Zero-crossing detection adjustment circuit, zero-crossing detection adjustment chip and system

Abstract

The present application discloses a zero-crossing detection regulation circuit, a zero-crossing detection regulation chip and a system, and relates to the field of circuit design. The zero-crossing detection regulation circuit includes: a clamping circuit module, connected to a first capacitor, charging the first capacitor when the AC input voltage is in a positive half-cycle, generating a first voltage and a first current; a mirror circuit module, connected to the clamping circuit module, for generating a second voltage according to the first voltage; a slope detection module, for detecting the slope of the first voltage and outputting a slope detection voltage; a first voltage comparison module, for comparing the slope detection voltage with the first reference voltage, and controlling the first switch to close or open based on the comparison result; a second voltage comparison module, for controlling the second switch to close or open according to the positive and negative cycles of the AC input voltage. While providing an accurate zero-crossing edge signal, the present application can also provide a zero-crossing pulse width proportional to the AC input voltage amplitude to meet the needs of high-precision control scenarios.

Description

Technical Field

[0001] The present invention relates to the field of circuit design, and in particular to a zero-crossing detection and regulation circuit, a zero-crossing detection and regulation chip and a system. Background Art

[0002] Zero-crossing detection circuits are widely used in both modern household appliances and power electronic systems. For example, to control the temperature of a heating wire in a household appliance, it is necessary to perform cycle control or phase cutting control at a specified phase of the AC power, which requires accurate zero-crossing phase information. In power line carrier communication, in order to perform high-quality carrier and detection, waveform synchronization is required at the zero-crossing point of the AC power, which also requires accurate zero-crossing phase information.

[0003] The principle of the zero-crossing detection circuit in the prior art is as follows: Figure 1 As shown, a resistor R11, a clamping diode D11 and an optocoupler U11 are usually used to cooperate for zero-crossing signal detection. Although this circuit structure is simple and easy to use, it has the following obvious shortcomings: First, the power consumption is too large. Under the general power grid conditions, the power consumption of the resistor can be as high as 0.5W, resulting in excessive standby power consumption of the system; second, the waveform quality is poor. Due to the small gain of the optocoupler, the driving current provided by the resistor before and after zero crossing presents a sine wave characteristic, the output waveform quality is poor, and the application accuracy is low and unstable; third, the anti-aging adaptability of the optocoupler is not strong. The optocoupler gradually ages over time, and the transmission gain continues to decrease, resulting in a further decrease in the quality of the output signal, and even unable to output effective zero-crossing high and low level signals, resulting in the failure of the system zero-crossing detection.

[0004] In addition, the existing zero-crossing detection circuit usually only provides the zero-crossing signal of the AC power and cannot detect the AC input voltage. In some application scenarios, for example, when accurate temperature control of a heating device is required, in addition to knowing the phase and frequency of the AC power, the amplitude of the AC voltage is also required to reduce the working time when the AC power amplitude is high and increase the working time when the AC power amplitude is low, thereby maintaining precise temperature control. However, the existing circuit cannot meet the needs of current high-precision application scenarios. Summary of the invention

[0005] The purpose of the present invention is to provide a zero-crossing detection and regulation circuit, a zero-crossing detection and regulation chip and a system, which can provide a precise zero-crossing edge signal and a zero-crossing pulse width proportional to the AC input voltage amplitude to meet the needs of high-precision control.

[0006] To achieve the above object, the present invention discloses the following technical solution:

[0007] In one aspect, the present invention provides a zero-crossing detection adjustment circuit, comprising:

[0008] A clamping circuit module, electrically connected to the first capacitor, for limiting the circuit input voltage to a set value when the AC input voltage is in a positive half cycle, and charging the first capacitor to generate a first voltage and a first current;

[0009] a mirror circuit module, electrically connected to the clamp circuit module via a first switch, and configured to generate a second voltage according to the first voltage;

[0010] A slope detection module, used for detecting the slope of the first voltage and outputting a slope detection voltage;

[0011] A first voltage comparison module, used for comparing the slope detection voltage with a first reference voltage, and outputting a first switch signal to control the first switch to be closed or opened based on the comparison result;

[0012] The second voltage comparison module is electrically connected to the mirror circuit module through a second switch, and is used to output a second switch signal according to the positive and negative cycles of the AC input voltage to control the second switch to be closed or opened.

[0013] Furthermore, in the above zero-crossing detection adjustment circuit:

[0014] When the AC input voltage is in the rising stage of the positive half cycle, the first voltage rises and the first switch is closed, the second switch is opened, and the second voltage is equal to the first voltage;

[0015] When the AC input voltage is in the decreasing stage of the positive half cycle, the first voltage decreases and the first switch is disconnected, the second switch is disconnected, and the second voltage is the maximum value of the first voltage;

[0016] When the AC input voltage is in a negative half cycle, the first voltage is 0V and the first switch is open, the second switch is closed, and the second voltage changes according to the external circuit.

[0017] Optionally, in the above-mentioned zero-crossing detection and adjustment circuit, the clamping circuit module includes a first MOS tube, a second MOS tube, a third resistor and a fourth resistor, the first MOS tube is a PMOS tube, the second MOS tube is an NMOS tube, the source of the first MOS tube is connected to one end of the third resistor and connected to the circuit input voltage, the gate of the first MOS tube is connected to the other end of the third resistor and one end of the fourth resistor, the drain of the first MOS tube is connected to the drain and gate of the second MOS tube, and the source of the second MOS tube is connected to the other end of the fourth resistor and grounded;

[0018] The gate of the second MOS tube is electrically connected to one end of the first capacitor, and the other end of the first capacitor is grounded. When the AC input voltage is in a positive half cycle, the source of the first MOS tube generates a first current and charges the first capacitor to generate a first voltage.

[0019] Optionally, in the above-mentioned zero-crossing detection and regulation circuit, the mirror circuit module includes a third MOS tube and a second capacitor, the third MOS tube is an NMOS tube and is a mirror image of the second MOS tube, the gate of the third MOS tube is connected to one end of the second capacitor and is connected to the gate of the second MOS tube through the first switch, the drain of the third MOS tube is connected to the external circuit through the second switch, the output end of the second voltage comparison module is connected to the control end of the second switch, and the drain of the third MOS tube is connected to the other end of the second capacitor and is grounded;

[0020] When the first switch is closed, the gate of the third MOS transistor generates the second voltage equal to the first voltage.

[0021] Optionally, in the above-mentioned zero-crossing detection and adjustment circuit, the slope detection module includes a differentiator circuit, an integrator circuit and / or a comparator circuit.

[0022] Optionally, in the above-mentioned zero-crossing detection and regulation circuit, the first voltage comparison module includes a first voltage comparator, one input end of the first voltage comparator is connected to the output end of the slope detection module, the other input end is connected to the first reference voltage, and its output end is connected to the control end of the first switch, for controlling the first switch to close or open according to the slope detection voltage and the first reference voltage.

[0023] Preferably, in the above-mentioned zero-crossing detection adjustment circuit, the first reference voltage is set to the center value of the slope detection voltage.

[0024] Optionally, in the above-mentioned zero-crossing detection and regulation circuit, the second voltage comparison module includes a second voltage comparator, one input end of the second voltage comparator is connected to the circuit input voltage, the other input end is grounded, and its output end is connected to the control end of the second switch, and is used to control the second switch to be closed or opened according to the AC input voltage, and the second switch switches between closed and open states when the positive and negative cycles of the AC input voltage change.

[0025] Another aspect of the present invention provides a zero-crossing detection and regulation chip, comprising the zero-crossing detection and regulation circuit as described above, and further comprising an input voltage terminal, a power supply voltage terminal, an output control terminal and a ground terminal.

[0026] In addition, the present invention also provides a zero-crossing detection and regulation system, comprising a current limiting resistor, a zero-crossing detection and regulation chip, an energy storage capacitor and a photoelectric coupler, wherein the zero-crossing detection and regulation chip comprises an input voltage terminal, a power supply voltage terminal, an output control terminal and a ground terminal, an AC input voltage is connected to the input voltage terminal after passing through the current limiting resistor, one end of the energy storage capacitor is connected to the power supply voltage terminal, and the other end is connected to the ground terminal, and the output control terminal is connected to the input terminal of the photoelectric coupler;

[0027] When the AC input voltage is in a positive half cycle, the zero-crossing detection and regulation chip charges the energy storage capacitor through the power supply voltage terminal, and controls the photoelectric coupler to be turned off through the output control terminal, and outputs a zero-crossing signal of a high level;

[0028] When the AC input voltage enters the negative half cycle, the zero-crossing detection and regulation chip controls the photoelectric coupler to turn on through the output control terminal, and the output zero-crossing signal is a low level; then when the voltage of the output control terminal is lower than the preset voltage, the photoelectric coupler is controlled to turn off, and the output zero-crossing signal is a high level; the duration of the zero-crossing signal being a low level is proportional to the amplitude of the AC input voltage.

[0029] Optionally, in the above-mentioned zero-crossing detection and regulation system, the input end of the photocoupler includes a photodiode, the anode of the photodiode is connected to the power supply voltage end of the zero-crossing detection and regulation chip, and the cathode is connected to the output control end; the output end of the photocoupler includes a phototransistor, the emitter of the phototransistor is grounded, and the collector is connected to the output power supply through the output end resistor and outputs a zero-crossing signal.

[0030] The effects provided in the content of the invention are only the effects of the embodiments, not all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects:

[0031] The zero-crossing detection and regulation circuit provided in the embodiment of the present application generates a first voltage through a clamping circuit module, and a mirror circuit module generates a second voltage according to the first voltage, and then controls the first switch and the second switch to be closed or disconnected respectively through a first voltage comparison module and a second voltage comparison module, so that when the AC input voltage changes from a positive half-cycle to a negative half-cycle, an accurate zero-crossing signal can be generated according to the change of the second voltage. And when the AC input voltage is a negative half-cycle, a zero-crossing pulse width proportional to the input voltage amplitude can be provided according to an external circuit, thereby improving the accuracy and stability of the circuit zero-crossing detection.

[0032] The zero-crossing detection and regulation system provided in the embodiment of the present application, when the AC input voltage is in the positive half cycle, the zero-crossing detection and regulation chip charges the energy storage capacitor through the power supply voltage terminal to provide working power for the system. When the AC input voltage enters the negative half cycle, the zero-crossing detection and regulation chip controls the conduction of the photoelectric coupler through the output control terminal, and the output zero-crossing signal is a low level, and when the voltage of the output control terminal is lower than the preset voltage, the photoelectric coupler is controlled to be turned off, and the output zero-crossing signal is a high level. The system can provide both accurate zero-crossing edge signals and zero-crossing pulse width information proportional to the AC amplitude, so that the power of the external device can be adjusted according to the level of the input voltage to meet the high-precision control requirements of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0034] Figure 1 It is a schematic diagram of a zero-crossing detection circuit in the prior art;

[0035] Figure 2 This is a schematic diagram of the structure of a zero-crossing detection and adjustment circuit according to an embodiment of the present application;

[0036] Figure 3 This is a schematic diagram of a zero-crossing detection and adjustment circuit according to an embodiment of the present application;

[0037] Figure 4 for Figure 3 Signal waveform diagram of zero-crossing detection and regulation circuit;

[0038] Figure 5 This is a schematic diagram of the structure of a zero-crossing detection and adjustment chip according to an embodiment of the present application;

[0039] Figure 6 This is a schematic diagram of the structure of a zero-crossing detection and adjustment system according to an embodiment of the present application;

[0040] Figure 7 for Figure 6 The circuit schematic diagram of the zero-crossing detection and regulation system in FIG.

[0041] Figure 8 for Figure 7 Signal waveform diagram of the zero-crossing detection and regulation system.

[0042] Reference numerals:

[0043] 200-zero-crossing detection and adjustment circuit, 210-clamping circuit module, 220-mirror circuit module, 230-slope detection module, 240-first voltage comparison module, 250-second voltage comparison module, 260-first capacitor, 270-first switch, 280-second switch;

[0044] 500-Zero-crossing detection and regulation chip. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] It should be noted that references to "one embodiment", "embodiment", "example embodiment", etc. in this specification refer to the embodiment being described which may include specific features, structures or characteristics, but not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Furthermore, when describing specific features, structures or characteristics in conjunction with an embodiment, whether or not there is an explicit description, it is indicated that incorporating such features, structures or characteristics into other embodiments is within the knowledge of those skilled in the art.

[0047] In addition, certain words are used in the specification and subsequent claims to refer to specific components or parts. Those with ordinary knowledge in the relevant field should understand that manufacturers can use different nouns or terms to refer to the same component or part. This specification and subsequent claims do not use differences in names as a way to distinguish components or parts, but use differences in the functions of components or parts as the criteria for distinction. "Including" and "including" mentioned throughout the specification and subsequent claims are open-ended terms and should be interpreted as "including but not limited to". In addition, the word "connected" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connection through other devices.

[0048] Zero-crossing detection circuits are widely used and play an important role in modern electronic devices. High-quality zero-crossing signal output can not only improve the efficiency and reliability of the system, but also meet the needs of various complex application scenarios. Since the existing zero-crossing detection circuit can usually only provide zero-crossing signals for alternating current, the accuracy and stability are poor, and the AC input voltage cannot be detected, and the high-precision requirements of modern products cannot be met. Based on this, the core of the embodiment of the present application is to provide a zero-crossing detection adjustment circuit, a zero-crossing detection adjustment chip and a system, which can provide a pulse width proportional to the amplitude of the alternating current in addition to providing a traditional zero-crossing edge signal, and can also provide a reliable zero-crossing signal when the photoelectric coupler gain is small, meeting the use requirements of high precision and multiple scenarios.

[0049] refer to Figure 2 , Figure 2The zero-crossing detection regulating circuit structure schematic diagram of an embodiment of the present application is shown. As shown in the figure, the zero-crossing detection regulating circuit 200 of the present embodiment includes a clamping circuit module 210, a mirror circuit module 220, a slope detection module 230, a first voltage comparison module 240 and a second voltage comparison module 250. Among them, the clamping circuit module 210 is electrically connected to the first capacitor 260, and is used to limit the circuit input voltage VIN to a set value when the AC input voltage AC is a positive half cycle, and to charge the first capacitor 260, to generate a first voltage V1 at the end of the first capacitor 260, and to generate a first current inside the clamping circuit module 210. The mirror circuit module 220 is electrically connected to the clamping circuit module 210 through the first switch 270, and is used to generate a second voltage V2 according to the first voltage V1. The slope detection module 230 is used to detect the slope of the first voltage V1 and output the slope detection voltage V0. The first voltage comparison module 240 is used to compare the slope detection voltage V0 with the first reference voltage Vref1, and output the first switch signal Va based on the comparison result to control the first switch 270 to be closed or opened. The second voltage comparison module 250 is electrically connected to the mirror circuit module 220 through the second switch 280, and is used to output the second switch signal Vb to control the second switch 280 to be closed or opened according to the positive and negative cycles of the AC input voltage. In the circuit of this embodiment:

[0050] When the AC input voltage is in the rising stage of the positive half cycle, the first voltage V1 rises, the first voltage comparison module 240 controls the first switch 270 to close, and the second voltage comparison module 250 controls the second switch V2 to open. At this time, the second voltage V2 is equal to the first voltage V1;

[0051] When the AC input voltage is in the positive half-cycle falling stage, the first voltage V1 falls, the first voltage comparison module 240 controls the first switch 270 to be disconnected, and the second voltage comparison module 250 controls the second switch 280 to be disconnected, and at this time, the second voltage V2 remains at the maximum value of the first voltage V1;

[0052] When the AC input voltage is in the negative half cycle, the clamping circuit module 210 limits the circuit input voltage VIN to 0V, the first voltage is 0V, the first voltage comparison module 240 controls the first switch 270 to be disconnected, and at the same time, since VIN is 0V, the second voltage comparison module 250 controls the second switch 280 to be closed, and the mirror circuit module 220 is connected to the peripheral circuit through the second switch 280. At this time, the second voltage V2 changes according to the external circuit.

[0053] Specific reference Figure 3 , Figure 3 This is a schematic diagram of the zero-crossing detection and adjustment circuit of an embodiment of the present application. As shown in the figure:

[0054] In this embodiment, the clamping circuit module 210 includes a first MOS tube M1, a second MOS tube M2, a third resistor R3 and a fourth resistor R4, wherein the first MOS tube M1 is a PMOS tube and the second MOS tube M2 is an NMOS tube. Specifically, the source of the first MOS tube M1 is connected to one end of the third resistor R3 and connected to the circuit input voltage VIN, the gate of the first MOS tube M1 is connected to the other end of the third resistor R3 and one end of the fourth resistor R4, and the drain of the first MOS tube M1 is connected to the drain and gate of the second MOS tube M2. The source of the second MOS tube M2 is connected to the other end of the fourth resistor R4 and grounded.

[0055] In addition, the gate of the second MOS transistor M2 is electrically connected to one end of the first capacitor 260, and the other end of the first capacitor 260 is grounded. When the AC input voltage is in a positive half cycle, the first MOS transistor M1 is turned on, and its source generates a first current, and charges the first capacitor 260 to generate a first voltage V1.

[0056] In this embodiment, the mirror circuit module 220 includes a third MOS tube M3 and a second capacitor C2, and the third MOS tube M3 is an NMOS tube and is a mirror image of the second MOS tube M2. The gate of the third MOS tube M3 is connected to one end of the second capacitor C2 and is connected to the gate of the second MOS tube M2 through the first switch K1, and the drain of the third MOS tube M3 is connected to the peripheral circuit through the second switch K2. The output end of the comparison module 250 is connected to the control end of the second switch K2, and the source of the third MOS tube is connected to the other end of the second capacitor C2 and grounded. Among them, the first switch K1 and the second switch K2 can be relay switches, transistor switches or logic control switches, etc., and the present application is not limited thereto.

[0057] Depend on Figure 3 It can be known that when the first switch K1 is closed, the gate of the third MOS transistor M3 will generate a second voltage V2 which is equal to the first voltage V1.

[0058] In this embodiment, the slope detection module 230 may be a conventional differentiator circuit, an integrator circuit or a comparator circuit, etc., which will not be described in detail herein.

[0059] In this embodiment, the first voltage comparison module 240 uses a first voltage comparator CMP1. One input terminal of the first voltage comparator CMP1 is connected to the output terminal of the slope detection module 230, the other input terminal is connected to the first reference voltage Vref1, and the output terminal is connected to the first switch K1. The first switch control signal Va is output according to the slope detection voltage V0 and the first reference voltage Vref1, so as to control the first switch K1 to be closed or opened. In this circuit, the first reference voltage Vref1 is specifically set to the center value of the slope detection voltage V0, so that the first switch K1 switches between the closed and open states when the slope detection voltage is at the center value.

[0060] In this embodiment, the second voltage comparison module 250 uses a second voltage comparator CMP2. One input terminal of the second voltage comparator CMP2 is connected to the circuit input voltage VIN, the other input terminal is grounded, and the output terminal is connected to the second switch K2, and the second switch K2 is controlled to be closed or opened according to the circuit input voltage VIN. The second switch K2 switches between the closed and open states when the positive and negative cycles of the circuit input voltage change.

[0061] Specifically, Figure 4 for Figure 3 The signal waveform diagram of the zero-crossing detection and adjustment circuit in the next section Figure 4 ,right Figure 3 The circuit working principle and working process of the embodiment are described in detail.

[0062] During the period of 0 to t1, the AC input voltage AC is in the positive half cycle and the voltage rise stage, and the circuit input voltage VIN rises and is limited to the set value. The third resistor R3 provides a bias voltage for the first MOS tube M1, M1 is turned on, and the first current i1 flows through M1 to charge the first capacitor C1. At the same time, the first voltage V1 rises, and when V1 is greater than the turn-on voltage of the second MOS tube M2, M2 is turned on. The slope detection module 230 detects that the slope of V1 is positive and outputs the slope detection voltage V0. Since the slope detection voltage V0 is less than the first reference voltage Vref1 at the beginning, the first comparator CMP1 outputs the first switch signal Va as a high level, controlling the first switch K1 to close. At the same time, the second comparator CMP2 outputs the second switch signal Vb as a low level, controlling the second switch K2 to open. Since the second MOS tube M2 and the third MOS tube M3 are mirror images of each other, the second voltage V2=V1 at this time.

[0063] At time t1, the AC input voltage AC is at the peak of the positive half cycle. Correspondingly, the first current i1 reaches the maximum value i1 MAX , the first voltage V1 also reaches the maximum value V1 MAXThe slope detection module 230 detects that the slope of V1 is 0, and outputs a slope detection voltage VO equal to the first reference voltage Vref1. The first comparator CMP1 outputs a first switch signal Va as a low level, controlling the first switch K1 to be disconnected, and the second comparator CMP2 outputs a second switch signal Vb as a low level, controlling the second switch K2 to be disconnected. At this time, the second voltage V2 maintains the maximum value V1 of V1. MAX .

[0064] During the period t1 to t2, the AC input voltage AC is in the positive half cycle and the voltage is falling, and the first voltage V1 and the first current i1 fall synchronously. The slope detection module 230 detects that the slope of V1 is negative, and the output slope detection voltage VO is greater than the first reference voltage Vref1. The first comparator CMP1 outputs the first switch signal Va as a low level, and controls the first switch K1 to be disconnected. At the same time, the second comparator CMP2 outputs the second switch signal Vb as a low level, and controls the second switch K2 to be disconnected. At this time, the second voltage V2 still maintains the maximum value V1 of V1. MAX .

[0065] During the period t2 to t3, the AC input voltage AC is in the negative half cycle, the circuit input voltage VIN is limited to 0V, and the first voltage V1 also drops to 0V. The slope detection module 230 detects that the slope of V1 is 0, and the output slope detection voltage VO is equal to the first reference voltage Vref1. The first comparator CMP1 outputs the first switch signal Va as a low level, controls the first switch K1 to be disconnected, and the second comparator CMP2 outputs the second switch signal Vb as a high level, controls the second switch K2 to be closed. At this time, the second voltage V2 changes according to the external circuit.

[0066] As mentioned above, the existing zero-crossing detection circuit has poor accuracy and stability. However, the above circuit structure of this embodiment can generate more accurate signal detection through the change of the second voltage when the AC input voltage changes from the positive half cycle to the negative half cycle, that is, the zero-crossing voltage, thereby improving the accuracy and stability of zero-crossing signal detection.

[0067] Of course, it should be noted that Figure 3 The zero-crossing detection and adjustment circuit structure shown is only a preferred circuit structure for achieving the purpose of the present invention. In other embodiments, each circuit module or device may also use other circuit structures that can achieve the same function, and the present application is not limited thereto.

[0068] In order to better apply the zero-crossing detection and adjustment circuit in the above embodiment, it can be packaged in a zero-crossing detection and adjustment chip in the form of an integrated circuit. Figure 5 , Figure 5This is a schematic diagram of the structure of a zero-crossing detection and regulation chip according to an embodiment of the present application, in which a zero-crossing detection and regulation circuit 200 is encapsulated. As shown in the figure, the outside of the zero-crossing detection and regulation chip 500 includes at least 5 pins, wherein the first pin is a power supply voltage terminal VDD, which is used to provide a working power supply for the chip or system; the second pin is a ground terminal GND; the third pin is an empty pin NC, which can float or be connected to an adjacent pin; the fourth pin is an input voltage terminal IN, which is used to connect the circuit input voltage VIN; the fifth pin is an output control terminal OUT, which is used to connect to an external circuit. Of course, in other embodiments, the zero-crossing detection and regulation chip can also be designed as other structural forms according to actual needs, and the present application is not limited thereto.

[0069] Next, in combination with a specific application system, the use principle and process of the zero-crossing detection adjustment circuit and the zero-crossing detection adjustment chip in the embodiment of the present application are explained more clearly.

[0070] Specific reference Figure 6 , Figure 7 , Figure 6 This is a schematic diagram of the structure of a zero-crossing detection and adjustment system according to an embodiment of the present application. Figure 7 for Figure 6 The corresponding circuit schematic diagram is shown in the figure:

[0071] The zero-crossing detection and regulation system includes the zero-crossing detection and regulation chip in the above embodiment, and also includes a current limiting resistor R1, an energy storage capacitor C and a photoelectric coupler P. Specifically, the AC input voltage AC generates a circuit input voltage VIN after passing through the current limiting resistor R1 and is connected to the input voltage terminal IN of the zero-crossing detection and regulation chip. The power supply voltage terminal VDD of the zero-crossing detection and regulation chip is connected to one end of the energy storage capacitor C, and the other end of the energy storage capacitor C is connected to the ground terminal GND of the chip. The output control terminal OUT of the zero-crossing detection and regulation chip is connected to the input end of the photoelectric coupler P.

[0072] In this embodiment, the input end of the photocoupler P includes a photodiode D1, the anode of the photodiode is connected to the power supply voltage terminal VDD, and the cathode is connected to the output control terminal OUT; the output end of the photocoupler includes a phototransistor, the emitter of the phototransistor is grounded, and the collector is connected to the output power supply (for example, 5V / 3.3V) through the output resistor R2 and outputs a zero-crossing signal ZERO.

[0073] Figure 8 for Figure 7 Signal waveform diagram of zero-crossing detection and regulation system. Figure 4 , Figure 8 As can be seen from the above embodiments, the working process of the zero-crossing detection and adjustment system of this embodiment is as follows:

[0074] According to the above, during the period of 0 to t1, the AC input voltage AC is in the rising stage of the positive half cycle, and the second voltage V2 = V1. The clamping voltage point of VDD can be set by the proportional relationship between R3 and R4. The connection method of R3 and M1 forms negative feedback, and the voltage on R3 eventually stabilizes to the turn-on voltage of M1. For example, if the turn-on voltage of M1 is 1V, set R3:R4 = 1:4. When AC is greater than 5V, VDD is clamped and stabilized at 5V. The relationship between the pull-down current of M1 and AC can be approximately i1 = (V AC -V VDD ) / R1≈V AC / R1, that is, the current i1 is proportional to the voltage AC. At time t1, the AC input voltage AC is at the peak moment of the positive half cycle, and the second voltage V2 maintains the maximum value V1 of V1 MAX , and is proportional to the voltage AC. During the period t1 to t2, the AC input voltage AC is in the positive half-cycle decreasing stage, at which time the second voltage V2 still maintains the maximum value V1 of V1 MAX .

[0075] Further combined with the system circuit of the present embodiment, when the AC input voltage AC is in the positive half cycle, the zero-crossing detection adjustment chip provides current to the VDD terminal through the input voltage waveform, and the VDD terminal is externally connected to the energy storage capacitor C, and the current is accumulated in the energy storage capacitor C to provide working power for the system. Therefore, when the system operates normally in the positive half cycle of the AC voltage, no external working power supply is required, and the zero-crossing detection adjustment chip will be self-powered. At this time, the output control terminal OUT of the zero-crossing detection adjustment chip is disconnected, the photoelectric coupler P is turned off, and the output zero-crossing signal ZERO is high.

[0076] During the period from t2 to t3, the AC input voltage AC is in the negative half cycle, the second switch K2 is closed, the first switch K1 is disconnected, the energy storage capacitor C stops replenishing power, and a discharge loop is formed through the optocoupler input terminal D1, the second switch K2 and the third MOS tube M3. Specifically, the size of the discharge current Iout is determined by the second voltage V2, and at this time V2=V1 MAX , then Iout=i1 MAX , while i1 MAX It is the maximum current generated when AC is at its peak value, which is proportional to the AC peak voltage. According to the relationship between capacitor charging or discharging in a certain period of time, C*ΔV=I*T, where C is the capacitance of the energy storage capacitor C, ΔV is the voltage change on the energy storage capacitor C (for example, when the energy storage capacitor C is discharged from 5V to the preset voltage Vref of 4V, the voltage change is 5V-4V=1V), and I is the discharge current of the energy storage capacitor C (i.e. Iout=i1 MAX ), T is the discharge time of the energy storage capacitor C, from which it can be known that the discharge current Iout is inversely proportional to the discharge time T.

[0077] Further combined with the system circuit of the present embodiment, when the AC input voltage AC is in the negative half cycle, the energy storage capacitor C discharges, the optocoupler input terminal D1, the second switch K2 and the third MOS tube M3 form a discharge loop, the optocoupler is turned on and outputs the zero-crossing signal ZERO as a low level; and when the voltage of the output control terminal OUT is lower than the preset voltage Vref, the pull-down current of the output control terminal OUT is stopped, the optocoupler P is turned off, and the zero-crossing signal ZERO is pulled up to a high level again.

[0078] From the above, it can be seen that after the current limiting resistor R1 and the energy storage capacitor C are determined, when the AC input voltage AC changes from the positive half cycle to the negative half cycle (i.e., the zero-crossing voltage), the zero-crossing signal ZERO has a falling edge and changes to a low-level pulse, and the pulse width Wp is related to the pull-down current Iout of the output control terminal OUT. AC The zero-crossing signal ZERO is proportional to the pulse width of the zero-crossing signal, and the duration of the low level of the zero-crossing signal ZERO is inversely proportional to the pull-down current Iout. After receiving this pulse, the downstream system can determine the level of the current input voltage based on the width of the pulse signal. That is, since the amplitude of the input voltage is proportional to the pulse width of the zero-crossing signal, the back-end circuit can infer the level of the current input voltage through the width of the pulse. In this embodiment, when the input voltage is high, the back-end system can adjust the external device to run at high power, otherwise, it can run at low power, thereby effectively improving the efficiency of the system and reducing power loss.

[0079] It should be emphasized that in the above embodiment, the amplitude of the input voltage is inversely proportional to the low-level pulse width of the zero-crossing signal. Of course, in practical applications, it can also be designed to be proportional to the specific situation, and the present application is not limited to this. For example, in one embodiment, the pulse width corresponding to each volt of voltage is 1us, and the actual input voltage AC of the system is 80-300V, then the pulse width can be 80-300us according to the AC value, or the pulse width can be 113-424us according to the amplitude. After receiving this pulse, the downstream system can also derive the current input voltage based on the width of the reversed pulse.

[0080] In summary, the zero-crossing detection and adjustment system of this embodiment can not only provide accurate zero-crossing edge signals, but also provide zero-crossing pulse width information proportional to the AC amplitude, so that the AC amplitude information can be obtained on the system output side, meeting the control requirements of high-precision application scenarios. In addition, the system integrates the zero-crossing detection and adjustment circuit into the zero-crossing detection and adjustment chip, and can realize the zero-crossing detection and adjustment function with the help of the original optocoupler and peripheral devices, without adding additional external devices, with a simple structure and easy use. In addition, the pull-down current design of the output control terminal of the system can provide a reliable zero-crossing signal even when the optocoupler gain is small, thereby extending the service life of the optocoupler.

[0081] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A zero-crossing detection and regulation circuit, characterized in that: include: A clamping circuit module, electrically connected to the first capacitor, for limiting the circuit input voltage to a set value when the AC input voltage is in a positive half cycle, and charging the first capacitor to generate a first voltage and a first current; a mirror circuit module, electrically connected to the clamp circuit module via a first switch, and configured to generate a second voltage according to the first voltage; A slope detection module, used for detecting the slope of the first voltage and outputting a slope detection voltage; A first voltage comparison module, used for comparing the slope detection voltage with a first reference voltage, and outputting a first switch signal to control the first switch to be closed or opened based on the comparison result; The second voltage comparison module is electrically connected to the mirror circuit module through a second switch, and is used to output a second switch signal according to the positive and negative cycles of the AC input voltage to control the second switch to be closed or opened.

2. The circuit according to claim 1, characterized in that When the AC input voltage is in the rising stage of the positive half cycle, the first voltage rises and the first switch is closed, the second switch is opened, and the second voltage is equal to the first voltage; When the AC input voltage is in the decreasing stage of the positive half cycle, the first voltage decreases and the first switch is disconnected, the second switch is disconnected, and the second voltage is the maximum value of the first voltage; When the AC input voltage is in a negative half cycle, the first voltage is 0V and the first switch is open, the second switch is closed, and the second voltage changes according to the external circuit.

3. The circuit according to claim 2, characterized in that The clamping circuit module includes a first MOS tube, a second MOS tube, a third resistor and a fourth resistor, the first MOS tube is a PMOS tube, the second MOS tube is an NMOS tube, the source of the first MOS tube is connected to one end of the third resistor and connected to the circuit input voltage, the gate of the first MOS tube is connected to the other end of the third resistor and one end of the fourth resistor, the drain of the first MOS tube is connected to the drain and gate of the second MOS tube, and the source of the second MOS tube is connected to the other end of the fourth resistor and grounded; The gate of the second MOS tube is electrically connected to one end of the first capacitor, and the other end of the first capacitor is grounded. When the AC input voltage is in a positive half cycle, the source of the first MOS tube generates a first current and charges the first capacitor to generate a first voltage.

4. The circuit according to claim 3, characterized in that The mirror circuit module includes a third MOS tube and a second capacitor, the third MOS tube is an NMOS tube and is a mirror image of the second MOS tube, the gate of the third MOS tube is connected to one end of the second capacitor and is connected to the gate of the second MOS tube through the first switch, the drain of the third MOS tube is connected to the external circuit through the second switch, the output end of the second voltage comparison module is connected to the control end of the second switch, and the source of the third MOS tube is connected to the other end of the second capacitor and is grounded; When the first switch is closed, the gate of the third MOS transistor generates the second voltage equal to the first voltage.

5. The circuit according to claim 1, characterized in that The slope detection module includes a differentiator circuit, an integrator circuit or a comparator circuit.

6. The circuit according to any one of claims 1 to 5, characterized in that: The first voltage comparison module includes a first voltage comparator, one input end of the first voltage comparator is connected to the output end of the slope detection module, the other input end is connected to the first reference voltage, and the output end is connected to the control end of the first switch, and is used to control the first switch to be closed or opened according to the slope detection voltage and the first reference voltage.

7. The circuit according to claim 6, characterized in that The first reference voltage is set to a center value of the slope detection voltage.

8. The circuit according to any one of claims 1 to 5, characterized in that: The second voltage comparison module includes a second voltage comparator, one input end of the second voltage comparator is connected to the circuit input voltage, the other input end is grounded, and the output end is connected to the control end of the second switch, and is used to control the second switch to be closed or opened according to the AC input voltage. The second switch switches between the closed and open states when the positive and negative cycles of the AC input voltage change.

9. A zero-crossing detection and adjustment chip, characterized in that: The zero-crossing detection and regulation circuit comprises the zero-crossing detection and regulation circuit as claimed in any one of claims 1 to 8, wherein the zero-crossing detection and regulation circuit is packaged in a zero-crossing detection and regulation chip, and the zero-crossing detection and regulation chip further comprises a ground terminal; an input voltage terminal for connecting to a circuit input voltage; A power supply voltage terminal, used to provide working power for the zero-crossing detection and regulation chip; Output control terminal, used to connect external circuit.

10. A zero-crossing detection and adjustment system, characterized in that: It comprises a current limiting resistor, a zero-crossing detection and regulation chip as claimed in claim 9, an energy storage capacitor and a photoelectric coupler, wherein the AC input voltage is connected to the input voltage terminal after passing through the current limiting resistor, one end of the energy storage capacitor is connected to the power supply voltage terminal, and the other end is connected to the ground terminal, and the output control terminal is connected to the input terminal of the photoelectric coupler; When the AC input voltage is in a positive half cycle, the zero-crossing detection and regulation chip charges the energy storage capacitor through the power supply voltage terminal, and controls the photoelectric coupler to be turned off through the output control terminal, and outputs a zero-crossing signal of a high level; When the AC input voltage enters the negative half cycle, the zero-crossing detection and regulation chip controls the photoelectric coupler to turn on through the output control terminal, and the output zero-crossing signal is a low level; then when the voltage of the output control terminal is lower than the preset voltage, the photoelectric coupler is controlled to turn off, and the output zero-crossing signal is a high level; the duration of the zero-crossing signal being a low level is proportional to the amplitude of the AC input voltage.

11. The system according to claim 10, characterized in that The input end of the photoelectric coupler includes a photodiode, the anode of the photodiode is connected to the power supply voltage end of the zero-crossing detection and regulation chip, and the cathode is connected to the output control end; the output end of the photoelectric coupler includes a phototransistor, the emitter of the phototransistor is grounded, and the collector is connected to the output power supply through the output end resistor and outputs a zero-crossing signal.

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