CN213817221U - Anti-interference power supply overvoltage protection circuit - Google Patents
Anti-interference power supply overvoltage protection circuit Download PDFInfo
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- CN213817221U CN213817221U CN202022749616.2U CN202022749616U CN213817221U CN 213817221 U CN213817221 U CN 213817221U CN 202022749616 U CN202022749616 U CN 202022749616U CN 213817221 U CN213817221 U CN 213817221U
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Abstract
The utility model discloses an anti-interference power supply overvoltage protection circuit, which comprises a power input end, a power output end, a relay and an overvoltage protection circuit, wherein the input end of the overvoltage protection circuit is connected with the power input end, and the relay is connected between the output end of the overvoltage protection circuit and the power output end; the overvoltage protection circuit comprises a voltage reduction circuit, a rectification filter circuit, a comparator and a latch, the voltage reduction circuit, the rectification filter circuit, the comparator, the latch and the relay are sequentially connected, and a voltage division resistor and a reference voltage source are arranged between the rectification filter circuit and the comparator. The protection circuit has strong anti-interference capability, can ensure the normal work of the relay, and has simple structure and low hardware cost.
Description
Technical Field
The utility model belongs to the technical field of circuit protection, concretely relates to anti-interference power supply overvoltage crowbar.
Background
In the existing elevator electric loop, AC380V is mostly adopted for supplying power to a main loop frequency converter, and AC220V is mainly used for supplying power to an auxiliary control loop. Because the car needs to move up and down in the well, the position is not fixed, and an auxiliary control loop at the top of the car needs to be connected with an elevator control cabinet through a traveling cable. The number of travelling cables is large, the wiring is complex, and the risk of connecting the AC380V power supply to the AC220V control loop is high. Therefore, in order to improve the reliability of the elevator system, for electronic products powered by the AC220V, an overvoltage protection circuit needs to be designed at the input end of the power supply so as to prevent the components from being damaged due to the fact that a 380V power supply loop is connected by mistake.
The overvoltage protection circuit at the input end of the existing power supply adopts the following two methods: 1. the device with higher voltage resistance is selected, and when the input power supply is connected with 380V for power supply by mistake, the selected device can bear the voltage without being damaged; 2. the relay disconnection method is characterized in that the input voltage is directly rectified or the direct current voltage after being subjected to voltage reduction and rectification through the transformer is divided through the voltage stabilizing tube and then controls the relay connected in series with the input end, when the input voltage is overvoltage, the relay is disconnected, and the input voltage is cut off to play a role in protecting rear-end devices.
However, the two overvoltage protection methods have the following disadvantages: the adoption of a device with higher voltage resistance can cause the volume of part of the devices to be increased, and the cost of hardware such as a rectifier tube, a bus capacitor and the like is increased; when the relay disconnection method is adopted, in the running process of the elevator, because the output voltage waveform of the frequency converter is high-frequency square wave, high-frequency interference signals can be introduced into the whole power supply loop, the control signals of the relay coil can be influenced, and misoperation is easy to occur.
Disclosure of Invention
An object of the utility model is to provide an anti interference power supply overvoltage crowbar, this protection circuit interference killing feature is strong, can guarantee relay normal work, and this protection circuit simple structure, and the hardware is with low costs.
The technical scheme is as follows:
the anti-interference power supply overvoltage protection circuit comprises a power supply input end, a power supply output end, a relay and an overvoltage protection circuit, wherein the input end of the overvoltage protection circuit is connected with the power supply input end, and the relay is connected between the output end of the overvoltage protection circuit and the power supply output end; the overvoltage protection circuit comprises a voltage reduction circuit, a rectification filter circuit, a comparator and a latch, the voltage reduction circuit, the rectification filter circuit, the comparator, the latch and the relay are sequentially connected, and a voltage division resistor and a reference voltage source are arranged between the rectification filter circuit and the comparator.
In one embodiment, the voltage reduction circuit comprises a first resistor and a first capacitor, the first resistor and the first capacitor are connected in parallel to form a resistance-capacitance voltage reduction component, one end of the resistance-capacitance voltage reduction component is connected with the power supply input end, and the other end of the resistance-capacitance voltage reduction component is connected with the rectification filter circuit.
In one embodiment, the rectifying and filtering circuit comprises a first diode, a second diode, a third diode and a fourth diode, wherein the cathode of the first diode is connected with the cathode of the second diode, the anode of the third diode is connected with the anode of the fourth diode and grounded, the anode of the first diode is connected with the cathode of the third diode, the anode of the second diode is connected with the cathode of the fourth diode, and the resistance-capacitance voltage reduction component is respectively connected with the anodes of the first diode and the second diode.
In one embodiment, the rectifying and filtering circuit further comprises a filter capacitor, wherein one end of the filter capacitor is connected with the cathode of the second diode, and the other end of the filter capacitor is grounded.
In one embodiment, a first power line and a second power line are connected between the power input end and the power output end, the resistance-capacitance voltage reduction component is connected with the input end of the second power line, the anode of the first diode is connected with the input end of the first power line, and the relay is connected with the output end of the first power line.
In one embodiment, the voltage dividing resistor includes a second resistor and a third resistor, the second resistor and the third resistor are connected in series, one end of the second resistor and one end of the third resistor after the second resistor and the third resistor are connected with the cathode of the second diode, the other end of the second resistor and the third resistor are grounded, and the connection position of the second resistor and the third resistor is connected with the first input end of the comparator.
In one embodiment, the reference voltage source is connected in parallel with the second resistor and the third resistor after being connected in series, and the reference voltage source is connected with the second input end of the comparator.
In one embodiment, the output terminal of the comparator is connected to the input pin D of the latch, and the output pin Q of the latch is connected to the relay.
In one embodiment, the input pin OE of the latch is grounded, and the input pin LE of the latch inputs a control signal.
The overvoltage protection circuit of the anti-interference power supply provided by the utility model carries out overvoltage protection on the circuit by arranging the voltage reduction circuit in the overvoltage protection circuit; a rectification filter circuit is arranged to rectify and filter the circuit, so that the voltage stabilization precision of the voltage is improved; the latch can effectively prevent the control signal of the relay caused by the influence of the high-frequency harmonic wave of the power supply end, thereby effectively preventing the misoperation of the relay; the protection circuit has strong anti-interference capability, can ensure the normal work of the relay, and has simple structure and low hardware cost.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles, principles and effects of the invention.
Unless otherwise specified or defined, the same reference numerals in different figures refer to the same or similar features, and different reference numerals may be used for the same or similar features.
Fig. 1 is a circuit connection diagram of an anti-interference power supply overvoltage protection circuit according to an embodiment of the present invention.
Fig. 2 is a logic table for controlling the latch in the overvoltage protection circuit for the anti-interference power supply according to the embodiment of the present invention.
Description of reference numerals:
10. a voltage reduction circuit; 20. and a rectification filter circuit.
Detailed Description
In order to facilitate an understanding of the invention, specific embodiments thereof will be described in more detail below with reference to the accompanying drawings.
Unless specifically stated or otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the case of combining the technical solution of the present invention with realistic scenarios, all technical and scientific terms used herein may also have meanings corresponding to the objects of realizing the technical solution of the present invention.
As used herein, unless otherwise specified or defined, "first" and "second" … are used merely for name differentiation and do not denote any particular quantity or order.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items, unless specified or otherwise defined.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present; when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present; when an element is referred to as being "mounted on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present.
As used herein, unless otherwise specified or defined, the terms "comprises," "comprising," and "comprising" are used interchangeably to refer to the term "comprising," and are used interchangeably herein.
It is needless to say that technical contents or technical features which are contrary to the object of the present invention or clearly contradict each other should be excluded.
As shown in fig. 1, the anti-interference power supply overvoltage protection circuit includes a power supply input terminal, a power supply output terminal, a relay K1 and an overvoltage protection circuit, wherein the input terminal of the overvoltage protection circuit is connected with the power supply input terminal, and the relay K1 is connected between the output terminal of the overvoltage protection circuit and the power supply output terminal; the overvoltage protection circuit comprises a voltage reduction circuit 10, a rectifying and filtering circuit, a comparator U1 and a latch U2, wherein the voltage reduction circuit 10, the rectifying and filtering circuit 20, the comparator U1, the latch U2 and a relay K1 are sequentially connected, and a voltage division resistor and a reference voltage source Q1 are arranged between the rectifying and filtering circuit 20 and the comparator U1. In this embodiment, the latch is model SN74AHC 573.
Through the arrangement, the input voltage is input through the power input end, is reduced by the voltage reduction circuit 10 and then is rectified by the rectifying and filtering circuit 20 to obtain the direct current voltage VCC, and the direct current voltage VCC is filtered, so that the voltage stabilization precision of the VCC voltage is improved; the voltage divider resistor divides the direct-current voltage VCC to obtain a voltage sampling signal Vcom, a reference voltage source Q1 provides a 5V reference voltage which is not converted by the direct-current voltage VCC, and the voltage sampling signal Vcom is compared with the 5V reference voltage through a comparator U1, so that an output signal of the comparator U1 controls the working state of a latch U2, the control signal of the relay K1 caused by the influence of high-frequency harmonics of a power supply end is effectively prevented, and the misoperation of the relay K1 is effectively prevented; therefore, the utility model provides an anti-interference power supply overvoltage crowbar interference killing feature is strong, can guarantee relay K1 normal work, and this protection circuit simple structure, and the hardware is with low costs.
In this embodiment, a first power line and a second power line are connected between the power input end and the power output end, where the first power line is a live line and the second power line is a neutral line, as shown in fig. 1, an input end of the first power line is L1, an output end of the first power line is L11, an input end of the second power line is L2, and an output end of the second power line is L22, and the relay K1 is connected to the output end L11 of the first power line.
The voltage reduction circuit 10 comprises a first resistor R1 and a first capacitor C1, the first resistor R1 and the first capacitor C1 are connected in parallel to form a resistance-capacitance voltage reduction component, one end of the resistance-capacitance voltage reduction component is connected with the input end L2 of the second power line, and the other end of the resistance-capacitance voltage reduction component is connected with the rectification filter circuit 20. The first resistor R1 and the first capacitor C1 are connected in parallel to form a resistance-capacitance voltage reduction assembly, so that the input voltage can be reduced, and the overvoltage protection of the circuit is realized; the voltage reduction circuit 10 is used for replacing devices with higher withstand voltage, the size of partial devices cannot be increased, the installation space of electronic products is saved, the cost increase of hardware such as rectifier tubes and bus capacitors cannot be caused, and the structure of the circuit is simpler.
The rectifying and filtering circuit 20 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, the anode of the first diode D1 is connected to the input end L1 of the first power line, the cathode of the first diode D1 is connected to the cathode of the second diode D2, the anode of the third diode D3 is connected to the anode of the fourth diode D4 and grounded, the anode of the first diode D1 is connected to the cathode of the third diode D3, the anode of the second diode D2 is connected to the cathode of the fourth diode D4, and in addition, the resistance-capacitance voltage dropping component is connected to the anodes of the first diode D1 and the second diode D2 respectively, so as to realize the connection between the voltage dropping circuit 10 and the rectifying and filtering circuit 20. The four diodes are connected in the above connection mode to form a full-wave rectification circuit, and the input voltage is reduced by the voltage reduction circuit 10 and then the full-wave rectification circuit obtains a direct-current voltage VCC.
The rectifying and filtering circuit 20 further includes a filter capacitor C2, wherein one end of the filter capacitor C2 is connected to the negative electrode of the second diode D2, and the other end is grounded. The direct-current voltage VCC is filtered by the filter capacitor C2, and the voltage stabilization precision of the VCC voltage is improved. In addition, the impedance across the filter capacitor C2 is related to the frequency of the input power, and the impedance transformation of the capacitor C1 affects the magnitude of the dc voltage VCC. In an elevator system, due to the use of components such as a frequency converter and an elevator switching power supply, a large number of high-frequency harmonics exist in a power supply, and after passing through a capacitor C1, the voltage drop across the capacitor C1 is reduced, and the dc voltage VCC is increased.
The voltage dividing resistor comprises a second resistor R2 and a third resistor R3, in this embodiment, the second resistor R2 and the third resistor R3 both adopt precise voltage dividing resistors, the second resistor R2 and the third resistor R3 are connected in series, one end of the second resistor R2 and one end of the third resistor R3 after being connected in series are connected with the negative electrode of the second diode D2, the other end of the second resistor R2 and the third resistor R3 are connected with the ground, and the joint of the second resistor R2 and the third resistor R3 is connected with the first input end of the comparator U1. Through the arrangement, the second resistor R2 and the third resistor R3 divide the direct current voltage VCC to obtain the voltage sampling signal Vcom, wherein the voltage sampling signal Vcom is subjected to signal sampling from the connection position between the second resistor R2 and the third resistor R3.
The reference voltage source Q1 is connected in parallel with the second resistor R2 and the third resistor R3 after being connected in series, and the reference voltage source Q1 is connected with the second input end of the comparator U1. The voltage sampling signal Vcom is compared with a 5V reference voltage through a comparator U1, and the use of a reference voltage source Q1 and a latch U2 can effectively prevent the influence of high-frequency harmonics of a power supply end from causing the misoperation of a relay K1.
The output end of the comparator U1 is connected with the input pin D of the latch U2, and the output pin Q of the latch U2 is connected with the relay K1. The input pin OE of the latch U2 is grounded, and the input pin LE of the latch U2 inputs the control signal Vcon. The voltage sampling signal Vcom is compared with a 5V reference voltage through a comparator U1, and the comparator U1 outputs a high level or a low level, and inputs the high level or the low level to the latch U2 through an input pin D; an output signal Vk of the latch U2 is controlled by a pin OE/LE/D, before power-on, the OE pin is grounded and always has a low level, a pin control signal Vcon of the LE pin is a high level, and an output pin Q is controlled by an input pin D; after power-on, after detecting that the input voltage is in a normal power supply range, the control signal Vcon is changed into low level, and the output pin Q latches and outputs and is not controlled by the input pin D any more; after power down, the input pin of latch U2 returns to the state before the first power up; the control logic table for latch U2 is shown in FIG. 2.
The following is the utility model provides an anti-interference power supply overvoltage crowbar's working process:
when the power is powered on for the first time, when the input is connected to the normal AC220V, the voltage sampling signal Vcom is smaller than the reference voltage of 5V, the input pin D of the latch U2 inputs high level, the relay K1 does not act, the power output end is kept connected and normally supplies power for the back end circuit;
after the power is switched on for a period of time, the control signal Vcon is changed into low level, the output pin Q of the latch U2 latches the output and is not controlled by the input pin D any more, and the relay K1 is kept not to act.
When the input is misconnected with the AC380V during initial power-on, the voltage sampling signal Vcom is larger than 5V reference voltage, the low level is input to the pin D of the latch U2, the relay K1 acts, the output end L11 of the first power transmission line is disconnected, and the effect of protecting the back end circuit is achieved.
It should be noted that, in the present embodiment, both the comparator U1 and the latch U2 are directly powered by the VCC of the circuit itself, and thus, power supply from an external auxiliary source is not required, and the circuit operation response time can be effectively shortened. In addition, in the embodiment, all the used devices are conventional devices, and the output end devices can be subjected to model selection according to the AC220V voltage level, so that the device cost and the model selection difficulty can be effectively reduced. The anti-interference power supply overvoltage protection circuit provided by the utility model is not limited to the power supply overvoltage protection circuit of the electrical component for the elevator, but also can be used for other electronic products; and the overvoltage protection circuit is not limited to the overvoltage protection circuit of the input AC220V, and can also be used for overvoltage protection circuits powered by AC power supplies with other voltage classes.
In other embodiments, the number and the selection of the components of the circuit may be different from the above, for example, the filter capacitor C1 may be formed by two or more capacitors connected in parallel; the full-wave rectifier circuit may be replaced by a half-wave rectifier circuit; the specific model of the latch U2 can be replaced by other devices with latch functions with similar functions; other reference voltage sources Q1 may be selected to provide different reference voltages.
The utility model provides an anti-interference power supply overvoltage crowbar, through set up the step-down circuit 10 in overvoltage crowbar, can step down the input voltage, realize the overvoltage crowbar of the circuit; a rectification filter circuit 20 is arranged to rectify and filter the circuit, so as to improve the voltage stabilization precision of the voltage; the latch is arranged, so that the control signal of the relay K1 caused by the influence of high-frequency harmonic waves of a power supply end can be effectively prevented, and the misoperation of the relay K1 is effectively prevented; the protection circuit has strong anti-interference capability, can ensure the normal work of the relay K1, and has simple structure and low hardware cost.
The above embodiments are intended to be illustrative, and should not be construed as limiting the scope of the invention, and the technical solutions, objects and effects of the present invention are described in full herein.
The above examples are not intended to be exhaustive list of the present invention, and there may be many other embodiments not listed. Any replacement and improvement made on the basis of not violating the conception of the utility model belong to the protection scope of the utility model.
Claims (9)
1. The anti-interference power supply overvoltage protection circuit is characterized by comprising a power supply input end, a power supply output end, a relay and an overvoltage protection circuit, wherein the input end of the overvoltage protection circuit is connected with the power supply input end, and the relay is connected between the output end of the overvoltage protection circuit and the power supply output end; the overvoltage protection circuit comprises a voltage reduction circuit, a rectification filter circuit, a comparator and a latch, the voltage reduction circuit, the rectification filter circuit, the comparator, the latch and the relay are sequentially connected, and a voltage division resistor and a reference voltage source are arranged between the rectification filter circuit and the comparator.
2. The anti-jamming power supply overvoltage protection circuit of claim 1, wherein the voltage reduction circuit comprises a first resistor and a first capacitor, the first resistor and the first capacitor are connected in parallel to form a resistance-capacitance voltage reduction component, one end of the resistance-capacitance voltage reduction component is connected with the power supply input end, and the other end of the resistance-capacitance voltage reduction component is connected with the rectification filter circuit.
3. The anti-jamming power supply overvoltage protection circuit of claim 2, wherein the rectifying and filtering circuit comprises a first diode, a second diode, a third diode and a fourth diode, a cathode of the first diode is connected with a cathode of the second diode, an anode of the third diode is connected with an anode of the fourth diode and grounded, an anode of the first diode is connected with a cathode of the third diode, an anode of the second diode is connected with a cathode of the fourth diode, and the resistor-capacitor voltage reduction components are respectively connected with anodes of the first diode and the second diode.
4. The anti-jamming power supply overvoltage protection circuit of claim 3, wherein the rectifying filter circuit further comprises a filter capacitor, one end of the filter capacitor is connected to a cathode of the second diode, and the other end of the filter capacitor is grounded.
5. A tamper-resistant power supply overvoltage protection circuit as recited in claim 3, wherein a first power line and a second power line are connected between the power supply input and the power supply output, the resistance-capacitance voltage dropping component is connected to an input of the second power line, the anode of the first diode is connected to the input of the first power line, and the relay is connected to the output of the first power line.
6. The anti-jamming power supply overvoltage protection circuit of claim 3, wherein the voltage dividing resistor comprises a second resistor and a third resistor, the second resistor and the third resistor are connected in series, one end of the second resistor and one end of the third resistor after being connected in series are connected with a cathode of the second diode, the other end of the second resistor and one end of the third resistor are connected with the ground, and a joint of the second resistor and the third resistor is connected with the first input end of the comparator.
7. The antijam power supply overvoltage protection circuit of claim 6, wherein the reference voltage source is connected in parallel with the second resistor and the third resistor after being connected in series, and the reference voltage source is connected to the second input terminal of the comparator.
8. The anti-jamming power supply overvoltage protection circuit of claim 7, wherein an output of the comparator is connected to an input pin D of a latch, and an output pin Q of the latch is connected to a relay.
9. The antijam power supply overvoltage protection circuit of claim 8, wherein an input pin OE of said latch is grounded and an input pin LE of said latch inputs a control signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022749616.2U CN213817221U (en) | 2020-11-24 | 2020-11-24 | Anti-interference power supply overvoltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022749616.2U CN213817221U (en) | 2020-11-24 | 2020-11-24 | Anti-interference power supply overvoltage protection circuit |
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| Publication Number | Publication Date |
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| CN213817221U true CN213817221U (en) | 2021-07-27 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202022749616.2U Active CN213817221U (en) | 2020-11-24 | 2020-11-24 | Anti-interference power supply overvoltage protection circuit |
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| CN (1) | CN213817221U (en) |
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