Signal detection circuit and system

Abstract

The utility model relates to a signal detection circuit and system. The signal detection circuit comprises a zero line input end, a live line input end, a switch control signal end, a signal detection end, an electro-sensitive module and a rectifier module, the live wire input end is connected in series with the electro-sensitive module through the rectifier module; the zero line input end is connected in series with the electro-sensitive module through the rectification module, and the output end of the electro-sensitive module is electrically connected with the signal detection end; the switch control signal end is connected in series with the electro-sensitive module. Thus, the switch control signal end, the zero line input end and the live line input end are all connected with the electro-sensitive module in series, so that a loop between the live line input end and the zero line input end and a loop where the switch control signal end is located share the electro-sensitive module, and then follow-up zero-cross detection and switch state detection are carried out through the same signal detection end. And less hardware resources are occupied.

Description

Technical Field

[0001] The present disclosure relates to the field of signal detection technology, and in particular to a signal detection circuit and system. Background Art

[0002] At present, existing household appliances usually have switch detection functions and zero-crossing detection functions. For the zero-crossing detection function, existing household appliances are provided with a neutral wire terminal and a live wire terminal for power supply, and the AC signal of the mains is obtained to detect the zero-crossing point therein; for the switch detection function, existing household appliances are provided with a switch terminal. By connecting the switch terminal to a household wall switch, the AC signal of the mains is obtained to determine the user's switch action, and on this basis, a photoelectric coupler is set for signal isolation and signal transmission.

[0003] However, in existing detection schemes for household appliances, an optocoupler is usually set in the circuit where the neutral terminal and the live terminal are located, and the circuit where the switch terminal is located, respectively. As a result, the subsequent circuit needs to use the general-purpose input / output (GPIO) ports of two microprocessors for signal detection, which occupies a large amount of hardware resources. Utility Model Content

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides a signal detection circuit and system.

[0005] In a first aspect, the present disclosure provides a signal detection circuit, comprising: a neutral line input terminal, a live line input terminal, a switch control signal terminal, a signal detection terminal, an electric sensitive module, and a rectifier module;

[0006] The live wire input terminal is connected in series with the electric sensitive module through the rectifier module; the neutral wire input terminal is connected in series with the electric sensitive module through the rectifier module, and the output terminal of the electric sensitive module is electrically connected to the signal detection terminal; the switch control signal terminal is connected in series with the electric sensitive module;

[0007] During the positive cycle of the AC power supply, the circuit between the live wire input terminal and the neutral wire input terminal is connected; during the negative cycle of the AC power supply, the circuit between the live wire input terminal and the neutral wire input terminal is disconnected; during the positive cycle or negative cycle of the AC power supply, the switch of the circuit where the switch control signal terminal is located is closed, and the circuit where the switch control signal terminal is located is connected; the signal detection terminal outputs a detection signal to the controller, so that the controller performs zero-crossing detection switch state detection according to the waveform of the detection signal.

[0008] In the second aspect, the present disclosure also provides a signal detection system, including a controller and the signal detection circuit described in the first aspect; the controller is electrically connected to the signal detection end of the signal detection circuit, and is used to perform zero-crossing detection switch state detection based on the waveform of the detection signal output by the signal detection end.

[0009] The technical solution provided by the embodiments of the present disclosure has the following advantages over the prior art:

[0010] The signal detection circuit provided by the embodiment of the present disclosure includes: a neutral input terminal, a live input terminal, a switch control signal terminal, a signal detection terminal, an electric sensitive module, and a rectifier module; the live input terminal is connected in series with the electric sensitive module via the rectifier module; the neutral input terminal is connected in series with the electric sensitive module via the rectifier module, and the output terminal of the electric sensitive module is electrically connected to the signal detection terminal; the switch control signal terminal is connected in series with the electric sensitive module. In this way, the switch control signal terminal, the neutral input terminal, and the live input terminal are all connected in series with the electric sensitive module, so that the loop between the live input terminal and the neutral input terminal and the loop where the switch control signal terminal is located share the electric sensitive module, thereby realizing the use of the same signal detection terminal for subsequent zero-crossing detection and switch state detection, occupying fewer hardware resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0012] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0013] Figure 1 A schematic structural diagram of a signal detection circuit provided in an embodiment of the present disclosure;

[0014] Figure 2 A schematic structural diagram of another signal detection circuit provided in an embodiment of the present disclosure;

[0015] Figure 3 A schematic diagram comparing the waveforms of an AC power supply and a detection signal provided in an embodiment of the present disclosure;

[0016] Figure 4 A schematic diagram comparing the waveforms of another AC power supply and a detection signal provided in an embodiment of the present disclosure.

[0017] Among them, 110, neutral line input terminal; 120, live line input terminal; 130, switch control signal terminal; 140, signal detection terminal; 150, electric sensitive module; 160, rectifier module; 161, first diode; 162, second diode; 163, third diode; 164, fourth diode; 171, first resistor; 172, second resistor; 181, third resistor; 182, fourth resistor; 190, current discharge module; 200, AC and DC conversion module; 210, fifth resistor. DETAILED DESCRIPTION

[0018] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features therein can be combined with each other in the absence of conflict.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0020] First, a brief description is given of the related art and its existing defects, as well as the solutions of the embodiments of the present disclosure proposed to improve them.

[0021] Exemplarily, an existing signal detection circuit includes a zero-crossing detection circuit and a switch detection circuit, each independently configured to include a photocoupler and a signal detection terminal. The switch detection circuit is externally connected to a switch. Specifically, for the zero-crossing detection circuit, a power signal can be output from the signal detection terminal via the photocoupler to detect the zero-crossing point of the power signal transmitted by the zero-crossing detection circuit. For the switch detection circuit, when the switch is closed, the power signal can be output from the signal detection terminal via the photocoupler. When the switch is open, no power signal enters the switch detection circuit, thereby determining the state of the switch connected to the switch detection circuit.

[0022] It is understandable that the power signal is an AC signal, usually in the form of an AC sine wave. For an AC voltage sine wave, it can be seen that on the time-voltage coordinate, the voltage starts from zero and rises to a positive peak over time according to the trajectory of the sine wave, then drops to zero, then continues to drop to a negative peak, and then rises to zero, continuing the next cycle. The position where the voltage sine wave reaches zero is the zero crossing point. It is not difficult to see that by detecting the zero crossing point of the power signal and controlling the load to be connected under low input voltage conditions such as the zero crossing point, the inrush current caused by excessive voltage in the power signal can be reduced, protecting the load from damage, and thus increasing the service life of the load.

[0023] In the zero-crossing detection circuit, when the power signal is transmitted to the optocoupler, if the current voltage of the power signal is insufficient to drive the light-emitting diode in the optocoupler to turn on, the optocoupler will not be able to transmit the power signal to the corresponding signal detection terminal. Based on this, the controller can perform zero-crossing detection based on the power signal output by the signal detection terminal to determine the zero-crossing point in the power signal. For example, it will treat the voltage that is insufficient to drive the light-emitting diode in the optocoupler to turn on as the zero-crossing point.

[0024] In summary, the applicant has found through research that in the existing detection scheme, the zero-crossing detection circuit and the switch detection circuit are each equipped with a photocoupler and a signal detection end. In actual applications, these two signal detection ends need to be connected one-to-one with two general IO ports, resulting in them occupying more hardware resources.

[0025] In response to the above-mentioned defects, an embodiment of the present disclosure provides a signal detection circuit, in which the switch control signal terminal, the neutral line input terminal and the live line input terminal are all connected in series with the electric sensitive module, so that the loop between the live line input terminal and the neutral line input terminal and the loop where the switch control signal terminal is located share the electric sensitive module, thereby realizing the use of the same signal detection terminal for subsequent zero-crossing detection and switch status detection, occupying fewer hardware resources.

[0026] The signal detection circuit and system provided by the embodiments of the present disclosure are exemplarily described below with reference to the accompanying drawings.

[0027] Figure 1 This is a schematic diagram of the structure of a signal detection circuit provided by an embodiment of the present disclosure. Figure 1 The signal detection circuit includes: a neutral line input terminal 110, a live line input terminal 120, a switch control signal terminal 130, a signal detection terminal 140, an electric sensing module 150 and a rectifier module 160.

[0028] Among them, the live wire input terminal 120 is connected in series with the electrosensitive module 150 through the rectifier module 160; the neutral wire input terminal 110 is connected in series with the electrosensitive module 150 through the rectifier module 160, and the output terminal of the electrosensitive module 150 is electrically connected to the signal detection terminal 140; the switch control signal terminal 130 is connected in series with the electrosensitive module 150.

[0029] Specifically, during a positive cycle of the AC power supply, the circuit between the live input terminal 120 and the neutral input terminal 110 is connected; during a negative cycle of the AC power supply, the circuit between the live input terminal 120 and the neutral input terminal 110 is disconnected; during a positive or negative cycle of the AC power supply, the switch in the circuit where the switch control signal terminal 130 is located is closed, and the circuit where the switch control signal terminal 130 is located is connected; the signal detection terminal 140 outputs a detection signal to a controller (not shown in the figure), so that the controller performs zero crossing detection and switch state detection based on the waveform of the detection signal. For example, the controller can be a microprocessor.

[0030] The live input terminal 120 and the neutral input terminal 110 are input terminals for the power signal, and are used to connect the live wire and the neutral wire, respectively. The rectifier module 160 is used to at least perform half-wave rectification on the waveform of the power signal, allowing only the voltage in one direction of the power signal to pass through. The live input terminal 120 and the neutral input terminal 110 are each connected in series with the electrosensitive module 150 through the rectifier module 160, forming a loop between the live input terminal 120 and the neutral input terminal 110. When the power signal provided by the AC power source is input from the live input terminal 120, due to the rectification characteristics of the rectifier module 160, the rectifier module 160 allows the positive cycle of the power signal to pass through and blocks the negative cycle of the power signal from passing through. As a result, during the positive cycle of the AC power source, the loop between the live input terminal 120 and the neutral input terminal 110 is conductive, while during the negative cycle of the AC power source, the loop between the live input terminal 120 and the neutral input terminal 110 is disconnected.

[0031] The electrosensitive module 150 is sensitive to electrical signals such as voltage and current, and when electrical signals such as voltage and current act on the electrosensitive module 150, the working state of the electrosensitive module 150 will change. Therefore, the period, pulse width and other parameters of the detection signal can be determined based on the change in the working state of the electrosensitive module 150, thereby realizing zero-crossing detection and switch state detection. Exemplarily, the electrosensitive module 150 includes but is not limited to a photoelectric coupler, a microprocessor, a transistor, etc., wherein for the scenario of zero-crossing detection, the working principles of the photoelectric coupler, the transistor, and the transistor are similar. When the power signal is transmitted, the cut-off voltage of the power signal can be determined by judging whether the above devices are disconnected. For example, when the above devices are disconnected, it indicates that the current voltage of the power signal is insufficient to drive it to conduct, and this voltage is the cut-off voltage. The specific type of the electrosensitive module 150 is not limited here.

[0032] The switch control signal terminal 130 is a terminal for connecting a switch. For example, the switch can be located on the live or neutral line. When the user closes the switch, the line connected to the switch is connected, and the switch control signal terminal 130 can receive the power signal transmitted from the live or neutral line. The power signal then passes through the electric sensing module 150 and the rectifier module 160 in sequence and reaches the live input terminal 120 or the neutral input terminal 110. Conversely, when the user opens the switch, the line connected to the switch is disconnected, and no power signal is input to the switch control signal terminal 130.

[0033] Specifically, because the circuit containing switch control signal terminal 130 is equipped with a rectifier module 160, only half a cycle of the power signal is transmitted within this circuit. Furthermore, because the line connected to switch control signal terminal 130 is either the live or neutral line, the direction of the half-cycle power signal varies depending on the line being connected—for example, it may be a positive cycle or a negative cycle, respectively. Thus, when a user triggers the switch, closing the circuit containing switch control signal terminal 130, and the circuit containing switch control signal terminal 130 is conducting, the circuit transmits either a positive cycle or a negative cycle of the power signal.

[0034] The signal detection terminal 140 is a port for receiving a detection signal output by the electric-sensing module 150. For example, the power signal transmitted by the loop between the live input terminal 120 and the neutral input terminal 110 and the power signal transmitted by the loop where the switch control signal terminal 130 is located can reach the electric-sensing module 150 together. In this case, the two power signals can be superimposed to form a detection signal and transmitted to the signal detection terminal 140. The signal detection terminal 140 receives the detection signal and outputs it to the controller so that the controller can perform zero-crossing detection and switch state detection based on the waveform of the detection signal. For example, for zero-crossing detection, the zero-crossing point is determined by determining the cutoff voltage of the waveform of the detection signal. For switch state detection, since a power signal exists in the loop where the switch control signal terminal 130 is located when the switch is closed, and no power signal exists in the loop where the switch control signal terminal 130 is located when the switch is open, the switch state can be determined by determining the waveform change of the detection signal, such as the change in the waveform period or pulse width.

[0035] In the signal detection circuit provided by the embodiment of the present disclosure, the switch control signal terminal 130, the neutral line input terminal 110 and the live line input terminal 120 are all connected in series with the electric sensitive module 150, so that the loop between the live line input terminal 120 and the neutral line input terminal 110 and the loop where the switch control signal terminal 130 is located share the electric sensitive module 150, thereby achieving the use of the same signal detection terminal 140 to output the detection waveform to the controller for zero-crossing detection and switch state detection. With this arrangement, less hardware resources of the microprocessor are occupied.

[0036] Furthermore, in the prior art, when a zero-crossing detection circuit and a switch detection circuit are each provided with a photocoupler, the resulting circuits are complex, occupying a large area of ​​a printed circuit board (PCB). This, in turn, requires a large number of components, resulting in a high overall circuit application cost. The signal detection circuit provided in the disclosed embodiment utilizes a single electrosensitive module 150, resulting in a simple structure and a reduced number of components, thereby reducing the overall circuit application cost.

[0037] In some embodiments, Figure 2This is a structural diagram of another signal detection circuit provided by an embodiment of the present disclosure. Figure 1 and Figure 2 The rectifier module 160 includes a first diode 161, a second diode 162, a third diode 163 and a fourth diode 164; the anode of the first diode 161 is electrically connected to the cathode of the third diode 163; the cathode of the first diode 161 is electrically connected to the cathode of the second diode 162; the anode of the second diode 162 is electrically connected to the cathode of the fourth diode 164; the anode of the fourth diode 164 is electrically connected to the anode of the third diode 163; the live wire input terminal 120 is electrically connected to the anode of the second diode 162; the neutral wire input terminal 110 is electrically connected to the anode of the first diode 161; the electrosensitive module 150 is connected in series between the switch control signal terminal 130 and the anode of the third diode 163, and the electrosensitive module 150 is connected in series between the anode of the second diode 162 and the anode of the third diode 163.

[0038] The first diode 161, the second diode 162, the third diode 163, and the fourth diode 164 form a rectifier bridge. Specifically, by electrically connecting the live input terminal 120 to the anode of the second diode 162 and the neutral input terminal 110 to the anode of the first diode 161, a diode, namely the third diode 163, is provided in the loop between the live input terminal 120 and the neutral input terminal 110. Furthermore, by connecting the switch control signal terminal 130 in series with the electrosensitive module 150, a diode, such as the third diode 163 or the fourth diode 164, is also provided in the loop containing the switch control signal terminal 130.

[0039] It can be seen that, since the diode has unidirectional conductivity, the power signal transmitted in the loop between the live wire input terminal 120 and the neutral wire input terminal 110 and the power signal transmitted in the loop where the switch control signal terminal 130 is located are both half a cycle, wherein the direction of the power signal transmitted in the loop between the live wire input terminal 120 and the neutral wire input terminal 110 is a positive cycle. As for the direction of the power signal transmitted in the loop where the switch control signal terminal 130 is located, it depends on whether the switch control signal terminal 130 is connected to the live wire or the neutral wire. In other words, it depends on whether the power signal received by the live wire input terminal 120 and the signal received by the switch control signal terminal 130 are in phase or out of phase. This will be explained exemplarily later.

[0040] Compared with the prior art, in which the zero-crossing detection circuit and the switch detection circuit are independently arranged, the zero-crossing detection circuit and the switch detection circuit each transmit a power supply signal, and respectively perform zero-crossing detection and switch state detection. In the embodiment of the present disclosure, by establishing an electrical connection between the rectifier bridge and both ends of the electro-sensitive module 150, the power supply signal received by the live wire input terminal 120 and the power supply signal received by the switch control signal terminal 130 both pass through the electro-sensitive module 150 and the rectifier bridge, so that the two power supply signals are both half a cycle, and the directions of the two are the same or different, so that the zero-crossing point and the switch state can be judged based on the waveform after the two are superimposed, thereby improving the signal detection efficiency; in addition, it can also reduce the number of devices and improve the integration between the devices, thereby effectively saving the printed circuit board area and reducing the application cost.

[0041] In some embodiments, combined Figure 1 and Figure 2 The electrosensitive module 150 includes a photocoupler U1; the live wire input terminal 120 is electrically connected to the primary first terminal of the photocoupler U1 through the rectifier module 160; the neutral wire input terminal 110 is electrically connected to the primary second terminal of the photocoupler U1 through the rectifier module 160, and the secondary of the photocoupler U1 is electrically connected to the signal detection terminal 140; the switch control signal terminal 130 is electrically connected to the primary first terminal of the photocoupler U1.

[0042] Among them, the primary of the photocoupler U1 is a light emitting diode, and the secondary of the photocoupler U1 is a phototransistor; illustratively, the primary first end of the photocoupler U1 can be the anode of the light emitting diode, and the primary second end of the photocoupler U1 can be the cathode of the light emitting diode.

[0043] Specifically, by connecting the live wire input terminal 120 and the switch control signal terminal 130 to the primary first terminal of the optocoupler U1, the loop between the live wire input terminal 120 and the neutral wire input terminal 110, and the loop where the switch control signal terminal 130 is located share the optocoupler U1. Compared with the existing technology, the number of optocouplers is reduced, and the optocoupler U1 can be used to isolate, collect and transmit the power signal received by the live wire input terminal 120 and the power signal received by the switch control signal terminal 130, thereby improving signal isolation and reducing electrical noise.

[0044] In some embodiments, combined Figure 1 and Figure 2, the power signal received by the switch control signal terminal 130 is in phase with the power signal received by the neutral line input terminal 110; in the positive cycle of the AC power supply, the electrosensitive module 150 is turned on, and the circuit between the live wire input terminal 120 and the neutral line input terminal 110 is connected; in the negative cycle of the AC power supply, the switch of the circuit where the switch control signal terminal 130 is located is closed, the electrosensitive module 150 is turned on, the circuit between the live wire input terminal 120 and the neutral line input terminal 110 is disconnected, and the circuit where the switch control signal terminal 130 is located is connected.

[0045] The power signal received by the switch control signal terminal 130 is in phase with the power signal received by the neutral line input terminal 110 , indicating that both the switch control signal terminal 130 and the neutral line input terminal 110 are connected to the neutral line.

[0046] Specifically, after the live wire input terminal 120 receives the power signal, the power signal can return to the neutral wire input terminal 110 along the electro-sensitive module 150 and the third diode 163. According to the unidirectional conduction characteristics of the third diode 163, in the positive cycle of the AC power supply, the loop between the live wire input terminal 120 and the neutral wire input terminal 110 is connected to transmit the power signal of the positive cycle, which can be understood as a positive half-wave signal. In the negative cycle of the AC power supply, the loop between the live wire input terminal 120 and the neutral wire input terminal 110 is disconnected, preventing the power signal of the negative cycle from passing through.

[0047] When the user closes the switch and the switch control signal terminal 130 receives the power signal, the power signal can then be returned to the live wire input terminal 120 along the electro-sensitive module 150 and the fourth diode 164. Due to the unidirectional conduction characteristics of the fourth diode 164, during the negative cycle of the AC power supply, the circuit containing the switch control signal terminal 130 is conductive, transmitting the power signal of the negative cycle, which can be understood as a negative half-wave signal. During the positive cycle of the AC power supply, the circuit containing the switch control signal terminal 130 is disconnected, preventing the power signal of the positive cycle from passing through. When the user opens the switch, no power signal is input to the switch control signal terminal 130.

[0048] For example, Figure 3 A schematic diagram comparing the waveforms of an AC power supply and a detection signal provided by an embodiment of the present disclosure. Figure 3 , the horizontal axis X1, the horizontal axis X2, and the horizontal axis X3 all represent time, the unit is millisecond (ms), the vertical axis Y1, the vertical axis Y2, and the vertical axis Y3 all represent voltage, the unit is volt (V); the sine wave corresponding to the AC power supply is located in the coordinate system defined by the horizontal axis X1 and the vertical axis Y1, the square wave corresponding to one detection signal (which can be regarded as the first square wave) is located in the coordinate system defined by the horizontal axis X2 and the vertical axis Y2, and the square wave corresponding to the other detection signal (which can be regarded as the second square wave) is located in the coordinate system defined by the horizontal axis X3 and the vertical axis Y3; among them, the period of the sine wave corresponding to the AC power supply is 20 milliseconds and the frequency is 50 Hz.

[0049] Specifically, when switch control signal terminal 130 is connected to the neutral line, if the user closes the switch, causing the circuit containing switch control signal terminal 130 to conduct, the circuit containing switch control signal terminal 130 generates a negative half-wave signal, and the circuit between hot input terminal 120 and neutral input terminal 110 generates a positive half-wave signal. When these two signals are transmitted to electro-sensitive module 150, the negative half-wave signal and the positive half-wave signal are superimposed to form a complete sine wave, i.e., the detection signal. Conversely, if the user opens the switch, disconnecting the circuit containing switch control signal terminal 130, no power signal is input to switch control signal terminal 130, and the circuit between hot input terminal 120 and neutral input terminal 110 generates a positive half-wave signal. The positive half-wave signal transmitted to electro-sensitive module 150, i.e., the detection signal, is generated. To this end, the controller can generate a corresponding square wave based on the detection signal.

[0050] For example, Figure 3 Both square waves contain information about the cutoff voltage, that is, when the square wave is at a high level, it indicates that the electrosensitive module 150, such as the photoelectric coupler, is turned on. When the square wave is at a low level, it indicates that the photoelectric coupler is turned off. Based on this, the cutoff voltage that is insufficient to drive the photoelectric coupler to turn on can be obtained according to the falling edge. In addition, the two square waves in the figure also contain information about the switch state. The first square wave corresponds to the scenario of the switch being closed. The detection signal is a complete sine wave. The high-level distribution in the first square wave formed by it is relatively dense, indicating that the frequency is high. The second square wave corresponds to the scenario of the switch being disconnected. The detection signal is a positive half-wave. The high-level distribution in the second square wave formed by it is relatively sparse, indicating that the frequency is low. In this way, by determining the frequency of the square wave, the switch state can be further determined, and the judgment method is simple.

[0051] It should be noted that the zero-crossing detection circuit in the prior art may include a diode. Since the diode has unidirectional conductivity, it only allows the voltage in one direction of the power signal, that is, half a cycle of the power signal (positive cycle or negative cycle) to pass through, and prevents the remaining half cycle of the power signal from passing through. As a result, the power signal transmitted to the optocoupler has only half a waveform (referred to as half-wave). When detecting the zero crossing point, on the one hand, it is necessary to combine the cycle to calculate the zero crossing point in the complete sine wave, which is cumbersome. On the other hand, the time interval required to detect a zero crossing point based on the half wave is large, and the detection speed is slow.

[0052] In this regard, combined with Figure 3 , the advantages of zero-crossing detection are listed as follows:

[0053] On the other hand, compared to the prior art which can only detect the zero crossing point based on the positive half-wave or the negative half-wave, and calculate the zero crossing point within the complete sine wave in combination with the period, the disclosed embodiment can directly determine the zero crossing point based on the detection signal of the complete sine wave when the switch is closed, thereby reducing the calculation process and thereby reducing the difficulty and complexity of zero crossing detection.

[0054] On the other hand, when the switch is disconnected, the detection signal formed is a positive half-wave, and the zero crossing point can be detected once every 20 milliseconds. When the switch is closed, the detection signal formed is a complete sine wave, and the zero crossing point can be detected once every 10 milliseconds. In this way, by performing zero-crossing detection on the detection signal formed when the switch is closed, the detection speed of the zero-crossing point is improved, so that the load access can be controlled in time according to the detected zero-crossing point. Other advantages of zero-crossing detection will be explained in the following text.

[0055] In some embodiments, combined Figure 1 and Figure 2 , the power signal received by the switch control signal terminal 130 is in phase with the power signal received by the live wire input terminal 120; in the positive cycle of the AC power supply, the switch of the circuit where the switch control signal terminal 130 is located is closed, the electro-sensitive module 150 is turned on, the circuit where the switch control signal terminal 130 is located is turned on, and the circuit between the live wire input terminal 120 and the neutral wire input terminal 110 is connected; in the negative cycle of the AC power supply, the electro-sensitive module 150 is disconnected, the circuit where the switch control signal terminal 130 is located is disconnected, and the circuit between the live wire input terminal 120 and the neutral wire input terminal 110 is disconnected.

[0056] The power signal received by the switch control signal terminal 130 is in phase with the power signal received by the live wire input terminal 120 , indicating that the power signal received by the switch control signal terminal 130 and the live wire input terminal 120 are both connected to the live wire.

[0057] Specifically, after the live wire input terminal 120 and the switch control signal terminal 130 each receive the power supply signal, the power supply signal returns to the neutral wire input terminal 110 along the electro-sensitive module 150 and the third diode 163. In this way, the loop between the live wire input terminal 120 and the neutral wire input terminal 110 and the loop where the switch control signal terminal 130 is located both transmit positive half-wave signals.

[0058] For example, Figure 4 This is another waveform comparison diagram of an AC power supply and a detection signal provided by an embodiment of the present disclosure. Figure 4, the horizontal axis X5, the horizontal axis X6, and the horizontal axis X7 all represent time, the unit is millisecond (ms), the vertical axis Y5, the vertical axis Y6, and the vertical axis Y7 all represent voltage, the unit is volt (V); the sine wave corresponding to the AC power supply is located in the coordinate system defined by the horizontal axis X5 and the vertical axis Y5, the square wave corresponding to one detection signal (which can be regarded as the third wave) is located in the coordinate system defined by the horizontal axis X6 and the vertical axis Y6, and the square wave corresponding to the other detection signal (which can be regarded as the fourth square wave) is located in the coordinate system defined by the horizontal axis X7 and the vertical axis Y7; among them, the period of the sine wave corresponding to the AC power supply is 20 milliseconds and the frequency is 50 Hz.

[0059] Specifically, when the switch control signal terminal 130 is connected to the live wire, if the user closes the switch, causing the circuit containing the switch control signal terminal 130 to conduct, the circuit containing the switch control signal terminal 130 generates a positive half-wave signal. Furthermore, the circuit between the live wire input terminal 120 and the neutral wire input terminal 110 generates a positive half-wave signal. When these two signals are transmitted to the electro-sensitive module 150, the two positive half-wave signals superimpose to form a positive half-wave signal with a longer pulse width, i.e., the detection signal. Conversely, if the user opens the switch, disconnecting the circuit containing the switch control signal terminal 130, no power signal is input to the switch control signal terminal 130. Furthermore, the circuit between the live wire input terminal 120 and the neutral wire input terminal 110 generates a positive half-wave signal, resulting in the positive half-wave signal transmitted to the electro-sensitive module 150, i.e., the detection signal. Similarly, the controller can generate a corresponding square wave based on the detection signal.

[0060] For example, Figure 4 Both square waves in the figure contain information about the cutoff voltage. That is, when the square wave is at a high level, it indicates that the electrosensitive module 150, such as a photocoupler, is conducting. When the square wave is at a low level, it indicates that the photocoupler is disconnected. Based on this, the cutoff voltage that is insufficient to drive the photocoupler to conduct can be obtained based on the falling edge. For example, the voltage near the falling edge is used as the cutoff voltage. Furthermore, the two square waves in the figure also contain information about the switch state. The third square wave corresponds to the scenario where the switch is closed, and the pulse width of the high-level state in the third wave is longer, such as 9 milliseconds. The fourth square wave corresponds to the scenario where the switch is open, and the pulse width of the high-level state in the fourth square wave is shorter, such as 7 milliseconds. Thus, by determining the pulse width of the high-level state in the square wave, the switch state can be further determined.

[0061] In some embodiments, combined Figure 1 and Figure 2 The signal detection circuit further includes a first voltage divider module 170 ; the first voltage divider module 170 is connected in series between the rectifier module 160 and the electrosensitive module 150 .

[0062] Specifically, by connecting the first voltage divider module 170 in series between the rectifier module 160 and the electrosensitive module 150, when the power signal is input to the live wire input terminal 120, the first voltage divider module 170 can be used to reduce the voltage so that the voltage of the power signal is within a certain range, thereby ensuring that the electrosensitive module 150 can operate at an appropriate voltage and avoiding damage to the electrosensitive module 150 due to excessive voltage of the power signal.

[0063] The first voltage dividing module 170 may include a plurality of resistors. Figure 2 It is shown by way of example that the first voltage divider module 170 may include a first resistor 171 and a second resistor 172 connected in series, and to ensure the voltage reduction effect, the power consumption of each of the first resistor 171 and the second resistor 172 is less than or equal to 0.25W. The resistance value of the first voltage divider module 170 can be set according to the actual requirements of the signal detection circuit. There is no limitation on the number of resistors included in the first voltage divider module 170.

[0064] In some embodiments, combined Figure 1 and Figure 2 The signal detection circuit further includes a second voltage divider module 180 ; the second voltage divider module 180 is connected in series between the switch control signal terminal 130 and the electrosensitive module 150 ; the resistance value of the first voltage divider module is greater than the resistance value of the second voltage divider module 180 .

[0065] Specifically, by connecting a second voltage divider module in series between the switch control signal terminal 130 and the electrosensitive module 150, when the power signal is input to the switch control signal terminal 130, the second voltage divider module can be used to reduce the voltage so that the voltage of the power signal is within a certain range, thereby ensuring that the electrosensitive module 150 can operate at an appropriate voltage and avoiding damage to the electrosensitive module 150 due to excessive voltage of the power signal.

[0066] The second voltage dividing module 180 may include a plurality of resistors. Figure 2 It is shown by way of example that the second voltage divider module 180 may include a third resistor 181 and a fourth resistor 182 connected in series, and to ensure the voltage reduction effect, the power consumption of the third resistor 181 and the fourth resistor 182 is less than or equal to 0.25W respectively. The resistance value of the second voltage divider module 180 can be set according to the actual requirements of the signal detection circuit. There is no limitation on the number of resistors included in the second voltage divider module 180.

[0067] The power signal received by the switch control signal terminal is in phase with the power signal received by the live wire input terminal. When the switch is disconnected, the switch control signal terminal 130 does not receive the power signal, and a current is formed in the loop between the live wire input terminal 120 and the neutral wire input terminal 110. The light-emitting diode in the electrosensitive module 150, such as the photoelectric coupler U1, is driven to turn on according to the current. At this time, the conduction time of the light-emitting diode will be shorter, and its cut-off voltage will be larger, such as 30V, which is far away from the actual zero crossing point (0V). Therefore, the error when it is used as the zero crossing point is larger, and the ability to resist voltage fluctuation interference is poor. Correspondingly, when the detection signal is in square wave form, the pulse width of its high level state is shorter, such as 7 milliseconds.

[0068] It should be noted that in the prior art, since the power consumption of the resistor provided in the zero-crossing detection circuit is certain, the current formed in its loop is limited, the light-emitting diode in the photoelectric coupler is turned on for a short time, and the voltage (cut-off voltage) in the corresponding half-wave that is insufficient to drive the light-emitting diode to turn on will be relatively high, usually a voltage near the true zero-crossing point (0V), such as 30V. Because its value is quite different from the true zero-crossing point, if the cut-off voltage is used as the true zero-crossing point, the accuracy of the zero-crossing detection will be poor, and there will be a large time interval before the cut-off voltage reaches the true zero-crossing point, which is equivalent to a certain delay from the cut-off voltage to the true zero-crossing point. If a load is connected when the cut-off voltage is large, it will cause adverse consequences such as a large impact current and damage to the load, affecting the accuracy of the load connection time.

[0069] In this regard, in the embodiment of the present disclosure, when the switch is closed, a current is formed in the loop where the switch control signal terminal 130 is located, and a current is also formed in the loop between the live wire input terminal 120 and the neutral wire input terminal 110. After the two currents merge into a larger current, the light-emitting diode in the optocoupler U1 is driven to turn on. At this time, the light-emitting diode is turned on for a longer time, and its cut-off voltage is smaller, such as 15V, thereby approaching the true zero-crossing point (0V), so that it is more accurate to use it as the zero-crossing point, and the ability to resist voltage fluctuation interference is stronger. Correspondingly, when the detection signal is in square wave form, the pulse width of its high-level state is longer, such as 9 milliseconds.

[0070] However, when the power signal received at the switch control signal end is in phase with the power signal received at the live wire input end, there may be interference from AC mains voltage fluctuations, such as the mains voltage jumping between 170V and 260V, causing the detection signal formed when the switch is disconnected to be not much different from the detection signal formed when the switch is closed. For example, the detection signal formed when the switch is disconnected may have a pulse width of 7 milliseconds in the high-level state of the square wave, and the detection signal formed when the switch is closed may have a pulse width of 7.5 milliseconds or 8 milliseconds in the high-level state of the square wave, making it difficult to distinguish between the above two detection signals, thereby affecting the accuracy of switch state detection.

[0071] To this end, by setting the resistance value of the first voltage divider module 170 to be greater than the resistance value of the second voltage divider module 180, the pulse width of the detection signal formed when the switch is closed can be extended, ensuring that the pulse width difference between the detection signal formed when the switch is disconnected and the detection signal formed when the switch is closed is greater than 1 millisecond, thereby avoiding misjudgment of the switch state due to interference from voltage fluctuations, and greatly improving the accuracy of switch state detection.

[0072] In addition, by setting the resistance value of the first voltage divider module 170 to be greater than the resistance value of the second voltage divider module 180, it indicates that the resistance value of the first voltage divider module 170 is larger. When the switch is disconnected, that is, no power signal is input to the switch control signal terminal 130, the current formed in the loop between the live wire input terminal 120 and the neutral wire input terminal 110 will be smaller, thereby reducing the power consumption generated by the loop and further extending the service life of the relevant components in the loop.

[0073] In some embodiments, combined Figure 1 and Figure 2 , the resistance value R1 of the first voltage dividing module 170 and the resistance value R2 of the second voltage dividing module 180 satisfy:

[0074]

[0075] Among them, U n Indicates the equivalent voltage value of AC power, P2 indicates the upper limit of power consumption of the first and second voltage divider modules, U m Indicates the pressure difference corresponding to the pulse width difference threshold, I oc Indicates the conduction current of the electrosensitive module. The pulse width difference threshold can be set according to the actual situation. For example, if the pulse width difference caused by the interference of voltage fluctuation is A, then the pulse width difference threshold can be set to be greater than or equal to A. m There is an associated mapping relationship between them, for example: the associated mapping relationship can be based on the pulse width difference threshold and U m The established correlation lookup table, correlation formula or other forms of correlation known to those skilled in the art can be used to determine the U corresponding to the pulse width difference threshold through the correlation mapping relationship. m , not limited here.

[0076] In some embodiments, the resistance value R1 of the first voltage dividing module 170 and the resistance value R2 of the second voltage dividing module 180 further satisfy:

[0077] P R1 <P1,P R1 / / R2 <P2

[0078] Among them, P R1represents the power consumption of R1 before the switch is closed, and P1 represents the upper limit of the power consumption of a single resistor. For example, P1 can be 0.2W; P R1 / / R2 It represents the power consumption of R1 and R2 as a whole after the switch is closed, and P2 represents the upper limit of the power consumption of R1 and R2 as a whole.

[0079]

[0080] therefore,

[0081]

[0082] For example, P1 can be 0.2W and P2 can be 0.6W. This setting can ensure that R2 and R1 meet the required power consumption requirements. n =264V, we can get

[0083] R1>350K;

[0084]

[0085] The voltage corresponding to the detection signal before the switch is closed is V 开 , the voltage corresponding to the detection signal after the switch is closed is V 闭 .

[0086] V 开 -V 闭 >U m , V 开 =I oc *R1;

[0087]

[0088] You can get:

[0089]

[0090] In this embodiment, I oc Specifically, in combination with the above, when the power signal received by the switch control signal terminal is in phase with the power signal received by the live wire input terminal, the embodiment of the present disclosure sets the pulse width difference threshold to 1 millisecond and sets I oc And the pulse width difference threshold corresponding to U m , substituting into the above formula, the size relationship that R2 and R1 should satisfy can be determined. This not only makes the resistance value R2 of the second voltage divider module 180 as small as possible as small as the resistance value R1 of the first voltage divider module 170, but also achieves a more reliable and effective distinction between the detection signal formed when the switch is open and the detection signal formed when the switch is closed.

[0091] Exemplarily, the resistance value R1 of the first voltage dividing module 170 can be 500 KΩ, and the resistance value R2 of the second voltage dividing module 180 can be 200 KΩ. There is no limitation on the number and specific size of the resistors included therein.

[0092] R1 should be set to be applicable to the situation where there is a certain pulse width during the positive cycle of the AC power supply with voltages ranging from 176 V to 264 V. Therefore:

[0093] R1 * I OC <a * U P

[0094] where, U p represents the positive peak value of the AC power supply, a is the coefficient of Up, and 0 < a < 1.

[0095] Exemplarily, a can be 0.8, then it satisfies: R1 * I oc <0.8 * Up, where Up takes the lowest value within the applicable voltage range: If I oc is 0.2 mA, it can be obtained that R1 < 990 K. With such a setting, it can be applicable to the situation where there is a certain pulse width during the positive cycle of the AC power supply with voltages of 176 V and 264 V.

[0096] Thus, it is obtained that 350 K < R1 < 990 K; in addition, at different resistance values of R1, the corresponding V 开 is different, and the voltage fluctuation time difference is also different.

[0097] Combining the above formulas, to find the overall proportional relationship between R1 and R2, it can be set that R2 ≤ βR1,

[0098] From it can be obtained that

[0099] and 350 K < R1 < 990 K, resulting in β ∈ [0.12, 0.49], and further obtaining:

[0100]

[0101] In some embodiments, in combination with Figure 1 and Figure 2 , the signal detection circuit further includes a current discharging module 190; the current discharging module 190 is connected in parallel with the electric sensing module 150.

[0102] The current discharge module 190 is a module for discharging the current at the discharge-sensitive module 150. For example, the current discharge module 190 can be connected in parallel with the light-emitting diode in the photocoupler U1, thereby increasing the input threshold current and preventing the light-emitting diode from being mis-conducted under low current conditions. Furthermore, when the photocoupler U1 is not conducting, the current at the photocoupler U1 can be discharged as quickly as possible, thereby ensuring that the photocoupler U1 can be reliably turned on and enhancing its anti-interference capability.

[0103] Exemplarily, the current discharge module 190 may be a resistor, and its resistance value may be set to 1K. In other embodiments, the current discharge module 190 may also be other types of devices and design parameters, which are not limited here.

[0104] In some embodiments, combined Figure 1 and Figure 2 , further comprising an AC and DC conversion module 200; one end of the AC and DC conversion module 200 is connected to the cathode of the first diode 161, and the other end is connected to the anode of the third diode 163.

[0105] The AC / DC converter module 200 is configured to convert AC voltage into DC voltage. Specifically, when the live input terminal 120 or the neutral input terminal 110 receives a power signal, the power signal is first rectified by the rectifier module 160. The AC / DC converter module 200 then converts the AC voltage into DC voltage, providing DC power to subsequent stages such as a load.

[0106] In some embodiments, combined Figure 1 and Figure 2 The electrosensitive module 150 includes a photocoupler U1; the collector of the phototransistor in the photocoupler U1 is connected to VCC through the fifth resistor 210, and the emitter of the phototransistor in the photocoupler U1 is grounded; the collector of the phototransistor in the photocoupler U1 is connected to the signal detection terminal 140.

[0107] For example, the resistance value of the fifth resistor 210 may be 4.7K, which is not limited herein.

[0108] An embodiment of the present disclosure also provides a signal detection system, including a controller and any one of the signal detection circuits provided in the above embodiments; the controller is electrically connected to the signal detection end of the signal detection circuit, and is used to perform zero-crossing detection and switch state detection based on the waveform of the detection signal output by the signal detection end.

[0109] For example, the signal detection circuit and system provided by the embodiments of the present disclosure may be applied to household appliances equipped with loads such as motors and lamps, but are not limited thereto.

[0110] It should be noted that the signal detection circuit and system provided in the embodiments of the present disclosure are all implemented in hardware, and perform the above-mentioned zero-crossing detection and switch state detection based on the computer program stored in the controller.

[0111] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0112] The foregoing description is intended only to provide specific embodiments of the present disclosure, intended to enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments described herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A signal detection circuit, characterized in that: include: Neutral line input terminal, live line input terminal, switch control signal terminal, signal detection terminal, electric sensitive module and rectifier module; The live wire input terminal is connected in series with the electric sensitive module through the rectifier module; the neutral wire input terminal is connected in series with the electric sensitive module through the rectifier module, and the output terminal of the electric sensitive module is electrically connected to the signal detection terminal; the switch control signal terminal is connected in series with the electric sensitive module; During the positive cycle of the AC power supply, the circuit between the live wire input terminal and the neutral wire input terminal is connected; during the negative cycle of the AC power supply, the circuit between the live wire input terminal and the neutral wire input terminal is disconnected; during the positive cycle or negative cycle of the AC power supply, the switch of the circuit where the switch control signal terminal is located is closed, and the circuit where the switch control signal terminal is located is connected; the signal detection terminal outputs a detection signal to the controller, so that the controller performs zero crossing detection and switch state detection according to the waveform of the detection signal.

2. The signal detection circuit according to claim 1, wherein: The rectifier module includes a first diode, a second diode, a third diode and a fourth diode; The anode of the first diode is electrically connected to the cathode of the third diode; the cathode of the first diode is electrically connected to the cathode of the second diode; the anode of the second diode is electrically connected to the cathode of the fourth diode; the anode of the fourth diode is electrically connected to the anode of the third diode; The live wire input terminal is electrically connected to the anode of the second diode; the neutral wire input terminal is electrically connected to the anode of the first diode; the electrosensitive module is connected in series between the switch control signal terminal and the anode of the third diode, and the electrosensitive module is connected in series between the anode of the second diode and the anode of the third diode.

3. The signal detection circuit according to claim 1, wherein: The electrosensitive module includes a photoelectric coupler; The live wire input end is electrically connected to the primary first end of the photoelectric coupler through the rectifier module; the neutral wire input end is electrically connected to the primary second end of the photoelectric coupler through the rectifier module, and the secondary of the photoelectric coupler is electrically connected to the signal detection end; the switch control signal end is electrically connected to the primary first end of the photoelectric coupler.

4. The signal detection circuit according to claim 1, wherein: The power signal received by the switch control signal terminal is in phase with the power signal received by the neutral line input terminal; During the positive cycle of the AC power supply, the electro-sensitive module is turned on, and the circuit between the live wire input terminal and the neutral wire input terminal is connected; during the negative cycle of the AC power supply, the switch of the circuit where the switch control signal terminal is located is closed, the electro-sensitive module is turned on, the circuit between the live wire input terminal and the neutral wire input terminal is disconnected, and the circuit where the switch control signal terminal is located is turned on.

5. The signal detection circuit according to claim 1, wherein: The power signal received by the switch control signal terminal is in phase with the power signal received by the live wire input terminal; In the positive cycle of the AC power supply, the switch of the circuit where the switch control signal terminal is located is closed, the electrosensitive module is turned on, the circuit where the switch control signal terminal is located is turned on, and the circuit between the live wire input terminal and the neutral wire input terminal is turned on; During the negative cycle of the AC power supply, the electrosensitive module is disconnected, the circuit where the switch control signal terminal is located is disconnected, and the circuit between the live wire input terminal and the neutral wire input terminal is disconnected.

6. The signal detection circuit according to claim 1, wherein: It also includes a first voltage dividing module; the first voltage dividing module is connected in series between the rectifier module and the electrosensitive module.

7. The signal detection circuit according to claim 6, wherein: It also includes a second voltage dividing module; the second voltage dividing module is connected in series between the switch control signal terminal and the electrosensitive module; the resistance value of the first voltage dividing module is greater than the resistance value of the second voltage dividing module.

8. The signal detection circuit according to claim 7, wherein: The resistance value R1 of the first voltage divider module and the resistance value R2 of the second voltage divider module satisfy: Among them, U n represents the AC equivalent voltage value, P2 represents the upper limit of power consumption of the first voltage divider module and the second voltage divider module, U m Indicates the pressure difference corresponding to the pulse width difference threshold, I oc Indicates the conduction current of the electro-sensitive module.

9. The signal detection circuit according to claim 1, wherein: It also includes a current discharge module; the current discharge module is connected in parallel with the electric sensitive module.

10. A signal detection system, characterized in that: It comprises a controller and the signal detection circuit according to any one of claims 1 to 9; the controller is electrically connected to the signal detection end of the signal detection circuit, and is used to perform zero-crossing detection and switch state detection according to the waveform of the detection signal output by the signal detection end.

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