Overvoltage detection protection circuit

Abstract

The utility model provides an overvoltage detection protection circuit comprising a power supply input module, a first power supply path, a second power supply path, a switch module and a detection control module. When the power input module is powered on, the switch module is not switched on. And detecting the voltage detected by the control module and adding the voltage drop of the first power path to restore the input voltage of the power input module. When the input voltage is smaller than the set threshold value, the switch module is switched on, and the voltage detected by the detection control module directly restores the input voltage. When the input voltage is larger than the set threshold value, the switch module is switched off, and the power supply supplies power to the detection control module through the first power supply path again. According to the overvoltage detection protection circuit, the high-power load circuit of the second power supply path can be protected by adding the first power supply path with lower cost to be matched with the switch module and the detection control module behind, and perfect overvoltage detection and protection functions of the input power supply can be realized with lower cost.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to an overvoltage detection protection circuit. Background Art

[0002] Overvoltage detection protection is a common function of the control board. Its purpose is to prevent serious consequences caused by the input power being mistakenly connected to a voltage that exceeds the control board's allowable voltage. However, the general practice is mostly achieved through a combination of a fuse and a varistor at the power input end. When the input voltage is higher than the varistor's withstand voltage, the varistor is turned on, and the large current triggers the fuse to blow, thereby protecting the subsequent important circuits from damage. However, this approach will still cause damage to the varistor and fuse, and the power must not be cut off to restore. (It is also possible to use a self-recovery fuse for the fuse, but the high-voltage and high-current self-recovery fuse is large in size and cost. The key is that the varistor is permanently damaged and cannot be restored by itself). Therefore, the current common practices will cause damage to the control board components, causing the control board to not work properly and require repair.

[0003] In reality, there are some occasions where the power supply voltage overvoltage is more likely to occur (for example, during the elevator installation phase, due to temporary electricity on site, it is likely that AC380V will be connected to the AC220V control board). In this case, a control board for this occasion is needed that has overvoltage detection protection and does not damage the control board. Utility Model Content

[0004] In view of the above-mentioned deficiencies in the prior art, the utility model provides an overvoltage detection protection circuit, including a power input module, a first power path, a second power path, a switch module and a detection control module;

[0005] The second power supply path electrically connects the switch module and the detection control module, and the first power supply path electrically connects the power input module and the detection control module, and has a function of reducing the voltage of the power input module;

[0006] The detection control module is connected to the switch module and is used to control the switch module to be turned off when the switch module is turned on and detects that the voltage of the power input module is greater than a preset voltage, so that the second power path is disconnected from the power input module; the detection control module is also used to control the switch module to be turned on when the switch module is disconnected and detects that the voltage of the power input module is less than a preset voltage, so that the second power path is connected to the power input module.

[0007] In a specific embodiment, the first power path and the second power path are connected via a diode.

[0008] In a specific embodiment, the anode of the diode is electrically connected to the second power path, and the cathode of the diode is electrically connected to the first power path.

[0009] In a specific embodiment, a voltage regulator tube is provided in the first power path for reducing the voltage of the power input module.

[0010] In a specific embodiment, the number of voltage regulator tubes in the first power path is greater than one.

[0011] In a specific embodiment, a resettable fuse is provided in the first power path, which is used to automatically disconnect the circuit when the current flowing through the first power path exceeds the rated current of the resettable fuse.

[0012] In a specific implementation, the rated current of the resettable fuse is smaller than the rated current of the voltage regulator tube, so as to disconnect the circuit before the voltage regulator tube is damaged by overcurrent.

[0013] In a specific embodiment, it also includes a display module, and the detection control module includes an MCU. The MCU is connected to the display module and is used to output a display signal to the display module to display the on-off state of the switch module. The display module is used to display the on-off state of the switch module according to the display signal.

[0014] In a specific embodiment, it also includes a DC power supply module for converting the voltage of the power input module into the working voltage of the detection control module.

[0015] In a specific embodiment, the detection control module includes an MCU and a voltage dividing resistor, the voltage dividing resistor is connected to the MCU, and is used to divide the first power channel or the second power channel to obtain a voltage signal, and the MCU is used to control the on and off of the switch module according to the voltage signal.

[0016] Beneficial effect: The utility model adds a low-cost switch module, a detection control module and a first power supply path, so that the switch module is disconnected, and the first power supply path divides the power supply and then detects it through the detection control module. The switch module is turned on only when the power supply voltage is less than a preset voltage, thereby avoiding damage to high-power devices in the second power supply path and reducing the cost of the overvoltage detection protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the principle structure of the utility model;

[0019] Figure 2 It is a schematic diagram of the structure of the circuit of the utility model;

[0020] Figure 3 This is a circuit diagram of the utility model.

[0021] The accompanying drawings are marked as follows: 1-power input module; 2-step-down module; 3-switch module; 4-detection control module; 5-output module; 6-detection module; 7-DC power module; 8-DC-DC DC power chip; 9-control module; 10-detection control module; 11-first port of the power input module; 12-second port of the power input module; 21-first port of the step-down module; 22-second port of the step-down module; 51-first port of the output module; 52-second port of the output module; 53-third port of the output module; 54-ground terminal. DETAILED DESCRIPTION

[0022] The concept, specific structure and technical effects of the present invention will be clearly and completely described below in combination with the embodiments and drawings to fully understand the purpose, features and effects of the present invention.

[0023] In the following, various embodiments of the present invention will be described more fully. The present invention may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present invention to the specific embodiments disclosed herein, but rather the present invention should be understood to cover all adjustments, equivalents and / or alternatives that fall within the spirit and scope of the various embodiments of the present invention.

[0024] Hereinafter, the terms "include" or "may include" used in various embodiments of the present invention indicate the presence of disclosed functions, operations or elements, and do not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing.

[0025] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0026] The expressions (such as "first", "second", etc.) used in the various embodiments of the present invention may modify the various components in the various embodiments, but may not limit the corresponding components. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present invention, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0027] It should be noted that in the present invention, unless otherwise clearly specified and defined, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, those skilled in the art need to understand that the terms indicating orientation or positional relationship herein are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0029] The terms used in the various embodiments of the present invention are only used for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical terms and scientific terms) have the same meaning as the meanings commonly understood by ordinary technicians in the field of the various embodiments of the present invention. The terms (such as the terms defined in the dictionary used in general) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments of the present invention.

[0030] Embodiment 1

[0031] This embodiment provides an overvoltage detection protection circuit, which can prevent damage to high-power devices in the output module 5 and reduce the cost of the overvoltage detection protection circuit.

[0032] like Figures 1 to 3 As shown, an overvoltage detection protection circuit includes a power input module 1, a switch module 3, a first power path, a display module, a second power path and a detection control module 10. Among them, the first power path includes a step-down module 2, and the second power path includes an output module 5. The power input module 1 includes a power access port J1, a switch S1, a first insurance device F1 and a power internal resistor RV. The power access port J1 is connected to a live wire L, a neutral wire N and a ground terminal (EGND) respectively. The two output ends of the power input module 1 are respectively a first port 11 of the power input module and a second port 12 of the power input module. The live wire L is connected in series with the switch S1 and the first insurance device F1, and then connected to the first port 11 of the power input module. The neutral wire N is connected to the second port 12 of the power input module. The power internal resistor RV is connected between the first port 11 of the power input module and the second port 12 of the power input module. The switch S1 is preferably a manual switch or an automatic switch with a higher rated current and rated voltage capacity, such as a knife switch or an electronic switch. The first insurance device F1 is preferably a fuse.

[0033] Further, the first port 11 of the power input module 1 is connected to the input end of the switch module 3 and the first port 21 of the step-down module respectively. The input end of the output module 5 includes the second port 52 of the output module and the third port 53 of the output module, and the output end of the output module 5 includes the first port 51 of the output module and the ground terminal 54. The second port 22 of the step-down module is connected to the cathode of the first diode B10, the output end of the switch module 3 is connected to the second port 52 of the output module, and the second port 12 of the power input module is connected to the third port 53 of the output module. Figure 1 and Figure 3As shown, the detection control module 10 is connected in parallel with the output module 5, and is used to control the switch module 3 to be turned off when the switch module 3 is turned on and the detected voltage of the output module 5 is greater than the preset voltage; the detection control module 10 is also used to control the switch module 3 to be turned on when the switch module 3 is turned off and the detected voltage of the output module 6 is less than the preset voltage minus the voltage of the step-down module 2. It should be noted that the preset voltage is related to the withstand voltage value of the high-power device in the output module 5.

[0034] In a specific embodiment, the output module 5 includes a first capacitor C5. The second capacitor C24 is located in the detection control module 10, one end of the first capacitor C5 is connected to the positive electrode of the first diode, the other end of the first capacitor C5 and the negative electrode of the first diode B10 are connected in parallel with the second capacitor, and the external load is connected in parallel with the first capacitor C5. The second capacitor C24 is preferably 4.7μF, and the rated voltage is an electrolytic capacitor of 450V, and the first capacitor C5 is preferably 180μF, and the rated voltage is an electrolytic capacitor of 450V, and the load is connected to the two ends of the first capacitor C5. The first capacitor C5 is a high-power device and has a high cost. The first diode B10 can disconnect the first capacitor C5 from the electrical connection with the power input module 1 when the switch module 3 is turned on (i.e., the voltage of the output module 5 is too high), so as to avoid excessive voltage from damaging the second capacitor C5.

[0035] In a specific embodiment, the output module 5 further includes a rectifier bridge D1 and a filter capacitor C3, and the rectifier bridge D1 can convert the AC power of the power input module 1 into DC power. The filter capacitor C3 is connected in parallel with the two input ports of the rectifier bridge D1, the input end of the rectifier bridge D1 is respectively connected to the second port of the switch module 3 and the second port 12 of the power input module, and the output end of the rectifier bridge D1 is respectively connected to the two ends of the first capacitor C5.

[0036] In a specific embodiment, the step-down module 2 includes a second safety device L6, a voltage-stabilizing diode Z1, a voltage-stabilizing diode Z2, and a second diode B12. The positive electrode of the second diode B12 is connected to the first port 11 of the power input module, and the negative electrode of the voltage-stabilizing diode is connected to the first port 51 of the output module. The second safety device is connected in series between the first port 21 and the second port of the step-down module, and is used to disconnect when the current is too large. The second safety device is preferably a self-recovering fuse. The self-recovering fuse will automatically disconnect the circuit in the case of overload or short circuit to protect the device from damage. The fuse does not need to be replaced. The circuit can be automatically reconnected after the overload or short circuit problem is solved, which can save the time and cost of replacing the fuse. The rated current of the self-recovering fuse is less than the rated current of the voltage-stabilizing tubes Z1 and Z2, which prevents the voltage-stabilizing tube from being damaged due to overcurrent in advance. The overcurrent damage of the voltage-stabilizing tube is a short-circuit state, which will cause the detection and control module to misjudge. The Zener diodes Z1 and Z2 are preferably Zener diodes with a rated voltage of 75V and a rated power of 5W to increase the circuit's tolerable voltage. The second diode B12 can prevent the circuit from being short-circuited when the switch module 3 is turned on.

[0037] In a specific embodiment, the switch module 3 includes a relay U23, which includes a switch contact and a coil. The coil is used to control the on and off of the switch contact. The switch contacts of the relay U23 are respectively connected to the first port 11 of the power input module and the second port 52 of the output module, and the detection control module 10 is connected to the coil.

[0038] In a specific embodiment, a DC power supply module 7 is further included, and the DC power supply module 7 is connected to the detection control module 10 and the switch module 3 respectively, and is used to supply power to the detection control module 10 and the switch module 3. The DC power supply module 7 is preferably a DC (Direct Current, DC)-DC direct current power supply chip 8, and the DC-DC direct current power supply chip 8 can convert a larger DC voltage into a lower DC voltage, and is used to supply power to the detection control module 10 and the switch module 3.

[0039] In a specific embodiment, the detection control module 10 includes a control module 9 and a detection module 6. The control module 9 is preferably a single chip microcomputer (MCU). The control module 9 is connected to the output module 5 and the switch module 3 respectively, and is used to calculate the voltage of the output module 5, and control the switch module 3 according to the voltage of the output module 5 obtained after calculation. The detection module 6 includes a second capacitor C24 and a first voltage-dividing resistor R4, a second voltage-dividing resistor R5, a third voltage-dividing resistor R6 and a fourth voltage-dividing resistor R7 connected in series in sequence. Among them, the first voltage-dividing resistor R4, the second voltage-dividing resistor R5, and the third voltage-dividing resistor R6 preferably have a resistance value of 200K ohms and a tolerance of 1%. The fourth resistor R7 is a resistor of 2.67K ohms and a tolerance of 1%, so that a lower voltage is obtained on the fourth resistor R7, which is convenient for the control module 9 to detect. The control module 9 is connected between the fourth resistor and the third resistor to detect the voltage of the fourth resistor. The power supply end of the control module 9 is also provided with a filter capacitor C4, so as to obtain a more stable and pure DC power supply. The MCU is connected to the display module and is used to output a display signal showing the on / off state of the switch module to the display module. The display module is used to display the on / off state of the switch module according to the display signal. The display module is, for example, a digital tube.

[0040] In a specific embodiment, the switch module 3 further includes a transistor T8, a third diode B13, a fifth resistor and a sixth resistor, the base of the transistor T8 is connected to the detection control module 10, the collector of the transistor T8 is connected to the switch module 3, and the emitter of the transistor T8 is connected to the ground terminal 54. The fifth resistor is located in series between the base of the transistor T8 and the control module 9, and is used to provide a bias current. The sixth resistor is connected to the base and emitter of the transistor T8, and is used to improve the linearity of the transistor T8. The third diode B13 is connected to the collector of the transistor T8 and is connected in parallel with the coil to protect the circuit from the high voltage spike generated when the coil is turned off.

[0041] The specific working process is as follows: when the power input module 1 is connected to the power supply, the first power supply path is turned on first, and the detection and control module determines the voltage of the power input module 1 according to the voltage generated by the first power supply path on the second capacitor C24 plus the voltage on the Zener diode Z1 and the Zener diode Z2 in the first power supply path. When the voltage of the power input module 1 is less than the preset voltage (for example, 450V), the control switch module 3 is turned on to turn on the second power supply path. At this time, the voltage generated on the second capacitor C24 is equal to the voltage of the power input module 1. When the detection and control module determines that the voltage of the power input module 1 is greater than the preset voltage, the control switch module is turned off to turn on the first power supply path. Specifically, when the power input module 1 is connected to the power supply, the switch S1 is turned off, and the current flows back to the power input module 1 through the step-down module 2, the second capacitor C24 and the rectifier bridge D1 to form the first power supply path. At this time, the second capacitor C24 withstands a voltage of 450V, the Zener diode Z1 and the Zener diode Z2 withstand a voltage of 150V in total, and the total withstand voltage value of the circuit can reach 600V. At this time, since the first diode B10 is turned off, the first capacitor C5 is protected. The control module 9 calculates the voltage on the second capacitor C24 by detecting the voltage on the fourth resistor R7. If the voltage on the second capacitor C24 is less than the preset voltage (for example, 450V) minus the voltage (150V) of the step-down module 2, the collector and emitter of the transistor T8 are turned on, and the coil is energized to connect the switch contact of the relay U23. After the switch contact of the relay U23 is turned on (that is, the switch module 3 is turned on), the first port 11 and the second port of the power input module are respectively connected to the two input ends of the rectifier bridge D1, and the current forms a loop through the rectifier bridge D1, the second capacitor C24 and the first diode B10. At this time, the first diode B10 is turned on, and the voltage on the second capacitor C24 plus the voltage of the first diode B10 is equal to the voltage on the first capacitor C5. If the control module 9 detects that the voltage of the second capacitor C24 exceeds the preset voltage (450V), the collector and emitter of the transistor T8 are controlled to be cut off, so that the coil is de-energized, so that the switch contacts of the relay U23 are disconnected (that is, the switch module 3 is cut off), thereby avoiding damage to the first capacitor C5.

[0042] The utility model adds a low-cost switch module, a detection control module and a first power supply path, so that the switch module is disconnected, and the first power supply path divides the power supply voltage and then detects it through the detection control module. The switch module is turned on only when the power supply voltage is less than a preset voltage, thereby avoiding damage to high-power devices in the second power supply path and reducing the cost of the overvoltage detection protection circuit.

[0043] The above is a specific description of the preferred implementation of the utility model, but the invention of the utility model is not limited to the described embodiments. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the utility model. These equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An overvoltage detection protection circuit, characterized in that: It includes a power input module, a first power path, a second power path, a switch module and a detection control module; The second power supply path electrically connects the switch module and the detection control module, and the first power supply path electrically connects the power input module and the detection control module, and has the function of reducing the voltage of the power input module; The detection control module is connected to the switch module and is used to control the switch module to be turned off when the switch module is turned on and detects that the voltage of the power input module is greater than a preset voltage, so that the second power path is disconnected from the power input module; the detection control module is also used to control the switch module to be turned on when the switch module is disconnected and detects that the voltage of the power input module is less than a preset voltage, so that the second power path is connected to the power input module.

2. An overvoltage detection protection circuit according to claim 1, characterized in that: The first power path and the second power path are connected via a diode.

3. An overvoltage detection protection circuit according to claim 2, characterized in that: The anode of the diode is electrically connected to the second power path, and the cathode of the diode is electrically connected to the first power path.

4. The overvoltage detection protection circuit according to claim 1, characterized in that: A voltage regulator tube is arranged in the first power supply path for reducing the voltage of the power input module.

5. An overvoltage detection protection circuit according to claim 4, characterized in that: The number of voltage regulator tubes in the first power supply path is greater than one.

6. The overvoltage detection protection circuit according to claim 4, characterized in that: A resettable fuse is provided in the first power supply path, which is used to automatically disconnect the circuit when the current flowing through the first power supply channel exceeds the rated current of the resettable fuse.

7. An overvoltage detection protection circuit according to claim 6, characterized in that: The rated current of the resettable fuse is smaller than the rated current of the voltage regulator tube, so as to disconnect the circuit before the voltage regulator tube is damaged by overcurrent.

8. The overvoltage detection protection circuit according to claim 1, characterized in that: It also includes a display module, and the detection control module includes an MCU. The MCU is connected to the display module and is used to output a display signal to the display module to display the on-off state of the switch module. The display module is used to display the on-off state of the switch module according to the display signal.

9. The overvoltage detection protection circuit according to claim 1, characterized in that: It also includes a DC power supply module, which is used to convert the voltage of the power input module into the working voltage of the detection control module.

10. The overvoltage detection protection circuit according to claim 1, characterized in that: The detection control module includes an MCU and a voltage-dividing resistor, wherein the voltage-dividing resistor is connected to the MCU and is used to divide the voltage of the first power supply channel or the second power supply channel to obtain a voltage signal, and the MCU is used to control the on and off of the switch module according to the voltage signal.

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