Power supply output protection circuit and circuit protection device

Abstract

The present application relates to a power output protection circuit, comprising an output detection circuit, a protection control circuit, and a switch device. The output detection circuit is connected to a power input terminal, a power output terminal, and a protection control circuit. The protection control circuit is connected to the switch device, and the switch device is connected to the power input terminal and the power output terminal. The power input terminal is used to connect to a main power supply, and the power output terminal is used to connect to a subsequent power circuit. By adopting a fault pre-diagnosis method, before turning on the main power supply, the subsequent power circuit is diagnosed in advance to determine whether the subsequent power circuit is working properly. Once a fault is found in the subsequent power circuit, the main power supply circuit will not be turned on, thereby avoiding the possibility of safety hazards caused by a fault in the subsequent power circuit and improving the reliability of power supply protection.

Description

Technical Field

[0001] The present application relates to the technical field of equipment power supply protection, and in particular to a power supply output protection circuit and a circuit protection device. Background Art

[0002] Currently, many devices are designed to supply power to external devices. These devices often experience short circuits or overloads, causing the power supply current to increase sharply, exceeding the maximum power supply capacity of the device's power supply. Without proper protection measures, the circuit will continue to overload and output, causing electronic components to burn out due to overheating, and in severe cases, fires may occur.

[0003] Traditional output short-circuit protection circuits use recoverable fuses or sampling circuits to control the output chip for short-circuit protection. This makes signal sampling difficult at low voltage outputs, resulting in low identifiability of the sampled signal and low reliability of power supply protection. Summary of the Invention

[0004] Based on this, it is necessary to provide a power supply output protection circuit and circuit protection device that can improve the reliability of power supply protection in order to address the problem of low power supply protection reliability of traditional output short circuit protection circuits.

[0005] A power output protection circuit includes an output detection circuit, a protection control circuit, and a switch device. The output detection circuit is connected to a power input terminal, a power output terminal, and the protection control circuit. The protection control circuit is connected to the switch device. The switch device is connected to the power input terminal and the power output terminal. The power input terminal is used to connect to a main power supply, and the power output terminal is used to connect to a subsequent power circuit.

[0006] The output detection circuit is used to output a protection signal to the protection control circuit when it detects a fault in the subsequent power circuit before the main power supply supplies power to the subsequent power circuit; when the protection control circuit receives the protection signal, it controls the switching device to disconnect, so that the subsequent power circuit is not powered.

[0007] In one embodiment, the output detection circuit includes a resistor R1, a resistor R5, a resistor R6, a resistor RL and a control switch, one end of the resistor R1 is connected to the power input end through the resistor R5, the other end of the resistor R1 is connected to the power output end, and the other end of the resistor R1 is grounded through the resistor RL; one end of the control part of the control switch is connected to the common end of the resistor R1 and the resistor R5 through the resistor R6, the other end of the control part of the control switch is connected to the power output end, and the controlled part of the control switch is connected to the protection control circuit.

[0008] In one embodiment, the control switch is a bidirectional optocoupler, one end of the control part of the bidirectional optocoupler is connected to the resistor R6, and the other end is connected to the power supply output end, and one end of the controlled part of the bidirectional optocoupler is connected to the protection control circuit, and the other end is grounded.

[0009] In one embodiment, the protection control circuit includes a resistor R2 and a switch tube Q1, the control end of the switch tube Q1 is connected to the output detection circuit and connected to the power supply end through the resistor R2, the input end of the switch tube Q1 is connected to the switching device, and the output end of the switch tube Q1 is grounded.

[0010] In one embodiment, the switching device includes a relay, one end of the coil of the relay is connected to the power supply end, and the other end is connected to the input end of the switching tube Q1, and one end of the contact switch of the relay is connected to the power supply input end, and the other end is connected to the power supply output end.

[0011] In one embodiment, the protection control circuit includes a resistor R2, a resistor R3, a resistor R4, a controller and a switch tube Q2. The resistor R2 and the resistor R3 are connected in series, and the common end is connected to the output detection circuit. The other end of the resistor R2 is connected to the power supply end, and the other end of the resistor R3 is connected to the controller. The controller is connected to the control end of the switch tube Q2 through the resistor R4. The input end of the switch tube Q2 is connected to the power supply end, and the output end of the switch tube Q2 is connected to the switching device.

[0012] In one embodiment, the switching device includes a relay, one end of the coil of the relay is connected to the output end of the switching tube Q2, and the other end is grounded, one end of the contact switch of the relay is connected to the power input end, and the other end is connected to the power output end.

[0013] In one embodiment, the protection control circuit includes a resistor R2, a resistor R3, a resistor R4, a switch tube Q1, a switch tube Q2, and a controller. The resistor R2 and the resistor R3 are connected in series, and the common end is connected to the control end of the switch tube Q1. The control end of the switch tube Q1 is connected to the output detection circuit. The other end of the resistor R2 is connected to the power supply end, and the other end of the resistor R3 is connected to the controller. The input end of the switch tube Q1 is connected to the switching device, and the output end of the switch tube Q1 is grounded. The controller is connected to the control end of the switch tube Q2 through the resistor R4. The input end of the switch tube Q2 is connected to the power supply end, and the output end of the switch tube Q2 is connected to the switching device.

[0014] In one embodiment, the switching device includes a relay, one end of the coil of the relay is connected to the output end of the switching tube Q2, and the other end is connected to the input end of the switching tube Q1, one end of the contact switch of the relay is connected to the power input end, and the other end is connected to the power output end.

[0015] In one embodiment, the power output protection circuit further includes an interactive device connected to the protection control circuit, and the protection control circuit controls the interactive device to output fault reminder information when receiving a protection signal.

[0016] In one embodiment, the interactive device includes a display device and / or an audible and visual alarm device connected to the protection control circuit.

[0017] A circuit protection device comprises a main power supply and the power output protection circuit mentioned above.

[0018] The power supply output protection circuit and circuit protection device described above, before the main power supply is supplied to the subsequent power circuit, uses the output detection circuit to detect a fault in the subsequent power circuit and outputs a protection signal to the protection control circuit. Upon receiving the protection signal, the protection control circuit controls the switch device to disconnect, preventing power from being supplied to the subsequent power circuit. By employing a fault pre-diagnosis approach, the subsequent power circuit is diagnosed in advance before the main power supply is turned on to determine whether it is functioning properly. If a fault is detected in the subsequent power circuit, the main power supply circuit will not be turned on, thus avoiding the possibility of safety hazards caused by subsequent power circuit faults and improving the reliability of power supply protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the structural principle diagram of a conventional output short-circuit protection circuit;

[0020] Figure 2 This is a structural block diagram of a power output protection circuit in one embodiment;

[0021] Figure 3 is a schematic diagram of a power output protection circuit in one embodiment;

[0022] Figure 4 is a schematic diagram of a power output protection circuit in another embodiment;

[0023] Figure 5 is a schematic diagram of a power output protection circuit in yet another embodiment;

[0024] Figure 6 FIG. 4 is a structural block diagram of a power output protection circuit in another embodiment. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0026] like Figure 1 As shown, a conventional sampling detection circuit uses sampling circuit 1, composed of resistors R1, R2, and R3, to detect output overload. When an output overload is detected, MOS transistor Q1 is turned off, cutting off the output power. Conventional sampling detection circuits have difficulty sampling signals at low output voltages, resulting in low sampled signal recognizability. They are only suitable for DC power supply detection and are unable to perform sampling analysis for AC power supply.

[0027] In one embodiment, a power supply output protection circuit is provided, such as Figure 2 As shown, the output detection circuit 110 includes an output detection circuit 110, a protection control circuit 120, and a switch device 130. The output detection circuit 110 is connected to the power input terminal POWER-INPUT, the power output terminal POWER-OUTPUT, and the protection control circuit 120. The protection control circuit 120 is connected to the switch device 130, and the switch device 130 is connected to the power input terminal POWER-INPUT and the power output terminal POWER-OUTPUT. The power input terminal POWER-INPUT is used to connect to the main power supply, and the power output terminal POWER-OUTPUT is used to connect to the subsequent power circuit. The output detection circuit 110 is used to detect a fault in the subsequent power circuit before the main power supply supplies power to the subsequent power circuit, and output a protection signal to the protection control circuit 120. Upon receiving the protection signal, the protection control circuit 120 controls the switch device 130 to disconnect, thereby preventing the subsequent power circuit from receiving power.

[0028] A fault occurs in the subsequent power circuit, which may specifically be a short circuit or overload fault. When a short circuit or overload fault occurs in the subsequent power circuit, it will cause the current in the circuit to increase. When the output detection circuit 110 detects a short circuit or overload in the subsequent power circuit, it outputs a protection signal to the protection control circuit 120. The protection control circuit 120 controls the switch device 130 to disconnect, thereby preventing the subsequent power circuit from being powered. Among them, the short circuit or overload detection of the subsequent power circuit can be achieved by configuring the parameters of each electronic component in the output detection circuit 110. The specific type of the protection signal output by the output detection circuit 110 is not unique and can be a high level or a low level. For ease of understanding, the following explanation is based on the overload detection of the subsequent power circuit as an example.

[0029] Before the main power supply is turned on to supply power to the downstream power circuit, the output detection circuit 110 is used to detect whether an overload fault has occurred in the downstream power circuit. When an overload is detected in the downstream power circuit, the protection control circuit 120 controls the switch device 130 to open, thereby preventing the downstream power circuit from receiving power. Testing the downstream power circuit before the main power supply is turned on can determine in advance whether the output is overloaded. Once an output overload is detected, the main power supply circuit will not be turned on, thereby avoiding the possibility of safety hazards caused by output overload. It is understood that if the output detection circuit 110 does not detect an overload in the downstream power circuit, the protection control circuit 120 can control the switch device 130 to close, connecting the main power supply to supply power to the downstream power circuit, and the downstream power circuit can be powered and operated. In addition, when the subsequent power circuit is powered on, the output detection circuit 110 can continue to monitor the subsequent power circuit for faults. If an overload occurs during the power-on process of the subsequent power circuit, the protection control circuit 120 can also control the switch device 130 to disconnect, causing the subsequent power circuit to lose power and perform overload protection.

[0030] The power supply output protection circuit and circuit protection device described above, before the main power supply supplies power to the subsequent power circuit, uses the output detection circuit 110 to detect a fault in the subsequent power circuit and output a protection signal to the protection control circuit 120. Upon receiving the protection signal, the protection control circuit 120 controls the switch device 130 to disconnect, thereby preventing power from being supplied to the subsequent power circuit. By employing a fault pre-diagnosis approach, the subsequent power circuit is diagnosed in advance before the main power supply is turned on to determine whether the subsequent power circuit is operating properly. If a fault in the subsequent power circuit is detected, the main power supply circuit will not be turned on, thus avoiding the possibility of safety hazards caused by faults in the subsequent power circuit and improving the reliability of power supply protection.

[0031] The specific structure of the output detection circuit 110 is not unique. In one embodiment, Figure 3 As shown, the output detection circuit 110 includes resistors R1, R5, R6, RL, and a control switch. One end of resistor R1 is connected to the power input terminal POWER-INPUT through resistor R5, and the other end of resistor R1 is connected to the power output terminal POWER-OUTPUT. The other end of resistor R1 is grounded through resistor RL. One end of the control unit of the control switch is connected to the common end of resistors R1 and R5 through resistor R6, and the other end of the control unit of the control switch is connected to the power output terminal POWER-OUTPUT. The controlled portion of the control switch is connected to the protection control circuit 120.

[0032] The output overload current can be set by setting the resistance values ​​of resistors R1 and R5. The voltage generated across resistor R1 by the overload current and the on-state voltage of the control switch can be used to accurately detect the output overload and output a protection signal. The specific type of control switch is not unique and can be a switching tube or an optocoupler. In this embodiment, the control switch is a bidirectional optocoupler U1. One end of the control portion of the bidirectional optocoupler U1 is connected to resistor R6, and the other end is connected to the power output terminal POWER-OUTPUT. One end of the controlled portion of the bidirectional optocoupler U1 is connected to the protection control circuit 120, and the other end is grounded.

[0033] Specifically, when the subsequent power circuit is overloaded and the current exceeds the overload current value, the control part of the bidirectional optocoupler U1 is energized and illuminated, causing the controlled part to conduct, and the low level is transmitted to the protection control circuit 120 as a protection signal, so that the protection control circuit 120 controls the switch device 130 to disconnect. Correspondingly, if the subsequent power circuit is not overloaded, the controlled part of the bidirectional optocoupler U1 will not conduct, the switch device 130 is closed, and the main power supply is connected to supply power to the subsequent power circuit. In this embodiment, the bidirectional conductivity of the bidirectional optocoupler U1 is used to achieve universal AC and DC overload protection, which has strong versatility. The power supply circuit is completely isolated from the control circuit to achieve enhanced insulation and avoid the risk of electric shock.

[0034] In one embodiment, referring to Figure 3 The protection control circuit 120 includes a resistor R2 and a switch Q1. The control terminal of the switch Q1 is connected to the output detection circuit 110, specifically to the controlled portion of the bidirectional optocoupler U1 in the output detection circuit 110. The control terminal of the switch Q1 is connected to the power supply terminal via the resistor R2. The input terminal of the switch Q1 is connected to the switch device 130, and the output terminal of the switch Q1 is grounded. The power supply terminal is used to connect to an external power supply. The switch Q1 can be a transistor, a MOS transistor, or other control element with a switching function. In this embodiment, the switch Q1 is a transistor with a base as the control terminal, a collector as the input terminal, and an emitter as the output terminal.

[0035] Correspondingly, in one embodiment, switch device 130 includes a relay K1. One end of the relay K1's coil is connected to the power supply, and the other end is connected to the input of switch Q1. One end of the relay K1's contact switch is connected to the power input terminal POWER-INPUT, and the other end is connected to the power output terminal POWER-OUTPUT. Relay K1 primarily controls the output power supply. When relay K1 is closed, the output power is connected, and the downstream load is energized. When relay K1 is open, the output power is disconnected, and the downstream load is not energized.

[0036] When the downstream power circuit is overloaded, switch Q1 will actively disconnect the control circuit of relay K1, thereby disconnecting the output voltage and preventing the downstream load from receiving power. The entire process is completed independently by the hardware circuit, which is simple and low-cost. It is understood that in other embodiments, switch device 130 can also adopt other switching devices with switch control functions.

[0037] In another embodiment, Figure 4 As shown, the protection control circuit 120 includes a resistor R2, a resistor R3, a resistor R4, a controller, and a switch Q2. Resistors R2 and R3 are connected in series, and their common end is connected to the output detection circuit 110, specifically to the controlled portion of the bidirectional optocoupler U1 in the output detection circuit 110. The other end of resistor R2 is connected to the power supply, and the other end of resistor R3 is connected to the controller. The controller is connected to the control end of the switch Q2 through resistor R4. The input end of the switch Q2 is connected to the power supply, and the output end of the switch Q2 is connected to the switch device 130. The controller is a single-chip microcomputer with logic operation functions. Specifically, the controller can be an IC (Integrated Circuit) chip U2, with pin 8 of IC chip U2 connected to resistor R3 and pin 5 connected to resistor R9. The switch Q2 can also be a transistor, MOS transistor, or other control element with a switching function. In this embodiment, the switch Q2 is a transistor with the base as the control end, the emitter as the input end, and the collector as the output end.

[0038] Correspondingly, in one embodiment, continue to refer to Figure 4 The switch device 130 includes a relay K1, one end of the coil of the relay K1 is connected to the output end of the switch tube Q2, and the other end is grounded. One end of the contact switch of the relay K1 is connected to the power input end POWER-INPUT, and the other end is connected to the power output end POWER-OUTPUT.

[0039] Resistors R3 and R4, switch Q2, and IC chip U2 together form a software protection circuit. When the downstream power circuit is overloaded, IC chip U2 detects the protection signal from bidirectional optocoupler U1. IC chip U2 then outputs a software protection signal to shut down switch Q2, thereby disconnecting the output voltage and preventing power from reaching the downstream load. In this embodiment, upon receiving a low-level signal from bidirectional optocoupler U1, IC chip U2 transmits a high-level signal as the software protection signal to switch Q2, shutting it down.

[0040] In yet another embodiment, Figure 5As shown, the protection control circuit 120 includes resistors R2, R3, R4, a switch Q1, Q2, and a controller. Resistors R2 and R3 are connected in series, with their common end connected to the control end of switch Q1. The control end of switch Q1 is connected to the output detection circuit 110, specifically to the controlled portion of the bidirectional optocoupler U1 in the output detection circuit 110. The other end of resistor R2 is connected to the power supply, and the other end of resistor R3 is connected to the controller. The input end of switch Q1 is connected to the switching device 130, and the output end of switch Q1 is grounded. The controller is connected to the control end of switch Q2 via resistor R4, the input end of switch Q2 is connected to the power supply, and the output end of switch Q2 is connected to the switching device 130. Similarly, in this embodiment, both switch Q1 and switch Q2 can be transistors, and the controller can be an IC chip U2.

[0041] Correspondingly, in one embodiment, continue to refer to Figure 5 The switching device 130 includes a relay K1, one end of the coil of the relay K1 is connected to the output end of the switch tube Q2, and the other end is connected to the input end of the switch tube Q1. One end of the contact switch of the relay K1 is connected to the power input end POWER-INPUT, and the other end is connected to the power output end POWER-OUTPUT.

[0042] In this embodiment, software protection and hardware protection are connected in series within the control circuit of relay K1. As soon as either the hardware protection signal or the software protection signal becomes active, relay K1's output is immediately cut off, implementing output overload protection. This dual hardware and software protection significantly improves reliability.

[0043] Furthermore, in one embodiment, Figure 6 As shown, the power output protection circuit also includes an interactive device 140 connected to the protection control circuit 120. When the protection control circuit 120 receives the protection signal, it controls the interactive device 140 to output fault reminder information. Specifically, the interactive device 140 can be connected to the IC chip U2 in the protection control circuit 120. After receiving the protection signal sent by the bidirectional optocoupler U1, the IC chip U2 controls the interactive device 140 to output fault reminder information, reminding the user to perform overload or short circuit detection on the subsequent power circuit, so as to facilitate the user to locate the cause of the fault in the subsequent power circuit and quickly eliminate the fault. It can be understood that in other embodiments, if the protection control circuit 120 does not involve a software protection circuit, the interactive device 140 can also be directly connected to the control end of the switch tube Q1. The interactive device 140 outputs fault reminder information after receiving the protection signal sent by the bidirectional optocoupler U1.

[0044] The structure of the interactive device 140 is not unique. Depending on the structure of the interactive device 140, the specific method of outputting the fault reminder information will also be different. In one embodiment, the interactive device 140 includes a display device and / or an audible and visual alarm device connected to the protection control circuit 120. Taking the interactive device 140 as an example, the display device can specifically be an LED (Light Emitting Diode) display screen or an LCD (Liquid Crystal Display) display screen, etc. After the IC chip U2 detects an output overload, it displays preset text, patterns and other information through the display device, and controls the audible and visual alarm device to sound and light alarm, so as to intuitively display the fault information, which is convenient for users to quickly locate the cause of the fault in the subsequent power circuit and quickly troubleshoot.

[0045] In one embodiment, a circuit protection device is provided, comprising a main power supply and the power output protection circuit described above, wherein the main power supply can be a DC power supply or an AC power supply, and the main power supply is connected to a power input terminal of the power output protection circuit.

[0046] Before the main power supply is turned on to the downstream power circuit, the circuit protection device uses the output detection circuit to detect a fault in the downstream power circuit and output a protection signal to the protection control circuit. Upon receiving the protection signal, the protection control circuit controls the switch device to disconnect, depriving the downstream power circuit of power. By employing a fault pre-diagnosis approach, the downstream power circuit is diagnosed before the main power supply is turned on to determine whether it is functioning properly. If a fault is detected in the downstream power circuit, the main power supply circuit will not be turned on, thus avoiding the possibility of safety hazards caused by faults in the downstream power circuit and improving the reliability of power supply protection.

[0047] To facilitate a better understanding of the above-mentioned power supply output protection circuit and circuit protection device, detailed explanations are provided below in conjunction with specific embodiments.

[0048] This application provides a power output protection circuit, such as Figure 5 As shown in Figure 1, the protection circuit consists of two main parts: a detection circuit and a control circuit. The output detection circuit is primarily composed of resistors R5, R1, R6, a bidirectional optocoupler U1, and a load resistor RL. The protection control circuit primarily comprises a hardware control circuit consisting of a bidirectional optocoupler U1, resistor R2, a switch Q1, and a relay K1, and a software control circuit consisting of a bidirectional optocoupler U1, resistor R3, IC chip U2, resistor R4, a switch Q2, and a relay K1.

[0049] When the subsequent power circuit is not overloaded, resistors R5, R1, and RL are connected in series, and a divided voltage V1 is generated at both ends of resistor R1. By reasonably configuring the parameters of resistors R5 and R1, the divided voltage V1 generated at both ends of resistor R1 is smaller than the minimum conduction voltage V2 of the bidirectional optocoupler U1, and the bidirectional optocoupler U1 is not conducting. Resistor R2 is equivalent to a pull-up resistor, and the control end of the switch tube Q1 is a high voltage, and the switch tube Q1 is in the on state; the synchronous IC chip U2 also detects a high level and will not detect an output overload. IC chip U2 sends a start signal (specifically a low level) to turn on the switch tube Q2, and the control loop of relay K1 is connected, relay K1 is closed, and the subsequent power circuit is energized.

[0050] When the subsequent power circuit is overloaded, the resistors R5, R1 and RL are connected in series. Due to the output overload, the resistance value of the resistor RL becomes smaller, and the divided voltage V1 generated at both ends of the resistor R1 will increase. By reasonably configuring the parameters of the resistors R5 and R1, the divided voltage V1 generated at both ends of the resistor R1 is greater than the minimum conduction voltage V2 of the bidirectional optocoupler U1 when an overload occurs. The bidirectional optocoupler U1 is turned on, and the control end level of the switch tube Q1 is pulled down by the bidirectional optocoupler U1, and the switch tube Q1 cannot be turned on; the synchronous IC chip U2 also detects a low level, which is determined to be an output overload. The IC chip U2 will not send a start signal (specifically, pin 5 is set to a high level), which makes the switch tube Q2 unable to be turned on, the control circuit of the relay K1 unable to be turned on, the relay K1 is disconnected, and the subsequent power circuit is not powered.

[0051] In addition, the IC chip U2 can also control the corresponding display device to display the short circuit fault in the form of a fault code or other means to prompt the user what fault has occurred, making it easier for the user to quickly troubleshoot the fault.

[0052] The detection process of the entire circuit occurs before relay K1 is turned on, that is, the main power supply circuit of the subsequent power circuit has not yet been turned on, realizing output overload pre-diagnosis, which can detect circuit abnormalities in advance and avoid danger.

[0053] In the above solution, the relay K1 can be replaced by a thyristor or other electronic components with switch control function or a circuit module with switch function. The switch tubes Q1 and Q2 can be triodes, field effect transistors or other control elements with switch function.

[0054] In order to reduce costs, the output control can only do hardware protection without software protection. The specific implementation plan is as follows: cancel the resistor R3, IC chip U2, resistor R4, and switch tube Q2. The derived circuit is as follows: Figure 3 .

[0055] When the downstream power circuit is not overloaded, resistors R5, R1, and RL are connected in series. Wind pressure voltage V1 is generated at both ends of resistor R1. By reasonably configuring the parameters of resistors R5 and R1, the divided voltage V1 generated at both ends of resistor R1 is smaller than the minimum conduction voltage V2 of the bidirectional optocoupler U1. The bidirectional optocoupler U1 is not conducting, and resistor R2 is equivalent to a pull-up resistor. The control end of the switch tube Q1 is a high voltage, the switch tube Q1 is in the on state, the control loop of the relay K1 is connected, the relay K1 is closed, and the downstream power circuit is energized.

[0056] When the downstream power circuit is overloaded, resistors R5, R1, and RL are connected in series. Due to the output overload, the resistance of resistor RL decreases, and the wind pressure voltage V1 generated across resistor R1 increases. By properly configuring the parameters of resistors R5 and R1, the voltage divider voltage V1 generated across resistor R1 during an overload is greater than the minimum conduction voltage V2 of the bidirectional optocoupler U1. The bidirectional optocoupler U1 conducts, and the control terminal voltage of the switch tube Q1 is pulled down by the bidirectional optocoupler U1, preventing the switch tube Q1 from conducting. The control circuit of relay K1 is also blocked, and relay K1 is disconnected, thus depriving the downstream power circuit of power. The advantages of this solution are simple circuit and low cost.

[0057] In addition, the output control can also be protected by software only without hardware protection. Figure 4 .

[0058] When the subsequent power circuit is not overloaded, resistors R5, R1 and RL are connected in series, and a wind pressure voltage V1 is generated at both ends of resistor R1. By reasonably configuring the parameters of resistors R5 and R1, the divided voltage V1 generated at both ends of resistor R1 is smaller than the minimum conduction voltage V2 of the bidirectional optocoupler U1. The bidirectional optocoupler U1 is not conducting, and resistor R2 is pulled up. The IC chip U2 detects a high level and will not detect an output overload. The IC chip U2 sends a start signal to turn on the switch tube Q2, and the control loop of the relay K1 is turned on. The relay K1 is closed, and the subsequent power circuit is energized.

[0059] When the subsequent power circuit is overloaded, resistors R5, R1 and RL are connected in series. Due to the output overload, the resistance value of resistor RL becomes smaller, and the wind pressure voltage V1 generated at both ends of resistor R1 will increase. By reasonably configuring the parameters of resistors R5 and R1, the divided voltage V1 generated at both ends of resistor R1 when an overload occurs is greater than the minimum conduction voltage V2 of the bidirectional optocoupler U1. The bidirectional optocoupler U1 is turned on, and the IC chip U2 detects a low level, which is determined to be an output overload. The IC chip U2 will not send a start signal, so that the switch tube Q2 cannot be turned on, the control circuit of the relay K1 cannot be turned on, the relay K1 is disconnected, and the subsequent power circuit cannot be powered.

[0060] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A power output protection circuit, characterized in that: The device comprises an output detection circuit, a protection control circuit, and a switch device, wherein the output detection circuit is connected to a power supply input terminal, a power supply output terminal, and the protection control circuit; the protection control circuit is connected to the switch device; and the switch device is connected to the power supply input terminal and the power supply output terminal; wherein the power supply input terminal is used to connect to a main power supply, and the power supply output terminal is used to connect to a subsequent power circuit; The output detection circuit is used to output a protection signal to the protection control circuit when it detects a fault in the subsequent power circuit before the main power supply supplies power to the subsequent power circuit; the protection control circuit controls the switch device to open upon receiving the protection signal, so that the subsequent power circuit is not powered; wherein the output detection circuit is used to detect whether the subsequent power circuit has a fault before the switch device is closed; The output detection circuit includes a resistor R1, a resistor R5, a resistor R6, a resistor RL, and a control switch, one end of the resistor R1 is connected to the power input terminal through the resistor R5, the other end of the resistor R1 is connected to the power output terminal, and the other end of the resistor R1 is grounded through the resistor RL; one end of the control part of the control switch is connected to the common end of the resistor R1 and the resistor R5 through the resistor R6, the other end of the control part of the control switch is connected to the power output terminal, and the controlled part of the control switch is connected to the protection control circuit; The control switch is a bidirectional optocoupler, one end of the control part of the bidirectional optocoupler is connected to the resistor R6, and the other end is connected to the power output end, and one end of the controlled part of the bidirectional optocoupler is connected to the protection control circuit, and the other end is grounded; When the downstream power circuit is overloaded and the current exceeds the overload current value, the control part of the bidirectional optocoupler is powered on and emits light, so that the controlled part is turned on and a low level is transmitted as a protection signal to the protection control circuit, so that the protection control circuit controls the switch device to be disconnected; If the subsequent power circuit is not overloaded, the controlled part of the bidirectional optocoupler is not conducting, the switch device is closed, and the main power supply supplies power to the subsequent power circuit; The protection control circuit includes a resistor R2 and a switch tube Q1, wherein the control end of the switch tube Q1 is connected to the output detection circuit and connected to the power supply end through the resistor R2, the input end of the switch tube Q1 is connected to the switching device, and the output end of the switch tube Q1 is grounded; The switching device includes a relay, one end of the relay coil is connected to the power supply end, and the other end is connected to the input end of the switch tube Q1, one end of the relay contact switch is connected to the power supply input end, and the other end is connected to the power supply output end.

2. The circuit according to claim 1, wherein: Alternatively, the protection control circuit includes a resistor R2, a resistor R3, a resistor R4, a controller, and a switch tube Q2, wherein the resistors R2 and R3 are connected in series, and a common end is connected to the output detection circuit, the other end of the resistor R2 is connected to a power supply end, the other end of the resistor R3 is connected to the controller, the controller is connected to a control end of the switch tube Q2 through the resistor R4, the input end of the switch tube Q2 is connected to a power supply end, and the output end of the switch tube Q2 is connected to the switching device; The switching device includes a relay, one end of the coil of the relay is connected to the output end of the switch tube Q2, and the other end is grounded. One end of the contact switch of the relay is connected to the power input end, and the other end is connected to the power output end.

3. The circuit according to claim 1, wherein: Alternatively, the protection control circuit includes a resistor R2, a resistor R3, a resistor R4, a switch tube Q1, a switch tube Q2, and a controller. The resistors R2 and R3 are connected in series, and a common end is connected to the control end of the switch tube Q1. The control end of the switch tube Q1 is connected to the output detection circuit. The other end of the resistor R2 is connected to the power supply end, and the other end of the resistor R3 is connected to the controller. The input end of the switch tube Q1 is connected to the switching device, and the output end of the switch tube Q1 is grounded. The controller is connected to the control end of the switch tube Q2 via the resistor R4. The input end of the switch tube Q2 is connected to the power supply end, and the output end of the switch tube Q2 is connected to the switching device. The switching device includes a relay, one end of the coil of the relay is connected to the output end of the switch tube Q2, and the other end is connected to the input end of the switch tube Q1, one end of the contact switch of the relay is connected to the power input end, and the other end is connected to the power output end.

4. The circuit according to any one of claims 1 to 3, characterized in that: It also includes an interactive device connected to the protection control circuit, and the protection control circuit controls the interactive device to output fault reminder information when receiving the protection signal.

5. The circuit according to claim 4, characterized in that The interactive device includes a display device and / or an audible and visual alarm device connected to the protection control circuit.

6. A circuit protection device, characterized in that: The device comprises a main power supply and a power output protection circuit as claimed in any one of claims 1 to 5.

Images