Overvoltage protection circuit, AC electrical equipment controller and AC electrical equipment

Abstract

The invention discloses an overvoltage protection circuit, an AC electrical equipment controller and AC electrical equipment, and belongs to the field of overvoltage protection. The overvoltage protection circuit comprises a sampling unit, a switch unit, a controllable switch tube and a control unit. The sampling unit is used for acquiring voltage between a live wire and a zero wire; the input of the control unit is connected with the sampling unit, the control electrode of the controllable switch tube is connected with the sampling unit, the input electrode is connected with the second path, and the output electrode is connected with the zero line or the live line. The output of the control unit is connected with the switch unit; the switch unit comprises two paths, when the voltage between the live wire and the null line is smaller than or equal to a threshold value, the first path is conducted, and the live wire or the null line is directly connected with the load unit; when the voltage between the live wire and the zero wire is greater than a threshold value, the second path is conducted, and the controllable switch tube is conducted; part or all of the current flows to the output stage from the input stage of the controllable switching tube, so that the subsequent load unit cannot be damaged due to overvoltage, and the reliable operation of the load unit is ensured.

Description

Technical Field

[0001] This application relates to the field of overvoltage protection technology, and in particular, to an overvoltage protection circuit, an AC electrical equipment controller, and an AC electrical equipment. Background Technology

[0002] Existing controllers for air conditioners, air source water heaters, and refrigerators typically rectify and filter the AC 220V high-voltage power into DC 310V, and then use a switching power supply to convert it into isolated DC 12V / 5V / 3.3V to power the chips and other loads.

[0003] The rectifier bridge, large electrolytic capacitor, and switching power supply chip are the core components of the controller. Their withstand voltage is generally around 450V. Therefore, when the rectified voltage reaches 400V, the switching power supply chip will activate high voltage protection, and the controller will not work. If the voltage continues to rise, it will cause the rectifier bridge and large electrolytic capacitor to be permanently damaged.

[0004] If there were a way to reduce the voltage when the input voltage is too high, allowing components such as the rectifier bridge, large electrolytic capacitor, and switching power supply chip to operate at a safe voltage, it would prevent the controller from malfunctioning due to excessive voltage and ensure the long-term stable operation of the controller and the unit. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, this application provides an overvoltage protection circuit, an AC electrical equipment controller, and an AC electrical equipment to solve the problem that current AC electrical equipment will activate high voltage protection when the AC voltage exceeds a certain level, and the controller will not work; if the voltage continues to rise, it will cause permanent breakdown and damage to the rectifier bridge and large electrolytic capacitor.

[0006] The technical solution adopted by this application to solve its technical problem is: In a first aspect, an overvoltage protection circuit is provided, comprising: a sampling unit, a switching unit, a controllable switching transistor, and a control unit; The sampling unit is used to obtain the voltage between the live wire and the neutral wire; The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit. The switching unit includes two paths. When the voltage between the live wire and the neutral wire is less than or equal to a threshold, the first path is turned on, and the live wire or the neutral wire is directly connected to the load unit. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is turned on, and the controllable switch is turned on. The controllable switch is connected to the sampling unit at its controllable electrode, to the second path at its input electrode, and to the neutral or live wire at its output electrode.

[0007] As an optional implementation of this application, a current-limiting resistor is provided on the second path; The current-limiting resistor is connected to the input terminal of the controllable switch.

[0008] As an optional implementation of this application, the second path is provided with a current-limiting resistor and a protection resistor; One end of the protection resistor is connected to the current-limiting resistor, and the other end is connected to the input terminal of the controllable switching transistor; The load unit is connected to the connection point of the current-limiting resistor and the protection resistor.

[0009] As an optional implementation of this application, the control unit includes an optocoupler; The positive terminal of the light-emitting diode of the optocoupler is connected to the sampling unit, and the negative terminal of the light-emitting diode is connected to the live wire or the neutral wire; The collector of the optocoupler's phototransistor is connected to a DC power supply, and the emitter of the phototransistor is connected to the switching unit.

[0010] As an optional implementation of this application, the switching unit is a single-pole double-throw relay; The coil portion of the single-pole double-throw relay is connected to the output of the control unit; the stationary terminal of the single-pole double-throw switch portion of the single-pole double-throw relay is connected to the neutral or live wire; and the two moving terminals of the single-pole double-throw switch tube portion of the single-pole double-throw relay are respectively connected to the first path and the second path.

[0011] As an optional implementation of this application, the sampling unit includes a series path consisting of two resistors, the series path being disposed between the live wire and the neutral wire; The output of the sampling unit is the voltage between two resistors.

[0012] As an optional implementation of this application, the input terminal of the controllable switch is also connected to a diode.

[0013] As an optional implementation of this application, the controllable switching transistor may be any of the following: MOSFET; IGBT; triode.

[0014] In a second aspect, an AC electrical equipment controller is provided, including the overvoltage protection circuit described in any of the above claims.

[0015] Thirdly, an AC electrical appliance is provided, which uses the aforementioned AC electrical appliance controller.

[0016] Beneficial effects: This application provides an overvoltage protection circuit, an AC electrical equipment controller, and an AC electrical equipment. The overvoltage protection circuit includes a sampling unit, a switching unit, a controllable switching transistor, and a control unit. The sampling unit acquires the voltage between the live wire and the neutral wire. The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit. The switching unit includes two paths: when the voltage between the live wire and the neutral wire is less than or equal to a threshold, the first path is activated, and the live wire or neutral wire is directly connected to the load unit; when the voltage between the live wire and the neutral wire is greater than the threshold, the second path is activated, and the controllable switching transistor is activated. The control electrode of the controllable switching transistor is connected to the sampling unit, its input electrode is connected to the second path, and its output electrode is connected to the neutral wire or the live wire. In this application, when the voltage between the live wire and the neutral wire is less than or equal to a threshold, the load unit is normally connected to the live wire and the neutral wire. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is turned on. At this time, the controllable switch is turned on, and part or all of the current flows from the input terminal of the controllable switch to the output stage. In this way, the subsequent load unit will not be damaged due to overvoltage, ensuring the reliable operation of the load unit. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a block diagram of an overvoltage protection circuit provided in an embodiment of this application; Figure 2 This is a circuit diagram of an overvoltage protection circuit using MOSFETs provided in an embodiment of this application; Figure 3 This is a circuit diagram of an overvoltage protection circuit using an IGBT provided in an embodiment of this application; Figure 4 This is a circuit diagram of an overvoltage protection circuit using a transistor provided in an embodiment of this application; Figure 5 This is a circuit diagram of another overvoltage protection circuit using MOSFETs provided in an embodiment of this application; Figure 6 This is a circuit diagram of another overvoltage protection circuit using IGBT provided in an embodiment of this application; Figure 7 This is a circuit diagram of another overvoltage protection circuit using a transistor provided in an embodiment of this application; Figure 8This is a circuit diagram of an AC electrical equipment controller provided in an embodiment of this application; Figure 9 This is one of the embodiments provided in this application. Figure 8 The control flow diagram of the circuit shown.

[0019] Explanation of reference numerals in the attached figures: L-Firewire; N-Neutral wire; G1 - Sampling unit output signal; G2 - Second sampling unit output signal R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; R6 - the sixth resistor; R7 - the seventh resistor; R8 - Second current-limiting resistor; R9 - Ninth resistor; R10 - Current-limiting resistor; R11 - Protection resistor; Q1 - Controllable switching transistor; Q2 - Second controllable switch transistor; K1 - Single-pole double-throw relay; K2 - Second Single-Pole Double-Throw Relay; D21 - Fourth diode; D2 - Second diode; D3 - Third diode; D1 - First diode; Q3 - Optocoupler; Q4 - Second optocoupler; DB1 - Rectifier bridge; C1 - Capacitor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] Existing overvoltage protection technologies often employ Zener diodes, such as TVS diodes (Transient Voltage Suppressor). TVS diodes are highly efficient transient voltage suppression devices, operating on the principle of avalanche breakdown, resulting in extremely fast response times (picoseconds). Under normal conditions, they present high impedance to the circuit; however, when encountering transient overvoltages (such as ESD or surges), they rapidly (<1ns) transition to low impedance, discharging the large overcurrent to ground and clamping the voltage to a safe value, thus protecting downstream precision components. They do not react to low voltages. However, they suffer from relatively large junction capacitance, leakage current issues, and limited response time. Furthermore, TVS diodes have a limited number of uses; after a few overvoltage protection cycles, the TVS diode needs to be replaced to maintain its overvoltage protection effectiveness, leading to high costs.

[0022] Alternatively, an overvoltage protection circuit and method, as disclosed in patent application CN120657682A, includes a sampling circuit, a current mirror circuit, a charging circuit, and a comparator circuit. The sampling circuit samples the voltage at the voltage detection terminal to obtain a sampled voltage. The current mirror circuit scales down the sampled voltage and charges the charging circuit. The comparator circuit detects the voltage of the charging circuit and issues an overvoltage protection signal when the charging voltage exceeds a preset overvoltage protection threshold. This invention uses a current mirror circuit to scale down the current flowing through a first capacitor, then uses the scaled-down current to charge a second capacitor. When the voltage across the capacitor reaches a threshold, overvoltage protection is triggered. In this invention, the voltage sampling network is a capacitor, resulting in no static power consumption. Furthermore, the capacitors can be integrated into the chip, effectively improving system integration. However, this method uses a large number of thyristors, leading to higher costs.

[0023] Furthermore, all of the above are overvoltage protection applications for DC power.

[0024] To solve this problem, refer to Figure 1 This application provides an overvoltage protection circuit, including: a sampling unit, a switching unit, a controllable switching transistor, and a control unit; The sampling unit is used to obtain the voltage between the live wire and the neutral wire; The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit. The switching unit includes two paths. When the voltage between the live wire and the neutral wire is less than or equal to a threshold, the first path is turned on, and the live wire or the neutral wire is directly connected to the load unit. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is turned on, and the controllable switch is turned on. The controllable switch is connected to the sampling unit at its controllable electrode, to the second path at its input electrode, and to the neutral or live wire at its output electrode.

[0025] In this application, when the voltage between the live wire and the neutral wire is less than or equal to a threshold, the load unit is normally connected to the live wire and the neutral wire. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is turned on. At this time, the controllable switch is turned on, and part or all of the current flows from the input terminal of the controllable switch to the output stage. In this way, the subsequent load unit will not be damaged due to overvoltage, ensuring the reliable operation of the load unit.

[0026] Example 1 like Figure 2 , Figure 3 and Figure 4 As shown, the overvoltage protection circuit includes: a sampling unit, a switching unit, a controllable switching transistor Q1, and a control unit; The sampling unit is used to obtain the voltage between the live wire L and the neutral wire N; the sampling unit includes a series path composed of a first resistor R1 and a second resistor R2, the series path being set between the live wire L and the neutral wire N; the output signal G1 of the sampling unit is the voltage between the first resistor R1 and the second resistor R2.

[0027] The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit; as a preferred implementation of this application embodiment, the control unit includes an optocoupler Q3; The positive terminal of the LED of the optocoupler Q3 is connected to the sampling unit through the seventh resistor R7, i.e., the output signal G1 of the sampling unit. The negative terminal of the LED is connected to the live wire L or the neutral wire N. Specifically, when the overvoltage protection circuit is used for overvoltage protection of the live wire L, the negative terminal of the LED is connected to the neutral wire N. When the overvoltage protection circuit is used for overvoltage protection of the neutral wire N, the negative terminal of the LED is connected to the live wire L.

[0028] The collector of the phototransistor of the optocoupler Q3 is connected to a DC power supply through the fifth resistor R5, such as Figures 2-4 The +12V voltage is used to power the switching unit, and the emitter of the photoelectric crystal is connected to the switching unit. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the LED of optocoupler Q3 does not conduct, and the DC power supply cannot power the switching unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the LED of optocoupler Q3 conducts, and the DC power supply powers the switching unit.

[0029] Understandably, utilizing the isolation function of optocoupler Q3 ensures electrical safety and enables it to function as a switch. In practice, other circuits can be used instead of optocoupler Q3, such as using an isolation chip for circuit isolation followed by control with a transistor or MCU chip.

[0030] The switching unit includes two paths. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the first path is turned on, and either the live wire L or the neutral wire N is directly connected to the load unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the second path is turned on, and the controllable switch Q1 is turned on. Preferably, the switching unit is a single-pole double-throw relay K1; The coil portion of the single-pole double-throw relay K1 is connected to the output of the control unit. The stationary terminal of the single-pole double-throw switch portion of the single-pole double-throw relay K1 is connected to either the neutral wire N or the live wire L. When the overvoltage protection circuit is used for overvoltage protection of the live wire L, the stationary terminal is connected to the live wire L; when the overvoltage protection circuit is used for overvoltage protection of the neutral wire N, the stationary terminal is connected to the neutral wire N. Furthermore, for safety, a fourth diode D21 is connected in parallel with the coil portion of the single-pole double-throw relay K1. After the coil is de-energized, the coil can discharge through the fourth diode D21.

[0031] The single-pole double-throw relay K1 has two moving terminals connected to the first and second paths, respectively. When the first path is open, the live wire L or the neutral wire N is directly connected to the load unit, and the load unit operates normally. The second path is equipped with a current-limiting resistor R10, which is connected to the input terminal of the controllable switch Q1. When the second path is open, the controllable switch Q1 is turned on, short-circuiting the load unit. This protects the load unit when the voltage between the live wire L and the neutral wire N exceeds a threshold value, and the current-limiting resistor R10 prevents excessive current from flowing through the controllable switch Q1.

[0032] The controllable switch Q1 is connected to the sampling unit at its controllable electrode, to the second path at its input electrode, and to the neutral line N or the live line L at its output electrode.

[0033] Preferably, the input terminal of the controllable switch Q1 is also connected to a second diode D2.

[0034] The controllable switch Q1 can be any of the following: MOSFET; such as Figure 2 As shown, an N-channel enhancement-mode MOSFET is used, with the gate as the control electrode, the source as the input electrode, and the drain as the output electrode.

[0035] IGBT; such as Figure 3 As shown, the control electrode is the gate, the input electrode is the source, and the output electrode is the drain.

[0036] Transistor; such as Figure 4 As shown, an NPN transistor is used, with the control electrode at the base, the input electrode at the collector, and the output electrode at the emitter.

[0037] The load unit can be an AC device, such as a light bulb or a motor. It can also be a module with a rectifier unit, such as a rectifier bridge or capacitors. This embodiment does not impose specific limitations.

[0038] It should be noted that the parameters of each component are determined based on actual conditions, and the embodiments in this application do not impose specific limitations.

[0039] The overvoltage protection circuit provided in this application includes a sampling unit, a switching unit, a controllable switch Q1, and a control unit. The sampling unit is used to acquire the voltage between the live wire L and the neutral wire N. The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit. The switching unit includes two paths. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the first path is turned on, and the live wire L or the neutral wire N is directly connected to the load unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the second path is turned on, and the controllable switch Q1 is turned on. The control electrode of the controllable switch Q1 is connected to the sampling unit, the input electrode is connected to the second path, and the output electrode is connected to the neutral wire N or the live wire L. In this application, when the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the load unit is normally connected to the live wire L and the neutral wire N. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the second path is turned on. At this time, the controllable switch Q1 is turned on, and all the current flows from the input terminal of the controllable switch Q1 to the output stage. In this way, the subsequent load unit is short-circuited and will not be damaged due to overvoltage, thus ensuring the reliable operation of the load unit.

[0040] Example 2 In Example 1, when the voltage between the live wire L and the neutral wire N is greater than the threshold, the load unit is short-circuited by the second path where the controllable switch Q1 is located. Although this avoids damage to the load unit, the load unit is not powered at this time, which may affect the use of the load unit under certain circumstances.

[0041] Based on this, such as Figure 5 , Figure 6 and Figure 7 As shown, the overvoltage protection circuit includes: a sampling unit, a switching unit, a controllable switching transistor Q1, and a control unit; The sampling unit is used to obtain the voltage between the live wire L and the neutral wire N; the sampling unit includes a series path composed of a first resistor R1 and a second resistor R2, the series path being set between the live wire L and the neutral wire N; the output signal G1 of the sampling unit is the voltage between the first resistor R1 and the second resistor R2.

[0042] The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit; as a preferred implementation of this application embodiment, the control unit includes an optocoupler Q3; The positive terminal of the LED of the optocoupler Q3 is connected to the sampling unit through the seventh resistor R7, i.e., the output signal G1 of the sampling unit. The negative terminal of the LED is connected to the live wire L or the neutral wire N. Specifically, when the overvoltage protection circuit is used for overvoltage protection of the live wire L, the negative terminal of the LED is connected to the neutral wire N. When the overvoltage protection circuit is used for overvoltage protection of the neutral wire N, the negative terminal of the LED is connected to the live wire L.

[0043] The collector of the phototransistor of the optocoupler Q3 is connected to a DC power supply through the fifth resistor R5, such as Figures 2-4 The +12V voltage is used to power the switching unit, and the emitter of the photoelectric crystal is connected to the switching unit. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the LED of optocoupler Q3 does not conduct, and the DC power supply cannot power the switching unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the LED of optocoupler Q3 conducts, and the DC power supply powers the switching unit.

[0044] Understandably, utilizing the isolation function of optocoupler Q3 ensures electrical safety and enables it to function as a switch. In practice, other circuits can be used instead of optocoupler Q3, such as using an isolation chip for circuit isolation followed by control with a transistor or MCU chip.

[0045] The switching unit includes two paths. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the first path is turned on, and either the live wire L or the neutral wire N is directly connected to the load unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the second path is turned on, and the controllable switch Q1 is turned on. Preferably, the switching unit is a single-pole double-throw relay K1; The coil portion of the single-pole double-throw relay K1 is connected to the output of the control unit. The stationary terminal of the single-pole double-throw switch portion of the single-pole double-throw relay K1 is connected to either the neutral wire N or the live wire L. When the overvoltage protection circuit is used for overvoltage protection of the live wire L, the stationary terminal is connected to the live wire L; when the overvoltage protection circuit is used for overvoltage protection of the neutral wire N, the stationary terminal is connected to the neutral wire N. Furthermore, for safety, a fourth diode D21 is connected in parallel with the coil portion of the single-pole double-throw relay K1. After the coil is de-energized, the coil can discharge through the fourth diode D21.

[0046] The single-pole double-throw relay K1 has two moving terminals connected to the first and second paths, respectively. When the first path is active, the live wire L or neutral wire N is directly connected to the load unit, and the load unit operates normally. The second path is equipped with a current-limiting resistor R10 and a protection resistor R11; one end of the protection resistor R11 is connected to the current-limiting resistor R10, and the other end is connected to the input terminal of the controllable switch Q1; the load unit is connected to the connection point of the current-limiting resistor R10 and the protection resistor R11. When the second path is active, the controllable switch Q1 is active. At this time, the load unit and the protection resistor R11 are connected in series and then in parallel with the load unit to form a parallel circuit. The parallel circuit is then connected in series with the current-limiting resistor R10. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the current-limiting resistor R10 actually acts as a voltage divider, reducing the voltage across the parallel circuit. This makes the voltage across the load unit less than the threshold, protecting the load unit. The protective resistor R11 is used to protect the controllable switch Q1 and prevent excessive current from flowing through it.

[0047] In a preferred implementation of this application, the current-limiting resistor R10 and / or the protection resistor R11 are adjustable resistors (i.e., resistors whose resistance value can be adjusted). By setting a control chip, the values ​​of the protection resistor R11 and / or the current-limiting resistor R10 are controlled according to the signal obtained from the sampling unit. This ensures that the voltage output from the load unit is the preset voltage. Because when both the protection resistor R11 and the current-limiting resistor R10 are fixed resistors, the voltages of the live wire L and the neutral wire N may exceed the threshold values ​​differently, resulting in voltage instability at the load unit. Therefore, the resistance value of one of the protection resistor R11 and the current-limiting resistor R10 can be adjusted according to the sampling value at the sampling unit to ensure that the voltage across the load unit is the preset voltage, guaranteeing the normal operation of the load unit.

[0048] Preferably, the current-limiting resistor R10 is a variable resistor, and the protection resistor R11 is a resistor with a fixed resistance value.

[0049] The controllable switch Q1 is connected to the sampling unit at its controllable electrode, to the second path at its input electrode, and to the neutral line N or the live line L at its output electrode.

[0050] Preferably, the input terminal of the controllable switch Q1 is also connected to a second diode D2.

[0051] The controllable switch Q1 can be any of the following: MOSFET; such as Figure 5 As shown, an N-channel enhancement-mode MOSFET is used, with the gate as the control electrode, the source as the input electrode, and the drain as the output electrode.

[0052] IGBT; such as Figure 6 As shown, the control electrode is the gate, the input electrode is the source, and the output electrode is the drain.

[0053] Transistor; such as Figure 7 As shown, an NPN transistor is used, with the control electrode at the base, the input electrode at the collector, and the output electrode at the emitter.

[0054] The load unit can be an AC device, such as a light bulb or a motor. It can also be a module with a rectifier unit, such as a rectifier bridge or capacitors. This embodiment does not impose specific limitations.

[0055] It should be noted that the parameters of each component are determined based on actual conditions, and the embodiments in this application do not impose specific limitations.

[0056] The overvoltage protection circuit provided in this application includes a sampling unit, a switching unit, a controllable switching transistor, and a control unit. The sampling unit is used to acquire the voltage between the live wire and the neutral wire. The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit. The switching unit includes two paths. When the voltage between the live wire and the neutral wire is less than or equal to a threshold, the first path is open, and the live wire or neutral wire is directly connected to the load unit. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is open, and the controllable switching transistor is turned on. The control electrode of the controllable switching transistor is connected to the sampling unit, the input electrode is connected to the second path, and the output electrode is connected to the neutral wire or the live wire. In this application, when the voltage between the live wire and the neutral wire is less than or equal to the threshold, the load unit is normally connected to the live wire and the neutral wire. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is open, the controllable switching transistor is turned on, and the current-limiting resistor diverts a portion of the voltage. This ensures that the voltage across the load unit is below the threshold and will not be damaged due to overvoltage, thus guaranteeing the reliable operation of the load unit.

[0057] Based on the same inventive concept, embodiments of this application provide an AC electrical equipment controller, which includes an overvoltage protection circuit on both the live wire and the neutral wire. The overvoltage protection circuit can be implemented in any of the above embodiments.

[0058] The following is based on Figure 8 The circuit shown is explained below: The overvoltage protection circuit on the live wire L includes: a sampling unit, a switching unit, a controllable switching transistor Q1, and a control unit; The sampling unit is used to obtain the voltage between the live wire L and the neutral wire N; the sampling unit includes a series path composed of a first resistor R1 and a second resistor R2, the series path being set between the live wire L and the neutral wire N; the output signal G1 of the sampling unit is the voltage between the first resistor R1 and the second resistor R2.

[0059] The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit; as a preferred implementation of this application embodiment, the control unit includes an optocoupler Q3; The positive terminal of the LED of the optocoupler Q3 is connected to the sampling unit through the seventh resistor R7, which is the output signal G1 of the sampling unit, and the negative terminal of the LED is connected to the neutral line N.

[0060] The collector of the phototransistor of the optocoupler Q3 is connected to a DC power supply through the fifth resistor R5, such as Figure 8 The +12V voltage is used to power the switching unit, and the emitter of the photoelectric crystal is connected to the switching unit. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the LED of optocoupler Q3 does not conduct, and the DC power supply cannot power the switching unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the LED of optocoupler Q3 conducts, and the DC power supply powers the switching unit.

[0061] Understandably, utilizing the isolation function of optocoupler Q3 ensures electrical safety and enables it to function as a switch. In practice, other circuits can be used instead of optocoupler Q3, such as using an isolation chip for circuit isolation followed by control with a transistor or MCU chip.

[0062] The switching unit includes two paths. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the first path is turned on, and either the live wire L or the neutral wire N is directly connected to the load unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the second path is turned on, and the controllable switch Q1 is turned on. Preferably, the switching unit is a single-pole double-throw relay K1; The coil portion of the single-pole double-throw relay K1 is connected to the output of the control unit; the stationary terminal of the single-pole double-throw switch portion of the single-pole double-throw relay K1 is connected to the live wire L. Furthermore, for safety, a fourth diode D21 is connected in parallel with the coil portion of the single-pole double-throw relay K1, allowing the coil to discharge through the fourth diode D21 after power is cut off.

[0063] The single-pole double-throw relay K1 has two moving terminals connected to the first and second paths, respectively. When the first path is open, the live wire L or the neutral wire N is directly connected to the load unit, and the load unit operates normally. The second path is equipped with a current-limiting resistor R10, which is connected to the input terminal of the controllable switch Q1. When the second path is open, the controllable switch Q1 is turned on, short-circuiting the load unit. This protects the load unit when the voltage between the live wire L and the neutral wire N exceeds a threshold value, and the current-limiting resistor R10 prevents excessive current from flowing through the controllable switch Q1.

[0064] The controllable switch Q1 is connected to the sampling unit at its controllable electrode, to the second path at its input electrode, and to the neutral line N or the live line L at its output electrode.

[0065] Preferably, the input terminal of the controllable switch Q1 is also connected to a second diode D2.

[0066] The controllable switch Q1 is an N-channel enhancement-mode MOSFET, with the gate as the control electrode, the source as the input electrode, and the drain as the output electrode.

[0067] The overvoltage protection circuit on the neutral line N includes: a second sampling unit, a second switching unit, a second controllable switch Q2, and a second control unit; The second sampling unit is used to acquire the voltage between the live wire L and the neutral wire N; the second sampling unit includes a series path composed of a fourth resistor R4 and a third resistor R3, the series path being set between the live wire L and the neutral wire N; the output signal G2 of the second sampling unit is the voltage between the fourth resistor R4 and the third resistor R3.

[0068] The input of the second control unit is connected to the second sampling unit, and the output of the second control unit is connected to the second switching unit; as a preferred implementation of this application embodiment, the second control unit includes a second optocoupler Q4; The positive terminal of the LED of the second optocoupler Q4 is connected to the second sampling unit, i.e., the output signal G2 of the second sampling unit, through the sixth resistor R6, and the negative terminal of the LED is connected to the live wire L.

[0069] The collector of the phototransistor of the second optocoupler Q4 is connected to a DC power supply through the ninth resistor R9, such as... Figure 8 The +12V voltage is used to power the second switching unit, and the emitter of the photoelectric crystal is connected to the second switching unit. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the LED of the second optocoupler Q4 does not conduct, and the DC power supply cannot power the second switching unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the LED of the second optocoupler Q4 conducts, and the DC power supply powers the second switching unit.

[0070] Understandably, utilizing the isolation function of the second optocoupler Q4 ensures electrical safety and enables the switching action. In practice, other circuits can be used instead of the second optocoupler Q4, such as using an isolation chip for circuit isolation followed by control with a transistor or MCU chip.

[0071] The second switching unit includes two paths. When the voltage between the live wire L and the neutral wire N is less than or equal to a threshold, the first path is turned on, and either the live wire L or the neutral wire N is directly connected to the load unit. When the voltage between the live wire L and the neutral wire N is greater than the threshold, the second path is turned on, and the second controllable switch Q2 is turned on. Preferably, the second switching unit is a second single-pole double-throw relay K2; The coil portion of the second single-pole double-throw relay K2 is connected to the output of the second control unit; the stationary terminal of the single-pole double-throw switch portion of the second single-pole double-throw relay K2 is connected to the neutral wire N. Furthermore, for safety, a first diode D1 is connected in parallel with the coil portion of the second single-pole double-throw relay K2, allowing the coil to discharge through the first diode D1 after power is cut off.

[0072] The two moving terminals of the single-pole double-throw (SPDT) switching transistor of the second single-pole double-throw relay K2 are connected to the first path and the second path, respectively. When the first path is open, the live wire L or the neutral wire N is directly connected to the load unit, and the load unit operates normally. A second current-limiting resistor R8 is provided on the second path; the second current-limiting resistor R8 is connected to the input terminal of the second controllable switching transistor Q2. When the second path is open, the second controllable switching transistor Q2 is turned on, short-circuiting the load unit. This protects the load unit when the voltage between the live wire L and the neutral wire N exceeds a threshold value. The second current-limiting resistor R8 prevents excessive current from flowing through the second controllable switching transistor Q2.

[0073] The control electrode of the second controllable switch Q2 is connected to the second sampling unit, the input electrode is connected to the second path, and the output electrode is connected to the neutral line N or the live line L.

[0074] Preferably, the input terminal of the second controllable switch Q2 is also connected to a third diode D3.

[0075] The second controllable switch Q2 is an N-channel enhancement-mode MOSFET, with the gate as the control electrode, the source as the input electrode, and the drain as the output electrode.

[0076] As a preferred implementation of this application, the load unit includes a rectifier bridge DB1, a capacitor C1, and a subsequent switching power supply circuit.

[0077] Its core lies in adding a dual-path overvoltage protection circuit to the AC input terminal of the controller (since it is AC, dual paths are required, as a single path cannot simultaneously protect against L-N overvoltage and N-L overvoltage), thereby enabling real-time monitoring and dynamic response to the instantaneous peak value of the input voltage, effectively protecting the downstream circuit under overvoltage conditions and ensuring the stable operation of the controller in a high-voltage environment.

[0078] Add switching devices Q1 / Q2 to the controller voltage input terminal, and add resistors R1, R2, R3, and R4 to set the overvoltage conduction preset value. Figure 8 The selected Q1 and Q2 are designed to conduct when Vgs is greater than 15V, in conjunction with the values ​​of resistors R1, R2, R3, and R4. Figure 8 The preset overvoltage conduction value is 405V; the corresponding optocoupler (here the optocoupler serves as isolation and control, but other circuits can be used instead, such as using an isolation chip for circuit isolation followed by control with a transistor or MCU chip) is selected. U6 and U7 are 5mA conduction, and with the help of resistors R6 and R7, when the instantaneous input voltage value exceeds the set value of 405V, the optocoupler conducts, and the relay is energized. Diodes D2 and D3 prevent the body diodes of Q1 and Q2 from shooting through. Figure 8 The MOSFET used is the N-channel enhancement-mode MOSFET commonly used in Q1 and Q2, but it can also be replaced by controllable switching transistors such as IGBT and transistors. The control method is the same: when the gate voltage (called the base in the case of a transistor) reaches the turn-on voltage, the drain and source conduct (called the collector and emitter in the case of a transistor). The working process is the same as that of a MOSFET.

[0079] Control process such as Figure 9 As shown: After the whole machine is powered on, the L and N AC input terminals are energized. When the peak value of the input voltage is less than the overvoltage protection preset value of 405V, the switching devices Q1 and Q2 are in the off state, the optocouplers U6 and U7 are in the off state, and the single-pole double-throw relays K1 and K2 are in the off state. At this time, the first path of the relay is open, and the current normally supplies power to the rectifier bridge DB1, the large electrolytic capacitor C1 and the downstream circuit.

[0080] When the peak value of the AC input voltage between L and N exceeds the overvoltage protection preset value of 405V, when the instantaneous voltage between L and N reaches 405V, Vgs of Q1 reaches 15V, and Q1 conducts; the current of the LED of U7 reaches 5mA, U7 conducts, the coil of relay K1 is energized, and K1 is energized. At this time, the first path of K1 is open. The current dissipates the high voltage energy through the switching transistor Q1 and the bleeder resistor R10. Similarly, when the instantaneous voltage between N and L reaches 405V, Q2 and U6 conduct, relay K2 is energized, and the current dissipates the high voltage energy through the switching transistor Q2 and the bleeder resistor R8.

[0081] When the instantaneous values ​​of the AC input voltages at L and N are less than the overvoltage protection preset value of 405V, the switching devices and optocouplers return to the off state, and the current normally supplies power to the rectifier bridge DB1, the large electrolytic capacitor C1, and the downstream circuitry. Since the switching devices operate for a very small percentage of the AC cycle, and the large electrolytic capacitor has sufficient capacity, it can ensure that the operation of the downstream switching power supply circuit is not affected, thus enabling the controller to continue operating normally under high voltage.

[0082] It should be noted that any process or method description in the flowchart or otherwise described herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which the embodiments of this application pertain.

[0083] The AC electrical equipment controller provided in this application adds a switching device to the voltage input terminal of the controller. When the instantaneous value of the input voltage is higher than the set value, the switching device is turned on to discharge the high voltage energy and protect the downstream circuit. When the instantaneous value of the input voltage is lower than the set value, the switching device is turned off to restore normal power supply. This achieves the effect of reducing the voltage of the downstream circuit when the voltage is too high, so that the controller can operate normally even under high voltage.

[0084] Based on the same inventive concept, this application also provides an AC electrical appliance, including the AC electrical appliance controller provided in the above embodiments.

[0085] Examples of AC electrical appliances include air conditioners, refrigerators, and washing machines.

[0086] The AC electrical equipment provided in this application embodiment, through the AC electrical equipment controller provided in the above embodiment, enables the load unit to be normally connected to the live wire and neutral wire when the voltage between the live wire and neutral wire is less than or equal to a threshold. When the voltage between the live wire and neutral wire is greater than the threshold, the second path is turned on. At this time, the controllable switch is turned on, and part or all of the current flows from the input terminal of the controllable switch to the output stage. In this way, the downstream load unit will not be damaged due to overvoltage, ensuring the reliable operation of the controller, and thus ensuring the reliability of the AC electrical equipment.

[0087] Furthermore, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0088] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0089] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means at least two.

[0090] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An overvoltage protection circuit, characterized in that, include: Sampling unit, switching unit, controllable switching transistor and control unit; The sampling unit is used to obtain the voltage between the live wire and the neutral wire; The input of the control unit is connected to the sampling unit, and the output of the control unit is connected to the switching unit. The switching unit includes two paths. When the voltage between the live wire and the neutral wire is less than or equal to a threshold, the first path is turned on, and the live wire or the neutral wire is directly connected to the load unit. When the voltage between the live wire and the neutral wire is greater than the threshold, the second path is turned on, and the controllable switch is turned on. The controllable switch is connected to the sampling unit at its controllable electrode, to the second path at its input electrode, and to the neutral or live wire at its output electrode.

2. The overvoltage protection circuit according to claim 1, characterized in that: The second path is equipped with a current-limiting resistor; The current-limiting resistor is connected to the input terminal of the controllable switch.

3. The overvoltage protection circuit according to claim 1, characterized in that: The second path is equipped with a current-limiting resistor and a protection resistor; One end of the protection resistor is connected to the current-limiting resistor, and the other end is connected to the input terminal of the controllable switching transistor; The load unit is connected to the connection point of the current-limiting resistor and the protection resistor.

4. The overvoltage protection circuit according to claim 1, characterized in that: The control unit includes an optocoupler; The positive terminal of the light-emitting diode of the optocoupler is connected to the sampling unit, and the negative terminal of the light-emitting diode is connected to the live wire or the neutral wire; The collector of the optocoupler's phototransistor is connected to a DC power supply, and the emitter of the phototransistor is connected to the switching unit.

5. The overvoltage protection circuit according to claim 1, characterized in that: The switching unit is a single-pole double-throw relay; The coil portion of the single-pole double-throw relay is connected to the output of the control unit; the stationary terminal of the single-pole double-throw switch portion of the single-pole double-throw relay is connected to the neutral or live wire; and the two moving terminals of the single-pole double-throw switch tube portion of the single-pole double-throw relay are respectively connected to the first path and the second path.

6. The overvoltage protection circuit according to claim 1, characterized in that: The sampling unit includes a series path consisting of two resistors, the series path being positioned between the live wire and the neutral wire; The output of the sampling unit is the voltage between two resistors.

7. The overvoltage protection circuit according to claim 1, characterized in that: A diode is also connected to the input terminal of the controllable switch.

8. The overvoltage protection circuit according to claim 1, characterized in that, The controllable switching transistor can be any of the following: MOSFET; IGBT; triode.

9. A controller for AC electrical equipment, characterized in that: An overvoltage protection circuit as described in any one of claims 1-8 is provided on both the live wire and the neutral wire.

10. An AC electrical appliance, characterized in that, Includes the controller as described in claim 9.

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