivalent structure made by using the content of the present application specification and drawings, directly or indirectly used in other related technical fields, is also within the patent protection scope of the present application.

Claims

1. A power protection device comprising a rectifier bridge (10), the input side of the rectifier bridge (10) being connected to the live wire and the neutral wire of an alternating current power supply (20) respectively, and the output side of the rectifier bridge (10) being connected to a bus capacitor unit (30) and a load (40) respectively; characterized in that, The power protection device further comprises: a pre-charging module (50) comprising an NTC pre-charging resistor and a PTC pre-charging resistor; the firewire comprises a first branch connected to the PTC pre-charging resistor and a second branch connected to the NTC pre-charging resistor; a zero sequence current transformer (60); the zero line and the first branch pass through the zero sequence current transformer (60) and are connected to the rectifier bridge (10); the zero sequence current transformer (60) is used to generate induced current according to the current condition of the first branch and the second branch; a tripping protection module (70) connected to the zero sequence current transformer (60) and the alternating current power supply (20) respectively; the tripping protection module (70) is used to make the firewire in an open circuit state according to the induced current.

2. The power protection device of claim 1, wherein The pre-charging module (50) further comprises a relay K1. The NTC pre-charging resistor and the PTC pre-charging resistor are arranged in parallel; one end of the input side of the rectifier bridge (10) is connected to the PTC pre-charging resistor and the NTC pre-charging resistor respectively; Both ends of the PTC pre-charging resistor are connected in parallel with the relay K1.

3. The power protection device of claim 1 or 2, wherein The NTC pre-charging resistor and the PTC pre-charging resistor are arranged closely.

4. The power protection device of claim 1, wherein The power protection device further comprises: a sampling processing module (80) whose input end is connected to the output winding of the zero sequence current transformer (60); the sampling processing module (80) is used to rectify and filter the induced current to form a voltage signal; a signal output module (90) whose input end is connected to the output end of the sampling processing module (80) and whose output end is connected to the first input end of the tripping protection module (70); the signal output module (90) is used to receive and compare the voltage signal and make the firewire in an open circuit state according to the comparison result.

5. The power protection device of claim 4, wherein, The tripping protection module (70) comprises a thyristor SCR, a trip coil L10, a switching device K2, rectifier diodes D1, D2, D3 and D4; The rectifier diodes D1 and D2 are connected in series to form a first bridge arm, and the rectifier diodes D3 and D4 are connected in series to form a second bridge arm; The gate of the thyristor SCR is connected to the output end of the signal output module (90); the cathode and the anode of the thyristor SCR are connected to both ends of the first bridge arm and both ends of the second bridge arm respectively; The firewire is connected in series with the switching device K2, and the switching device K2 is also magnetically coupled to the trip coil L10; The first end of the switching device K2 is connected to the original firewire, the second end of the switching device K2 is connected to the second end of the trip coil L10, the first end of the trip coil L10 is connected to the midpoint of the second bridge arm, and the midpoint of the first bridge arm is connected to the zero line that does not pass through the zero sequence current transformer (60).

6. The power protection device of claim 5, wherein, The switching device K2 is a manually reset switch.

7. The power protection device of claim 5, wherein The power supply protection device further comprises a power supply processing module, an output end of the power supply processing module is connected with the sampling processing module (80) and the signal output module (90) respectively, and an input end of the power supply processing module is connected with the second input end of the tripping protection module (70).

8. The power protection device of claim 1, wherein, The power supply protection device further comprises a test circuit (110) in series with a key S1, a first end of the test circuit (110) is connected with a zero line not passing through the zero sequence current transformer (60), and a second end of the test circuit (110) is connected with a first branch passing through the PTC pre-charging resistor. The test circuit (110) does not pass through the zero sequence current transformer (60).

9. The power protection device of claim 1, wherein, The power supply protection device further comprises a shell (100), the shell (100) encapsulates the rectifier bridge (10), the bus capacitor unit (30), the load (40) and the pre-charging module (50).

10. A single-phase power supply device, characterized by comprising: The single-phase power supply device comprises the power supply protection device according to any one of claims 1-9.

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