Zero-cross detection device and household appliance

Abstract

The utility model discloses a zero-cross detection device and a household appliance, in the device, because a signal amplification circuit with a current amplification function is added between a signal acquisition circuit and a signal detection circuit, the signal acquisition circuit is allowed to realize zero-cross detection of alternating current even if providing small current. And the current of the signal acquisition circuit is relatively small, which means that the power consumption superposed on the signal acquisition circuit is relatively small, so that the zero-cross detection device has the characteristics of energy conservation and emission reduction.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to a zero-crossing detection device and a household appliance. Background Technology

[0002] With continuous technological advancements, zero-crossing detection circuit technology will evolve towards higher efficiency and lower power consumption. Its application in household appliances such as washing machines will drive the upgrading of these devices towards intelligence and energy efficiency, providing users with a more convenient and reliable user experience. Utility Model Content

[0003] In a first aspect, this utility model provides a zero-crossing detection device, which includes a signal acquisition circuit, a signal amplification circuit, and a signal detection circuit; wherein the signal amplification circuit is connected to the signal acquisition circuit and the signal detection circuit respectively.

[0004] The signal acquisition circuit is used to acquire AC signals and cuts off when the AC signals are in the positive half-cycle, thereby cutting off the signal amplification circuit and causing the signal detection circuit to output a first-level signal to the controller.

[0005] The signal acquisition circuit is also used to turn on when the AC signal changes to a negative half-cycle signal, thereby driving the signal amplification circuit to turn on. After the signal amplification circuit is turned on, it amplifies the input current signal so that the signal detection circuit outputs a second level signal to the controller.

[0006] The controller determines the positive and negative zero-crossing points based on the first and second level signals output by the signal detection circuit.

[0007] Thus, by adding a signal amplification circuit with current amplification function between the signal acquisition circuit and the signal detection circuit, the signal acquisition circuit can achieve zero-crossing detection of AC current even with a smaller current. The smaller current in the signal acquisition circuit means less power consumption superimposed on it, thereby giving the zero-crossing detection device energy-saving and emission-reducing characteristics.

[0008] Secondly, this utility model provides a household appliance, which includes the zero-crossing detection device, controller, and load described in the first aspect; wherein:

[0009] The controller is used to determine the positive and negative zero crossing points based on the first level signal and the second level signal output by the zero crossing detection device, and to control the working state of the load based on the determination result.

[0010] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this utility model. Attached Figure Description

[0011] Figure 1 A schematic diagram of the structure of a zero-crossing detection device provided in this embodiment of the utility model. Figure 1 ;

[0012] Figure 2A A schematic diagram of a zero-crossing detection device provided for an embodiment of this utility model is shown in Figure 2.

[0013] Figure 2B A schematic diagram of the structure of a zero-crossing detection device provided in this embodiment of the utility model. Figure 3 ;

[0014] Figure 3 A schematic diagram of the structure of a zero-crossing detection device provided in this embodiment of the utility model. Figure 4 ;

[0015] Figure 4 This is a schematic diagram of the structure of a household appliance provided in an embodiment of the present utility model. Detailed Implementation

[0016] To gain a more detailed understanding of the features and technical content of the embodiments of this utility model, the implementation of the embodiments of this utility model will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference and illustration only and are not intended to limit the embodiments of this utility model.

[0017] 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 invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0018] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0019] It should also be noted that the terms "first, second, third" used in the embodiments of this utility model are only used to distinguish similar objects and do not represent a specific order of objects. It is understood that "first, second, third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this utility model described herein can be implemented in an order other than that illustrated or described herein.

[0020] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] Zero-crossing detection circuits are essential during the operation of washing machines. They detect the zero-point position of the AC mains power, thus enabling load engagement. The reason for engaging the load at the zero-crossing point is that the voltage drop (Dv) / discharge ratio (Dt) is relatively small, minimizing damage to components. With increasing environmental protection requirements, energy conservation and emission reduction need to be integrated into our daily lives. Therefore, reducing the standby power consumption of zero-crossing detection circuits is particularly important.

[0022] Figure 1 Schematic diagram of the zero-crossing detection circuit provided in the embodiment of this utility model Figure 1 ;like Figure 1 As shown, the live wire input terminal L1 and the neutral wire input terminal AC_N of the alternating current form a conducting circuit through diode D15, resistors R98, R99, and R100, and then through an optocoupler. However, the inventors of this application discovered during their research and analysis that... Figure 1 The zero-crossing detection circuit shown has certain drawbacks. To ensure reliable conduction of the optocoupler, the current-limiting resistor is typically selected to be around 56KΩ-100KΩ. Under normal circumstances, this zero-crossing detection circuit runs continuously during washing machine operation, resulting in constant power consumption across resistors R98, R99, and R100. This causes unnecessary energy loss. In areas with high energy consumption requirements, this poses a risk of excessive standby power consumption.

[0023] Based on this, this utility model embodiment provides a zero-crossing detection device, which includes a signal acquisition circuit, a signal amplification circuit, and a signal detection circuit. The signal amplification circuit is connected to both the signal acquisition circuit and the signal detection circuit. The signal acquisition circuit acquires an AC signal and cuts off when the AC signal is in its positive half-cycle, thereby cutting off the signal amplification circuit. The signal detection circuit then outputs a first-level signal to the controller. The signal acquisition circuit also conducts when the AC signal changes to its negative half-cycle, thereby driving the signal amplification circuit to conduct. After conduction, the signal amplification circuit amplifies the input current signal so that the signal detection circuit outputs a second-level signal to the controller. The controller determines the positive and negative zero-crossing points based on the first and second-level signals output by the signal detection circuit.

[0024] Thus, by adding a signal amplification circuit with current amplification function between the signal acquisition circuit and the signal detection circuit, the signal acquisition circuit can achieve zero-crossing detection of AC current even with a smaller current. The smaller current in the signal acquisition circuit means less power consumption superimposed on it, thereby giving the zero-crossing detection device energy-saving and emission-reducing characteristics.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] This utility model embodiment provides a zero-crossing detection device. Figure 2A A schematic diagram of the zero-crossing detection circuit provided in this embodiment of the utility model is shown in Figure 2; Figure 2A As shown, the zero-crossing detection device 200 includes: a signal acquisition circuit 201, a signal amplification circuit 202, and a signal detection circuit 203; wherein: the signal amplification circuit 202 is connected to the signal acquisition circuit 201 and the signal detection circuit 203 respectively;

[0027] The signal acquisition circuit 201 is used to acquire AC signals and cut off when the AC signal is a positive half-cycle signal, thereby cutting off the signal amplification circuit, which in turn causes the signal detection circuit 203 to output a first level signal to the controller 300.

[0028] The signal acquisition circuit 201 is also used to turn on when the AC signal changes to a negative half-cycle signal, thereby driving the signal amplification circuit 202 to turn on. After the signal amplification circuit 202 turns on, it amplifies the input current signal so that the signal detection circuit 203 outputs a second level signal to the controller 300.

[0029] The controller 300 determines the positive and negative zero-crossing points based on the first level signal and the second level signal output by the signal detection circuit 203.

[0030] Thus, by adding a signal amplification circuit with current amplification function between the signal acquisition circuit and the signal detection circuit, the signal acquisition circuit can achieve zero-crossing detection of AC current even with a smaller current. The smaller current in the signal acquisition circuit means less power consumption superimposed on it, thereby giving the zero-crossing detection device energy-saving and emission-reducing characteristics.

[0031] Furthermore, Figure 2B Schematic diagram of the zero-crossing detection circuit provided in the embodiment of this utility model Figure 3 ;like Figure 2B As shown, the zero-crossing detection device 200 also includes a signal transmission circuit 204;

[0032] Among them, the signal amplification circuit 202 is connected to the signal acquisition circuit 201 and the signal transmission circuit 204 respectively, and the signal detection circuit 203 is connected to the signal transmission circuit 204;

[0033] The signal acquisition circuit 201 is used to acquire AC signals and is cut off when the AC signal is a positive half-cycle signal, so that the signal amplification circuit 202 and the signal transmission circuit 204 are both cut off, and then the signal detection circuit 203 outputs a first level signal to the controller 300.

[0034] The signal acquisition circuit 201 is also used to turn on when the AC signal changes to a negative half-cycle signal, thereby driving the signal amplification circuit 202 to turn on. After the signal amplification circuit 202 turns on, it amplifies the input current signal and outputs it to the signal transmission circuit 204, thereby driving the signal transmission circuit 204 to turn on, which in turn causes the signal detection circuit 203 to output a second level signal to the controller 300.

[0035] The controller 300 determines the positive and negative zero-crossing points based on the first level signal and the second level signal output by the signal detection circuit 203.

[0036] Understandable, Figure 2B In the zero-crossing detection device 200 shown, because a signal amplification circuit 202 with current amplification function is added between the signal acquisition circuit 201 and the signal transmission circuit 204, the signal acquisition circuit 201 can provide a small current to drive the signal transmission circuit 204 to conduct through the signal amplification circuit 202. The smaller current in the signal acquisition circuit 201 means smaller power consumption superimposed on it, thus giving the zero-crossing detection device energy-saving and emission-reducing characteristics.

[0037] As mentioned above, the signal amplification circuit 202 has the function of amplifying current. In one possible implementation, the signal amplification circuit 202 includes a current-controlled transistor. When the signal acquisition circuit 201 is turned on, the current-controlled transistor connects the signal acquisition circuit and the signal transmission circuit, and after being turned on, it amplifies the input current signal and outputs it to the signal transmission circuit.

[0038] In this embodiment of the invention, the current-controlled transistor can be any type of transistor with current amplification. For example, the current-controlled transistor is a PNP transistor. In some embodiments, the current amplification factor of the current-controlled transistor is greater than 1.

[0039] Furthermore, in some embodiments, such as Figure 3 As shown, the signal acquisition circuit 201 includes a first diode D1 and a voltage divider circuit 2011; wherein, the negative terminal (cathode) of the first diode D1 is connected to the live wire input terminal L, the positive terminal (anode) of the first diode D1 is connected to the first terminal 1 of the voltage divider circuit 2011, the second terminal 2 of the voltage divider circuit 2011 is connected to the base (B terminal) of the PNP transistor Q1, the emitter (E terminal) of the PNP transistor Q1 is connected to the neutral wire input terminal N, and the collector (C terminal) of the PNP transistor Q1 is connected to the signal transmission circuit 204.

[0040] It is understandable that the function of the voltage divider circuit 2011 is to convert the high voltage from the live wire input terminal into a low voltage, thereby preventing the components in the signal amplifier circuit 202 from being damaged.

[0041] In one possible implementation, such as Figure 3 As shown, the voltage divider circuit 2011 includes at least two first resistors R1, which are connected in series.

[0042] In one possible implementation, such as Figure 3 As shown, the signal acquisition circuit 201 also includes a second resistor R2 and a second diode D2; wherein:

[0043] The first terminal 1 of the second resistor R2 is connected to the emitter (E terminal) of the PNP transistor Q1, and the second terminal 2 of the second resistor R2 is connected to the base (B terminal) of the PNP transistor Q1.

[0044] The positive terminal (anode) of the second diode D2 is connected to the second terminal 2 of the voltage divider circuit 2011, and the negative terminal (cathode) of the second diode D2 is connected to the emitter (E terminal) of the PNP transistor Q1.

[0045] It is understandable that, because a signal amplifier circuit 202 with current amplification function is added between the signal acquisition circuit 201 and the signal transmission circuit 204, a larger value first resistor can be used in the voltage divider circuit 2011 of the signal acquisition circuit 201. This allows the signal acquisition circuit 201 to drive the signal transmission circuit 204 to conduct even when providing a small current. And according to power consumption = U... 2 As can be seen from / R, the resistance of the first resistor in the voltage divider circuit 2011 is relatively large, which can effectively reduce the power consumption on the voltage divider circuit, thereby effectively reducing the standby power consumption of the zero-crossing detection device 100 and achieving the purpose of energy saving and emission reduction.

[0046] In this embodiment of the invention, the resistance values ​​of the first resistors in the voltage divider circuit 2011 can be different, partially the same, or all the same. Furthermore, the value of the first resistor is not limited; for example, the resistance value can be greater than 100KΩ. In practical applications, a suitable first resistor value can be selected based on performance specifications. For example… Figure 3 As shown, the voltage divider circuit 2011 includes three first resistors R1 connected in series, and the resistance of each of the three first resistors R1 is 470KΩ.

[0047] In some embodiments, such as Figure 3 As shown, the signal amplification circuit 202 also includes a third resistor R3 and a fourth resistor R4; wherein, the first terminal 1 of the third resistor R3 is connected to the collector (C terminal) of the PNP transistor Q1, the second terminal 2 of the third resistor R3 is connected to the first terminal 1 of the fourth resistor R4 and the signal transmission circuit 204; the second terminal 2 of the fourth resistor R4 and the signal transmission circuit 204 are connected to the first power supply terminal 501.

[0048] It is understandable that the role of the series resistor R3 at the collector (C terminal) of the PNP transistor Q1 is:

[0049] (1) Current limiting function: In the signal amplifier circuit 202, the collector (C) current may be large. The series resistor can limit the current and prevent the transistor Q1 from being overloaded or damaged.

[0050] (2) Voltage drop: The voltage drop across the series resistor R3 can provide a suitable operating voltage for transistor Q1, ensuring that transistor Q1 operates in the amplification region.

[0051] As mentioned earlier, the signal transmission circuit 204 is also in the off state when the signal acquisition circuit 201 is off, which causes the signal detection circuit 203 to output a first level signal to the controller 300; when the signal acquisition circuit 201 is on, the signal amplification circuit 202 is also on and amplifies the input current to drive the signal transmission circuit 204 to be on.

[0052] In one possible implementation, such as Figure 3 As shown, the signal transmission circuit 204 includes an optocoupler O1; wherein:

[0053] The positive terminal (anode) of the light-emitting diode of the optocoupler O1 is connected to the second terminal 2 of the third resistor R3 and the first terminal 1 of the fourth resistor R4. The negative terminal (cathode) of the light-emitting diode is connected to the first power supply terminal 501, which is a negative voltage; for example, the power supply voltage of the first power supply terminal is -12V.

[0054] The first end 1 of the photosensitive element of the optocoupler O1 is connected to the second power supply end 502, and the second end 2 of the photosensitive element is connected to the ground end; the signal detection circuit 203 is connected to the second power supply end 502 and the first end 1 of the photosensitive element; the power supply voltage of the second power supply end 502 is a positive voltage, for example, the power supply voltage of the second power supply end 502 is +5V.

[0055] Furthermore, in some embodiments, the signal acquisition circuit 201 is used to acquire AC signals and cut off when the AC signals are in the positive half-cycle, so that the signal detection circuit 203 outputs the first level signal, which is a high level signal;

[0056] Furthermore, in some embodiments, the signal acquisition circuit 201 is also used to turn on when the AC signal changes to a negative half-cycle signal, thereby driving the emitter (E) and collector (C) of the PNP transistor Q1 to turn on and amplify the input current signal after turning on, and output it to the positive terminal of the light-emitting diode of the optocoupler O1 to drive the light-emitting diode to emit light, thereby driving the first terminal 1 and the second terminal 2 of the photosensitive element of the optocoupler O1 to turn on, and then causing the signal detection circuit 203 to output the second level signal, which is a low level signal.

[0057] Furthermore, in some embodiments, such as Figure 3 As shown, the signal detection circuit 203 includes a fifth resistor R5 and a sixth resistor R6; wherein, the first end 1 of the fifth resistor R5 is connected to the first end 1 of the photosensitive element and the first end 1 of the sixth resistor R6, the second end 2 of the fifth resistor R5 is connected to the second power supply terminal 502, and the second end 2 of the sixth resistor R6 is used to connect to the controller 300 to output the first level signal and the second level signal to the controller 300.

[0058] Furthermore, in some embodiments, the signal detection circuit 203 further includes a first capacitor C1, the first terminal 1 of the first capacitor C1 is connected to the second terminal 2 of the sixth resistor R6, and the second terminal 2 of the first capacitor C1 is connected to ground.

[0059] In some embodiments, the zero-crossing detection device 200 is applied in a washing machine, dryer, or washer-dryer combo. The controller 300 is used to determine the positive and negative zero-crossing points based on the first level signal and the second level signal output by the zero-crossing detection device 200, and to control the operating state of the load in the washing machine, dryer, or washer-dryer combo according to the determination result.

[0060] Figure 4 This is a schematic diagram of the structure of the household appliance provided in the embodiment of this utility model, such as... Figure 4 As shown, the household appliance 400 includes a zero-crossing detection device 200, a controller 300, and a load 401; wherein:

[0061] The controller 300 is used to determine the positive and negative zero-crossing points based on the first level signal and the second level signal output by the zero-crossing detection device 200, and to control the operating state of the load 401 according to the determination result. For example, the controller 300 engages the load 401 when the determination result is a zero-crossing point.

[0062] It should be noted that, in this embodiment of the utility model, there is no limitation on the type of household appliance 400. In short, the household appliance is a household appliance that needs to use a zero-crossing detection device to achieve load control. For example, household appliance 400 is a washing machine, dry cleaning machine, washer-dryer combo, air conditioner, or vacuum cleaner, etc.

[0063] It should also be noted that, in this embodiment of the utility model, the type of controller 300 is not limited, for example, controller 300 is a microcontroller unit (MCU).

[0064] It is understandable that the zero-crossing detection circuit / device is an important component of the washing machine control system. It is mainly used to detect the zero-crossing point of the AC power supply voltage in order to achieve precise control of loads such as motors and heaters.

[0065] It is understood that the advantage of the zero-crossing detection device 200 provided in this embodiment of the present invention is that by utilizing the current amplification effect of the transistor, the resistance value of the resistor in the voltage divider circuit can be effectively increased; in this way, the power consumption of the voltage divider circuit can be effectively reduced, and the characteristics of energy saving and emission reduction can be achieved.

[0066] And in Figure 1 In the zero-crossing detection circuit shown, the current flows directly from the live wire input terminal L1 to the neutral wire input terminal AC_N. Therefore, resistors R98, R99, and R100 need to have relatively small values ​​(usually around 56KΩ-100KΩ), otherwise they would be insufficient to turn on the optocoupler; while... Figure 3 In the zero-crossing detection device shown, the first resistor R1 in the voltage divider circuit 2011 has a value of nearly 500KΩ, which is greater than... Figure 1The resistors R98, R99, and R100 have large resistance values, which significantly reduces power consumption. This is because power consumption = U... 2 / R, the larger the resistance value R, the lower the power consumption; and the reason why Figure 3 The resistance value of the first resistor R1 in the circuit can be designed to be relatively large because... Figure 3 The zero-crossing detection device 200 incorporates a transistor Q1. This current-controlled transistor Q1 requires only a small current (around μA) to conduct, and its current amplification function enables the optocoupler O1 to conduct. Therefore, the zero-crossing detection device 200 provided in this embodiment achieves voltage conversion through the current amplification effect of the signal amplification circuit 202. This allows the voltage divider circuit 2011 of the device 200 to use a resistor with a larger resistance value, thereby reducing standby power consumption and achieving energy saving and emission reduction.

[0067] It should be noted that the "connection" mentioned in the embodiments of this utility model can be a direct connection or an indirect connection, or other electrical connection methods, in order to realize the transmission of electrical signals. The embodiments of this utility model do not limit this in any way.

[0068] It should be noted that, in this utility model, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, product, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, product, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes that element.

[0069] In the several embodiments provided by this utility model, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0070] 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; they may be located in one place or distributed across multiple network units; some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the various embodiments of this utility model, all functional units may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the integrated unit may be implemented in hardware or in a combination of hardware and software functional units.

[0071] The above are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A zero-crossing detection device, characterized in that, The device includes a signal acquisition circuit, a signal amplification circuit, and a signal detection circuit; wherein the signal amplification circuit is connected to both the signal acquisition circuit and the signal detection circuit. The signal acquisition circuit is used to acquire AC signals and cuts off when the AC signal is in the positive half-cycle, thereby cutting off the signal amplification circuit and causing the signal detection circuit to output a first-level signal to the controller. The signal acquisition circuit is also used to turn on when the AC signal changes to a negative half-cycle signal, thereby driving the signal amplification circuit to turn on. After the signal amplification circuit is turned on, it amplifies the input current signal so that the signal detection circuit outputs a second level signal to the controller. The controller determines the positive and negative zero-crossing points based on the first and second level signals output by the signal detection circuit.

2. The apparatus according to claim 1, characterized in that, The device further includes a signal transmission circuit; the signal amplification circuit is connected to the signal acquisition circuit and the signal transmission circuit respectively, and the signal detection circuit is connected to the signal transmission circuit; The signal transmission circuit is cut off when the signal amplification circuit is cut off, thereby causing the signal detection circuit to output the first level signal to the controller; After being turned on, the signal amplification circuit amplifies the input current signal and outputs it to the signal transmission circuit, thereby driving the signal transmission circuit to turn on, which in turn causes the signal detection circuit to output a second-level signal to the controller.

3. The apparatus according to claim 2, characterized in that, The signal amplification circuit includes a current-controlled transistor; the current-controlled transistor is used to connect the signal acquisition circuit and the signal transmission circuit when the signal acquisition circuit is turned on, and to amplify the input current signal and output it to the signal transmission circuit after it is turned on.

4. The apparatus according to claim 3, characterized in that, The current-controlled transistor is a PNP transistor.

5. The apparatus according to claim 4, characterized in that, The signal acquisition circuit includes a first diode and a voltage divider circuit; wherein, the negative terminal of the first diode is connected to the live wire input terminal, the positive terminal of the first diode is connected to the first terminal of the voltage divider circuit, the second terminal of the voltage divider circuit is connected to the base of the PNP transistor, the emitter of the PNP transistor is connected to the neutral wire input terminal, and the collector of the PNP transistor is connected to the signal transmission circuit.

6. The apparatus according to claim 5, characterized in that, The voltage divider circuit includes at least two first resistors connected in series.

7. The apparatus according to claim 6, characterized in that, The signal acquisition circuit further includes a second resistor and a second diode; wherein: The first end of the second resistor is connected to the emitter of the PNP transistor, and the second end of the second resistor is connected to the base of the PNP transistor. The positive terminal of the second diode is connected to the second terminal of the voltage divider circuit, and the negative terminal of the second diode is connected to the emitter of the PNP transistor.

8. The apparatus according to any one of claims 4-7, characterized in that, The signal amplification circuit further includes a third resistor and a fourth resistor; wherein, the first end of the third resistor is connected to the collector of the PNP transistor, the second end of the third resistor is connected to the first end of the fourth resistor and the signal transmission circuit; the second end of the fourth resistor and the signal transmission circuit are connected to the first power supply terminal.

9. The apparatus according to claim 8, characterized in that, The signal transmission circuit includes an optocoupler; wherein: The positive terminal of the light-emitting diode of the optocoupler is connected to the second terminal of the third resistor and the first terminal of the fourth resistor, and the negative terminal of the light-emitting diode is connected to the first power supply terminal, wherein the power supply voltage of the first power supply terminal is a negative voltage. The first end of the photosensitive element of the optocoupler is connected to the second power supply terminal, and the second end of the photosensitive element is connected to the ground terminal; the signal detection circuit is connected to the second power supply terminal and the first end of the photosensitive element; the second power supply terminal is a positive voltage.

10. The apparatus according to claim 9, characterized in that, The signal acquisition circuit is used to acquire AC signals and cuts off when the AC signals are in the positive half-cycle, so that the signal detection circuit outputs the first level signal, which is a high level signal.

11. The apparatus according to claim 9 or 10, characterized in that, The signal acquisition circuit is also used to turn on when the AC signal changes to a negative half-cycle signal, thereby driving the emitter and collector of the PNP transistor to conduct and amplifying the input current signal after conduction, and outputting it to the positive terminal of the light-emitting diode of the optocoupler to drive the light-emitting diode to emit light, thereby driving the first end and the second end of the photosensitive element of the optocoupler to conduct, and then causing the signal detection circuit to output the second level signal, which is a low level signal.

12. The apparatus according to claim 9, characterized in that, The signal detection circuit includes a fifth resistor and a sixth resistor; wherein, the first end of the fifth resistor is connected to the first end of the photosensitive element and the first end of the sixth resistor, the second end of the fifth resistor is connected to the second power supply terminal, and the second end of the sixth resistor is used to connect to the controller to output the first level signal and the second level signal to the controller.

13. The apparatus according to claim 12, characterized in that, The signal detection circuit further includes a first capacitor, the first end of which is connected to the second end of the sixth resistor, and the second end of which is connected to ground.

14. The apparatus according to any one of claims 1-7, 9-10, and 12-13, characterized in that, The device is used in washing machines, dryers, or washer-dryer combos.

15. A household appliance, characterized in that, The household appliance includes the zero-crossing detection device, controller, and load as described in any one of claims 1 to 14; wherein: The controller is used to determine the positive and negative zero crossing points based on the first level signal and the second level signal output by the zero crossing detection device, and to control the working state of the load based on the determination result.

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