Alternating voltage positive and negative half cycle detection circuit and zero-crossing detection method

Abstract

The embodiment of the application discloses an alternating voltage positive and negative half cycle detection circuit and a zero-crossing detection method, wherein the positive half cycle and the negative half cycle of the alternating voltage are rectified by a rectification module to obtain a positive half cycle rectification signal and a negative half cycle rectification signal; an isolation coupling module changes the output voltage of a first output end according to the positive half cycle rectification signal; and changes the output voltage of a second output end according to the negative half cycle rectification signal; on the one hand, the positive half cycle and the negative half cycle of the alternating voltage are rectified and detected respectively, and then whether the positive half cycle and the negative half cycle are missing can be judged according to the output waveform of the first output end and the output waveform of the second output end, and the abnormal phenomenon of the power grid can be found in time; on the other hand, the time period between the first output voltage corresponding to the positive half cycle rectification signal and the second output voltage corresponding to the negative half cycle rectification signal in the same period of the alternating voltage is determined to determine the zero-crossing point of the alternating voltage, and the zero-crossing detection precision can be improved.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to an AC voltage positive and negative half-cycle detection circuit and a zero-crossing detection method. Background Technology

[0002] Zero-crossing detection or AC positive and negative half-cycle detection is widely used in many fields.

[0003] In existing technologies, zero-crossing detection or AC positive and negative half-cycle detection is usually a single-channel output, which cannot distinguish whether there is a missing phenomenon in the positive or negative half-cycle. It cannot make a judgment when the power grid is abnormal, and there is a problem of low zero-crossing detection accuracy. Summary of the Invention

[0004] This invention provides an AC voltage positive and negative half-cycle detection circuit and a zero-crossing detection method to detect the positive and negative half-cycles of AC voltage, so as to identify abnormal phenomena in the power grid in a timely manner and improve the accuracy of zero-crossing detection.

[0005] According to one aspect of the present invention, an AC voltage positive and negative half-cycle detection circuit is provided, comprising: a rectifier module, an isolation coupling module, and an output module; the rectifier module has an AC voltage connected to its rectifier input terminal and an AC voltage connected to its rectifier output terminal electrically connected to the isolation coupling module, for rectifying the positive and negative half-cycles of the AC voltage respectively to obtain a positive half-cycle rectified signal and a negative half-cycle rectified signal; the output module includes a first output terminal and a second output terminal, which are respectively electrically connected to the isolation coupling module; the isolation coupling module is used to change the first output voltage of the first output terminal according to the positive half-cycle rectified signal; and to change the second output voltage of the second output terminal according to the negative half-cycle rectified signal.

[0006] Optionally, the rectifier module includes a first rectifier unit and a second rectifier unit, and the rectifier input terminals include a first rectifier input terminal and a second rectifier input terminal; the first rectifier unit is connected between the first rectifier input terminal and a first terminal of the isolation coupling module, and the second terminal of the isolation coupling module is electrically connected to the second rectifier input terminal; the second rectifier unit is connected between the second rectifier input terminal and a third terminal of the isolation coupling module, and the fourth terminal of the isolation coupling module is electrically connected to the first rectifier input terminal; the isolation coupling module is used to turn on the first terminal and the second terminal according to the positive half-cycle rectified signal to output a first reference voltage to the first output terminal; the isolation coupling module is also used to turn on the third terminal and the fourth terminal according to the negative half-cycle rectified signal to output a second reference voltage to the second output terminal.

[0007] Optionally, the isolation coupling module includes a first isolation coupling unit and a second isolation coupling unit; the first isolation coupling unit is electrically connected to a first terminal, a second terminal and a first output terminal respectively, and is used to turn on the first terminal and the second terminal according to the positive half-cycle rectified signal, so as to connect the fifth terminal and the sixth terminal of the isolation coupling module, wherein the fifth terminal is electrically connected to a first reference voltage source and the sixth terminal is electrically connected to the first output terminal; The second isolation coupling unit is electrically connected to the third terminal, the fourth terminal, and the second output terminal, respectively, and is used to turn on the third terminal and the fourth terminal according to the negative half-cycle rectified signal, so as to connect the seventh terminal and the eighth terminal of the isolation coupling module. The seventh terminal is electrically connected to the second reference voltage source, and the eighth terminal is electrically connected to the second output terminal.

[0008] Optionally, the first isolation coupling unit and the second isolation coupling unit each include an input subunit, an isolation subunit, and an output subunit; the isolation subunit is located between the input subunit and the output subunit and is used to isolate the transmission of the output signal of the input subunit to the output subunit. In the first isolation coupling unit, the input subunit is connected between the first terminal and the second terminal and is used to conduct according to the positive half-cycle rectified signal; the output subunit is connected between the fifth terminal and the sixth terminal and is used to conduct between the fifth terminal and the sixth terminal when the first terminal and the second terminal are conducting. In the second isolation coupling unit, the input subunit is connected between the third and fourth terminals and is used to conduct according to the negative half-cycle rectified signal; the output subunit is connected between the seventh and eighth terminals and is used to conduct between the seventh and eighth terminals when the third and fourth terminals are conducting.

[0009] Optionally, the AC voltage positive and negative half-cycle detection circuit also includes a first current limiting module and a second current limiting module. The first current limiting module is connected in series between the first rectifier unit and the first terminal, and the second current limiting module is connected in series between the second rectifier unit and the third terminal.

[0010] Optionally, the first rectifier input terminal is used to connect to the live wire, and the second rectifier input terminal is used to connect to the neutral wire; or the first rectifier input terminal is used to connect to the neutral wire, and the second rectifier input terminal is used to connect to the live wire.

[0011] Optionally, the output module includes a third current limiting module and a fourth current limiting module. The first terminal of the third current limiting module is electrically connected to the third reference voltage source, and the second terminal of the third current limiting module is electrically connected to the first output terminal. The first terminal of the fourth current limiting module is electrically connected to the fourth reference voltage source, and the second terminal of the fourth current limiting module is electrically connected to the second output terminal.

[0012] Optionally, the isolation coupling module includes an optocoupler emulator.

[0013] Optionally, the optocoupler simulator includes a diode analog circuit, a signal modulation circuit, a capacitor isolation barrier, a signal demodulation circuit, and an output circuit. The input terminal of the diode analog circuit is electrically connected to the rectified output terminal, and the signal modulation circuit is electrically connected to the output terminal of the diode analog circuit, used to modulate the output signal of the diode analog circuit into a modulation signal of a set frequency. The set frequency is higher than the frequency of the output signal of the diode analog circuit. The capacitor isolation barrier is used to isolate the modulation signal and transmit it to the signal demodulation circuit, which demodulates the modulation signal and outputs the demodulated signal to the output circuit. The output circuit is used to change the output voltage of the first or second output terminal according to the demodulated signal.

[0014] According to another aspect of the present invention, a zero-crossing detection method is provided, comprising: The first output voltage of the first output terminal and the second output voltage of the second output terminal of the AC voltage positive and negative half-cycle detection circuit are obtained; the AC voltage positive and negative half-cycle detection circuit is any embodiment of the AC voltage positive and negative half-cycle detection circuit of the present invention. The zero-crossing time of the AC voltage is determined based on the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage.

[0015] The AC voltage positive and negative half-cycle detection circuit and zero-crossing detection method of this invention rectify the positive and negative half-cycles of the AC voltage separately through a rectifier module to obtain positive half-cycle rectified signals and negative half-cycle rectified signals. An isolation coupling module changes the output voltage of the first output terminal based on the positive half-cycle rectified signal and the output voltage of the second output terminal based on the negative half-cycle rectified signal. This achieves separate rectification and detection of the positive and negative half-cycles of the AC voltage, allowing for the determination of whether any missing half-cycles exist based on the output waveforms of the first and second output terminals, thus enabling timely detection of power grid anomalies. Furthermore, since the first output terminal outputs a detection waveform corresponding to the positive half-cycle and the second output terminal outputs a detection waveform corresponding to the negative half-cycle, the zero-crossing point of the AC voltage is determined based on the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage. Compared to existing technologies that use the transition edge of the positive or negative half-cycle detection waveform as the zero-crossing point, this method improves the accuracy of zero-crossing point detection.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

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

[0018] Figure 1 This is a schematic diagram of the structure of an AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the input and output of the AC voltage positive and negative half-cycle detection circuit; Figure 3 This is a schematic diagram of another AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of another AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of an optical coupler simulator provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of another AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention; Figure 7 This is a flowchart of a zero-crossing detection method provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of an intelligent switch control system provided in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Figure 1 This is a schematic diagram of an AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention. (Refer to...) Figure 1 The detection circuit includes a rectifier module 100, an isolation coupling module 200, and an output module 300. The rectifier module 100's rectifier input terminal IN is connected to an AC voltage, and its rectifier output terminal is electrically connected to the isolation coupling module 200. This allows for the rectification of the positive and negative half-cycles of the AC voltage, respectively, to obtain a positive half-cycle rectified signal and a negative half-cycle rectified signal. The output module 300 includes a first output terminal OUT1 and a second output terminal OUT2, both of which are electrically connected to the isolation coupling module 200. The isolation coupling module 200 is used to change the first output voltage of the first output terminal OUT1 according to the positive half-cycle rectified signal, and to change the second output voltage of the second output terminal OUT2 according to the negative half-cycle rectified signal.

[0022] The rectifier module 100 rectifies the current and voltage input to the rectifier input terminal IN. Specifically, the rectifier module 100 rectifies the positive and negative half-cycles of the AC voltage respectively to obtain positive half-cycle rectified signals and negative half-cycle rectified signals. Optionally, the rectifier module 100 includes a positive half-cycle rectifier unit and a negative half-cycle rectifier unit. The positive half-cycle rectifier unit rectifies the positive half-cycle of the AC voltage to obtain a positive half-cycle rectified signal; the negative half-cycle rectifier unit rectifies the negative half-cycle of the AC voltage to obtain a negative half-cycle rectified signal.

[0023] The isolation coupling module 200 is electrically connected to the rectified output terminal of the rectifier module 100. The isolation coupling module 200 isolates the electrical signals between its input and output terminals, achieving isolated signal transmission. In some embodiments, the isolation coupling module 200 includes an optocoupler. In other embodiments, the isolation coupling module 200 may include an optocoupler emulator. When no AC voltage is input to the AC voltage positive and negative half-cycle detection circuit, the first output terminal OUT1 of the output module 300 outputs a first fixed voltage, and the second output terminal OUT2 of the output module 300 outputs a second fixed voltage. The first and second fixed voltages can be the same or different. After the positive half-cycle rectified signal is input to the isolation coupling module 200, the isolation coupling module 200 outputs a voltage different from the first fixed voltage to the first output terminal OUT1 according to the positive half-cycle rectified signal, thereby changing the output voltage of the first output terminal OUT1. After the negative half-cycle rectified signal is input to the isolation coupling module 200, the isolation coupling module 200 outputs a voltage different from the second fixed voltage to the second output terminal OUT2 according to the negative half-cycle rectified signal, thereby changing the output voltage of the second output terminal OUT2. For example, when there is no AC voltage input, the voltages of the first output terminal OUT1 and the second output terminal OUT2 are both first-level voltages. The isolation coupling module 200 outputs a second-level voltage to the first output terminal OUT1 according to the positive half-cycle rectified signal; the isolation coupling module 200 outputs a second-level voltage to the second output terminal OUT2 according to the negative half-cycle rectified signal. One of the first-level voltage and the second-level voltage is a high-level voltage, and the other is a low-level voltage.

[0024] Figure 2 This is a schematic diagram of the input and output of an AC voltage positive and negative half-cycle detection circuit. The rectifier input terminal IN is connected to the AC voltage U0. The rectifier module 100 obtains a positive half-cycle rectified signal based on the positive half-cycle of the AC voltage U0. The isolation coupling module 200 changes the first output voltage from a first-level voltage to a second-level voltage based on the positive half-cycle rectified signal. The voltage at the second output terminal OUT2 is the first-level voltage. Similarly, the rectifier module 100 obtains a negative half-cycle rectified signal based on the negative half-cycle of the AC voltage U0. The isolation coupling module 200 changes the second output voltage from the first-level voltage to a second-level voltage based on the positive half-cycle rectified signal. The voltage at the first output terminal OUT1 is the first-level voltage. Figure 2 The example is illustrated using a first-level voltage as a high-level voltage and a second-level voltage as a low-level voltage. Based on the first output voltage of the first output terminal OUT1 and the second output voltage of the second output terminal OUT2 within one AC voltage cycle U0, the zero-crossing time of the AC voltage U0 can be determined.

[0025] Optionally, the zero-crossing time of the AC voltage U0 is determined based on the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage U0. Figure 2 Taking the illustrated example, the time period corresponding to the first output voltage of the positive half-cycle rectified signal is the time period when the first output voltage is at the second level voltage, and the time period corresponding to the second output voltage of the negative half-cycle rectified signal is the time period when the second output voltage is at the second level voltage. The time period between these two periods is the overlap period of the first level voltage of the first output terminal OUT1 and the first level voltage of the second output terminal OUT2. Therefore, the zero-crossing point of the AC voltage U0 can be determined based on the overlap period t0 of the first level voltage of the first output terminal OUT1 and the first level voltage of the second output terminal OUT2. Since the signal in the detection circuit inevitably has a delay, the duration of the overlap period t0 of the first level voltage of the first output terminal OUT1 and the first level voltage of the second output terminal OUT2 is greater than 0. In some embodiments, the zero-crossing point of the AC voltage U0 is determined by the midpoint of the time period between the first output voltage of the positive half-cycle rectified signal and the second output voltage of the negative half-cycle rectified signal within the same cycle of the AC voltage U0. Figure 2 As shown, for example, the midpoint of the overlap period t0 between the first level voltage of the first output terminal OUT1 and the first level voltage of the second output terminal OUT2 is determined as the zero-crossing point of the AC voltage U0.

[0026] The AC voltage positive and negative half-cycle detection circuit of this invention rectifyes the positive and negative half-cycles of the AC voltage separately through a rectifier module to obtain positive half-cycle rectified signals and negative half-cycle rectified signals. An isolation coupling module changes the output voltage of the first output terminal based on the positive half-cycle rectified signal and the output voltage of the second output terminal based on the negative half-cycle rectified signal. This achieves separate rectification and detection of the positive and negative half-cycles of the AC voltage, allowing for the determination of whether any missing half-cycles exist based on the output waveforms of the first and second output terminals, thus enabling timely detection of power grid anomalies. Furthermore, since the first output terminal outputs a detection waveform corresponding to the positive half-cycle and the second output terminal outputs a detection waveform corresponding to the negative half-cycle, the zero-crossing point of the AC voltage is determined based on the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage. Compared to existing technologies that use the transition edge of the positive or negative half-cycle detection waveform as the zero-crossing point, this method improves the accuracy of zero-crossing point detection.

[0027] Figure 3 This is a schematic diagram of another AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention, for reference. Figure 3Optionally, the rectifier module 100 includes a first rectifier unit 110 and a second rectifier unit 120, and the rectifier input terminals include a first rectifier input terminal IN1 and a second rectifier input terminal IN2. The first rectifier unit 110 is connected between the first rectifier input terminal IN1 and the first terminal A1 of the isolation coupling module 200, and the second terminal A2 of the isolation coupling module 200 is electrically connected to the second rectifier input terminal IN2. The second rectifier unit 120 is connected between the second rectifier input terminal IN2 and the third terminal A3 of the isolation coupling module 200, and the fourth terminal A4 of the isolation coupling module 200 is electrically connected to the first rectifier input terminal IN1. The isolation coupling module 200 is used to turn on the first terminal A1 and the second terminal A2 according to the positive half-cycle rectified signal to output a first reference voltage to the first output terminal OUT1. The isolation coupling module 200 is also used to turn on the third terminal A3 and the fourth terminal A4 according to the negative half-cycle rectified signal to output a second reference voltage to the second output terminal OUT2.

[0028] Optionally, the first rectifier input terminal IN1 is used to connect to the live wire, and the second rectifier input terminal IN2 is used to connect to the neutral wire; or the first rectifier input terminal IN1 is used to connect to the neutral wire, and the second rectifier input terminal IN2 is used to connect to the live wire. Thus, when the AC power supply is connected to the AC voltage positive and negative half-cycle detection circuit, the connections of the live wire and neutral wire to the two rectifier input terminals of the detection circuit can be interchanged for quick wiring. Specifically, when the first rectifier input terminal IN1 is connected to the live wire and the second rectifier input terminal IN2 is connected to the neutral wire, the first rectifier unit 110 acts as the positive half-cycle rectifier unit, and the second rectifier unit 120 acts as the negative half-cycle rectifier unit; when the first rectifier input terminal IN1 is connected to the neutral wire and the second rectifier input terminal IN2 is connected to the live wire, the first rectifier unit 110 acts as the negative half-cycle rectifier unit, and the second rectifier unit 120 acts as the positive half-cycle rectifier unit.

[0029] Taking the first rectifier input terminal IN1 connected to the live wire and the second rectifier input terminal IN2 connected to the neutral wire as an example, during the positive half-cycle of the AC voltage, the first rectifier unit 110 is turned on, so that the current flows from the live wire through the first rectifier input terminal IN1, the first rectifier unit 110, the first terminal A1 of the isolation coupling module 200, the second terminal A2 of the isolation coupling module 200, and the second rectifier input terminal IN2, and finally returns to the neutral wire. The first terminal A1 and the second terminal A2 of the isolation coupling module 200 are connected, so that the isolation coupling module 200 outputs a first reference voltage to the first output terminal OUT1. The first reference voltage is different from the first fixed voltage originally output by the first output terminal OUT1, so that the output voltage of the first output terminal OUT1 changes during the positive half-cycle of the AC voltage.

[0030] During the negative half-cycle of the AC voltage, the second rectifier unit 120 is turned on, causing current to flow from the neutral wire through the second rectifier input terminal IN2, the second rectifier unit 120, the third terminal A3 of the isolation coupling module 200, the fourth terminal A4 of the isolation coupling module 200, and the first rectifier input terminal IN1, finally returning to the live wire. The third terminal A3 and the fourth terminal A4 of the isolation coupling module 200 are connected, causing the isolation coupling module 200 to output a second reference voltage to the second output terminal OUT2. This second reference voltage differs from the original second fixed voltage output by the second output terminal OUT2, thus changing the output voltage of the second output terminal OUT2 during the negative half-cycle of the AC voltage. The first and second reference voltages can be the same or different; this embodiment of the invention does not impose specific limitations.

[0031] Continue to refer to Figure 3 Optionally, the isolation coupling module 200 includes a first isolation coupling unit 210 and a second isolation coupling unit 220. The first isolation coupling unit 210 is electrically connected to a first terminal A1, a second terminal A2, and a first output terminal OUT1, respectively, and is used to conduct the first terminal A1 and the second terminal A2 according to the positive half-cycle rectified signal, so as to conduct between the fifth terminal A5 and the sixth terminal A6 of the isolation coupling module 200, wherein the fifth terminal A5 is electrically connected to the first reference voltage source V1, and the sixth terminal A6 is electrically connected to the first output terminal OUT1. The second isolation coupling unit 220 is electrically connected to a third terminal A3, a fourth terminal A4, and a second output terminal OUT2, respectively, and is used to conduct the third terminal A3 and the fourth terminal A4 according to the negative half-cycle rectified signal, so as to conduct between the seventh terminal A7 and the eighth terminal A8 of the isolation coupling module 200, wherein the seventh terminal A7 is electrically connected to the second reference voltage source V2, and the eighth terminal A8 is electrically connected to the second output terminal OUT2.

[0032] Specifically, the isolation coupling module 200 also includes a fifth terminal A5, a sixth terminal A6, a seventh terminal A7, and an eighth terminal A8. The conduction state between the fifth terminal A5 and the sixth terminal A6 is determined by the conduction state between the first terminal A1 and the second terminal A2. Specifically, the first isolation coupling unit 210 conducts between the first terminal A1 and the second terminal A2 according to the positive half-cycle rectified signal, thereby conducting between the fifth terminal A5 and the sixth terminal A6 of the isolation coupling module 200, allowing the first reference voltage of the first reference voltage source V1 to be transmitted to the first output terminal OUT1. The second isolation coupling unit 220 conducts between the third terminal A3 and the fourth terminal A4 according to the negative half-cycle rectified signal, thereby conducting between the seventh terminal A7 and the eighth terminal A8 of the isolation coupling module 200, allowing the second reference voltage of the second reference voltage source V2 to be transmitted to the second output terminal OUT2. The output module 300 can be connected to a fixed voltage source. When the first terminal A1 and the second terminal A2 of the isolation coupling module 200 are not connected, the first output voltage is a first fixed voltage, which differs from the first reference voltage. When the third terminal A3 and the fourth terminal A4 of the isolation coupling module 200 are not connected, the second output voltage is a second fixed voltage, which differs from the second reference voltage. When the first terminal A1 and the second terminal A2 of the isolation coupling module 200 are disconnected (e.g., during the negative half-cycle of the AC voltage, or when there is no AC voltage input), the first output terminal OUT1 outputs the first fixed voltage. When the first terminal A1 and the second terminal A2 of the isolation coupling module 200 are connected, the output voltage of the first output terminal OUT1 jumps to the first reference voltage. When the third terminal A3 and the fourth terminal A4 of the isolation coupling module 200 are turned off (e.g., during the positive half-cycle of the AC voltage, or when there is no AC voltage input), the second output terminal OUT2 outputs a second fixed voltage; when the third terminal A3 and the fourth terminal A4 of the isolation coupling module 200 are turned on, the output voltage of the second output terminal OUT2 jumps to the second reference voltage.

[0033] In some embodiments, the first reference voltage source V1 and the second reference voltage source V2 are the same reference voltage source, and the fifth terminal A5 and the seventh terminal A7 of the isolation coupling module 200 can be the same port.

[0034] Figure 4 This is a schematic diagram of another AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention, for reference. Figure 4Optionally, the first isolation coupling unit 210 and the second isolation coupling unit 220 each include an input subunit, an isolation subunit, and an output subunit. The isolation subunit is located between the input subunit and the output subunit and is used to isolate the transmission of the input subunit's output signal to the output subunit. In the first isolation coupling unit 210, the input subunit is connected between the first terminal A1 and the second terminal A2, and is turned on according to the positive half-cycle rectified signal. The output subunit is connected between the fifth terminal A5 and the sixth terminal A6, and is used to connect the fifth terminal A5 and the sixth terminal A6 when the first terminal A1 and the second terminal A2 are turned on. In the second isolation coupling unit 220, the input subunit is connected between the third terminal A3 and the fourth terminal A4, and is used to turn on according to the negative half-cycle rectified signal. The output subunit is connected between the seventh terminal A7 and the eighth terminal A8, and is used to connect the seventh terminal A7 and the eighth terminal A8 when the third terminal A3 and the fourth terminal A4 are turned on.

[0035] For example, the first isolation coupling unit 210 includes a first input subunit 211, a first isolation subunit 212, and a first output subunit 213, with the first isolation subunit 212 located between the first input subunit 211 and the first output subunit 213. The second isolation coupling unit 220 includes a second input subunit 221, a second isolation subunit 222, and a second output subunit 223, with the second isolation subunit 222 located between the second input subunit 221 and the second output subunit 223. The first input subunit 211 is connected between the first terminal A1 and the second terminal A2. The first input subunit 211 is turned on according to the positive half-cycle rectified signal. The first isolation subunit 212 transmits the output signal of the first input subunit 211 to the first output subunit 213, causing the first output subunit 213 to turn on, connecting the fifth terminal A5 and the sixth terminal A6 of the isolation coupling module 200, thereby outputting a first reference voltage to the first output terminal OUT1. The second input subunit 221 is connected between the third terminal A3 and the fourth terminal A4. The second input subunit 221 is turned on according to the negative half-cycle rectified signal. The second isolation subunit 222 transmits the output signal of the second input subunit 221 to the second output subunit 223, so that the second output subunit 223 is turned on, connecting the seventh terminal A7 and the eighth terminal A8 of the isolation coupling module 200, and then outputting the second reference voltage to the second output terminal OUT2.

[0036] In some embodiments, the first isolation coupling unit 210 and the second isolation coupling unit 220 respectively include optical couplers. In this case, the input subunit includes a light-emitting element, the output subunit includes a light-receiving element, and the isolation unit may include an insulating isolation layer.

[0037] In other embodiments, the first isolation coupling unit 210 and the second isolation coupling unit 220 each include an optical coupler simulator, or the first isolation coupling unit 210 and the second isolation coupling unit 220 are integrated in the same optical coupler simulator. Figure 5 This is a schematic diagram of an optocoupler emulator provided in an embodiment of the present invention. The optocoupler emulator 30 includes a diode analog circuit 301, a signal modulation circuit 302, a capacitor isolation barrier 303, a signal demodulation circuit 304, and an output circuit 305. The input subunit includes the diode analog circuit 301 and the signal modulation circuit 302, the isolation subunit may include the capacitor isolation barrier 303, and the output subunit includes the signal demodulation circuit 304 and the output circuit 305. The input terminal of the diode analog circuit 301 is electrically connected to the rectified output terminal, and the signal modulation circuit 302 is electrically connected to the output terminal of the diode analog circuit 301, used to modulate the output signal of the diode analog circuit 301 into a modulation signal of a set frequency; the set frequency is higher than the frequency of the output signal of the diode analog circuit 301; the capacitor isolation barrier 303 is used to isolate and transmit the modulated signal to the signal demodulation circuit 304, the signal demodulation circuit 304 is used to demodulate the modulated signal and output the demodulated signal to the output circuit 305; the output circuit 305 is used to change the output voltage of the first output terminal OUT1 or the second output terminal OUT2 according to the demodulated signal.

[0038] Figure 5 The optical coupler simulator 30 shown can correspond to the structure of either the first isolation coupling unit or the second isolation coupling unit; that is, both the first and second isolation coupling units can be adopted. Figure 5 The structure of the optical coupler simulator 30 shown, or the isolation coupling module includes two... Figure 5 The structure of the optocoupler simulator 30 is shown. Correspondingly, combined with... Figure 4 and Figure 5 The two input terminals of the optocoupler emulator 30 (i.e., the third input terminal AN and the fourth input terminal CAT) are respectively used as the first terminal A1 or the second terminal A2 of the isolation coupling module 200, or the two input terminals of the optocoupler emulator 30 are respectively used as the third terminal A3 and the fourth terminal A4 of the isolation coupling module 200.

[0039] The diode analog circuit 301 simulates the characteristics of a traditional diode. It is electrically connected to the rectifier output terminal and receives either the positive or negative half-cycle rectified signal. The signal modulation circuit 302 modulates the output signal of the diode analog circuit 301 into a signal that can be transmitted through a set frequency of the capacitor isolation gate 303. This set frequency signal is a high-frequency signal higher than the output signal frequency of the diode analog circuit 301. The capacitor isolation gate 303 is the capacitor isolation section, commonly employing silicon dioxide (SiO2) isolation technology. Silicon dioxide (SiO2) is the material used for capacitor isolation, which can transmit high-frequency signals and provide effective electrical isolation. The signal demodulation circuit 304 demodulates the high-frequency signal transmitted through the capacitor isolation gate 303 to obtain a demodulated signal. The demodulated signal is, for example, the same as the signal input to the signal modulation circuit 302. The output circuit 305 outputs a voltage to the outside through the output terminal OUT of the optocoupler emulator 30 based on the demodulated signal. The optocoupler emulator 30 is also connected to a fixed voltage source VCC and a ground terminal GND. For example, the signal frequency of the AC voltage is 50Hz, and the frequency of the output signal of the diode analog circuit 301 is equal to the signal frequency of the AC voltage, which is 50Hz. The frequency range of the set frequency is between 1MHz and 100MHz.

[0040] For example, for the first isolation coupling unit, the output circuit 305 outputs a voltage to the first output terminal according to the demodulated signal; for the second isolation coupling unit, the output circuit 305 outputs a voltage to the second output terminal according to the demodulated signal.

[0041] The optocoupler emulator 30 uses capacitive isolation technology for electrical isolation, eliminating optical path transmission and thus avoiding the wear effects inherent in optocouplers (i.e., aging and clouding of the optical signal transmission medium). This wear typically causes optocoupler performance to degrade with increasing temperature, forward current, and device lifespan. By incorporating the optocoupler emulator 30 into the isolation coupling module 200, compared to optocoupler isolation devices, it offers a longer lifespan, avoids failure due to aging of the optical signal transmission medium in optocoupler devices, and provides faster transmission speeds and more accurate signal output.

[0042] refer to Figure 4 Optionally, the AC voltage positive and negative half-cycle detection circuit also includes a first current limiting module 400 and a second current limiting module 500. The first current limiting module 400 is connected in series between the first rectifier unit 110 and the first terminal A1, and the second current limiting module 500 is connected in series between the second rectifier unit 120 and the third terminal A3.

[0043] Figure 6 This is a schematic diagram of another AC voltage positive and negative half-cycle detection circuit provided in an embodiment of the present invention, for reference. Figure 6Optionally, the first current limiting module 400 and the second current limiting module 500 may each include at least one current limiting element, such as a resistor. For example, the first current limiting module 400 includes a first resistor R1 and a second resistor R2 connected in series, and the second current limiting module 500 includes a third resistor R3 and a fourth resistor R4 connected in series. By setting the first current limiting module 400 and the second current limiting module 500 to limit current, the operating current of the isolation coupling module 200 can be prevented from becoming excessive, thereby protecting the isolation coupling module 200. Furthermore, the time it takes for the first output voltage at the first output terminal to change can be adjusted by adjusting the first resistor R1 and the second resistor R2, and the time it takes for the first output voltage at the first output terminal to change can be adjusted by adjusting the third resistor R3 and the fourth resistor R4. For example, the larger the first resistor R1 and the second resistor R2, the longer it takes for the first terminal A1 and the second terminal A2 of the isolation coupling module 200 to conduct during the positive half-cycle, thus making the duration of the level corresponding to the rectified signal of the positive half-cycle output at the first output terminal shorter. The same applies to the second resistor R3 and the third resistor R4, and will not be elaborated further here. Thus, by adjusting the values ​​of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4, the duration of the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal can be adjusted, thereby adjusting the judgment of the zero-crossing moment of the AC voltage U0.

[0044] Continue to refer to Figure 4 Optionally, the output module 300 includes a third current limiting module 310 and a fourth current limiting module 320. The first terminal A1 of the third current limiting module 310 is electrically connected to the third reference voltage source V3, and the second terminal A2 of the third current limiting module 310 is electrically connected to the first output terminal OUT1. The first terminal A1 of the fourth current limiting module 320 is electrically connected to the fourth reference voltage source V4, and the second terminal A2 of the fourth current limiting module 320 is electrically connected to the second output terminal OUT2.

[0045] In this embodiment, the third reference voltage output by the third reference voltage source V3 is different from the first reference voltage output by the first reference voltage source V1, and the fourth reference voltage output by the fourth reference voltage source V4 is different from the second reference voltage output by the second reference voltage source V2. In some embodiments, the third reference voltage source V3 and the fourth reference voltage source V4 are the same reference voltage source. Figure 4 and Figure 6For example, the first reference voltage source V1 and the second reference voltage source V2 can be grounded (GND), and the third reference voltage source V3 and the fourth reference voltage source V4 can be fixed voltage sources (VCC). By setting the third current limiting module 310, the output current of the first output terminal OUT1 can be limited, preventing the third reference voltage source V3 from being short-circuited with the first reference voltage source V1; by setting the fourth current limiting module 320, the output current of the second output terminal OUT2 can be limited, preventing the fourth reference voltage source V4 from being short-circuited with the second reference voltage source V2.

[0046] like Figure 6 As shown, optionally, the third current limiting module 310 and the fourth current limiting module 320 each include at least one current limiting element, such as a resistor. For example, the third current limiting module 310 includes a fifth resistor R5, and the fourth current limiting module 320 includes a sixth resistor R6.

[0047] Continue to refer to Figure 6 The first rectifier unit 110 includes a first rectifier diode D1, and the second rectifier unit 120 includes a second rectifier diode D2. The anode of the first rectifier diode D1 is connected to the first rectifier input terminal IN1, and the anode of the second rectifier diode D2 is connected to the second rectifier input terminal IN2. The isolation coupling module 200 includes an optocoupler emulator. The optocoupler emulator includes a first pin 1, a second pin 2, a third pin 3, a fourth pin 4, a fifth pin 5, a sixth pin 6, a seventh pin 7, and an eighth pin 8. In the first current limiting module 400, a first resistor R1 and a second resistor R2 are connected in series between the cathode of the first rectifier diode D1 and the first pin 1. In the second current limiting module 500, a third resistor R3 is connected in series between the cathode of the second rectifier diode D2 and the fourth pin 4. The second pin 2 of the optocoupler emulator is electrically connected to the second rectifier input terminal IN2, and the third pin 3 of the optocoupler emulator is electrically connected to the first rectifier input terminal IN1. The fifth pin 5 of the optocoupler emulator is connected to the ground terminal GND, and the sixth pin 6 is connected to the fixed voltage source VCC through the fifth resistor R5. The voltage of the fixed voltage source VCC is higher than the ground voltage; for example, the voltage range of the fixed voltage source VCC is 3.3V-5V. Pin 7 of the optocoupler emulator is connected to the fixed voltage source VCC through resistor R6, and pin 8 is also connected to the fixed voltage source VCC. The fixed voltage source VCC supplies power to the optocoupler emulator through pin 8. Optionally, the AC voltage positive and negative half-cycle detection circuit also includes a filter circuit 800. The filter circuit 800 is connected to the power input pin of the isolation coupling module 200, such as pin 8 of the optocoupler emulator. The filter circuit 800 can perform filtering and voltage regulation. Optionally, the filter circuit includes a first capacitor C1. The optocoupler emulator model could be, for example, NIS7221-DSPR.

[0048] Taking the first rectifier input terminal IN1 connected to the live wire L and the second rectifier input terminal IN2 connected to the neutral wire N as an example, Figure 6 The working process of the AC voltage positive and negative half-cycle detection circuit shown is as follows: When the AC voltage is in the positive half-cycle, the first rectifier diode D1 is turned on, causing the current to flow from the AC power supply live wire L, the first rectifier diode D1, the first resistor R1, the second resistor R2, the first pin 1 of the optocoupler emulator, the second pin 2 of the optocoupler emulator, and finally back to the AC power supply neutral wire N. At this time, the diode simulation circuit of the optocoupler emulator starts to work, the AC power supply is in the positive half-cycle voltage signal input to the output side, the seventh pin 7 and the fifth pin 5 of the optocoupler emulator are turned on, and the first output terminal OUT1 changes from high level to low level. When the AC voltage is in the negative half-cycle, the second rectifier diode D2 conducts, causing the current to flow from the AC power supply neutral line L, the second rectifier diode D2, the third resistor R3, the fourth resistor R4, the fourth pin 4 of the optocoupler emulator, the third pin 3 of the optocoupler emulator, and finally back to the AC power supply live line N. At this time, the diode simulation circuit of the optocoupler emulator starts to work. The AC power supply is in the negative half-cycle, and the voltage signal is transmitted to the output side. The sixth pin 6 and the fifth pin 5 of the optocoupler emulator are connected, and the second output terminal OUT2 changes from high level to low level.

[0049] The zero-crossing point of the AC power supply is determined by the high and low levels of the two outputs, combined with... Figure 2 and Figure 6 When the detection circuit operates alternately during the positive and negative half-cycles of the AC power supply, the output waveforms of the first output terminal OUT1 and the second output terminal OUT2 are similar to a pair of complementary waveforms. The two output levels alternately switch to low-level outputs with the same low-level width. The zero-crossing point occurs during the period when both the first output terminal OUT1 and the second output terminal OUT2 are at a high level. Specifically, due to the presence of the first current-limiting module 400 and the second current-limiting module 500, this period of simultaneous high-level output is greater than zero. Therefore, the midpoint of the period when both the first output terminal OUT1 and the second output terminal OUT2 are at a high level can be considered the zero-crossing point of the AC power supply.

[0050] This invention also provides a zero-crossing detection method. Figure 7 This is a flowchart of a zero-crossing detection method provided in an embodiment of the present invention, referred to as... Figure 7 The zero-crossing detection method includes: S410: Obtain the first output voltage of the first output terminal and the second output voltage of the second output terminal of the AC voltage positive and negative half-cycle detection circuit.

[0051] S420. Determine the zero-crossing time of the AC voltage based on the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage.

[0052] Specifically, existing detection circuits only detect the voltage during the positive or negative half-cycle of the AC voltage, making it impossible to accurately determine the zero-crossing point. For example, when existing detection circuits only detect the voltage during the positive or negative half-cycle of the AC voltage, the transition edge of the detection circuit is taken as the zero-crossing point. However, due to the delay in the detection circuit, the position of the transition edge often deviates from the zero-crossing point, resulting in inaccurate zero-crossing point detection.

[0053] The zero-crossing detection method of this embodiment determines the zero-crossing time based on the first output voltage and the second output voltage of the AC voltage positive and negative half-cycle detection circuit according to any of the above embodiments of the present invention. Specifically, it determines the zero-crossing time of the AC voltage based on the time period between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage. Compared with the prior art that uses the transition edge of the positive half-cycle detection waveform or the negative half-cycle detection waveform as the zero-crossing point, the accuracy of zero-crossing detection can be improved.

[0054] Figure 8 This is a schematic diagram of the structure of an intelligent switch control system provided in an embodiment of the present invention. (Refer to...) Figure 8 The intelligent switch control system includes the AC voltage positive and negative half-cycle detection circuit of any of the above embodiments of the present invention. Figure 8 Intelligent switch control system includes Figure 6 The detection circuit shown is illustrated as an example. The intelligent switch control system also includes an AC / DC power supply module 40 and an intelligent switch control module 50. The AC / DC power supply module 40 is connected to the first rectifier input terminal IN1 and the second rectifier input terminal IN2, which rectifies AC power into DC power to supply the fixed voltage source VCC and the intelligent switch control module 50. The intelligent switch control module 50 is electrically connected to the first output terminal OUT1 and the second output terminal OUT2 of the AC voltage positive and negative half-cycle detection circuit. By processing the two output signals, it can accurately determine the zero-crossing point of the AC power supply, thereby performing the switching operation at the zero-crossing point of the AC voltage, avoiding arcing of the relay switch due to excessive current. It can also control the AC power conduction angle from the zero-crossing point of the AC power supply to achieve brightness adjustment. This circuit can also detect power supply faults and power failures, determining whether a missing positive or negative half-cycle occurs to protect the power safety of subsequent control circuits.

[0055] It should be noted that the above embodiment uses the application of the positive and negative half-cycle detection circuit of AC voltage in an intelligent switch control system as an example. The detection circuit can also be applied to other systems, and the embodiments of the present invention are not specifically limited here. It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0056] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An AC voltage positive and negative half-cycle detection circuit, characterized in that, include: Rectifier module, isolation coupling module, and output module; The rectifier module has an AC voltage input terminal connected to it, and an AC voltage output terminal connected to the isolation coupling module. It is used to rectify the positive and negative half-cycles of the AC voltage to obtain positive half-cycle rectified signals and negative half-cycle rectified signals, respectively. The output module includes a first output terminal and a second output terminal, and the first output terminal and the second output terminal are respectively electrically connected to the isolation coupling module. The isolation coupling module is used to change the first output voltage of the first output terminal according to the positive half-cycle rectified signal; And a second output voltage for changing the second output terminal according to the negative half-cycle rectified signal.

2. The AC voltage positive and negative half-cycle detection circuit according to claim 1, characterized in that, The rectifier module includes a first rectifier unit and a second rectifier unit, and the rectifier input terminal includes a first rectifier input terminal and a second rectifier input terminal; the first rectifier unit is connected between the first rectifier input terminal and a first terminal of the isolation coupling module, and the second terminal of the isolation coupling module is electrically connected to the second rectifier input terminal; the second rectifier unit is connected between the second rectifier input terminal and a third terminal of the isolation coupling module, and the fourth terminal of the isolation coupling module is electrically connected to the first rectifier input terminal; The isolation coupling module is used to turn on the first terminal and the second terminal according to the positive half-cycle rectified signal, so as to output a first reference voltage to the first output terminal; The isolation coupling module is also used to turn on the third terminal and the fourth terminal according to the negative half-cycle rectified signal, so as to output the second reference voltage through the second output terminal.

3. The AC voltage positive and negative half-cycle detection circuit according to claim 2, characterized in that, The isolation coupling module includes a first isolation coupling unit and a second isolation coupling unit; the first isolation coupling unit is electrically connected to the first terminal, the second terminal and the first output terminal respectively, and is used to conduct the first terminal and the second terminal according to the positive half-cycle rectified signal to connect the fifth terminal and the sixth terminal of the isolation coupling module, wherein the fifth terminal is electrically connected to the first reference voltage source and the sixth terminal is electrically connected to the first output terminal; The second isolation coupling unit is electrically connected to the third terminal, the fourth terminal and the second output terminal respectively, and is used to turn on the third terminal and the fourth terminal according to the negative half-cycle rectified signal to connect the seventh terminal and the eighth terminal of the isolation coupling module, wherein the seventh terminal is electrically connected to the second reference voltage source and the eighth terminal is electrically connected to the second output terminal.

4. The AC voltage positive and negative half-cycle detection circuit according to claim 3, characterized in that, The first isolation coupling unit and the second isolation coupling unit each include an input subunit, an isolation subunit, and an output subunit; the isolation subunit is located between the input subunit and the output subunit, and is used to isolate the transmission of the output signal of the input subunit to the output subunit. In the first isolation coupling unit, the input subunit is connected between the first end and the second end, and is used to conduct according to the positive half-cycle rectified signal; the output subunit is connected between the fifth end and the sixth end, and is used to conduct between the fifth end and the sixth end when the first end and the second end are conducting. In the second isolation coupling unit, the input subunit is connected between the third terminal and the fourth terminal and is used to conduct according to the negative half-cycle rectified signal; the output subunit is connected between the seventh terminal and the eighth terminal and is used to conduct between the seventh terminal and the eighth terminal when the third terminal and the fourth terminal are conducting.

5. The AC voltage positive and negative half-cycle detection circuit according to claim 2, characterized in that, It also includes a first current limiting module and a second current limiting module. The first current limiting module is connected in series between the first rectifier unit and the first terminal, and the second current limiting module is connected in series between the second rectifier unit and the third terminal.

6. The AC voltage positive and negative half-cycle detection circuit according to claim 2, characterized in that, The first rectifier input terminal is used to connect to the live wire, and the second rectifier input terminal is used to connect to the neutral wire; or the first rectifier input terminal is used to connect to the neutral wire, and the second rectifier input terminal is used to connect to the live wire.

7. The AC voltage positive and negative half-cycle detection circuit according to any one of claims 1-6, characterized in that, The output module includes a third current limiting module and a fourth current limiting module. The first terminal of the third current limiting module is electrically connected to a third reference voltage source, and the second terminal of the third current limiting module is electrically connected to the first output terminal. The first terminal of the fourth current limiting module is electrically connected to a fourth reference voltage source, and the second terminal of the fourth current limiting module is electrically connected to the second output terminal.

8. The AC voltage positive and negative half-cycle detection circuit according to any one of claims 1-6, characterized in that, The isolation coupling module includes an optical coupler simulator.

9. The AC voltage positive and negative half-cycle detection circuit according to claim 8, characterized in that, The optocoupler simulator includes a diode analog circuit, a signal modulation circuit, a capacitor isolation barrier, a signal demodulation circuit, and an output circuit. The input terminal of the diode analog circuit is electrically connected to the rectifier output terminal, and the signal modulation circuit is electrically connected to the output terminal of the diode analog circuit. The signal modulation circuit modulates the output signal of the diode analog circuit into a modulation signal of a set frequency, where the set frequency is higher than the frequency of the output signal of the diode analog circuit. A capacitor isolation barrier isolates the modulation signal and transmits it to the signal demodulation circuit. The signal demodulation circuit demodulates the modulation signal and outputs the demodulated signal to the output circuit. The output circuit changes the output voltage of either the first or second output terminal according to the demodulated signal.

10. A zero-crossing detection method, characterized in that, include: The first output voltage of the first output terminal and the second output voltage of the second output terminal of the AC voltage positive and negative half-cycle detection circuit are obtained; the AC voltage positive and negative half-cycle detection circuit is the AC voltage positive and negative half-cycle detection circuit according to any one of claims 1-9; The zero-crossing time of the AC voltage is determined based on the time interval between the first output voltage corresponding to the positive half-cycle rectified signal and the second output voltage corresponding to the negative half-cycle rectified signal within the same cycle of the AC voltage.

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