Zero-crossing detection circuit and appliance

Abstract

This application discloses a zero-crossing detection circuit and electrical appliance. The zero-crossing detection circuit includes a zero-crossing detection module and a control module. The control module is connected to the zero-crossing detection module. The zero-crossing detection module includes a step-down resistor unit and a signal detection unit. The step-down resistor unit is connected to both the power supply and the signal detection unit. The step-down resistor unit steps down a first voltage to obtain a second voltage. The signal detection unit outputs a zero-crossing signal based on the second voltage. The control module detects the pulse width of the zero-crossing signal and outputs a level signal to the zero-crossing detection module according to the pulse width. This level signal controls the zero-crossing detection module to adjust the resistance value of the step-down resistor unit so that the adjusted resistance value matches the peak voltage of the AC voltage, ensuring the accuracy of the zero-crossing signal output by the signal detection unit and improving the detection accuracy of the zero-crossing detection circuit.

Description

Technical Field

[0001] This application relates to the field of electrical technology, specifically to a zero-crossing detection circuit and electrical appliance. Background Technology

[0002] In various electrical appliances, especially those with loads, a zero-crossing detection circuit is usually provided. This zero-crossing detection circuit can output zero-point information corresponding to the AC voltage provided by the power supply.

[0003] However, in practical use, it has been found that if there is a large difference between the peak voltages of the AC voltage supplied by the power supply, the error between the zero-crossing information output by the zero-crossing detection circuit and the actual zero-point information of the AC voltage supplied by the power supply is large. Utility Model Content

[0004] This application discloses a zero-crossing detection circuit and electrical appliance, which can improve the detection accuracy of the zero-crossing detection circuit.

[0005] This application discloses a zero-crossing detection circuit, including:

[0006] The zero-crossing detection module includes a step-down resistor unit and a signal detection unit. The step-down resistor unit is connected to both the power supply and the signal detection unit. The step-down resistor unit is used to step down a first voltage to obtain a second voltage. The signal detection unit is used to output a zero-crossing signal based on the second voltage. The first voltage is obtained from the AC voltage provided by the power supply, and the zero-crossing signal is used to characterize the zero-point information of the AC voltage.

[0007] A control module is connected to the zero-crossing detection module. The control module is used to detect the pulse width of the zero-crossing signal and output a level signal to the zero-crossing detection module according to the pulse width. The level signal is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit.

[0008] In this embodiment, the zero-crossing detection circuit includes a zero-crossing detection module and a control module. The control module is connected to the zero-crossing detection module. The zero-crossing detection module includes a step-down resistor unit and a signal detection unit. The step-down resistor unit is connected to both the power supply and the signal detection unit. The step-down resistor unit steps down the first voltage to obtain a second voltage. The signal detection unit outputs a zero-crossing signal based on the second voltage. The control module detects the pulse width of the zero-crossing signal and outputs a level signal to the zero-crossing detection module according to the pulse width. This level signal controls the zero-crossing detection module to adjust the resistance value of the step-down resistor unit. The pulse width of the zero-crossing signal is related to the peak value of the AC voltage supplied by the power supply. By setting a control module and an adjustable voltage-dropping resistor unit in the zero-crossing detection circuit, and connecting the control module to the zero-crossing detection module, a level signal can be provided to the zero-crossing detection module. This ensures that the adjusted voltage-dropping resistor unit's resistance value matches the peak voltage of the AC voltage, thereby avoiding a large error in the zero-crossing signal output by the signal detection unit due to deviation of the peak voltage of the first voltage. This guarantees the accuracy of the zero-crossing signal output by the signal detection unit and improves the detection accuracy of the zero-crossing detection circuit.

[0009] In some embodiments, the zero-crossing detection module further includes a first resistor and a selection unit, wherein the first resistor is connected to the selection unit and the signal detection unit respectively, and the selection unit is also connected to the control module;

[0010] The selection unit includes a second resistor connected to the first resistor; the step-down resistor unit consists of the first resistor, or is composed of the first resistor and the second resistor.

[0011] The selection unit is configured to, based on the level signal, allow the current supplied by the power supply to pass through or not pass through the second resistor.

[0012] When the current supplied by the power source passes through the second resistor, the resistance value of the step-down resistor unit is determined based on the resistance values ​​of the first resistor and the second resistor.

[0013] When the current supplied by the power source does not pass through the second resistor, the resistance value of the step-down resistor unit is equal to the resistance value of the first resistor.

[0014] In this embodiment, the zero-crossing detection module includes a first resistor and a selection unit. The selection unit includes a second resistor. The selection unit selectively allows the current supplied by the power supply to pass through or not pass through the second resistor, so that the resistance value of the step-down resistor unit is equal to the resistance value of the first resistor, or determined by the resistance values ​​of the first resistor and the second resistor. In other words, the resistance value of the step-down resistor unit can be the resistance value of the first resistor, or deviate from the resistance value of the first resistor. This zero-crossing detection module can provide voltage resistor units with at least two resistance values, and the circuit structure is simple, which can reduce the cost and area of ​​the zero-crossing detection module.

[0015] In some embodiments, the selection unit is connected in parallel with the first resistor, and the selection unit is connected to the power supply and the signal detection unit respectively. The selection unit further includes a first switch, which is connected in series with the second resistor.

[0016] When the first switch is closed, the current supplied by the power source passes through the second resistor;

[0017] When the first switch is in the open state, the current supplied by the power source does not pass through the second resistor.

[0018] In this embodiment, when the first switch is closed, the current supplied by the power supply passes through the second resistor, and the resistance of the step-down resistor unit is the resistance value corresponding to the parallel resistance formed by the first resistor and the second resistor connected in parallel. When the first switch is open, the current supplied by the power supply does not pass through the second resistor, and the resistance of the step-down resistor unit is the resistance value of the first resistor. By adjusting the open / closed state of the first switch, the parallel connection of the second resistor and the first resistor can be dynamically adjusted, thereby adjusting the resistance value of the step-down resistor unit, ensuring the reliability of the resistance value adjustment, and at the same time, the adjustment method is simple.

[0019] In some embodiments, the first switch includes a first optocoupler;

[0020] The collector of the transistor in the first optocoupler is connected to the second resistor, the emitter of the first optocoupler is connected to the signal detection unit and the first resistor, the anode of the diode in the first optocoupler is connected to the first voltage input terminal, and the cathode of the diode in the first optocoupler is connected to the control module.

[0021] In this embodiment, the first switch includes a first optocoupler, which can isolate the high-voltage side from the control module, ensuring the safety and reliability of the control module and improving the safety and reliability of the zero-crossing detection circuit.

[0022] In some embodiments, the selection unit further includes a second switch, the second resistor is connected in series with the first resistor, and the second resistor is connected to the power supply or the signal detection unit, and the second switch is connected in parallel with the second resistor;

[0023] When the second switch is in the off state, the current supplied by the power source passes through the second resistor;

[0024] When the second switch is closed, the second resistor is short-circuited, and the current supplied by the power source does not pass through the second resistor.

[0025] In this embodiment, when the second switch is in the open state, the current supplied by the power supply passes through the second resistor, and the resistance of the step-down resistor unit is the resistance value corresponding to the parallel resistance formed by the first resistor and the second resistor connected in parallel. When the second switch is in the closed state, the current supplied by the power supply does not pass through the second resistor, and the resistance of the step-down resistor unit is the resistance value of the first resistor. By adjusting the open and closed state of the second switch, the series connection between the second resistor and the first resistor can be dynamically adjusted, thereby adjusting the resistance value of the step-down resistor unit, ensuring the reliability of the resistance value adjustment, and at the same time, the adjustment method is simple.

[0026] In some embodiments, the AC voltage of the power supply includes a third voltage or a fourth voltage, wherein the resistance values ​​of the first resistor and the second resistor are determined based on the peak voltage corresponding to the third voltage and the peak voltage corresponding to the fourth voltage.

[0027] In this embodiment, the resistance values ​​of the first resistor and the second resistor of the zero-crossing detection module are determined based on the peak voltage corresponding to the AC voltage that the power supply connected to the zero-crossing detection module may provide. This ensures that the resistance range of the step-down resistor unit can match the peak voltage corresponding to different AC voltages, further ensuring the accuracy of the zero-crossing detection circuit.

[0028] In some embodiments, the level signal includes a first level signal and a second level signal;

[0029] When the pulse width of the zero-crossing signal is greater than or equal to the pulse width threshold, the control module outputs a first level signal, which is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit to the first resistance value.

[0030] When the pulse width of the zero-crossing signal is less than the pulse width threshold, the control module outputs a second level signal, which is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit to the second resistance value.

[0031] The first resistance value is less than the second resistance value.

[0032] The pulse width threshold of the zero-crossing signal is positively correlated with the amplitude of the AC voltage supplied by the power supply. In this embodiment, when the pulse width of the zero-crossing signal is greater than or equal to the pulse width threshold, that is, when the AC voltage supplied by the power supply is relatively small, the resistance of the step-down resistor unit is relatively small to ensure that the current flowing through the zero-crossing detection circuit is large enough to ensure that the signal detection unit can work normally (such as the second optocoupler can conduct normally). When the pulse width is less than the pulse width threshold, that is, when the AC voltage supplied by the power supply is relatively large, the resistance of the step-down resistor unit is relatively large, which helps to suppress the current, protect the zero-crossing detection circuit, and reduce energy consumption. While ensuring the accuracy of zero-crossing detection, the energy consumption of the zero-crossing detection circuit can be reduced.

[0033] In some embodiments, the control module includes:

[0034] A capacitor, connected to the signal detection unit, is used to charge based on the zero-crossing signal to obtain a fifth voltage related to the pulse width of the zero-crossing signal;

[0035] A comparator, wherein the first input terminal of the comparator is connected to the capacitor, the second input terminal of the comparator is used to input a reference voltage, and the output terminal of the comparator is connected to the zero-crossing detection module, wherein the reference voltage is generated based on the pulse width threshold;

[0036] The comparator is used to compare the fifth voltage with the reference voltage and output a level signal.

[0037] In this embodiment, the control module includes a capacitor and a comparator. The capacitor is connected to the signal detection unit and is charged based on the zero-crossing signal to obtain a fifth voltage related to the pulse width of the zero-crossing signal. The first input terminal of the comparator is connected to the capacitor. The comparator compares the fifth voltage with a reference voltage and outputs a level signal corresponding to the comparison result. By setting hardware circuits to realize the output of a corresponding level signal based on the pulse width of the zero-crossing signal, the software design complexity of the control module is reduced.

[0038] In some embodiments, the control module further includes:

[0039] A controller is connected to both the signal detection unit and the load. The controller is used to control the load based on the zero-crossing signal output by the signal detection unit.

[0040] An isolation element is connected to the capacitor, the signal detection unit, and the controller, respectively. The isolation element is used to allow the zero-crossing signal to flow to the capacitor and to block the current flowing from the capacitor into the controller.

[0041] In this embodiment, the control module also includes a controller and an isolation element. The isolation element limits the flow of the zero-crossing signal, which can effectively prevent the interference current generated during the charging and discharging of the second capacitor from affecting the level stability of the controller input terminal. That is, it ensures the accuracy of the zero-crossing signal acquired by the controller. Thus, while adjusting the resistance value of the step-down resistor unit, it can ensure the accuracy and reliability of the controller's control of the load based on the zero-crossing signal.

[0042] This application discloses an electrical appliance, including any of the zero-crossing detection circuits disclosed in this application. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments 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.

[0044] Figure 1 This is one of the schematic diagrams of a zero-crossing detection circuit disclosed in an embodiment of this application;

[0045] Figure 2 This is a second schematic diagram of a zero-crossing detection circuit disclosed in an embodiment of this application;

[0046] Figure 3 This is a schematic diagram of a signal detection unit disclosed in an embodiment of this application;

[0047] Figure 4 This is a schematic diagram of another signal detection unit disclosed in an embodiment of this application;

[0048] Figure 5a This is a waveform diagram of an AC voltage with a peak voltage of 230V and a frequency of 60Hz disclosed in an embodiment of this application.

[0049] Figure 5b This is a waveform diagram of the first voltage obtained after full-wave rectification of an AC voltage with a peak voltage of 230V and a frequency of 60Hz, as disclosed in an embodiment of this application.

[0050] Figure 5c This is a waveform diagram of a zero-crossing signal corresponding to an AC voltage with a peak voltage of 230V and a frequency of 60Hz, as disclosed in an embodiment of this application.

[0051] Figure 6a This is a waveform diagram of an AC voltage with a peak voltage of 115V and a frequency of 60Hz disclosed in an embodiment of this application.

[0052] Figure 6b This is a waveform diagram of the first voltage obtained after full-wave rectification of an AC voltage with a peak voltage of 115V and a frequency of 60Hz, as disclosed in an embodiment of this application.

[0053] Figure 6c This is a waveform diagram of a zero-crossing signal corresponding to an AC voltage with a peak voltage of 115V and a frequency of 60Hz, as disclosed in an embodiment of this application.

[0054] Figure 7a This is one of the structural schematic diagrams of a zero-crossing detection module disclosed in an embodiment of this application;

[0055] Figure 7b This is a second schematic diagram of the structure of a zero-crossing detection module disclosed in an embodiment of this application;

[0056] Figure 8 This is the third schematic diagram of a zero-crossing detection module disclosed in the embodiments of this application;

[0057] Figure 9 This is a schematic diagram of the structure of a selection unit disclosed in an embodiment of this application;

[0058] Figure 10 This is a third schematic diagram of a zero-crossing detection circuit disclosed in an embodiment of this application;

[0059] Figure 11 This is a fourth schematic diagram of a zero-crossing detection module disclosed in an embodiment of this application;

[0060] Figure 12 This is a schematic diagram of a control module disclosed in an embodiment of this application;

[0061] Figure 13 This is a schematic diagram of another control module disclosed in an embodiment of this application. Detailed Implementation

[0062] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0063] 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 particular embodiments only and is not intended to be limiting of the application.

[0064] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0065] It is understood that in the following embodiments, "connection" should be interpreted as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., transmit electrical signals or data to each other. Meanwhile, in the following embodiments, "connection" can indicate either an indirect connection or a direct connection.

[0066] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0067] Zero-crossing detection circuits in electrical appliances typically use a step-down resistor to reduce the input voltage and obtain a zero-crossing signal based on the reduced voltage, thereby controlling the load (such as an AC motor or other AC load) in the appliance. In related technologies, zero-crossing detection circuits often use a step-down resistor with fixed parameters (fixed resistance value) to reduce the input voltage. If the AC voltage supplied by the power source connected to the zero-crossing detection circuit deviates from the target voltage, the zero-crossing information output by the circuit will deviate significantly from the actual zero-crossing information of the AC voltage.

[0068] Taking a power supply providing an AC voltage with a peak voltage of 230V and a frequency of 60Hz and a power supply providing an AC voltage with a peak voltage of 115V and a frequency of 60Hz as examples, the related technology sets up two zero-crossing detection circuits, which are used to connect to different power supplies to obtain accurate zero-crossing signals. The two zero-crossing detection circuits use different parameters for the step-down resistors. For example, when the zero-crossing detection circuit needs to be connected to a 230V / 60Hz power supply, the resistance of the step-down resistor is 150KΩ (kiloohms), while when the zero-crossing detection circuit needs to be connected to a 115V / 60Hz power supply, the resistance of the step-down resistor is 75KΩ. If a zero-crossing detection circuit with a 150KΩ step-down resistor is used to detect an AC voltage with a peak voltage of 115V and a frequency of 60Hz, the zero-point information output by this zero-crossing detection circuit will be inaccurate. Similarly, if a zero-crossing detection circuit with a 75KΩ step-down resistor is used to detect an AC voltage with a peak voltage of 230V and a frequency of 60Hz, the zero-point information output by this zero-crossing detection circuit will also be inaccurate.

[0069] It is evident that in related technologies, incompatibility of zero-crossing detection circuits leads to low detection accuracy. Different types of power supplies require different circuit structures, which is not conducive to circuit universality. In the market, installers may not pay attention to identifying the power supply type, resulting in the use of incompatible zero-crossing detection circuits and obtaining inaccurate zero-crossing signals.

[0070] This application provides a zero-crossing detection circuit and electrical appliance, which can improve the detection accuracy of the zero-crossing detection circuit.

[0071] Please refer to Figure 1 This illustrates one of the schematic diagrams of a zero-crossing detection circuit provided in an embodiment of this application. Figure 1 As shown, the zero-crossing detection circuit 110 may include a zero-crossing detection module 111 and a control module 112. The control module 112 is connected to the zero-crossing detection module 111. The zero-crossing detection module 111 may include a step-down resistor unit 111a and a signal detection unit 111b. The step-down resistor unit 111a is connected to the power supply 120 and the signal detection unit 111b, respectively. The step-down resistor unit 111a is used to step down the first voltage to obtain a second voltage. The signal detection unit 111b is used to output a zero-crossing signal based on the second voltage. The control module 112 is used to detect the pulse width of the zero-crossing signal and output a level signal to the zero-crossing detection module 111 according to the pulse width.

[0072] The first voltage is obtained based on the AC voltage provided by power supply 120. The first voltage can be either AC or DC. For example, the first voltage can be the AC voltage provided by power supply 120, or it can be a DC voltage obtained by rectifying the AC voltage provided by power supply 120. The zero-crossing signal is used to characterize the zero-point information of the AC voltage. Zero-point information can refer to the time information of the AC voltage as it transitions from positive to negative or from negative to positive and crosses the zero voltage (reference level), or in other words, the time information of the AC voltage intersecting with the zero voltage (reference level). The pulse width can refer to the duration of a certain state (such as high or low level) in the zero-crossing signal. For example, the zero-crossing signal can include a pulse signal, and the pulse width can refer to the duration of the high level of each pulse.

[0073] It should be noted that the level signal is used to control the zero-crossing detection module 111 to adjust the resistance value of the step-down resistor unit 111a. The control module 112 is connected to the signal detection unit 111b so that the control module 112 can acquire the zero-crossing signal output by the signal detection unit 111b. The pulse width of the zero-crossing signal is related to the peak voltage corresponding to the AC voltage provided by the power supply 120. For example, the pulse width of the zero-crossing signal is negatively correlated with the peak voltage corresponding to the AC voltage. In another example, the pulse width of the zero-crossing signal is positively correlated with the peak voltage corresponding to the AC voltage.

[0074] Since the AC voltages provided by different power supplies have different peak voltages, the pulse widths of the zero-crossing detection signals obtained are different. The control module 112 dynamically adjusts the resistance value of the step-down resistor unit 111a by detecting the pulse width and sending a level signal. This ensures that the resistance value of the step-down resistor unit 111a of the zero-crossing detection module 111 can be adapted to the AC voltage under different input voltages, thus ensuring that the zero-crossing signal output by the signal detection unit 111b can accurately reflect the zero-point information of the AC voltage.

[0075] Figure 2 The diagram below shows a second schematic of a zero-crossing detection circuit provided in an embodiment of this application. The zero-crossing detection circuit 210 may further include a rectifier module 211, which is connected to the power supply 220 and the step-down resistor unit 212a. The rectifier module 211 is used to rectify the AC voltage provided by the power supply 220 to obtain a first voltage.

[0076] It should be noted that in this embodiment, the first voltage is a DC voltage. A rectifier module 211 is set between the step-down resistor unit 212a and the power supply 220 to obtain a DC voltage. This makes it unnecessary to consider the processing logic such as AC voltage polarity reversal and level reversal when designing the zero-crossing detection circuit 210, thereby simplifying the design difficulty of the zero-crossing detection circuit 210, i.e., the signal detection unit 212b.

[0077] Optionally, the rectifier module 211 may include at least one of a half-wave rectifier module and a full-wave rectifier module. The half-wave rectifier module is connected to the power supply 220 and the step-down resistor unit 212a, respectively. It should be noted that a half-wave rectifier module refers to rectifying the AC current using one half-cycle, while the other half-cycle is wasted. Through the unidirectional conductivity of the diodes, half a cycle of the AC current is converted into a unidirectional pulsating DC voltage. A full-wave rectifier module may include two diodes, which can alternately conduct to form a complete rectified waveform.

[0078] Please continue to refer to this. Figure 2 The rectifier module 211 can be a full-wave rectifier module. Specifically, the rectifier module 211 may include a first diode D21 and a second diode D22. The zero-crossing detection circuit 210 is connected to the power supply 220 through the live wire and the neutral wire. The positive terminal of the first diode D21 is connected to the live wire L, and the negative terminal of the first diode D21 is connected to the step-down resistor unit 212a. The positive terminal of the second diode D22 is connected to the neutral wire N, and the negative terminal of the second diode D22 is connected to the step-down resistor unit 212a.

[0079] Please refer to the following for further explanation. Figure 2 The control module 213 is also connected to the load 230. Optionally, the load 230 may include, but is not limited to, an AC motor and a relay. The control module 213 can control the AC motor to commutate according to the zero-point signal to ensure the smooth operation of the AC motor. The control module 213 can also control the on / off state of the relay according to the zero-point signal to reduce sparking.

[0080] In this embodiment, since the resistance value of the step-down resistor unit 212a in the zero-crossing detection module 212 is adjustable, and the adjusted resistance value of the step-down resistor unit 212a is adapted to the AC voltage provided by the power supply 220, the accuracy of the obtained zero-point signal is guaranteed, thereby ensuring the control precision of the electrical appliance.

[0081] Figure 3 A schematic diagram of a signal detection unit provided in an embodiment of this application is shown. The signal detection unit 310 may include a second optocoupler E2 and a third resistor R3. The positive terminal of the diode of the second optocoupler E2 is connected to the step-down resistor unit 320. The collector of the transistor of the second optocoupler E2 is connected to the second voltage input terminal. The emitter of the transistor of the second optocoupler E2 is connected to the third resistor R3 and the control module 330, respectively. The third resistor R3 is connected to the third voltage input terminal.

[0082] It should be noted that when the current output from the step-down resistor unit 320 is insufficient to drive the diode of the second optocoupler E2 to conduct, the transistor of the second optocoupler E2 is in the off state, and the voltage at point A is determined by the voltage provided by the third voltage input terminal. When the current output from the step-down resistor unit 320 is sufficient to drive the diode of the second optocoupler E2 to conduct, the transistor of the second optocoupler E2 is in the on state, and the voltage at point A is determined by the voltage provided by the second voltage input terminal. Therefore, the voltage at point A differs depending on whether the current output from the step-down resistor unit 320 is greater than or equal to the on-state current of the diode of the second optocoupler E2, or when the current output from the step-down resistor unit 320 is less than the on-state current of the diode of the second optocoupler E2. Taking the pulse width as an example, the longer the duration for which the current output from the step-down resistor unit 320 is greater than or equal to the on-state current of the diode of the second optocoupler E2, the longer the pulse width. Taking the pulse width as an example, which indicates the time length determined by the voltage provided by the third voltage input terminal, the longer the current output by the step-down resistor is less than the conduction current of the diode of the second optocoupler E2, the longer the pulse width.

[0083] The formula for calculating the driving current of the second optocoupler E2 in the zero-crossing detection module circuit is: I1=[Um*Sin(2πft+θ)-U1-U2] / r11, where Um is the peak voltage corresponding to the AC voltage supplied by the power supply, U1 is the voltage drop of the first diode D21 or the second diode D22, U2 is the voltage drop of the diode of the second optocoupler E2, r11 is the resistance value of the step-down resistor unit 320, f is the frequency of the AC voltage supplied by the power supply, t is time, and θ is the phase angle. When the driving current I1≥I2, the diode of the second optocoupler E2 is turned on, where I2 is the conduction current of the diode of the second optocoupler E2; conversely, when I1<I2, the second optocoupler E2 is turned off.

[0084] As can be seen from the calculation formula of the driving current of the second optocoupler E2, when the zero-crossing detection circuit is connected to a power supply providing AC voltages with different peak values, the proportions of the conduction and cutoff times of the second optocoupler E2 are different, resulting in different pulse widths of the zero-crossing signal output by the signal detection unit 310. Therefore, by adjusting the resistance value of the step-down resistor unit 320 based on the pulse width, the adjusted step-down resistor unit 320 can be adapted to the peak voltage of the AC voltage provided by the power supply, ensuring the accuracy of the acquired zero-crossing signal.

[0085] In some embodiments, such as Figure 3 As shown, the voltage provided by the second voltage input terminal V2 is higher than the voltage provided by the third voltage input terminal. The voltage provided by the second voltage input terminal V2 is 12V, and the voltage provided by the third voltage input terminal is 0V.

[0086] In some embodiments, such as Figure 3 As shown, the negative terminal of the diode of the second optocoupler E2 is connected to the signal ground SGND, and the third input terminal is the common ground GND. It can be understood that the signal ground SGND is the reference ground line for analog signals or sensitive signals, mainly used for low-noise signal paths, while the common ground GND is the system common ground line, usually referring to power ground or circuit reference ground.

[0087] Figure 4 A schematic diagram of another signal detection unit provided in an embodiment of this application is shown. Figure 4 As shown, the signal detection unit may further include a first transistor Q1, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. The first terminal of the first transistor Q1 is connected to the sixth resistor R6, and the sixth resistor R6 is connected to the fourth voltage input terminal V4. The second terminal of the first transistor Q1 is connected to the third voltage input terminal and the fourth resistor R4. The fourth resistor R4 is also connected to the fifth resistor R5 and the emitter of the transistor of the second optocoupler E2. The fifth resistor R5 is also connected to the third terminal of the first transistor Q1.

[0088] It should be noted that the fifth resistor R5 prevents excessive current from flowing into the third terminal of the first transistor Q1, and the sixth resistor R6 prevents excessive current from flowing into the control module. The descriptions of the second optocoupler E2 and the third voltage input terminal can be found in the above embodiments and will not be repeated here.

[0089] Optionally, the voltage provided by the fourth voltage input terminal V4 may be less than or equal to the voltage provided by the second voltage input terminal. For example, the voltage provided by the fourth voltage input terminal V4 is 5V, and the voltage provided by the second voltage input terminal V2 is 12V. In another example, both the fourth voltage input terminal V4 and the second voltage input terminal V2 provide a voltage of 5V.

[0090] Optionally, the first transistor Q1 is an NPN transistor, with its first terminal being the collector, its second terminal being the emitter, and its third terminal being the base.

[0091] In this embodiment, the zero-crossing signal is a pulse signal, and the pulse width is the duration for which the pulse signal remains in a high-level state.

[0092] For example, using AC peak voltages of 230V and 115V, and a frequency of 60Hz, please refer to... Figures 5a-6c , Figure 5a The diagram shows a waveform of an AC voltage with a peak voltage of 230V and a frequency of 60Hz, according to an embodiment of this application. Figure 5b The diagram illustrates a waveform of the first voltage obtained after full-wave rectification of an AC voltage with a peak voltage of 230V and a frequency of 60Hz, according to an embodiment of this application. Figure 5c The diagram shows a waveform of a zero-crossing signal corresponding to an AC voltage with a peak voltage of 230V and a frequency of 60Hz, provided in an embodiment of this application. Figure 6a This diagram illustrates a waveform of an AC voltage with a peak voltage of 115V and a frequency of 60Hz, provided in an embodiment of this application. Figure 6b This illustration shows a waveform diagram of the first voltage obtained after full-wave rectification of an AC voltage with a peak voltage of 115V and a frequency of 60Hz, according to an embodiment of this application. Figure 6c The diagram shows a waveform of a zero-crossing signal corresponding to an AC voltage with a peak voltage of 115V and a frequency of 60Hz, provided in an embodiment of this application.

[0093] according to Figures 5a to 6c With the resistance of the step-down resistor unit remaining constant, different peak voltages of the AC voltage supplied by the power supply result in different pulse widths for the zero-crossing signal. When the pulse width of the zero-crossing signal is L1, the peak voltage of the AC voltage supplied by the power supply can be determined to be 230V with a frequency of 60Hz. When the pulse width of the zero-crossing signal is L2, the peak voltage of the AC voltage supplied by the power supply can be determined to be 115V with a frequency of 60Hz. Based on this, when the pulse width is large, the output level signal can be used to make the resistance of the step-down resistor a first resistance value, and when the pulse width is small, the output level signal can be used to make the resistance of the step-down resistor a first resistance value, wherein the first resistance value is less than the second resistance value.

[0094] It is understandable that a rectifier module may not be set in the zero-crossing detection circuit. For example, a device with bidirectional detection capability can be used to output a zero-crossing signal based on the AC voltage provided by the power supply. This embodiment does not limit this.

[0095] In this embodiment, the zero-crossing detection circuit includes a zero-crossing detection module and a control module. The control module is connected to the zero-crossing detection module. The zero-crossing detection module includes a step-down resistor unit and a signal detection unit. The step-down resistor unit is connected to both the power supply and the signal detection unit. The step-down resistor unit steps down the first voltage to obtain a second voltage. The signal detection unit outputs a zero-crossing signal based on the second voltage. The control module detects the pulse width of the zero-crossing signal and outputs a level signal to the zero-crossing detection module according to the pulse width. This level signal is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit. The pulse width of the zero-crossing signal is related to the peak value of the AC voltage supplied by the power supply. By setting a control module and a zero-crossing detection module that can adjust the resistance value of the step-down resistor unit in the zero-crossing detection circuit, and connecting the control module to the zero-crossing detection module, a level signal can be provided to the zero-crossing detection module. This ensures that the resistance value of the adjusted step-down resistor unit is matched with the peak voltage of the AC voltage, thereby avoiding a large error in the zero-crossing signal output by the signal detection unit due to deviation of the peak voltage of the first voltage. This ensures the accuracy of the zero-crossing signal output by the signal detection unit and improves the detection accuracy of the zero-crossing detection circuit.

[0096] Meanwhile, since the resistance value of the adjusted step-down resistor unit is adapted to the peak voltage of the AC voltage, the current of the zero-crossing detection module can be adapted to the peak voltage of the AC voltage. This ensures that the current of the zero-crossing detection module is within a suitable range, which not only ensures that the zero-crossing detection circuit can be driven normally, but also reduces the heat generation of the zero-crossing detection circuit, reduces the energy consumption of the zero-crossing detection circuit, and meets the energy-saving requirements.

[0097] Please refer to Figures 7a to 7b , Figure 7a This illustration shows one of the structural schematic diagrams of a zero-crossing detection module provided in an embodiment of this application. Figure 7b This is a second schematic diagram of the structure of a zero-crossing detection module provided in an embodiment of this application. For example... Figures 7a to 7b As shown, the zero-crossing detection module 710 may include a first resistor 711 and a selection unit 712. The selection unit 712 may include a second resistor 712a. The first resistor 711 is connected to the power supply 720, the selection unit 712, and the signal detection unit 713. The selection unit 712 is also connected to the control module 730. The second resistor 712a is connected to the first resistor 711. The selection unit 712 is used to determine whether the current supplied by the power supply 720 passes through the second resistor 712a based on the level signal.

[0098] The step-down resistor unit consists of a first resistor 711, or a first resistor 711 and a second resistor 712a. When the current supplied by the power supply 720 passes through the second resistor 712a, the resistance value of the step-down resistor unit is determined based on the resistance values ​​of the first resistor 711 and the second resistor 712a. When the current supplied by the power supply 720 does not pass through the second resistor 712a, the resistance value of the step-down resistor unit is equal to the resistance value of the first resistor 711.

[0099] It should be noted that the current supplied by the power supply 720 flows through the first resistor 711 at a constant current. The selection unit 712 causes the current supplied by the power supply 720 to pass through or not pass through the second resistor 712a, thereby adjusting the total current of the path between the power supply 720 and the signal detection unit 713.

[0100] In some embodiments, when the current supplied by the power supply 720 passes through the second resistor 712a, the current path of the current supplied by the power supply 720 becomes longer, relative to the current supplied by the current not passing through the second resistor 712a, so that the resistance value of the step-down resistor unit is greater than the resistance value of the first resistor 711.

[0101] For example, please refer to Figure 7a Taking the connection of the first terminal B of the first resistor 711 to the power supply 720, the second terminal C of the first resistor 711 to the first terminal D of the second resistor 712a, and the second terminal E of the second resistor 712a to the first terminal F of the signal detection unit 713 as an example, if the selection unit 712 opens the path between the second terminal C of the first resistor 711 and the first terminal F of the signal detection unit 713, then the current supplied by the power supply 720 does not flow through the second resistor 712a, and the step-down resistor unit is composed of the first resistor 711. If the selection unit 712 does not open the path between the second terminal C of the first resistor 711 and the first terminal F of the signal detection unit 713, then the current supplied by the power supply 720 flows through the second resistor 712a, and the first resistor 711 and the second resistor 712a are connected in series. The resistance value of the step-down resistor unit is equal to the resistance value corresponding to the series resistance formed by the first resistor 711 and the second resistor 712a.

[0102] It should be noted that, Figure 7a The diagram shows the case where the first resistor 711 and the second resistor 712a are connected in series. The second resistor 712a is connected in series between the first resistor 711 and the signal detection unit 713. It can be understood that the second resistor 712a can also be connected to the power supply 720 and the first resistor 711 respectively. When the current provided by the power supply 720 passes through the second resistor 712a, the second resistor 712a is connected in series between the power supply 720 and the first resistor 711.

[0103] In other embodiments, when the current supplied by the power supply 720 passes through the second resistor 712a, the cross-sectional area of ​​the current flow path supplied by the power supply 720 may become larger, so that the resistance of the step-down resistor unit is smaller than the resistance of the first resistor 711, compared to the current supplied by the power supply 720 not passing through the second resistor 712a.

[0104] It should be noted that, with Figure 7a The difference shown is that, Figure 7b This illustrates the connection between the first terminal D of the second resistor 712a and the first terminal B of the first resistor 711. The selection unit 712 can selectively connect or disconnect the path between the second terminal E of the second resistor 712a and the first terminal F of the signal detection unit 713, or selectively connect or disconnect the path between the first terminal B of the first resistor 711 and the first terminal D of the second resistor 712a. Figure 7b This illustrates a scenario where the selection unit 712 can selectively turn on or off the path between the second terminal E of the second resistor 712a and the first terminal F of the signal detection unit 713.

[0105] like Figure 7b As shown, if the selection unit 712 connects the second terminal E of the second resistor 712a to the first terminal F of the signal detection unit 713, the current supplied by the power supply 720 flows through the second resistor 712a. The first resistor 711 and the second resistor 712a are connected in parallel, and the resistance of the step-down resistor unit is equal to the resistance of the parallel resistance formed by the first resistor 711 and the second resistor 712a. If the selection unit 712 disconnects the second terminal E of the second resistor 712a from the first terminal F of the signal detection unit 713, the current supplied by the power supply 720 does not flow through the second resistor 712a, and the resistance of the step-down resistor unit is equal to the resistance of the first resistor 711.

[0106] In other embodiments, when the selection unit 712 is used to selectively connect or disconnect the path between the first terminal B of the first resistor 711 and the first terminal D of the second resistor 712a, if the selection unit 712 connects the path between the first terminal B of the first resistor 711 and the first terminal D of the second resistor 712a, the current supplied by the power supply 720 flows through the second resistor 712a, the first resistor 711 and the second resistor 712a are connected in parallel, and the resistance of the step-down resistor unit is equal to the resistance of the parallel resistance formed by the first resistor 711 and the second resistor 712a. If the selection unit 712 disconnects the path between the first terminal B of the first resistor 711 and the first terminal D of the second resistor 712a, the current supplied by the power supply 720 does not flow through the second resistor 712a, and the resistance of the step-down resistor unit is equal to the resistance of the first resistor 711.

[0107] In some embodiments, the zero-crossing detection module 710 may include a plurality of selection units 712, wherein the resistance value of the second resistor 712a in each selection unit 712 may be equal or unequal, so that the resistance value of the step-down resistor of the zero-crossing detection module 710 can provide more resistance values ​​to be compatible with more different types of power supplies 720.

[0108] In this embodiment, the zero-crossing detection module 710 includes a first resistor 711 and a selection unit 712. The selection unit 712 includes a second resistor 712a. The selection unit 712 selectively allows the current supplied by the power supply 720 to pass through or not pass through the second resistor 712a, so that the resistance value of the step-down resistor unit is equal to the resistance value of the first resistor 711, or determined by the resistance values ​​of the first resistor 711 and the second resistor 712a. In other words, the resistance value of the step-down resistor unit can be the resistance value of the first resistor 711, or deviate from the resistance value of the first resistor 711. The zero-crossing detection module 710 can provide voltage resistor units with at least two resistance values, and the circuit structure is simple, which can reduce the cost and area of ​​the zero-crossing detection module 710.

[0109] Figure 8 The third schematic diagram of a zero-crossing detection module provided in this application embodiment is shown. Figure 8 As shown, the selection unit 810 is connected in parallel with the first resistor 820, and the selection unit 810 is connected to the power supply 840 and the signal detection unit 830 respectively. The selection unit 810 may also include a first switch 811, and the first switch 811 is connected in series with the second resistor 812.

[0110] When the first switch 811 is closed, the current supplied by the power supply 840 passes through the second resistor 812. When the first switch 811 is open, the current supplied by the power supply 840 does not pass through the second resistor 812. It should be noted that, compared to when the first switch 811 is open, when the first switch 811 is closed, the first resistor 820 and the second resistor 812 are connected in parallel, increasing the total cross-sectional area of ​​the step-down resistor unit and reducing its resistance to the current supplied by the power supply 840. When the peak voltage of the AC voltage supplied by the power supply 840 is high, the first switch 811 should be open; when the peak voltage of the AC voltage supplied by the power supply 840 is low, the first switch 811 should be closed, so that the second voltage after being stepped down by the step-down resistor unit is close to the target voltage. This ensures that the position of the AC voltage corresponding to the second optocoupler's conduction is consistent, guaranteeing the accuracy of the acquired zero-crossing signal.

[0111] In some embodiments, such as Figure 8As shown, the first switch 811 is connected to the second resistor 812 and the signal detection unit 830, respectively. In other embodiments, the first switch 811 is connected to the power supply 840 and the second resistor 812, respectively.

[0112] Optionally, the first switch 811 may include, but is not limited to, transistors, field-effect transistors, and optocouplers, etc. The level signal may include a first level signal and a second level signal. The first switch 811 may be in an off state based on the second level signal, and the current provided by the power supply 840 may not pass through the second resistor 812, or the current provided by the power supply 840 may pass through the second resistor 812 based on the first level signal being in a conducting state.

[0113] Figure 9 A schematic diagram of the structure of a selection unit provided in an embodiment of this application is shown. Figure 9 As shown, the first switch may include a first optocoupler E1, the collector of the transistor of the first optocoupler E1 is connected to the second resistor R2, the emitter of the first optocoupler E1 is connected to the signal detection unit and the first resistor R1 respectively, the anode of the diode of the first optocoupler E1 is connected to the first voltage input terminal V1, and the cathode of the diode of the first optocoupler E1 is connected to the control module 910.

[0114] It should be noted that when the control module outputs a low-level signal, the first optocoupler E1 is in a closed state, and the resistance of the step-down resistor unit is equal to the resistance of the parallel resistor formed by the first resistor and the second resistor connected in parallel. When the control module outputs a high-level signal, the first optocoupler E1 is in a closed state, and the resistance of the step-down resistor unit is equal to the resistance of the first resistor.

[0115] Please continue to refer to this. Figure 9 The selection unit may also include a current-limiting resistor R7, which is connected to the negative terminal of the diode of the first optocoupler E1 and the control module 910 respectively. The current-limiting resistor R7 determines the magnitude of the driving current of the diode of the first optocoupler E1 to avoid excessive current flowing into the control module 910.

[0116] In this embodiment, the first switch includes a first optocoupler, which can isolate the power supply (high voltage side) from the control module, ensure the safety and reliability of the control module, and improve the safety and reliability of the zero-crossing detection circuit.

[0117] In this embodiment, when the first switch is closed, the current supplied by the power supply passes through the second resistor, and the resistance of the step-down resistor unit is the resistance value corresponding to the parallel resistance formed by the first resistor and the second resistor connected in parallel. When the first switch is open, the current supplied by the power supply does not pass through the second resistor, and the resistance of the step-down resistor unit is the resistance value of the first resistor. By adjusting the open and closed state of the first switch (open state and closed state), the parallel connection of the second resistor and the first resistor can be dynamically adjusted, thereby adjusting the resistance value of the step-down resistor unit, ensuring the reliability of the resistance value adjustment, and at the same time, the adjustment method is simple.

[0118] Please refer to Figure 10 The zero-point detection module may also include a first transistor Q1, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. For a description of the first transistor Q1, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6, please refer to the above embodiment, and it will not be repeated here.

[0119] In some embodiments, please refer to Figure 10 The zero-point detection circuit may further include a power conversion module 1001, a rectifier bridge 1002, and a first capacitor C1. One end of the power conversion module 1001 is connected to the rectifier bridge 1002 and the first capacitor C1, and the other end of the power conversion module 1001 is connected to the control module 1003. The AC power (such as 230V / 60Hz or 115V / 60Hz) supplied by the power supply is rectified into DC power by the rectifier bridge 1002 and the first capacitor C1, and then converted into DC power (such as 12V and 5V DC power) used by the power conversion module 1001 to power the control module 1003 and related circuits. Optionally, the fifth voltage input terminal V5 is 5V, and the first voltage input terminal V1 is 5V.

[0120] In some embodiments, the control module 1003 can be the control center of an electrical appliance. The control module 1003 includes a zero-crossing detection port and a selection port. The zero-crossing detection port is connected to the collector of the first transistor Q1 to obtain the zero-crossing signal output by the signal detection unit. The selection port is connected to the current-limiting resistor R7 and is used to output a level signal. Optionally, the control module 1003 may include, but is not limited to, an MCU (Microcontroller Unit).

[0121] When the AC voltage supplied by the power supply 1004 is 230V / 60Hz, the selection port of the control module 1003 outputs a high-level signal, the first optocoupler E1 is in the off state, and the resistance of the step-down resistor unit is the resistance of the first resistor R1.

[0122] When the AC voltage provided by the power supply 1004 is 115V / 60Hz, the selection port of the control module 1003 outputs a low-level signal, the first optocoupler E1 is in the conducting state, and the resistance value of the step-down resistor unit is the resistance value corresponding to the parallel resistance formed by the first resistor R1 and the second resistor R2 connected in parallel.

[0123] The zero-crossing detection module includes a first resistor R1, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first diode D21, a second diode D22, a second optocoupler E2, and a first transistor Q1.

[0124] Initially, the first optocoupler E1 is in the off state. The AC voltage supplied by the power supply is rectified into a first voltage by the rectifier module composed of the first diode D21 and the second diode D22. This first voltage is then stepped down by the first resistor R1 to obtain a second voltage. When the neutral and live wires N / L cross zero, that is, when the voltage values ​​of the neutral wire N and the live wire L are equal, the current through the first resistor R1 is 0, the second optocoupler E2 is cut off, and the emitter of the second optocoupler E2 is pulled down to ground by the fourth resistor R4. The zero-crossing detection module outputs a low-level signal. At this time, the base voltage of the first transistor Q1 is low, and the first transistor Q1 is in the off state. The zero-crossing detection port is pulled up to 5V by the sixth resistor R6 and inputs a high level. At this time, the zero-crossing signal detection port judges that the AC voltage has crossed zero.

[0125] When the voltages of the neutral line N and the live line L are not equal, the second optocoupler E2 is turned on, the voltage at the emitter of the second optocoupler E2 becomes high, the base voltage of the first transistor Q1 is high, at this time, the first transistor Q1 is in the on state, the collector output of the first transistor Q1 is low, and the zero-crossing detection port inputs a low level.

[0126] In this embodiment, the power supply type is determined by the pulse width of the zero-crossing signal detected by the zero-crossing detection module. By adding a selection unit to control the resistance value of the step-down resistor unit of the zero-crossing detection module, the identification and resistance adjustment for different power supply types are realized. This achieves a balance between circuit drive current and reduced circuit power consumption, realizes a universal circuit design, and solves the problem of abnormal air conditioner operation caused by market after-sales personnel not paying attention to identifying the power supply type due to different zero-crossing detection circuits for different power supplies.

[0127] Understandably, during use, if the peak voltage corresponding to the AC voltage supplied by the power supply changes, the pulse width of the zero-crossing signal will also change. Based on this change, the resistance value of the step-down resistor unit can be adjusted to obtain an accurate zero-crossing signal.

[0128] Figure 11 This is shown as a fourth schematic diagram of a zero-crossing detection module provided in an embodiment of this application. Figure 11As shown, the selection unit 1110 may also include a second switch 1111, a second resistor 1112 connected in series with the first resistor 1120, and the second resistor 1112 connected to the power supply 1140 or the signal detection unit 1130, and the second switch 1111 and the second resistor 1112 connected in parallel.

[0129] Specifically, when the second switch 1111 is in the open state, the current supplied by the power supply 1140 passes through the second resistor 1112. When the second switch 1111 is in the closed state, the second resistor 1112 is short-circuited, and the current supplied by the power supply 1140 does not pass through the second resistor 1112.

[0130] Please refer to the following for further explanation. Figure 11 When the second resistor 1112 is connected to the signal detection unit 1130, the second resistor 1112 is also connected to the first resistor 1120 and the signal detection unit 1130. If the second switch 1111 is in the open state, the current supplied by the power supply 1140 passes through the first resistor 1120 and the second resistor 1112 in sequence.

[0131] It should be noted that when the second switch 1111 is open, compared to when the second switch 1111 is closed, the first resistor 1120 and the second resistor 1112 are connected in series, increasing the total conductor length of the step-down resistor unit and enhancing its resistance to the current supplied by the power supply 1140. When the peak voltage of the AC voltage supplied by the power supply 1140 is high, the second switch 1111 should be open; when the peak voltage of the AC voltage supplied by the power supply 1140 is low, the second switch 1111 should be closed. This ensures that the second voltage after being stepped down by the step-down resistor unit is close to the target voltage, thereby ensuring that the AC voltage position corresponding to the second optocoupler's conduction is consistent and guaranteeing the accuracy of the acquired zero-crossing signal.

[0132] In some embodiments, the second switch 1111 may include a third optocoupler. The collector of the transistor in the third optocoupler is connected to both the first resistor 1120 and the second resistor 1112. The emitter of the transistor in the third optocoupler is connected to both the second resistor 1112 and the signal detection unit 1130. The anode of the diode in the third optocoupler is connected to the first voltage input terminal, and the cathode of the diode in the third optocoupler is connected to the control module. It should be noted that when the control module outputs a low-level signal, the third optocoupler is in a closed state, and the resistance of the step-down resistor unit is equal to the resistance of the first resistor 1120. When the control module outputs a high-level signal, the third optocoupler is in an open state, and the resistance of the step-down resistor unit is the resistance corresponding to the series resistance formed by the first resistor 1120 and the second resistor 1112.

[0133] In this embodiment, the second switch 1111 includes a third optocoupler, which can isolate the power supply (high voltage side) from the control module, ensure the safety and reliability of the control module, and improve the safety and reliability of the zero-crossing detection circuit.

[0134] In this embodiment, when the second switch is in the open state, the current supplied by the power supply passes through the second resistor, and the resistance of the step-down resistor unit is the resistance value corresponding to the series resistance formed by the first resistor and the second resistor connected in series. When the second switch is in the closed state, the current supplied by the power supply does not pass through the second resistor, and the resistance of the step-down resistor unit is the resistance value of the first resistor. By adjusting the open and closed state of the second switch (open state and closed state), the series connection between the second resistor and the first resistor can be dynamically adjusted, thereby adjusting the resistance value of the step-down resistor unit, ensuring the reliability of the resistance value adjustment, and at the same time, the adjustment method is simple.

[0135] In some embodiments, the AC voltage of the power supply includes a third voltage or a fourth voltage, wherein the resistance values ​​of the first resistor and the second resistor are determined based on the peak voltage corresponding to the third voltage and the peak voltage corresponding to the fourth voltage.

[0136] It should be noted that by reasonably selecting the resistance values ​​of the first resistor and the second resistor, the resistance value of the first resistor can be matched with one of the third voltage and the fourth voltage, and the resistance value of the resistor unit formed by the first resistor and the second resistor can be matched with the other of the third voltage and the fourth voltage. This allows the zero-crossing detection circuit to obtain a highly accurate zero-crossing signal when connected to different power supply types.

[0137] In some embodiments, the resistance value of the first resistor can be in the range of 75KΩ to 150KΩ, and the resistance value of the second resistor can be in the range of 75KΩ to 150KΩ. It should be noted that if the third voltage and the fourth voltage are equal, the resistance values ​​of the first resistor and the second resistor can also be equal.

[0138] by Figure 10 Taking the zero-crossing detection circuit shown as an example, the resistance of the first resistor can be 150KΩ, and the resistance of the second resistor can also be 150KΩ. It should be noted that when the pulse width of the zero-crossing signal output by the signal detection unit is L1, it can be assumed that the peak voltage of the AC voltage provided by the power supply 1004 is 230V, the control module 1003 outputs a high-level signal, the first optocoupler E1 is cut off, the resistance of the step-down resistor unit r11 is 150KΩ, and the average driving current of the second optocoupler E2 is I0=Um / r11=(230 / 150)=1.53mA.

[0139] When the pulse width of the zero-crossing signal output by the signal detection unit is L2, it can be assumed that the peak voltage of the AC voltage provided by the power supply 1004 is 115V. The control module 1003 outputs a low-level signal, the first optocoupler E1 is turned on, the first resistor R1 and the second resistor R2 are connected in parallel, the resistance value r11 of the step-down resistor unit is 75KΩ, and the average driving current I0 of the second optocoupler E2 is I0 = Um / r11 = (115 / 75) = 1.53mA, which is equal to the average driving current when the peak voltage is 230V, thus meeting the working requirements of the signal detection unit.

[0140] by Figure 11 In the zero-crossing detection circuit shown, taking the second switch including the third optocoupler as an example, the resistance of the first resistor can be 75KΩ, and the resistance of the second resistor can also be 75KΩ. It should be noted that the peak voltage of the AC voltage supplied by the power supply is 115V. When the control module outputs a low-level signal, the third optocoupler is turned on, the resistance of the step-down resistor unit r11 is 75KΩ, and the average drive current of the second optocoupler E2 is I0 = Um / r11 = (115 / 75) = 1.53mA.

[0141] The peak voltage of the AC voltage supplied by the power supply is 230V. The control module outputs a high-level signal, the third optocoupler is cut off, the resistance value r11 of the step-down resistor unit is 75KΩ + 75KΩ = 150KΩ, and the average drive current I0 of the second optocoupler E2 is I0 = Um / r11 = (230 / 150) = 1.53mA, which is equal to the average drive current when the peak voltage is 115V, thus reducing the energy consumption of the zero-crossing detection unit.

[0142] In this embodiment, the resistance values ​​of the first resistor and the second resistor of the zero-crossing detection module are determined based on the peak voltage corresponding to the AC voltage that the power supply connected to the zero-crossing detection module may provide. This ensures that the resistance range of the step-down resistor unit can match the peak voltage corresponding to different AC voltages, further ensuring the accuracy of the zero-crossing detection circuit.

[0143] In some embodiments, the level signal may include a first level signal and a second level signal. When the pulse width of the zero-crossing signal is greater than a pulse width threshold, the control module outputs the first level signal; when the pulse width of the zero-crossing signal is greater than the pulse width threshold, the control module outputs the second level signal.

[0144] The first level signal is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit to the first resistance value, and the second level signal is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit to the second resistance value, wherein the first resistance value is less than the second resistance value.

[0145] It should be noted that the pulse width threshold can be determined based on the pulse width of the zero-crossing signal corresponding to various power supplies that may be connected to the zero-crossing detection circuit. For example, the pulse width threshold can be less than L2 and greater than L1. If the pulse width of the zero-crossing signal is greater than or equal to the pulse width threshold, it indicates that the peak voltage of the AC voltage provided by the power supply is relatively small. In this case, the resistance value of the step-down resistor unit should be adjusted to a smaller first resistance value. If the pulse width of the zero-crossing signal is less than the pulse width threshold, it indicates that the peak voltage of the AC voltage of the power supply is relatively large. In this case, the resistance value of the step-down resistor unit should be adjusted to a smaller first resistance value so that the second voltage obtained by the step-down resistor unit after resistance adjustment is close after connecting different types of power supplies, thus ensuring the accuracy of the obtained zero-crossing signal.

[0146] Understandably, the control module can be used to detect the pulse width of the zero-crossing signal, compare the pulse width with the pulse width threshold, and output the corresponding level signal based on the comparison result. This function can be implemented using a controller with this software function available on the market, or it can be implemented through hardware circuitry.

[0147] The pulse width threshold of the zero-crossing signal is positively correlated with the amplitude of the AC voltage supplied by the power supply. In this embodiment, when the pulse width of the zero-crossing signal is greater than or equal to the pulse width threshold, that is, when the AC voltage supplied by the power supply is relatively small, the resistance of the step-down resistor unit is relatively small to ensure that the current flowing through the zero-crossing detection circuit is large enough to ensure that the signal detection unit can work normally (such as the second optocoupler can conduct normally). When the pulse width is less than the pulse width threshold, that is, when the AC voltage supplied by the power supply is relatively large, the resistance of the step-down resistor unit is relatively large, which helps to suppress the current, protect the zero-crossing detection circuit, and reduce energy consumption. While ensuring the accuracy of zero-crossing detection, the energy consumption of the zero-crossing detection circuit can be reduced.

[0148] Figure 12 A schematic diagram of a control module provided in an embodiment of this application is shown. For example... Figure 12As shown, the control module 1210 may include a second capacitor C2 and a comparator U1. The second capacitor C2 is connected to the signal detection unit 1221. The first input terminal of the comparator U1 is connected to the second capacitor C2, and the second input terminal of the comparator U1 is used to input a reference voltage Vref. The output terminal of the comparator U1 is connected to the zero-crossing detection module 1220. The second capacitor C2 is used to charge based on the zero-crossing signal to obtain a pulse width-dependent fifth voltage of the zero-crossing signal. The comparator U1 is used to compare the fifth voltage with the reference voltage and output a level signal.

[0149] The reference voltage is generated based on the pulse width threshold. For example, the reference voltage is positively correlated with the pulse width threshold; that is, the larger the pulse width threshold, the larger the reference voltage. It should be noted that in this embodiment, the pulse width of the zero-crossing signal is converted into a fifth voltage through the second capacitor C2. Then, the comparator U1 compares the fifth voltage with the reference voltage Vref, and outputs a corresponding level signal based on the comparison result. The fifth voltage is related to the pulse width of the zero-crossing signal. If the pulse width of the zero-crossing signal refers to the length of time the zero-crossing signal remains in a high-level state, the fifth voltage is positively correlated with the pulse width of the zero-crossing signal. If the pulse width of the zero-crossing signal refers to the length of time the zero-crossing signal remains in a low-level state, the fifth voltage is negatively correlated with the pulse width of the zero-crossing signal.

[0150] Optionally, comparator U1 can be an operational amplifier. If the first level signal is a high level signal and the second level signal is a low level signal, then the first input terminal of comparator U1 can be the non-inverting input terminal of the operational amplifier, and the second output terminal of comparator U1 can be the inverting input terminal of the operational amplifier. If the first level signal is a low level signal and the second level signal is a high level signal, then the first input terminal of comparator U1 can be the inverting input terminal of the operational amplifier, and the second output terminal of comparator U1 can be the non-inverting input terminal of the operational amplifier.

[0151] Figure 13 A schematic diagram of another control module provided in an embodiment of this application is shown. Figure 13 As shown, the control module may further include a second capacitor C2, a comparator U1, a controller 1311, and an isolation element 1312. The controller 1311 is connected to the signal detection unit 1321 and the load 1330, respectively. The isolation element 1312 is connected to the second capacitor C2, the signal detection unit 1321, and the controller 1311, respectively. The controller 1311 controls the load 1330 based on the zero-crossing signal output by the signal detection unit 1321. The isolation element 1312 allows the zero-crossing signal to flow to the second capacitor C2 and blocks the current flowing from the second capacitor C2 into the controller 1311.

[0152] It should be noted that an isolation element 1312 is provided between the second capacitor C2 and the controller 1311, and between the second capacitor C2 and the signal detection unit 1321. This can prevent the charging and discharging process of the second capacitor C2 from affecting the zero-crossing signal received by the controller 1311, and ensure that the signal received by the controller 1311 is more stable and reliable.

[0153] Optionally, the isolation element 1312 may include a third diode D3. The positive terminal of the third diode D3 is connected to both the signal detection unit 1321 and the controller 1311, and the negative terminal of the third diode D3 is connected to the second capacitor C2. It should be noted that the third diode D3 has unidirectional conduction and reverse cutoff characteristics. This feature effectively prevents the charging and discharging process of the second capacitor C2 from affecting the zero-crossing signal received by the controller 1311. Furthermore, the third diode D3 is a passive element, which, compared to active elements, reduces the price and size of the control module.

[0154] It is understood that the controller 1311 used in this embodiment can be any commercially available controller that can control the load 1330 according to the zero-crossing signal. The circuit structure of the control module provided in the above embodiment is only an example. Other hardware circuits that can achieve this function can also be used. This embodiment does not limit this.

[0155] In this embodiment, the control module also includes a controller and an isolation element. The isolation element limits the flow of the zero-crossing signal, which can effectively prevent the interference current generated during the charging and discharging of the second capacitor from affecting the level stability of the controller input terminal. That is, it ensures the accuracy of the zero-crossing signal acquired by the controller. Thus, while adjusting the resistance value of the step-down resistor unit, it can ensure the accuracy and reliability of the controller's control of the load based on the zero-crossing signal.

[0156] In this embodiment, the control module includes a second capacitor and a comparator. The second capacitor is connected to the signal detection unit and is charged based on the zero-crossing signal to obtain a fifth voltage related to the pulse width of the zero-crossing signal. The first input terminal of the comparator is connected to the second capacitor. The comparator compares the fifth voltage with a reference voltage and outputs a level signal corresponding to the comparison result. By setting hardware circuits to realize the output of the corresponding level signal based on the pulse width of the zero-crossing signal, the software design complexity of the control module is reduced.

[0157] This application also provides an electrical appliance that may include any of the zero-crossing detection circuits provided in the above embodiments. Optionally, the electrical appliance may further include a load, and the control of the load may be based on the zero-crossing signal output by the signal detection unit to improve the control accuracy of the load. Optionally, the electrical appliance may include, but is not limited to, refrigerators, air conditioners, water heaters, induction cookers, etc.

[0158] In this embodiment, by setting the zero-crossing detection circuit provided in the above embodiment in the electrical appliance, a high-accuracy zero-crossing detection signal can be obtained, thereby improving the control precision of the electrical appliance. At the same time, it can ensure the normal operation of the zero-crossing detection circuit and reduce the energy consumption of the zero-crossing detection circuit, thereby further improving the control precision of the electrical appliance while reducing its energy consumption.

[0159] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" 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 the present invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0160] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0161] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A zero-crossing detection circuit, characterized in that, include: The zero-crossing detection module includes a step-down resistor unit and a signal detection unit. The step-down resistor unit is connected to both the power supply and the signal detection unit. The step-down resistor unit is used to step down a first voltage to obtain a second voltage. The signal detection unit is used to output a zero-crossing signal based on the second voltage. The first voltage is obtained from the AC voltage provided by the power supply, and the zero-crossing signal is used to characterize the zero-point information of the AC voltage. A control module is connected to the zero-crossing detection module. The control module is used to detect the pulse width of the zero-crossing signal and output a level signal to the zero-crossing detection module according to the pulse width. The level signal is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit.

2. The zero-crossing detection circuit according to claim 1, characterized in that, The zero-crossing detection module further includes a first resistor and a selection unit. The first resistor is connected to the selection unit and the signal detection unit, respectively. The selection unit is also connected to the control module. The selection unit includes a second resistor connected to the first resistor; the step-down resistor unit consists of the first resistor, or is composed of the first resistor and the second resistor. The selection unit is configured to, based on the level signal, allow the current supplied by the power supply to pass through or not pass through the second resistor. When the current supplied by the power source passes through the second resistor, the resistance value of the step-down resistor unit is determined based on the resistance values ​​of the first resistor and the second resistor. When the current supplied by the power source does not pass through the second resistor, the resistance value of the step-down resistor unit is equal to the resistance value of the first resistor.

3. The zero-crossing detection circuit according to claim 2, characterized in that, The selection unit is connected in parallel with the first resistor, and the selection unit is connected to the power supply and the signal detection unit respectively. The selection unit also includes a first switch, which is connected in series with the second resistor. When the first switch is closed, the current supplied by the power source passes through the second resistor; When the first switch is in the open state, the current supplied by the power source does not pass through the second resistor.

4. The zero-crossing detection circuit according to claim 3, characterized in that, The first switch includes a first optocoupler; The collector of the transistor in the first optocoupler is connected to the second resistor, the emitter of the first optocoupler is connected to the signal detection unit and the first resistor, the anode of the diode in the first optocoupler is connected to the first voltage input terminal, and the cathode of the diode in the first optocoupler is connected to the control module.

5. The zero-crossing detection circuit according to claim 2, characterized in that, The selection unit further includes a second switch, the second resistor is connected in series with the first resistor, and the second resistor is connected to the power supply or the signal detection unit, and the second switch is connected in parallel with the second resistor; When the second switch is in the off state, the current supplied by the power source passes through the second resistor; When the second switch is closed, the second resistor is short-circuited, and the current supplied by the power source does not pass through the second resistor.

6. The zero-crossing detection circuit according to claim 2, characterized in that, The AC voltage of the power supply includes a third voltage or a fourth voltage, wherein the resistance values ​​of the first resistor and the second resistor are determined based on the peak voltage corresponding to the third voltage and the peak voltage corresponding to the fourth voltage.

7. The zero-crossing detection circuit according to claim 1, characterized in that, The level signal includes a first level signal and a second level signal; When the pulse width of the zero-crossing signal is greater than or equal to the pulse width threshold, the control module outputs a first level signal, which is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit to the first resistance value. When the pulse width of the zero-crossing signal is less than the pulse width threshold, the control module outputs a second level signal, which is used to control the zero-crossing detection module to adjust the resistance value of the step-down resistor unit to the second resistance value. The first resistance value is less than the second resistance value.

8. The zero-crossing detection circuit according to claim 7, characterized in that, The control module includes: A capacitor, connected to the signal detection unit, is used to charge based on the zero-crossing signal to obtain a fifth voltage related to the pulse width of the zero-crossing signal; A comparator, wherein the first input terminal of the comparator is connected to the capacitor, the second input terminal of the comparator is used to input a reference voltage, and the output terminal of the comparator is connected to the zero-crossing detection module, wherein the reference voltage is generated based on the pulse width threshold; The comparator is used to compare the fifth voltage with the reference voltage and output a level signal.

9. The zero-crossing detection circuit according to claim 8, characterized in that, The control module also includes: A controller is connected to both the signal detection unit and the load. The controller is used to control the load based on the zero-crossing signal output by the signal detection unit. An isolation element is connected to the capacitor, the signal detection unit, and the controller, respectively. The isolation element is used to allow the zero-crossing signal to flow to the capacitor and to block the current flowing from the capacitor into the controller.

10. An electrical appliance, characterized in that, Includes the zero-crossing detection circuit as described in any one of claims 1 to 9.

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