A voltage protection circuit and related devices

Abstract

The embodiment of the application provides a voltage protection circuit and related equipment, and belongs to the technical field of circuit protection. The application adopts a normally open contact relay, and combines the circuit structure design. No matter whether overvoltage is suddenly encountered in circuit operation or the device is powered on in an overvoltage state, the relay contact maintains a disconnected state. The control circuit can command the relay to be closed when the voltage is normal, instead of commanding the relay to be disconnected when the voltage is overvoltage. The possibility of the relay being incorrectly closed in the initial overvoltage stage due to power-on initialization of the control circuit, delay of judgment and the like is fundamentally eliminated, and instant protection of the subsequent circuit is realized.

Description

Technical Field

[0001] This application relates to the field of circuit protection technology, and in particular to a voltage protection circuit and related equipment. Background Technology

[0002] With the acceleration of urbanization, elevators have become an indispensable vertical transportation tool in modern buildings. The number of elevators in China continues to grow, bringing with it fierce market competition. Against this backdrop, cost control and reliability improvement of elevator control components have become key factors for manufacturers to gain a market advantage.

[0003] The installation and commissioning phases of elevators typically face unique power supply environments. During building construction, the elevator control system and its related components rely on temporary power supplies for functional testing. Only after the building is completed and handed over to the property management does it switch to the mains power grid. Temporary power grids are often unstable, with significant voltage fluctuations. Temporary power, nominally rated at AC380V or AC220V, may experience voltage spikes far exceeding design standards due to grid fluctuations, such as soaring to AC450V or even higher. Such abnormally high voltages can easily exceed the withstand voltage range of the elevator's internal electronic components, leading to permanent damage to critical components such as power modules, control chips, and sensors.

[0004] The component damage caused by the above two scenarios not only results in direct economic losses, but the time required for component replacement also significantly delays the construction schedule, placing additional reputational and cost pressures on elevator installers and manufacturers. Therefore, the technical challenge of integrating effective overvoltage protection circuits into elevator control systems needs to be addressed. Summary of the Invention

[0005] The main objective of this application is to provide a voltage protection circuit and related equipment to achieve effective overvoltage protection for elevators.

[0006] To achieve the above objectives, one aspect of this application provides a voltage protection circuit, comprising: The input AC rectifier circuit is used to rectify the AC input voltage into the DC bus voltage; A power supply circuit, connected to the output terminal of the input AC rectifier circuit, is used to convert the DC bus voltage into a first DC voltage; A reference source circuit is connected to the output terminal of the power supply circuit, and the reference source circuit is used to generate a reference voltage based on the first DC voltage. An input voltage comparison circuit is connected to the output terminal of the input AC rectifier circuit and the output terminal of the reference source circuit, respectively. The input voltage comparison circuit is used to compare the voltage divider signal of the DC bus voltage with the voltage divider signal of the reference voltage and output the comparison result signal. A relay control circuit is connected to the output terminal of the input voltage comparison circuit. The relay control circuit is used to control the on / off state of the relay according to the comparison result signal, so as to connect or disconnect the power supply to the downstream load. The relay control circuit includes a normally open contact relay.

[0007] In some embodiments, the input voltage comparison circuit includes a comparator; the inverting input terminal of the comparator is connected to the DC bus voltage through a first voltage divider resistor network; the non-inverting input terminal of the comparator is connected to the reference voltage through a second voltage divider resistor network; and the output terminal of the comparator is connected to the non-inverting input terminal through a feedback resistor.

[0008] In some embodiments, the inverting input terminal of the comparator is connected to a first filter capacitor, and the non-inverting input terminal of the comparator is connected to a second filter capacitor; the capacitance values ​​of the first filter capacitor and the second filter capacitor are configured such that when the circuit is powered on, the voltage at the inverting input terminal establishes up faster than the voltage at the non-inverting input terminal.

[0009] In some embodiments, the relay control circuit includes a transistor and the normally open contact relay; the base of the transistor receives the comparison result signal output by the input voltage comparison circuit through a current-limiting resistor; the collector of the transistor is connected to one end of the relay coil, and the emitter of the transistor is grounded; the other end of the relay coil is connected to the first DC voltage; when the comparison result signal is high, the transistor is turned on, the relay coil is energized, and the normally open contact of the normally open contact relay is closed; when the comparison result signal is low, the transistor is turned off, the relay coil is de-energized, and the normally open contact of the normally open contact relay is open.

[0010] In some embodiments, the circuit further includes: An overvoltage indicator circuit is connected to the output terminal of the input voltage comparison circuit. The overvoltage indicator circuit is used to illuminate when the comparison result signal indicates overvoltage.

[0011] In some embodiments, the overvoltage indicator circuit includes a current-limiting resistor, a Zener diode, and a light-emitting diode connected in series; one end of the current-limiting resistor is connected to the first DC voltage, and the cathode of the light-emitting diode is connected to the output terminal of the input voltage comparison circuit; when the input voltage comparison circuit outputs a low level, a voltage difference is formed across the light-emitting diode to emit light.

[0012] In some embodiments, the input AC rectifier circuit includes a surge suppression resistor connected in series on the AC input live wire and a rectifier bridge; at least two series-connected bus capacitors are connected in parallel between the positive and negative terminals of the DC output of the rectifier bridge, and a voltage equalization resistor is connected in parallel between the connection point of the at least two series-connected bus capacitors and the negative terminal of the DC output.

[0013] In some embodiments, the power supply circuit includes an integrated power chip, the input terminal of which is connected to the DC bus voltage via a Zener diode, and the output terminal of which is connected to the first DC voltage; the power supply circuit also includes a spike absorption circuit connected to the output terminal of the integrated power chip, the spike absorption circuit being composed of a diode, a resistor, and a capacitor.

[0014] In some embodiments, the reference source circuit includes a reference source chip and a third voltage divider resistor network; the input terminal of the reference source chip is connected to the first DC voltage, and the output terminal of the reference source chip outputs the reference voltage after voltage division by the third voltage divider resistor network.

[0015] To achieve the above objectives, another aspect of the embodiments of this application proposes an electronic device equipped with the circuit described above.

[0016] The embodiments of this application include at least the following beneficial effects: This application provides a voltage protection circuit, including: an input AC rectifier circuit for rectifying AC input voltage into DC bus voltage; a power supply circuit connected to the output terminal of the input AC rectifier circuit for converting the DC bus voltage into a first DC voltage; a reference source circuit connected to the output terminal of the power supply circuit, which generates a reference voltage based on the first DC voltage; an input voltage comparison circuit connected to the output terminals of the input AC rectifier circuit and the reference source circuit, which compares the voltage division signal of the DC bus voltage with the voltage division signal of the reference voltage and outputs a comparison result signal; and a relay control circuit connected to the output terminal of the input voltage comparison circuit, which controls the on / off state of the relay according to the comparison result signal to connect or disconnect the power supply to the downstream load. The relay control circuit includes a normally open contact relay. This application uses a normally open contact relay, and combined with the circuit structure design of this application, the relay contacts remain open regardless of whether the circuit encounters an overvoltage during operation or when powering on the device under an overvoltage condition. The control circuit can command the relay to close when the voltage is normal, rather than commanding it to open when there is an overvoltage. This fundamentally eliminates the possibility of the relay erroneously closing in the early stages of an overvoltage due to reasons such as power-on initialization and judgment delays in the control circuit, thus achieving immediate protection for subsequent circuits. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the voltage protection circuit provided in the embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0020] This embodiment provides a high input voltage protection circuit, which can be directly applied to the front end of elevator control systems or other electrical equipment requiring AC overvoltage protection to reliably cut off the power supply to downstream equipment when the input voltage is abnormal. Figure 1 As shown, the circuit mainly consists of six functional parts: input AC rectifier circuit 1, power supply circuit 2, reference source circuit 3, input voltage comparator circuit 4, relay control circuit 5, and overvoltage indicator circuit 6. Each part will be described in detail below.

[0021] The input AC rectifier circuit 1 serves as the front-end interface and energy preprocessing unit for the entire system. Its input is connected to an external AC power source, such as nominal AC 220V mains power or temporary construction site power, specifically including a live wire (220VLI) and a neutral wire (220VN). The output generates a high-voltage DC bus voltage V1.

[0022] The 220VLI live wire is first connected in series with a surge suppression resistor R2, and then connected to the two AC input terminals of rectifier bridge B1 along with the 220VN neutral wire. Rectifier bridge B1 consists of four diodes forming a full-bridge rectifier structure. The core advantage of this design is that regardless of the polarity of the external 220VLI and 220VN inputs, rectifier bridge B1 can guarantee a constant polarity at its DC output: the positive output is at a high potential, and the negative output is connected to system ground (AGND). This fundamentally achieves insensitivity to AC input polarity, improving the circuit's installation tolerance. It also solves the problem of electrical equipment issues that might occur if the live and neutral wires were reversed during construction.

[0023] The main function of the series resistor R2 is to suppress cold-start surge current. At the moment of power-on, the large-capacity filter capacitors (C3, C8) in the subsequent stage are essentially in a short-circuit state. Without the limitation of R2, the rectifier bridge B1 will be subjected to a huge instantaneous current surge, which is very easy to damage. R2 can effectively dampen this surge and protect the rectifier bridge.

[0024] The pulsating DC voltage output from rectifier bridge B1 is smoothed by a filter network consisting of capacitors C3 and C8 connected in series, forming a stable DC bus voltage V1. Since V1 is relatively high under normal operating conditions (approximately 310V with AC220V input), two electrolytic capacitors (C3 and C8) are connected in series to share the voltage. To ensure uniform voltage distribution across the series capacitors and prevent overvoltage in any capacitor due to individual capacitance differences, a voltage-equalizing resistor R1 is connected in parallel across capacitor C3, and a voltage-equalizing resistor R5 is connected in parallel across capacitor C8. R1 and R5 have equal and high-precision resistance values, forcing the DC voltages across C3 and C8 to be equal, thus ensuring the long-term reliability of the filter capacitors.

[0025] Power supply circuit 2 draws power from the high-voltage DC bus V1 and provides a stable, isolated (or non-isolated) low-voltage operating power supply for all subsequent low-voltage control circuits. Its input is connected to the DC bus voltage V1, and its output provides a first DC voltage VCC12 (e.g., +12V).

[0026] In this embodiment, the power supply circuit 2 includes an integrated switching power supply chip U1 as its core. This chip integrates a high-voltage startup unit, an oscillator, an error amplifier, a driver stage, and a power MOSFET, greatly simplifying the external circuitry. V1 is connected to the drain pin of chip U1 through a Zener diode D2, which serves as a step-down and preliminary voltage regulator. Chip U1 charges its external energy storage capacitors C1 and C2 on its VCC pin through an internal high-voltage current source. When the voltage across C1 / C2 reaches the chip's startup threshold, the internal controller starts working, driving the power MOSFET to perform high-frequency switching.

[0027] Switching energy is transferred and freewheeled through energy storage inductor L1 and freewheeling diode D1. The output uses an LCπ-type filter composed of C5 (electrolytic capacitor, low-frequency filter), C6 (ceramic capacitor, high-frequency filter), and inductor L1 to produce a stable output voltage VCC12 with minimal ripple. Capacitor C4 is connected in parallel to the input side of U1 to absorb high-frequency interference from the preceding stage.

[0028] A classic RCD (resistor-capacitor-diode) snubber circuit, consisting of resistor R3, capacitor C7, and diode D3, is connected to the switching node of chip U1 or the primary winding of the transformer (depending on the specific chip topology). This circuit effectively absorbs voltage spikes generated when the MOSFET is turned off due to transformer leakage inductance or line parasitic inductance, preventing the power transistor inside chip U1 from being overvoltage-damped. This is one of the key measures to ensure the stable operation of the power supply circuit itself under high input voltage.

[0029] Reference source circuit 3 generates a high-precision, low-temperature-drift reference voltage as a benchmark for the system to determine whether the input voltage is overvoltage. Its input is connected to VCC12, and its output provides the reference voltage VCC5. Reference source circuit 3 includes a three-terminal adjustable precision reference source chip U2. Its cathode (K) is connected to VCC12 through a current-limiting resistor, its anode (A) is grounded, and its reference terminal (R) is connected to the midpoint of a voltage divider network composed of resistors R11 and R15.

[0030] By precisely selecting the values ​​of R11 and R15, a stable and accurate 5V reference voltage can be obtained. Capacitor C9 is connected in parallel at the output terminal for further filtering, improving the purity of the reference voltage.

[0031] Input voltage comparison circuit 4 is responsible for monitoring the input voltage in real time and comparing it with a set threshold. It receives the V1 signal from circuit 1 and the VCC5 signal from circuit 3, and outputs logic control signals to circuits 5 and 6.

[0032] This embodiment uses a unit U3A from a dual voltage comparator chip (such as LM393). Its power supply pin (VCC) is connected to VCC12 and decoupled by capacitor C12. The ground pin (GND) is connected to AGND. At the inverting input of U3A, the DC bus voltage V1 is divided by high-resistance precision resistors R16 and R17. The voltage at the dividing point V- = V1 * [R17 / (R16 + R17)]. This voltage V- directly and linearly reflects the amplitude of the input AC voltage. At the non-inverting input of U3A, the reference voltage VCC5 is divided by precision resistors R12 and R13 to obtain a fixed reference threshold V+_normal = VCC5 * [R12 / (R12 + R13)]. A feedback resistor R10 is connected between the output of comparator U3A and its non-inverting input. This design introduces positive feedback, forming a hysteresis comparator with Schmitt trigger characteristics.

[0033] When the circuit is operating normally, the output is high. At this time, through the feedback effect of R10, the actual threshold voltage at the non-inverting input is raised to a higher level, V+high (its specific value is determined by R10, R12, R13, R7, and VCC5, etc.). Figure 1As shown in the equivalent circuit. When the input voltage rises to cause V -> V+_high, the output of the comparator flips to a low level. After the output is at a low level, the feedback reduces the threshold of the non-inverting input terminal to a lower level V+low. Only when the input voltage drops to make V- < V+low, the comparator outputs a high level again. The voltage difference between V+high and V+low forms a hysteresis window, effectively preventing output jitter caused by noise or ripple near the threshold point of the input voltage, ensuring that the relay operates crisply and stably.

[0034] Capacitor C14 is connected in parallel between the inverting input terminal (V-) and the ground. Capacitor C13 is connected in parallel between the non-inverting input terminal (V+) and the ground to achieve fast response and anti-interference filtering of the voltage comparator chip.

[0035] To ensure that at the moment of power-on, if the input is already in an overvoltage state, the protection can take effect immediately, in this embodiment, the capacitance value of capacitor C14 is intentionally selected to be smaller than that of capacitor C13. This makes the establishment speed of the V- signal reflecting the instantaneous input voltage (the time constant is determined by (R16 / / R17)*C14) faster than the establishment speed of the V+ signal reflecting the stable reference (the time constant is determined by (R12 / / R13)*C13). Therefore, during the power-on process, V- will reach the effective value earlier than V+. If the input is overvoltage at this time, V- will quickly exceed the still rising V+, forcing the output of the comparator to be locked at a low level from the beginning, creating conditions for the subsequent relay control circuit to achieve "zero-time" protection.

[0036] For the other unused comparator unit U3B in the dual comparator chip, short-circuit its non-inverting input terminal (pin 5) and inverting input terminal (pin 6) together through a resistor R18 and connect them to the system ground (AGND) together. At the same time, leave its output terminal (pin 7) floating. This processing method can prevent the floating input terminal from picking up environmental noise and interfering with the in-use U3A unit, improving the stability of the entire comparison circuit operation.

[0037] The relay control circuit 5 drives the relay to operate according to the logic level output by the comparator, directly controlling whether the main power supply is delivered to the subsequent load. The relay control circuit 5 uses an electromagnetic relay K1 with a normally open contact as the main path switch. When the relay coil of the electromagnetic relay K1 is not powered, its contacts are open. An NPN-type triode Q1 is used as the switch driving tube. Its base receives the control signal from the output terminal of the comparator U3A through a current-limiting and voltage-dividing network composed of resistors R7 and R8. The emitter is grounded (AGND). The collector is connected to one end of the relay K1 coil, and the other end of the coil is connected to VCC12. A freewheeling diode D4 is connected in anti-parallel across the relay coil to absorb the reverse induced electromotive force generated when the coil is powered off and protect the triode Q1 from being broken down.

[0038] When the input voltage is normal, and comparator U3A outputs a high level (approximately VCC12), this high level, through resistors R7 and R8, causes the base voltage Vbe of Q1 to exceed its conduction threshold (approximately 0.7V), causing Q1 to saturate and conduct. The relay K1 coil is energized, generating a magnetic field that attracts its normally open contacts, thus allowing the input live wire (220VLI) to be output (220VLO) through the contacts to the subsequent elevator control components.

[0039] When an overvoltage is detected, comparator U3A outputs a low level (close to 0V), and Q1 is cut off due to the lack of driving current at its base. The relay K1 coil is de-energized, the magnetic field disappears, and its normally open contact immediately resets and opens under the action of the spring, physically and completely cutting off the power supply path from 220VLI to the subsequent stage.

[0040] The relay control circuit design ensures the system's "fail-safe" characteristics. The circuit's default state (no control signal or control signal low) is the power-off state. Only after the protection circuit itself has completed power-on, self-testing, and clearly determined that the voltage is safe will it actively issue a closing command. This solves the problem of blind spots in overvoltage protection during power-on that exists in traditional solutions using normally closed contact relays.

[0041] The overvoltage indicator circuit 6 provides a clear status indication, allowing field personnel to quickly identify the system status. The overvoltage indicator circuit 6 includes a current-limiting resistor R14, a Zener diode D6, and an LED D5, connected in series. One end of these three components is connected to VCC12, and the other end is connected to the output of comparator U3A (i.e., the base drive point of transistor Q1). In normal operation, the comparator outputs a high level, the potentials across the indicator circuit are essentially equal, no current flows, and LED D5 is off. In overvoltage mode, the comparator outputs a low level, creating a voltage difference approximately equal to VCC12 across the indicator circuit. Current flows from VCC12 through R14, D6, and D5 to the low-level end. The Zener diode D6 establishes a suitable conduction threshold to prevent false triggering due to slight voltage fluctuations. When the current reaches the turn-on current of D5, D5 illuminates stably, clearly indicating that the system has entered overvoltage protection mode.

[0042] Based on the above circuit modules, the overvoltage protection circuit described in this embodiment operates as follows: Connect to an AC power supply (AC220V). Regardless of whether it is connected in reverse, the rectifier bridge B1 outputs the correct DC polarity.

[0043] The DC bus voltage V1 is established. Power supply circuit 2 starts working, generating a stable VCC12. Reference source circuit 3 then establishes a stable VCC5.

[0044] During the voltage establishment process, due to the design of C14 < C13, the V- signal in the input voltage comparison circuit 4 leads the V+ signal to establish. If the power-on voltage is overvoltage, V- rapidly exceeds the slowly rising V+, and the comparator U3A outputs and maintains a low level from the beginning. The relay K1 is never powered on, the normally open contact is always open, and the subsequent equipment has no power at all, obtaining absolute protection. If the power-on voltage is normal, V- stabilizes at a value lower than V+low, and the comparator U3A outputs a high level.

[0045] During normal power supply, the high level of the comparator drives the triode Q1 to conduct, the relay K1 is attracted, the normally open contact is closed, and the system supplies power to the subsequent stage normally. The indicator light D5 goes out.

[0046] When overvoltage occurs during operation, the input voltage rises abnormally → V1 rises → V- rises. When V->V+high, the comparator U3A quickly flips to a low level. The triode Q1 is instantaneously cut off, the coil of the relay K1 loses power, and its normally open contact mechanically disconnects within a few milliseconds. The power supply path is physically cut off, and the overvoltage indicator light D5 lights up.

[0047] When the overvoltage returns to normal, the input voltage drops → V1 drops → V- drops. When V-<V+low, the comparator U3A outputs a high level again. The triode Q1 conducts, the relay K1 is attracted, and the power supply is restored. The indicator light D5 goes out.

[0048] It can be understood that the content in the above method embodiments is applicable to the device embodiments of this application. The functions specifically implemented by the device embodiments of this application are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0049] The embodiments of this application also provide an electronic device, which includes the voltage protection circuit mentioned in the above embodiments. The electronic device can be any intelligent terminal including a tablet computer, a vehicle-mounted computer, etc.

[0050] It can be understood that the content in the above method embodiments is applicable to the device embodiments of this application. The functions specifically implemented by the device embodiments of this application are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0051] It can be understood that the content in the above method embodiments is applicable to the program product embodiments of this application. The functions specifically implemented by the program product embodiments of this application are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0052] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0053] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0054] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0055] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0056] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0057] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0058] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0059] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0060] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0061] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0062] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A voltage protection circuit, characterized in that, The circuit includes: The input AC rectifier circuit is used to rectify the AC input voltage into the DC bus voltage; A power supply circuit, connected to the output terminal of the input AC rectifier circuit, is used to convert the DC bus voltage into a first DC voltage; A reference source circuit is connected to the output terminal of the power supply circuit, and the reference source circuit is used to generate a reference voltage based on the first DC voltage. An input voltage comparison circuit is connected to the output terminal of the input AC rectifier circuit and the output terminal of the reference source circuit, respectively. The input voltage comparison circuit is used to compare the voltage divider signal of the DC bus voltage with the voltage divider signal of the reference voltage and output the comparison result signal. A relay control circuit is connected to the output terminal of the input voltage comparison circuit. The relay control circuit is used to control the on / off state of the relay according to the comparison result signal, so as to connect or disconnect the power supply to the downstream load. The relay control circuit includes a normally open contact relay.

2. The circuit according to claim 1, characterized in that, The input voltage comparison circuit includes a comparator; the inverting input terminal of the comparator is connected to the DC bus voltage through a first voltage divider resistor network; the non-inverting input terminal of the comparator is connected to the reference voltage through a second voltage divider resistor network; and the output terminal of the comparator is connected to the non-inverting input terminal through a feedback resistor.

3. The circuit according to claim 2, characterized in that, The inverting input of the comparator is connected to a first filter capacitor, and the non-inverting input of the comparator is connected to a second filter capacitor. The capacitance values ​​of the first filter capacitor and the second filter capacitor are configured such that when the circuit is powered on, the voltage at the inverting input is established faster than the voltage at the non-inverting input.

4. The circuit according to claim 1, characterized in that, The relay control circuit includes a transistor and the normally open contact relay. The base of the transistor receives the comparison result signal output by the input voltage comparison circuit through a current-limiting resistor. The collector of the transistor is connected to one end of the relay coil, and the emitter of the transistor is grounded. The other end of the relay coil is connected to the first DC voltage. When the comparison result signal is high, the transistor is turned on, the relay coil is energized, and the normally open contact of the normally open contact relay is closed. When the comparison result signal is low, the transistor is turned off, the relay coil is de-energized, and the normally open contact of the normally open contact relay is open.

5. The circuit according to claim 1, characterized in that, The circuit also includes: An overvoltage indicator circuit is connected to the output terminal of the input voltage comparison circuit. The overvoltage indicator circuit is used to illuminate when the comparison result signal indicates overvoltage.

6. The circuit according to claim 5, characterized in that, The overvoltage indicator circuit includes a current-limiting resistor, a Zener diode, and a light-emitting diode connected in series. One end of the current-limiting resistor is connected to the first DC voltage, and the cathode of the light-emitting diode is connected to the output terminal of the input voltage comparison circuit. When the input voltage comparison circuit outputs a low level, a voltage difference is formed across the light-emitting diode, causing it to emit light.

7. The high input voltage safe and stable overvoltage protection circuit according to claim 1, characterized in that, The input AC rectifier circuit includes a surge suppression resistor connected in series on the AC input live wire and a rectifier bridge; at least two series-connected bus capacitors are connected in parallel between the positive and negative terminals of the DC output of the rectifier bridge, and a voltage equalization resistor is connected in parallel between the connection point of the at least two series-connected bus capacitors and the negative terminal of the DC output.

8. The high input voltage safe and stable overvoltage protection circuit according to claim 1, characterized in that, The power supply circuit includes an integrated power chip. The input terminal of the integrated power chip is connected to the DC bus voltage through a Zener diode, and the output terminal of the integrated power chip is connected to the first DC voltage. The power supply circuit also includes a spike absorption circuit connected to the output terminal of the integrated power chip. The spike absorption circuit consists of a diode, a resistor, and a capacitor.

9. The high input voltage safe and stable overvoltage protection circuit according to claim 1, characterized in that, The reference source circuit includes a reference source chip and a third voltage divider resistor network; the input terminal of the reference source chip is connected to the first DC voltage, and the output terminal of the reference source chip outputs the reference voltage after voltage division by the third voltage divider resistor network.

10. An electronic device, characterized in that, The electronic device is equipped with the circuitry as described in any one of claims 1 to 9.

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