A short-circuit protection circuit and a power supply system

Abstract

The present invention discloses a short - circuit protection circuit and a power supply system. Among them, the short - circuit protection circuit includes: an auxiliary winding, a switch unit, and a relay; the auxiliary winding is wound on the same iron core as the primary coil and the secondary coil of the transformer. Its first end is connected to the switch unit through a first resistor, and its second end is grounded; the switch unit is connected between the first end of the auxiliary winding and the coil of the relay, and is used to control the relay to be energized when the load is short - circuited and control the relay to be de - energized when the load is operating normally; for the relay, its coil is connected between the voltage source and the reference ground, its second contact is connected to the live wire of the AC power supply, and its third contact is suspended, where the second contact is a normally - closed contact. Through the present invention, all components in the power supply system can be protected, the problem that serious heating of the power supply chip will occur when the load is short - circuited is solved, and the safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic power, and in particular, to a short - circuit protection circuit and a power supply system. Background Art

[0002] During actual production and testing processes, it often occurs that the power output end of the controller is short - circuited due to problems such as incorrect wiring or poor soldering. In addition, when semiconductor components such as ICs, transistors, and voltage - regulating chips are broken down and fail, they often exhibit a low - impedance state at the power - supply end, which is approximately a short - circuit state. When a short - circuit occurs in the circuit, it will cause the controller to fail to work properly, and it will also cause damage to the controller circuit or components due to over - current. In severe cases, major accidents such as fires will occur.

[0003] Currently, components such as the switching power - supply chip and buck chip inside the controller have a short - circuit protection function. If it is detected that the load is short - circuited and the short - circuit fault has not been eliminated, the power - supply chip will keep working in the "hiccup" state, which will cause the chip to heat up severely or even be damaged after a long time. In addition, the power - supply chip can only protect the local circuit at its output end, blocking the output path, but it will also bring problems such as false triggering.

[0004] In view of the problem that the short - circuit of the load in the prior art will cause the power - supply chip to heat up severely, no effective solution has been proposed yet. Summary of the Invention

[0005] An embodiment of the present invention provides a short - circuit protection circuit and a power supply system to solve the problem that the short - circuit of the load in the prior art will cause the power - supply chip to heat up severely.

[0006] To solve the above - mentioned technical problems, the present invention provides a short - circuit protection circuit, wherein the short - circuit protection circuit includes: an auxiliary winding, a switching unit, and a relay;

[0007] The auxiliary winding is wound on the same iron core as the primary coil and the secondary coil of the transformer. Its first end is connected to the switching unit through a first resistor, and its second end is grounded;

[0008] The switching unit is connected between the first end of the auxiliary winding and the coil of the relay, and is used to control the relay to be powered on when the load is short - circuited and to control the relay to be powered off when the load is working normally;

[0009] The relay, its coil is connected between the voltage source and the reference ground. Its first contact is connected to the neutral wire of the AC power supply, its second contact is connected to the live wire of the AC power supply, and its third contact is suspended. Among them, the second contact is a normally - closed contact.

[0010] Further, the switch unit includes:

[0011] A first switch, whose first pole is connected to the first resistor, whose second pole is connected between the voltage source and the first end of the coil of the relay through a second resistor, and whose third pole is grounded through a voltage dividing unit;

[0012] A second switch, whose first pole is connected between the third pole of the first switch and the voltage dividing unit through a third resistor, whose second pole is grounded, and whose third pole is connected to the second end of the coil of the relay.

[0013] Further, the switch unit further includes:

[0014] A third switch, whose first pole is connected to the third pole of the second switch, whose second pole is connected to the second end of the coil of the relay, and whose third pole is connected between the first pole of the second switch and the third resistor.

[0015] Further, the switch unit further includes:

[0016] A reset switch, whose first end is connected to the second end of the coil of the relay and whose second end is grounded, and is used to control the relay to return to the power-off state after the fault of the load short circuit is eliminated.

[0017] Further, the switch unit further includes:

[0018] A fourth resistor, whose first end is connected between the first pole of the second switch and the third resistor, and whose second end is grounded.

[0019] Further, the voltage dividing unit is at least one voltage dividing diode, the anode of the voltage dividing diode is connected to the third pole of the first switch, and the cathode is grounded.

[0020] Further, the short-circuit protection circuit further includes:

[0021] A fifth resistor, arranged between the voltage source and the first end of the coil of the relay, and is used to limit the current flowing through the coil of the relay.

[0022] Further, the short-circuit protection circuit further includes:

[0023] A unidirectional conduction element, connected in parallel between the first end and the second end of the coil of the relay, and is used to limit the direction of the current flowing through the coil of the relay.

[0024] Further, the short-circuit protection circuit further includes:

[0025] A rectification unit, connected between the first end of the auxiliary winding and the first resistor, and is used to convert the alternating current output by the auxiliary winding into direct current.

[0026] Furthermore, the short - circuit protection circuit further includes:

[0027] A first capacitor, whose first terminal is connected between the rectifying unit and the first resistor;

[0028] A second capacitor, arranged in parallel with the first capacitor, whose first terminal is connected between the first terminal of the first capacitor and the first resistor, and whose second terminal is connected to the second terminal of the first capacitor and then grounded;

[0029] The first capacitor and the second capacitor are used for filtering the current output by the rectifying unit.

[0030] Furthermore, the short - circuit protection circuit further includes:

[0031] A sixth resistor, whose first terminal is connected between the first resistor and the switching unit, and whose second terminal is grounded, for controlling the voltage input to the switching unit.

[0032] Furthermore, the short - circuit protection circuit further includes:

[0033] An indicating unit, whose first terminal is connected between the auxiliary winding and the first resistor through a seventh resistor, for indicating the state of the short - circuit protection circuit.

[0034] The present invention also provides a power supply system, including an AC power source, a fuse, a third capacitor, a varistor, a voltage - source output circuit, and the power supply system further includes the above - mentioned short - circuit protection circuit.

[0035] Furthermore, the voltage - source output circuit includes: a zener diode, a diode, an eighth resistor, a ninth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor;

[0036] Wherein, the anode of the zener diode is connected to the live wire of the AC power source, and the cathode is respectively connected to the first terminal of the eighth resistor and the anode of the diode. The ninth resistor and the fourth capacitor are connected in parallel and then connected between the second terminal of the eighth resistor and the reference ground. The fifth capacitor and the sixth capacitor are connected in parallel, one end is connected to the cathode of the diode, and the other end is grounded; the common connection point of the fifth capacitor, the sixth capacitor, and the cathode of the diode outputs a voltage source for supplying power to the short - circuit protection circuit.

[0037] Applying the technical solution of the present invention, based on the principle that when a load short - circuits, it will cause the output of the auxiliary winding to be unbalanced, resulting in the output voltage of the auxiliary winding approaching zero. When the load short - circuits, the switch unit connected to the output of the auxiliary winding controls the relay to be powered on, controls the global power supply input of the power supply system to be cut off, and locks the cut - off state, which can protect all components in the power supply system, solves the problem that the power supply chip overheats seriously when the load short - circuits, and improves the safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 FIG. is the circuit structure diagram of the short - circuit protection circuit according to an embodiment of the present invention;

[0039] Figure 2 FIG. is the circuit structure diagram of the short - circuit protection circuit according to another embodiment of the present invention;

[0040] Figure 3 FIG. is the circuit structure diagram of the power supply system according to an embodiment of the present invention;

[0041] Figure 4 FIG. is the circuit schematic diagram of the short - circuit protection circuit according to this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Several" generally includes at least two.

[0044] It should be understood that the term " / " used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0045] It should be understood that although the terms first, second, third, etc. may be used to describe resistors in the embodiments of the present invention, these resistors should not be limited to these terms. These terms are only used to distinguish different resistors. For example, without departing from the scope of the embodiments of the present invention, the first resistor may also be referred to as the second resistor, and similarly, the second resistor may also be referred to as the first resistor.

[0046] Depending on the context, as used herein, the words "if", "when" can be interpreted as "when...", "when...", or "in response to determining", or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detected (stated condition or event)" can be interpreted as "when determined", "in response to determining", "when detected (stated condition or event)", or "in response to detecting (stated condition or event)".

[0047] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a commodity or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.

[0048] The optional embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] Embodiment 1

[0050] This embodiment provides a short-circuit protection circuit. Figure 1 FIG. is a circuit structure diagram of a short-circuit protection circuit according to an embodiment of the present invention, as Figure 1 shown, the short-circuit protection circuit includes: an auxiliary winding T1, a switch unit 11, and a relay K;

[0051] The auxiliary winding T1 is wound on the same iron core as the primary coil T2 and the secondary coil T3 of the transformer 12 in the power supply system, and is wound on the same side of the iron core as the primary coil T2. Its first end is connected to the switch unit 11 through the first resistor R1, and the second end is grounded; the switch unit 11 is connected between the first end of the auxiliary winding T1 and the coil T4 of the relay K. When the load is short-circuited, since the voltage output by the auxiliary winding T1 approaches zero, the coil T4 of the relay K can be controlled to be powered on through the switch unit 11, so that the first contact 1 and the third contact 3 are connected, and then the neutral wire AC-N and the live wire AC-L of the power supply system are disconnected, and the system does not supply power. When the load is working normally, the coil T4 of the relay K is controlled to be powered off, so that the first contact 1 and the second contact 2 of the relay K are connected, and then the neutral wire and the live wire of the power supply system are connected, and the system supplies power normally; the relay K, its coil T3 is connected between the voltage source VCC and the reference ground, its first contact 1 is connected to the neutral wire of the AC power supply, its second contact 2 is connected to the live wire of the AC power supply, and its third contact is suspended. Among them, the second contact 2 is a normally closed contact.

[0052] Applying the technical solution of the present invention, based on the principle that when the load is short-circuited, it will cause the output of the auxiliary winding T1 to be unbalanced, resulting in the output voltage of the auxiliary winding T1 approaching zero. When the load is short-circuited, the relay is controlled to be powered on through the switch unit connected to the output of the auxiliary winding T1, and the global power supply input of the power supply system is cut off and the cut-off state is locked, which can protect all components in the power supply system and solve the problem that the power supply chip will overheat seriously when the load is short-circuited, improving the safety.

[0053] Embodiment 2

[0054] This embodiment provides another short-circuit protection circuit. Figure 2 It is the circuit structure diagram of the short-circuit protection circuit according to another embodiment of the present invention. In order to realize controlling the coil T4 of the relay K to be powered on when the load is short-circuited and powered off when the load is working normally, as Figure 2As shown in the figure, the switch unit 11 includes: a first switch Q1, whose base is connected to a first resistor R1, whose emitter is connected between a voltage source VCC and the first end of the coil T4 of a relay K through a second resistor R2, and whose collector is grounded through a voltage dividing unit; a second switch Q2, whose base is connected between the collector of the first switch Q1 and the voltage dividing unit through a third resistor R3, whose emitter is grounded, and whose collector is connected to the second end of the coil T4 of the relay K. When the load is operating normally, the base of the first switch Q1 is at a high level, the first switch Q1 is cut off, the base of the second switch Q2 is at a low level, the second switch Q2 is cut off, the coil T4 of the relay K is not powered on, the contact 1 is connected to the normally closed contact 2, so that the neutral wire AC-N and the live wire AC-L of the AC power supply are connected, and the power supply system supplies power normally. When the load is short-circuited, it will cause the output of the transformer 12 to be unbalanced, making the output voltage of the auxiliary winding T1 approach zero. The base of the first switch Q1 is at a low level, so the first switch Q1 conducts. Due to the voltage dividing effect of the voltage dividing unit, the base of the second switch Q2 is at a high level, and the second switch Q2 conducts, making the coil T4 of the relay K powered on, and then making the contact 1 connected to the suspended contact 3, resulting in the disconnection of the neutral wire and the live wire of the AC power supply, cutting off the power supply of the entire power supply system, and being able to protect all components in the entire power supply system. In this embodiment, the first switch Q1 is a PNP-type triode, which is cut off when its base is at a high level and conducts when its base is at a low level. The second switch Q2 is an NPN-type triode, which conducts when its base is at a high level and is cut off when its base is at a low level.

[0055] In order to achieve the accelerated saturation of the second switch Q2, make the above short-circuit protection circuit enter the short-circuit protection state and lock, the above switch unit 11 further includes: a third switch Q3, whose base is connected to the collector of the second switch Q2, whose emitter is connected to the second end of the coil T4, and whose collector is connected between the base of the second switch Q2 and the third resistor R3. After the second switch Q2 conducts, the base of the third switch Q3 is pulled to a low level state, and the third switch Q3 conducts. After the third switch Q3 conducts, the current flows from its emitter to its collector and then through the base of the second switch Q2, accelerating the conduction of the second switch Q2, and then forming a positive feedback to accelerate the conduction of the third switch Q3. Finally, the second switch Q2 and the third switch Q3 quickly enter the saturation state in a short time, making the above short-circuit protection circuit enter the short-circuit protection state and lock. In this embodiment, the third switch Q3 is a PNP-type triode, which is cut off when its base is at a high level and conducts when its base is at a low level.

[0056] When the above short - circuit protection circuit enters the locked state, it cannot recover to the normal state by itself. In order to make the short - circuit protection circuit recover to the normal state, that is, the state where the relay K is powered off, after the load short - circuit fault is removed, the switch unit 11 further includes: a reset switch Kr, whose first end is connected to the second end of the coil T4 of the relay K, and whose second end is grounded, and is used to manually control the relay K to recover to the power - off state after the load short - circuit fault is removed.

[0057] In addition, in order to jointly define the voltage input to the base of the second switch Q2 with the third resistor R3, the switch unit 11 further includes: a fourth resistor R4, whose first end is connected between the base of the second switch Q2 and the third resistor R3, and whose second end is grounded.

[0058] In this embodiment, the voltage - dividing unit is at least one voltage - dividing diode D1. The anode of the diode is connected to the collector of the first switch Q1, and the cathode is grounded, and is used to define the voltage input to the base of the first switch Q1. Another voltage - dividing diode D2 can also be included, and the voltage - dividing diode D1 and the voltage - dividing diode D2 are connected in series in the same direction.

[0059] Since the coil T4 of the relay K has a limit on the maximum operating current, in order to avoid too large current flowing through the coil T4 of the relay K, the above short - circuit protection circuit further includes: a fifth resistor R5, arranged between the voltage source VCC and the first end of the coil T4, and is used to limit the current flowing through the coil T4.

[0060] In this embodiment, in order to limit the direction of the current flowing through the coil T4, the above short - circuit protection circuit further includes: a unidirectional conduction element D3, connected in parallel between the first end and the second end of the coil T4 of the relay K, and is used to limit the direction of the current flowing through the coil T4 of the relay K. The unidirectional conduction element D3 can be a diode.

[0061] Since the auxiliary winding T1 outputs direct current, and in this embodiment, it is best to use direct current to control the on - off of the switch tube. Therefore, the above short - circuit protection circuit further includes: a rectification unit D4, connected between the first end of the auxiliary winding T1 and the first resistor R1, and is used to convert the alternating current output by the auxiliary winding T1 into direct current. The rectification unit D4 can be a diode.

[0062] Since there are ripples in the voltage output by the auxiliary winding T1, in order to eliminate the ripples, the above short - circuit protection circuit further includes: a first capacitor C1, whose first end is connected between the rectification unit D4 and the first resistor R1; a second capacitor C2, arranged in parallel with the first capacitor C1, whose first end is connected to the first end of the first capacitor C1 and the first resistor R1, and whose second end is connected to the second end of the first capacitor C1 and then grounded; the first capacitor C1 and the second capacitor C2 are jointly used to filter the current output by the rectification unit.

[0063] To further limit the input voltage of the base of the first switch Q1, the above short - circuit protection circuit further includes: a sixth resistor R6, whose first end is connected between the first resistor R1 and the switch unit 11, and the second end is grounded, for controlling the voltage input to the switch unit 11.

[0064] To visually observe the state of the protection circuit, the above short - circuit protection circuit further includes: an indicating unit LED1, whose first end is connected between the auxiliary winding T1 and the first resistor R1 through a seventh resistor R7, for indicating the state of the short - circuit protection circuit, that is, when the short - circuit protection circuit is in the short - circuit protection state, the indicating unit LED1 is turned off, and when it returns to normal, the indicating unit LED1 is turned on.

[0065] Embodiment 3

[0066] This embodiment provides a power supply system. Figure 3 As shown in the circuit structure diagram of the power supply system according to the embodiment of the present invention, Figure 3 the power supply system includes an AC power supply AC, a fuse FUSE1, a third capacitor C3, a varistor RV1, a voltage source output circuit 12, and also includes the short - circuit protection circuit in the above - mentioned embodiment.

[0067] In this embodiment, the voltage source output circuit includes: a voltage - regulating diode ZD1, a diode D5, an eighth resistor R8, a ninth resistor R9, a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6; wherein, the anode of the voltage - regulating diode ZD1 is connected to the live wire of the AC power supply, and the cathode is respectively connected to the first end of the eighth resistor R8 and the anode of the diode D5. The ninth resistor R9 and the fourth capacitor C4 are connected in parallel and then connected between the second end of the eighth resistor R8 and the reference ground. Among them, the ninth resistor R9 is a discharge resistor, which releases the electric energy stored at both ends of the fourth capacitor C4 after power - off. After the fifth capacitor C5 and the sixth capacitor C6 are connected in parallel, one end is connected to the cathode of the diode, and the other end is grounded; the common connection point of the fifth capacitor C5, the sixth capacitor C6, and the cathode of the diode outputs a voltage source VCC, which is used to supply power to the above - mentioned short - circuit protection circuit.

[0068] Embodiment 4

[0069] This embodiment provides another short - circuit protection circuit. Figure 4 As shown in the circuit schematic diagram of the short - circuit protection circuit according to this embodiment, Figure 4As shown, after the AC power supply is input, it will first pass through the short-circuit self-protection circuit 400, and then output to the transformer. The auxiliary winding T41 of the transformer will simultaneously provide a voltage signal and feedback it to the short-circuit self-protection circuit 400. When a short circuit in the load circuit is detected, the short-circuit self-protection circuit will cut off the AC power supply input, and at the same time, the circuit will enter the protection locking state. In the case where the short-circuit fault has not been resolved, this locking protection will always remain until the short-circuit fault is resolved, and the transformer can output normally.

[0070] The specific working process of the short-circuit protection circuit in this embodiment is as follows:

[0071] The AC power supply is input through two terminals AC-L and AC-N. Among them, the AC-L terminal is connected to the live wire, and the N terminal is connected to the neutral wire, and the input voltage is 220V. The zener diode ZD41, diode D45, eighth resistor R48, ninth resistor R49, fourth capacitor C44, fifth capacitor C45, and sixth capacitor C46 constitute the capacitive voltage-dividing circuit 410, which provides the voltage source VCC to supply power to the short-circuit protection circuit 400. In the figure, PGND is the power ground, and the ninth resistor R49 is the discharge resistor, which releases the electric energy stored at both ends of the capacitor C44 after power-off.

[0072] When the AC power supply is not connected, the contact 1 and the normally closed contact 2 of the relay K1 are connected. The reset button Kr1 remains in the open state. After the AC power supply is connected, the 220V alternating current will flow through the contact 1, contact 2 of the relay K1, fuse FSUE1, main circuit capacitor C43, varistor RV1, and the primary winding T42 of the transformer, and supply it to the secondary winding T43, so that the transformer starts to work to supply power to the load. At the same time, the capacitive voltage-dividing circuit 410 provides the voltage source VCC.

[0073] The AC voltage signal output by the auxiliary winding T41 is rectified by the rectifying element D44, filtered by the filter capacitors C41 and C42, and then outputs a smooth DC voltage to the base of the PNP-type triode Q41 and one end of the LED41, and the LED41 indicator light is lit. Since the base of the PNP-type triode Q41 is in the high-level state, the PNP-type triode Q41 is cut off, resulting in the base potential of the NPN-type triode Q42 being zero, and the NPN-type triode Q42 is also cut off, resulting in the base of the PNP-type triode Q43 being in the high-level state, so it is also in the cut-off state. The relay K1 does not work, and its normally closed contact 2 is connected, and the transformer normally supplies power to the load circuit.

[0074] When a short circuit occurs in the internal power output circuit of the load circuit, it will cause the output of the transformer to become unbalanced, that is, the output voltage of the auxiliary winding T41 approaches zero. At this time, the base of the PNP transistor Q41 is in a low level state, and the PNP transistor Q41 conducts. By selecting diodes D41 and D42 with certain parameters, each of the diodes D41 and D42 gets a voltage of 0.7V at this time. The base voltage of the NPN transistor Q42 is 1.4V, and the NPN transistor Q42 conducts. The base of the PNP transistor Q43 is pulled to a low level state, and the PNP transistor Q43 conducts. After the PNP transistor Q43 conducts, current flows from its emitter to the collector and then through the base of the NPN transistor Q42, accelerating the conduction of the NPN transistor Q42. Subsequently, positive feedback accelerates the conduction of the PNP transistor Q43. Finally, the NPN transistor Q42 and the PNP transistor Q43 quickly enter the saturation state within a short time. Since the voltage source VCC is not affected by the short circuit of the load circuit and always maintains a stable output state, that is, the voltage source VCC forms a loop through the fifth resistor R45, the coil T44 of the relay K1, the PNP transistor Q43, and the NPN transistor Q42 to the power ground. Therefore, the relay K1 is energized and attracted, the contact 1 and the contact 2 are disconnected, and the contact 1 and the contact 3 are connected. Since the input of the live wire is cut off, that is, the global power supply circuit is cut off.

[0075] Since the voltage of the voltage source VCC does not change, once a high level trigger occurs at the base of the NPN transistor Q42, regardless of whether the base voltage of the NPN transistor Q42 is high or low subsequently, the NPN transistor Q42 and the PNP transistor Q43 will always maintain the conducting state without change, ensuring that the relay K1 will also always be in the attracted state, thereby making the input live wire open circuit, the transformer has no output, and the light emitting diode LED41 goes out. The circuit enters the protection locking state, effectively protecting the components and lines of the load circuit from damage, and at the same time avoiding the circuit malfunction phenomenon caused by local circuit protection.

[0076] The reset button Kr1 overrides the protective lockout and controls relay K1 to restore its de-energized state. Even after the short-circuit fault is manually cleared, the circuit remains in the protective lockout state due to the previous short-circuit. Pressing the reset button Kr1 causes the current previously flowing through NPN transistor Q42 and PNP transistor Q43 to flow directly through the reset button Kr1 to the power ground. Consequently, the NPN transistor Q42 and PNP transistor Q43 lose their holding current, releasing the lockout state. NPN transistors Q42 and PNP transistor Q43 switch to the off state, de-energizing coil T44, and contacts 1 and 2 connect, restoring normal operation of the circuit. If the short-circuit fault persists, pressing the reset button Kr1 will not release the lockout state. If the reset button Kr1 is manually pressed, the circuit instantly reenters the self-protection lockout state.

[0077] If the load circuit is not short-circuited, but relay K1 fails to operate due to damage to RC step-down circuit 410 or the downstream associated circuitry of auxiliary winding T41 due to other factors, relay K1 will not energize, and contacts 1 and 2 will remain connected. The circuit will continue to operate normally. Therefore, even if a component failure occurs in the short-circuit self-protection circuit itself, the normal operation of the protected controller will not be affected, providing high reliability and redundancy.

[0078] The short-circuit self-protection circuit of this embodiment is completely isolated from the load circuit, and the action circuit for detecting short circuits and locking protection will not affect the output power or working state of the load circuit.

[0079] It should be noted that the first resistor R41, the second resistor R42, the third resistor R43, the fourth resistor R44, the fifth resistor R45, the sixth resistor R46, the seventh resistor R47, and the unidirectional conductive element D43 in this embodiment have the same functions as the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the unidirectional conductive element D3 in the above-mentioned embodiment, and are not repeated here.

[0080] In summary, this circuit automatically cuts off the global power input and locks the cutoff state when a short circuit occurs in the controller's power supply circuit. The controller circuit can be restored to normal operation by manually resetting it until the controller short circuit fault is manually resolved. This protects the global circuit from damage and prevents circuit malfunctions.

[0081] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of each embodiment or some parts of the embodiments.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A short circuit protection circuit, characterized in that: The short-circuit protection circuit includes: an auxiliary winding, a switch unit and a relay; The auxiliary winding is wound on the same iron core as the primary coil and the secondary coil of the transformer, a first end of the auxiliary winding is connected to the switch unit via a first resistor, and a second end of the auxiliary winding is grounded; The switch unit is connected between the first end of the auxiliary winding and the coil of the relay, and is used to control the relay to be energized when the load is short-circuited, and to control the relay to be de-energized when the load is operating normally. The switch unit includes: a first switch, whose first pole is connected to the first resistor, whose second pole is connected to between a voltage source and the first end of the coil of the relay through a second resistor, and whose third pole is grounded through a voltage divider; a second switch, whose first pole is connected to between the third pole of the first switch and the voltage divider through a third resistor, whose second pole is grounded, and whose third pole is connected to the second end of the coil of the relay; The relay has a coil connected between a voltage source and a reference ground, a first contact connected to a neutral line of an AC power source, a second contact connected to a live line of the AC power source, and a third contact left floating, wherein the second contact is a normally closed contact.

2. The short-circuit protection circuit according to claim 1, characterized in that: The switch unit further includes: The third switch has a first pole connected to the third pole of the second switch, a second pole connected to the second end of the coil of the relay, and a third pole connected between the first pole of the second switch and the third resistor.

3. The short-circuit protection circuit according to claim 1, characterized in that: The switch unit further includes: A reset switch, a first end of which is connected to the second end of the coil of the relay and a second end of which is grounded, is used to control the relay to return to a power-off state after the load short-circuit fault is resolved.

4. The short-circuit protection circuit according to claim 1, characterized in that: The switch unit further includes: A fourth resistor has a first end connected between the first electrode of the second switch and the third resistor, and a second end grounded.

5. The short-circuit protection circuit according to claim 1, wherein: The voltage dividing unit is at least one voltage dividing diode, an anode of the voltage dividing diode is connected to the third electrode of the first switch, and a cathode of the voltage dividing diode is grounded.

6. The short-circuit protection circuit according to claim 1, characterized in that: The short-circuit protection circuit further includes: a fifth resistor, disposed between the voltage source and the first end of the coil of the relay, and configured to limit the current flowing through the coil of the relay.

7. The short-circuit protection circuit according to claim 1, characterized in that: The short-circuit protection circuit further includes: A unidirectional conducting element is connected in parallel between the first end and the second end of the coil of the relay, and is used to limit the direction of the current flowing through the coil of the relay.

8. The short-circuit protection circuit according to claim 1, wherein: The short-circuit protection circuit further includes: A rectifier unit is connected between the first end of the auxiliary winding and the first resistor, and is used to convert the alternating current output by the auxiliary winding into direct current.

9. The short-circuit protection circuit according to claim 8, characterized in that: The short-circuit protection circuit further includes: a first capacitor, a first end of which is connected between the rectifier unit and the first resistor; a second capacitor, arranged in parallel with the first capacitor, with a first end connected between the first end of the first capacitor and the first resistor, and a second end connected to the second end of the first capacitor and then grounded; The first capacitor and the second capacitor are used to filter the current output by the rectifier unit.

10. The short-circuit protection circuit according to claim 1, wherein: The short-circuit protection circuit further includes: a sixth resistor, a first end of which is connected between the first resistor and the switch unit and a second end of which is grounded, and is used to control the voltage input to the switch unit.

11. The short-circuit protection circuit according to claim 1, wherein: The short-circuit protection circuit further includes: An indicating unit, a first end of which is connected between the auxiliary winding and the first resistor through a seventh resistor, and is used to indicate a state of the short-circuit protection circuit.

12. A power supply system comprising an AC power supply, a fuse, a third capacitor, a varistor, and a voltage source output circuit, characterized in that: The power supply system further comprises the short-circuit protection circuit according to any one of claims 1 to 11.

13. The power supply system according to claim 12, wherein: The voltage source output circuit includes: a voltage stabilizing diode, a diode, an eighth resistor, a ninth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor; Among them, the anode of the voltage-stabilizing diode is connected to the live wire of the AC power supply, and the cathode is respectively connected to the first end of the eighth resistor and the anode of the diode; the ninth resistor and the fourth capacitor are connected in parallel and connected between the second end of the eighth resistor and the reference ground; the fifth capacitor and the sixth capacitor are connected in parallel, one end is connected to the cathode of the diode, and the other end is grounded; the common connection point of the fifth capacitor, the sixth capacitor and the cathode of the diode outputs a voltage source for powering the short-circuit protection circuit.

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