Relay control circuit

Abstract

The utility model provides a relay control circuit, relates to the technical field of relay driving, and aims to solve the technical problems that the service life of a relay is shortened and the reliability of the circuit is affected due to the fact that the relay is easy to generate electric arc and electromagnetic interference during on-off. The relay control circuit comprises an isolation voltage threshold acquisition module which is used for acquiring a voltage value of a leading phase of a load phase connected with a relay and outputting an enable signal when the acquired voltage value reaches a target alternating voltage threshold, and the enable signal is a control signal which enables the relay to be on and off in a zero-crossing manner; the judgment module is used for outputting a driving signal when receiving the on-off signal and the enable signal; and the relay driving module is used for controlling the on-off of the relay based on the driving signal. The circuit can prevent the relay from generating electric arc during operation, thereby effectively prolonging the service life of the relay, reducing electromagnetic interference, and improving the influence of the electromagnetic interference on the circuit.

Description

Technical Field

[0001] The present application relates to the field of relay driving technology, and in particular to a relay control circuit. Background Art

[0002] The electromagnetic relay is a mechanical electromagnetic switch. When the electromagnetic relay is started, the current passes through the coil to generate a magnetic field, causing the armature to make contact or disconnect at the contact position. This process is based on mechanical principles and takes a certain amount of time to complete, which is called the action time.

[0003] In the related art, the relay is equipped with a zero-crossing detection circuit to control the on or off operation of the relay when the AC voltage waveform crosses the zero point, so as to avoid excessive impact on the relay during the peak current period, thereby extending its life. However, since the switching or on operation of the relay itself has a certain response delay, the contacts are not always at the zero point of the voltage waveform during operation. In this case, the contact or disconnection may cause arc discharge between the contacts due to the sudden change in current, accelerate the wear of the relay, and shorten its service life. In addition, the sudden change in current may also cause electromagnetic interference (EMI) and propagate in the circuit, affecting the normal operation of the components in the circuit and reducing the reliability of the circuit. Utility Model Content

[0004] The embodiment of the present application provides a relay control circuit to improve the technical problem that the relay is prone to arcing and electromagnetic interference when being switched on and off, thereby shortening its service life and affecting the circuit reliability.

[0005] An embodiment of the present application provides a relay control circuit, comprising:

[0006] An isolation voltage threshold acquisition module is used to acquire the voltage value of the leading phase of the load phase connected to the relay and output an enable signal;

[0007] A judgment module, used for receiving the on-off signal and the enable signal, and judging the enable signal, if the enable signal is a valid enable signal, outputting a drive signal, the valid enable signal is an enable signal when the voltage value of the leading phase of the load phase reaches the target AC voltage threshold, if the enable signal is an invalid enable signal, outputting a maintenance signal;

[0008] The relay driving module is used to control the on and off of the relay based on the driving signal, and to control the action maintenance of the relay based on the maintenance signal.

[0009] In some embodiments of the present application, the target AC voltage threshold is:

[0010]

[0011] Among them, T R Indicates the on-off action time of the relay, V ac Indicates the effective value of AC voltage, V th Indicates the target AC voltage threshold.

[0012] In some embodiments of the present application, the relay control circuit includes a phase A line, a phase B line and a phase C line, the load phase is the AB phase of the AC power supply, the leading phase is the CA phase of the AC power supply, the moving and static contacts of the relay are respectively connected to the phase A line and the phase B line, the input end of the isolation voltage threshold acquisition module is respectively connected to the phase A line and the phase C line, and the output end of the isolation voltage threshold is connected to the judgment module.

[0013] In some embodiments of the present application, the isolation voltage threshold acquisition module includes an acquisition circuit and a buffer circuit, the acquisition circuit is signal-connected to the input end of the buffer circuit, the acquisition circuit is used to acquire the voltage value of the leading phase of the load phase connected to the relay and output a voltage signal, the buffer circuit is used to receive the voltage signal and process the voltage signal into an enable signal, and the output end of the buffer circuit is signal-connected to the judgment module to output the enable signal to the judgment module.

[0014] In some embodiments of the present application, the acquisition circuit includes a bidirectional optocoupler U3 and a filter circuit RC3, the input end of the bidirectional optocoupler U3 is connected to the A phase line and the C phase line, the output end of the bidirectional optocoupler U3 is connected to the filter circuit RC3, and the output end of the filter circuit RC3 is connected to the buffer circuit.

[0015] In some embodiments of the present application, the on-voltage of the bidirectional optical coupler U3 is equal to the target AC voltage threshold.

[0016] In some embodiments of the present application, the filter circuit RC3 includes a resistor R12 and a capacitor C3, the input end of the resistor R12 is connected to the output end of the bidirectional optocoupler U3, the resistor R12 and the capacitor C3 are connected in parallel, and the parallel output end of the resistor R12 and the capacitor C3 is connected to the buffer circuit.

[0017] In some embodiments of the present application, the buffer circuit includes a signal processing chip, which has three input ports, three output ports and a group of power ports. The three input ports are respectively connected to the AB phase circuit, CA phase circuit and BC phase circuit of the acquisition circuit, and the three output ports are connected to the judgment module.

[0018] In some embodiments of the present application, the judgment module includes a logic chip, a clock circuit, a reset circuit and a data circuit, the logic chip has a clock port, a reset port and a data port, the clock port is connected to the clock circuit, the reset port is connected to the reset circuit, and the data port is connected to the data circuit, the reset port and the data circuit port.

[0019] In some embodiments of the present application, the relay driving module includes a relay K1, a light-emitting diode D2, a Schottky diode D1 and a MOS tube Q1, the relay K1, the light-emitting diode D2 and the Schottky diode D1 are connected in parallel to each other, the source of the MOS tube Q1 is grounded, the drain of the MOS tube Q1 is connected to the parallel output end of the relay K1, the light-emitting diode D2 and the Schottky diode D1, and the gate of the MOS tube Q1 is connected to the output end of the judgment module.

[0020] Beneficial effects of the embodiments of the present application:

[0021] In the embodiment of the present application, the leading phase voltage value of the load phase is collected and the enable signal is outputted mainly by using the isolation voltage threshold acquisition module, and then the enable signal is judged and outputted by the judgment module, and finally the relay drive module is used to receive the drive signal and control the relay to realize zero-crossing switching, thereby effectively avoiding arc discharge when the relay is switched on and off, and prolonging the service life of the relay, and by making the relay switch on and off at zero crossing, the current change can be made slower, the surge current is smaller, and the impact on other components in the current is reduced, thereby effectively reducing the generation of electromagnetic interference and improving the reliability and safety of the circuit. In detail, the isolation voltage threshold acquisition module is first used to collect the voltage value of the leading phase of the load phase connected to the relay and output the enable signal. Then the judgment module is used to receive the on-off signal, and the enable signal is continuously received to judge the enable signal. If the enable signal is a valid enable signal, that is, the enable signal output when the voltage value collected by the isolation voltage threshold acquisition module reaches the target voltage threshold, the judgment module outputs the drive signal, and finally the relay drive module is used to control the relay on and off based on the drive signal, so that the relay can offset the time of its own action delay by using the leading phase, so that the relay can achieve zero-crossing on and off, prevent the generation of arcs, and effectively extend the service life of the relay. If the enable signal received by the judgment module is an invalid enable signal, a maintenance signal will be output. The relay drive module keeps its current action unchanged based on the maintenance signal. If the current relay is closed, it continues to maintain the closed state. If the relay is disconnected, it continues to maintain the disconnected state until the enable signal is a valid enable signal. The relay drive module then drives the relay to perform on-off action based on the on-off signal and the drive signal, which can effectively avoid the relay from operating when it does not cross the zero point, and effectively reduce the probability of electromagnetic interference and arc generation. Furthermore, the present application only requires various hardware devices, without the need for a microcontroller, to achieve zero-crossing switching of the relay, which can effectively reduce the complexity and cost of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a connection diagram of a relay control circuit provided in an embodiment of the present application;

[0024] Figure 2 It is a structural schematic diagram of a relay control circuit provided in an embodiment of the present application;

[0025] Figure 3is a circuit diagram of an acquisition circuit in an isolation voltage threshold acquisition module provided in an embodiment of the present application;

[0026] Figure 4 is a circuit diagram of one phase of the judgment module provided in an embodiment of the present application;

[0027] Figure 5 is a circuit diagram of one phase of the relay drive module provided in an embodiment of the present application;

[0028] Figure 6 is a circuit diagram of a buffer circuit provided in an embodiment of the present application;

[0029] Figure 7 It is a flow chart of the relay zero switch control method provided in the embodiment of the present application;

[0030] Figure 8 It is a data diagram of the relay zero point test provided in the embodiment of the present application. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words such as "upper" and "lower" used generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0032] See also Figure 1 and Figure 2 , an embodiment of the present application provides a relay control circuit, comprising:

[0033] An isolation voltage threshold acquisition module is used to acquire the voltage value of the leading phase of the load phase connected to the relay and output an enable signal;

[0034] A judgment module, used for receiving the on-off signal and the enable signal, and judging the enable signal, if the enable signal is a valid enable signal, outputting a drive signal, the valid enable signal is an enable signal when the voltage value of the leading phase of the load phase reaches the target AC voltage threshold, if the enable signal is an invalid enable signal, outputting a maintenance signal;

[0035] The relay driving module is used to control the on and off of the relay based on the driving signal, and to control the action maintenance of the relay based on the maintenance signal.

[0036] The technical solution provided by the present application is mainly to collect the leading phase voltage value of the load phase and output the enable signal by using the isolation voltage threshold acquisition module, and then use the judgment module to judge the enable signal and output the drive signal, and finally use the relay drive module to receive the drive signal and control the relay to achieve zero-crossing switching, thereby effectively avoiding arc discharge when the relay is switched on and off, which can extend the service life of the relay, and by making the relay switch on and off at zero, the current change can be slower, the surge current is smaller, and the impact on other components in the current is reduced, thereby effectively reducing the generation of electromagnetic interference and improving the reliability and safety of the circuit. In detail, the isolation voltage threshold acquisition module is first used to collect the voltage value of the leading phase of the load phase connected to the relay and output the enable signal. Then the judgment module is used to receive the on-off signal, and the enable signal is continuously received to judge the enable signal. If the enable signal is a valid enable signal, that is, the enable signal output when the voltage value collected by the isolation voltage threshold acquisition module reaches the target voltage threshold, the judgment module outputs the drive signal, and finally the relay drive module is used to control the relay on and off based on the drive signal, so that the relay can offset the time of its own action delay by using the leading phase, so that the relay can achieve zero-crossing on and off, prevent the generation of arcs, and effectively extend the service life of the relay. If the enable signal received by the judgment module is an invalid enable signal, a maintenance signal will be output. The relay drive module keeps its current action unchanged based on the maintenance signal. If the current relay is closed, it continues to maintain the closed state. If the relay is disconnected, it continues to maintain the disconnected state until the enable signal is a valid enable signal. The relay drive module then drives the relay to perform on-off action based on the on-off signal and the drive signal, which can effectively avoid the relay from operating when it does not cross the zero point, and effectively reduce the probability of electromagnetic interference and arc generation. Furthermore, the present application only requires various hardware devices, without the need for a microcontroller, to achieve zero-crossing switching of the relay, which can effectively reduce the complexity and cost of the circuit.

[0037] It should be noted that the AC power supply includes phase A, phase B and phase C, and the contact end of the relay is connected to phase AB, that is, the load phase is phase AB of the AC power supply, and the leading phase is phase CA, and the CA phase leads the AB phase by 120°. In other embodiments, the contact end of the relay can also be connected to other phases, such as phase BC, as long as the leading phase can lead the phase to which the relay is connected by 120°.

[0038] In some embodiments, see Figure 2The relay control circuit may further include a time acquisition module and a threshold calculation module. The time acquisition module is signal-connected to the threshold calculation module, the isolation voltage threshold acquisition module is signal-connected to the threshold calculation module, the isolation voltage threshold acquisition module is also signal-connected to the judgment module, the judgment module is signal-connected to the relay drive module, and the relay drive module is signal-connected to the relay.

[0039] Among them, the time acquisition module is mainly responsible for capturing the start action time and the end action time of the relay in real time, so as to obtain the delayed action time of the relay, and collect the data of multiple groups of actions to take the average value, so as to obtain the average delay time of the relay, that is, to obtain the action time of the relay. Because by acquiring the action time of the relay in real time, it can effectively resist the situation that the action time of the relay may change due to the increase of the service life of the relay (as the service life of the relay increases, due to various reasons, such as mechanical wear, its action time generally changes). The action time information is directly transmitted to the threshold calculation module through a signal connection. The threshold calculation module calculates the exact moment of the next zero voltage crossing point according to the received action time data through a preset algorithm, so as to determine the best relay action time point. The signal connection between the time acquisition module and the threshold calculation module ensures that the threshold calculation module can obtain the relay action time information in real time, increases the accuracy and response speed of the circuit control, and avoids the negative impact of AC voltage fluctuations on the action of the relay. In other embodiments, the action time of the relay can also be measured by a measuring circuit, such as a circuit composed of an oscilloscope, a signal generator, a sensor, and a power supply.

[0040] The isolated voltage threshold acquisition module is connected to both the threshold calculation module signal and the judgment module signal. It is responsible for collecting the voltage threshold of the load phase and converting the information into the corresponding enable signal. This conversion process is completed through the buffer circuit to ensure the stability and reliability of the signal. The role of this module is not only to provide real-time voltage threshold data to the threshold calculation module to assist in calculation, but also to directly provide key enable signals to the judgment module, thereby improving the flexibility and responsiveness of the entire control circuit.

[0041] The judgment module performs logical judgment based on the enable signal received from the isolation voltage threshold acquisition module and the on-off instruction provided by the threshold calculation module. If the judgment result shows that the on-off condition is met (that is, there is an input of a valid enable signal and an on-off signal), the instruction to drive the relay action is output to the relay drive module. This connection ensures that the relay is driven to perform on-off operations at the correct time, reducing the wear of the electrical contact points and extending the service life of the relay.

[0042] The relay driver module receives the driving signal from the judgment module and effectively drives the relay through its internal driving circuit (such as MOS tube, light-emitting diode, etc.) to complete the on-off operation. This connection not only serves as a bridge between the judgment module and the relay, but also reduces the energy loss generated in the driving process through circuit design, thereby improving the overall energy efficiency of the system.

[0043] In some embodiments, the threshold calculation module calculates the target AC voltage threshold using the following formula:

[0044]

[0045] Among them, T R represents the action time, V ac Indicates the effective value of AC voltage, V th Represents the target AC voltage threshold. The effective value of AC voltage (RMS, Root Mean Square) is a measure of the size of AC voltage, which is equivalent to the DC voltage value that can produce the same thermal effect. The effective value of AC voltage is the statistical average value of voltage or current in an AC circuit, which can reflect the actual power of electrical energy transfer. The calculation formula for the effective value is the square root of the average value of the square of the time-varying function of voltage or current. The specific calculation formula is an existing formula and will not be repeated here. In sinusoidal AC, the effective value of voltage is approximately 0.707 times the peak voltage.

[0046] In some embodiments, the load phase is the B phase line of the AC power supply, the leading phase is the C phase line of the AC power supply, the power line of the AC power supply is the A phase line, the moving and static contacts of the relay are respectively connected to the A phase line and the B phase line, the input end of the isolation voltage threshold acquisition module is respectively connected to the A phase line and the C phase line, and the output end of the isolation voltage threshold is connected to the judgment module.

[0047] In some embodiments, the isolation voltage threshold acquisition module includes an acquisition circuit and a buffer circuit, the acquisition circuit is connected to the input end signal of the buffer circuit, the acquisition circuit is used to acquire the voltage value of the leading phase of the load phase connected to the relay, and outputs a voltage threshold signal when the acquired voltage value reaches the target AC voltage threshold, the buffer circuit is used to receive the voltage threshold signal, and process the voltage threshold signal into a valid enable signal, the output end of the buffer circuit is connected to the judgment module signal to output the valid enable signal to the judgment module. The acquisition circuit and the buffer circuit are connected by signals to ensure that the voltage information obtained from the acquisition circuit can be smoothly and accurately transmitted to the buffer circuit. The enable signal processed by the buffer circuit is transmitted to the judgment module through its output end.

[0048] Among them, the main task of the acquisition circuit is to detect and collect the voltage on the load phase, especially the voltage value near the time point of the relay action. Specifically, it is done by measuring the instantaneous voltage at each moment in the AC circuit, and then selecting the corresponding voltage threshold according to the action time point. By directly measuring the load voltage and capturing the voltage threshold at the exact moment, the acquisition circuit ensures the accuracy of the obtained signal. In addition, as the relay action characteristics change (for example, performance degradation due to age or environmental changes), the acquisition circuit can update the voltage threshold information near the action time point in real time. This means that the system can adapt itself to keep the relay action optimized, even when the device ages or environmental conditions change.

[0049] The function of the buffer circuit is to receive the voltage signal output by the acquisition circuit and perform necessary processing on the signal, such as signal amplification, filtering or conversion, to generate the correct enable signal. The buffer circuit can not only ensure the stable transmission of the signal and avoid signal errors due to load fluctuations, but also provide necessary signal conditioning functions, such as removing noise through filters and increasing signal strength through amplifiers, thereby ensuring that the enable signal output to the judgment module is stable and reliable.

[0050] In some embodiments, the judgment module mainly outputs the corresponding judgment result by judging whether the enable signal and the on-off signal are input at the same time and whether the enable signal is a valid enable signal or an invalid enable signal. In detail, if the judgment module receives the on-off signal and the valid enable signal, it outputs the drive signal; in other cases, the judgment module outputs the maintenance signal to make the relay inactive.

[0051] It should also be noted that the effective enable signal refers to the signal output when the voltage threshold of the load phase is equal to the target AC voltage threshold. The voltage threshold of the load phase refers to the voltage value measured directly from the load phase by the isolation voltage threshold acquisition module through its acquisition circuit. This voltage value changes in real time and changes with the periodic fluctuations of the grid voltage. The target AC voltage threshold refers to a preset voltage value, which is calculated by the threshold calculation module according to a specific algorithm (taking into account parameters such as the relay action time). This threshold is intended to determine the optimal relay on-off moment to ensure that the relay operation is performed close to the zero voltage point of the AC voltage waveform. By ensuring that the effective enable signal is output only when the voltage threshold of the load phase is equal to the set target AC voltage threshold, the scheme can accurately control the on-off moment of the relay to make it close to the zero point of the voltage waveform, which helps to minimize the arc generated during the on-off operation and reduce damage to the relay contacts.

[0052] In some embodiments, the control circuit also includes a correction module. The correction module is connected to the time acquisition module and is used to correct the action time of the relay. The correction module is mainly for the relay after being used for a period of time, especially after a long service life, which may cause some hardware wear due to the switch switching light of the relay, resulting in a large error between the action time marked in the relay parameters and the actual action time. The correction module is used to detect whether the action time of the relay matches the action time marked with it. If it does not match, the correction module will use the actual action time of the relay as the calculation time of the subsequent target AC voltage threshold, ensuring that the relay can eliminate the situation of inaccurate zero-point switching caused by long use time and more times of use, and always keep the relay able to act at zero.

[0053] In some embodiments, see Figure 3 , the isolation voltage threshold acquisition module includes an A-phase circuit, a B-phase circuit and a C-phase circuit connected to each other, and also includes a bidirectional optical coupler U3, a bidirectional optical coupler U2, a bidirectional optical coupler U1 and a filter circuit RC3, a filter circuit RC2 and a filter circuit RC1. The input end of the bidirectional optical coupler U3 is connected to the A-phase line and the C-phase line, the output end of the bidirectional optical coupler U3 is connected to the filter circuit RC3, and the output end of the filter circuit RC3 is connected to the buffer circuit. The input end of the bidirectional optical coupler U2 is connected to the B-phase line and the C-phase line, the output end of the bidirectional optical coupler U2 is connected to the filter circuit RC2, and the output end of the filter circuit RC2 is connected to the buffer circuit. The input end of the bidirectional optical coupler U1 is connected to the A-phase line and the B-phase line, the output end of the bidirectional optical coupler U1 is connected to the filter circuit RC1, and the output end of the filter circuit RC1 is connected to the buffer circuit. In a three-phase circuit, phase A, phase B and phase C represent three sinusoidal AC voltages with a phase difference of 120°. The A-phase circuit, the B-phase circuit, and the C-phase circuit are connected to the corresponding three-phase loads to monitor the corresponding voltages. Optocouplers are devices that use optical signals for electrical isolation. They enable circuits to transmit signals between different potentials without interfering with each other. In the module, bidirectional optocouplers U1, U2, and U3 are responsible for isolating the signals between phases A and B, phases B and C, and phases C and A, respectively. This design using optocouplers not only provides a channel for signal transmission, but also ensures the isolation safety between the control circuit and the high-voltage side. The function of the filter circuit is to filter out noise from the signal transmitted from the optocoupler, remove possible interference, and stabilize the output signal, thereby further improving the quality and reliability of the signal.

[0054] Furthermore, the structures of the bidirectional optical coupler U1, the bidirectional optical coupler U2, and the bidirectional optical coupler U3 are the same, and the structures of the filter circuits RC1, the filter circuits RC2, and the filter circuits RC3 are the same. The bidirectional optical coupler mainly serves as a medium between the sensing signal and the control signal, allowing the signal to cross the boundary of electrical isolation while preventing direct electrical connection between circuits to ensure the safety of the equipment and the user. The filter circuit RC1 includes a resistor R12 and a capacitor C3, the input end of the resistor R12 is connected to the output end of the bidirectional optical coupler U3, the resistor R12 is connected in parallel with the capacitor C3, and the parallel output end of the resistor R12 and the capacitor C3 is connected to the buffer circuit, effectively removing high-frequency noise generated by external interference, power supply fluctuations, or signal transmission.

[0055] Furthermore, the output ends of the bidirectional optical coupler U1 , the bidirectional optical coupler U2 , and the bidirectional optical coupler U3 are all provided with reserved ends, so as to increase the connection ports of the bidirectional optical coupler and improve the circuit compatibility of the bidirectional optical coupler.

[0056] It should be noted that the on-voltage of the bidirectional optocoupler U3 is equal to the target AC voltage threshold, thereby ensuring that the condition for the isolated voltage threshold acquisition module to be turned on must be that the collected voltage value is equal to the target AC voltage threshold. This allows the relationship between the collected voltage and the target AC voltage threshold to be determined without the need for the microcontroller to regulate the voltage, thereby outputting an effective enable signal that enables the relay to switch on and off at zero crossing.

[0057] In some embodiments, see Figure 6 The buffer circuit includes a signal processing chip, which has three input ports, three output ports and a group of power ports. The three input ports are respectively connected to the A phase circuit, the B phase circuit and the C phase circuit of the acquisition circuit, and the three output ports are connected to the judgment module.

[0058] In some embodiments, see Figure 4, the judgment module includes a logic chip, a clock circuit, a reset circuit and a data circuit. The logic chip has a clock port, a reset port and a data port. The clock port is connected to the clock circuit, the reset port is connected to the reset circuit, and the data port is connected to the data circuit. The reset port and the data circuit port. Among them, the logic chip is the core of the judgment module, which is used to process the input signal and generate output. These input signals usually include clock signals, reset signals and data signals from the data circuit. According to these inputs, the logic chip performs preset logical operations to determine whether to output a signal to drive the relay. The clock circuit provides a continuous clock signal (pulse sequence) to ensure that the operation of the judgment module can be synchronized at regular time intervals. The reset circuit can initialize the state of the logic chip, that is, reset the output of the logic chip to the initial state when the power is just turned on or under certain conditions, which can prevent the erroneous operation of the logic chip due to unexpected circuit fluctuations or abnormalities. The data circuit provides input data to the logic chip. These data come from the circuits in the previous stage, such as the filter circuit in the isolation voltage threshold acquisition module. These data carry information about the system status, such as whether the voltage threshold has been reached, whether the relay should be on or off, etc. The logic chip will make judgments based on these data and output corresponding control signals.

[0059] It should be noted that the clock circuit includes a resistor R17, a resistor R20 and a capacitor C6, the resistor R17 is connected in parallel with the resistor R20 and the capacitor C6, the resistor R20 is also connected in parallel with the flashlight C6, and the two ends of the clock circuit are connected to the output end of the buffer circuit and the start and end circuit end of the logic chip respectively. The reset circuit includes a resistor R18 and a capacitor C7, and the resistor R18 is connected in parallel with the capacitor C7. The data circuit includes a resistor R16 and a resistor R19, and the resistor R16 is connected in parallel with the resistor R19.

[0060] It should also be noted that the judgment module is connected to the three-phase power supply, so the logic chip, clock circuit, reset circuit and data circuit in the judgment module are set in each phase, and the structures are the same. For example, in the present embodiment, the judgment module includes the logic chip, clock circuit, reset circuit and data circuit of the C phase, and also includes the logic chip, clock circuit, reset circuit and data circuit of the A phase, and the logic chip, clock circuit, reset circuit and data circuit of the B phase. The structures of the logic chips, clock circuits, reset circuits and data circuits of the A phase, the B phase and the C phase are the same.

[0061] In some embodiments, see Figure 5The relay driving module includes a relay K1, a light emitting diode D2, a Schottky diode D1 and a MOS tube Q1. The relay K1, the light emitting diode D2 and the Schottky diode D1 are connected in parallel with each other. The source of the MOS tube Q1 is grounded, the drain of the MOS tube Q1 is connected to the parallel output end of the relay K1, the light emitting diode D2 and the Schottky diode D1, and the gate of the MOS tube Q1 is connected to the output end of the judgment module.

[0062] Among them, relay K1 is the core of the entire drive module, which closes or opens the circuit according to the control signal, thereby driving the corresponding equipment to be powered on or off. In this embodiment, because the vacuum pump needs to heat the pump body during operation, it is necessary to avoid condensation and deposition of products or other adverse consequences of the vacuum pump. The relay and relay control circuit in this embodiment are mainly used in the switch control of the heating device of the vacuum pump. By setting a relay control circuit that can be turned on and off at zero crossing to control the relay to be turned on and off at zero crossing, it is helpful to avoid arcing caused by the switching of the relay in a high voltage environment, affecting the service life of the relay, and generating surge current and electromagnetic interference due to the switching of the relay, which has an adverse effect on the control system of the entire vacuum pump.

[0063] Light emitting diode (LED) D2 In the relay drive module, the parallel light emitting diode D2 plays an indicating role. When the relay K1 is driven (that is, the MOS tube Q1 is turned on), D2 emits light, providing the operator with an intuitive working status indication.

[0064] Schottky diode D1 Schottky diode has the characteristics of low forward voltage drop and fast switching. In this driver module, Schottky diode D1 is connected in parallel with relays K1 and D2, mainly to prevent the reverse potential released by the relay coil when the MOS tube Q1 is turned off from damaging the driver tube or other sensitive components.

[0065] MOS tube Q1 is the switch element of the driving module, which is responsible for directly driving the relay K1 according to the output control signal of the judgment module. When Q1 is turned on, the current flows through the relay K1, the light-emitting diode D2 and the Schottky diode D1, so that the relay K1 is attracted and the status indicator LED is lit.

[0066] Relay K1, light emitting diode D2, and Schottky diode D1 are connected in parallel. This parallel connection ensures that when MOS tube Q1 is turned on, current can pass through relay K1, light emitting diode D2, and Schottky diode D1 at the same time. Among them, Schottky diode D1 provides a freewheeling circuit when the relay coil is powered off, and light emitting diode D2 provides an operation indication.

[0067] See also Figure 7The embodiment of the present application also provides a relay zero switch control method, which is applied to the relay control circuit described in any of the above embodiments. The control method includes:

[0068] S1, collects the voltage value of the leading phase of the load phase connected to the relay and outputs an enable signal;

[0069] S2, receiving the on-off signal and the enable signal, and judging the enable signal, if the enable signal is a valid enable signal, outputting the drive signal, the valid enable signal is the enable signal when the voltage value of the leading phase of the load phase reaches the target AC voltage threshold, if the enable signal is an invalid enable signal, outputting the maintenance signal;

[0070] S3. Control the on and off of the relay based on the driving signal, and control the action of the relay based on the maintaining signal.

[0071] In the step of collecting the voltage value of the leading phase of the load phase connected to the relay and outputting the enable signal, the collection of the voltage value and the output of the enable signal are continuous, that is, the voltage value is continuously collected and the enable signal is output. It should be noted that for the output enable signal, different enable signals will be output according to different voltage values. Specifically, the enable signal output when the collected voltage value reaches the target AC voltage threshold is a valid enable signal, and the rest of the enable signals are invalid enable signals.

[0072] In the step of outputting the driving signal according to the received on-off signal and the enable signal, the judgment module will output the result according to the signal received by itself. If the judgment module receives the on-off signal and the valid enable signal, the judgment module will output a positive judgment result, that is, output the driving signal. If only the on-off signal or the invalid enable signal is received, or the on-off signal and the invalid enable signal are not received, then the maintenance signal is output, the control relay does not operate, and continues to maintain the original state. If the relay is in the energized state, it continues to maintain the energized state, and if the relay is in the disconnected state, it continues to maintain the disconnected state.

[0073] In some embodiments, before step S1, the control method may further include:

[0074] Get the action time of the relay;

[0075] The target AC voltage threshold when the zero-point on-off signal is sent is determined according to the action time and the phase difference between the load phase and the leading phase.

[0076] Among them, in the step of obtaining the action time of the relay, the system first needs to determine the time required for the relay to actually act (i.e., close or open the contact) from receiving the on / off signal. This time can be obtained through testing or based on the specification parameters of the relay.

[0077] In the step of determining the target AC voltage threshold when the zero-point on-off signal is issued according to the action time and the phase difference between the load phase and the leading phase, it is necessary to calculate the required target AC voltage threshold according to the frequency, action time and load phase of the current power grid. This value indicates that an on-off command is issued when a specific voltage threshold is reached so that the relay action is synchronized with the AC voltage zero point.

[0078] In some embodiments, the step of determining the target AC voltage threshold when the zero-point on-off signal is issued according to the action time and the phase difference between the load phase and the leading phase includes:

[0079] Obtain the load phase and determine that the phase line that is 120° ahead of the load phase is the reference phase of the enable signal of the relay. In a three-phase AC system, the load phase refers to the specific phase line (such as phase A, phase B or phase C) to which the relay is connected. In this embodiment, another phase line that is 120° ahead of the load phase is used as the reference phase. Since the phase lines of the three-phase system are themselves offset by 120° relative to each other, selecting a reference phase that is 120° ahead means that the reference phase can be used to provide a forward-looking enable signal to ensure accurate control of the load phase.

[0080] The time when the relay actuates on the reference phase of the enable signal and the angle corresponding to the time are calculated based on the phase difference of the AC power and the actuation time. The time when the relay actuates on the reference phase is calculated based on the phase difference of the AC power and the actuation time of the relay. This time is calculated based on the frequency of the power grid and the physical characteristics of the actuation time of the relay. The corresponding angle value is also calculated at the same time, because in an AC circuit, time can be converted into an angle related to the frequency on the voltage waveform.

[0081] The effective value of the AC voltage is obtained, and the target AC voltage threshold is calculated based on the effective value of the AC voltage and the time and angle of the reference phase action of the enable signal. The system needs to obtain the effective value (RMS value) of the AC voltage. This is a fixed value, usually determined according to the power grid standard (such as 220V RMS). Based on the obtained effective value of the AC voltage and the time and angle of the reference phase action of the enable signal obtained by calculation, the target AC voltage threshold is then calculated. This threshold is the voltage level that needs to be considered when the on / off signal is sent. By calculating this threshold, it is ensured that the AC voltage is passing through the zero point when the contacts of the relay are actuated.

[0082] It should be noted that the calculation formula for the time of the reference phase action of the enable signal is:

[0083] T l =6.66-T R

[0084] Among them, T R represents the action time, T l It refers to the time when the enable signal reference phase acts.

[0085] The calculation formula for the angle corresponding to the reference phase action of the enable signal is:

[0086]

[0087] The target AC voltage threshold is calculated as:

[0088] V th = sin(α l )·V ac

[0089] Among them, V ac Indicates the effective value of AC voltage, V th Indicates the target AC voltage threshold.

[0090] In some embodiments, the step of collecting the voltage value of the leading phase of the load phase connected to the relay and outputting an enable signal includes:

[0091] The voltage threshold of the load phase is collected and a voltage threshold signal is output according to the voltage threshold. The system continuously collects the real-time voltage of the load phase through the monitoring circuit, and compares the collected voltage value with the predetermined voltage threshold. If the collected voltage value meets the range of the target AC voltage threshold, the collected voltage value is output as a voltage threshold signal. The purpose of this comparison process is to determine whether the current grid voltage has reached a specific level, which is calculated based on the actual application conditions and the characteristics of the relay, and ideally should be as close to the zero voltage crossing point as possible.

[0092] According to the voltage threshold signal, a valid enable signal corresponding to the voltage threshold signal is output. After the system generates the voltage threshold signal, it is necessary to convert the signal into a valid enable signal. The generation of the valid enable signal usually depends on a series of electronic circuit operations, including logic judgment, signal conversion, etc. These operations ensure that the output of the enable signal strictly corresponds to the voltage threshold signal, ensuring that the voltage is in an ideal state, that is, zero or close to zero, when the on-off operation is actually performed.

[0093] In some embodiments, the step of judging the enable signal based on the received on-off signal and the enable signal, outputting a drive signal if the enable signal is a valid enable signal, the valid enable signal being an enable signal when the voltage value of the leading phase of the load phase reaches the target AC voltage threshold, and outputting a maintenance signal if the enable signal is an invalid enable signal, comprises:

[0094] When the judgment module receives the on-off signal and the enable signal, and the enable signal is a valid enable signal, the judgment result of driving the relay action is output. The judgment module will output the drive signal only when it receives both the on-off signal and the valid enable signal. If the judgment module only receives the on-off signal and does not receive the enable signal, or receives the on-off signal and the enable signal, but the enable signal is judged to be an invalid enable signal, the judgment module will output a maintenance signal to keep the relay in the current state until a valid enable signal is received, thereby ensuring that the relay can achieve zero-point on-off, and the entire judgment process does not require the use of a microcontroller, making the control circuit simpler. The effective enable signal means that it reflects that the voltage threshold of the load phase has matched the preset target AC voltage threshold, that is, if the relay is activated at this time, the moment of the relay action will be at zero.

[0095] Based on the above control method and control circuit, this application provides an experiment of relay zero-crossing on and off, please refer to Figure 8 . Figure 8 It is a data diagram of the relay zero point test provided in the embodiment of the present application.

[0096] The embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A relay control circuit, characterized in that: include: An isolation voltage threshold acquisition module is used to acquire the voltage value of the leading phase of the load phase connected to the relay and output an enable signal; A judgment module, used for receiving the on-off signal and the enable signal, and judging the enable signal, if the enable signal is a valid enable signal, outputting a drive signal, the valid enable signal is an enable signal when the voltage value of the leading phase of the load phase reaches the target AC voltage threshold, if the enable signal is an invalid enable signal, outputting a maintenance signal; The relay driving module is used to control the on and off of the relay based on the driving signal, and to control the action maintenance of the relay based on the maintenance signal.

2. The relay control circuit according to claim 1, characterized in that: The target AC voltage threshold is: Among them, T R Indicates the on-off action time of the relay, V ac Indicates the effective value of AC voltage, V th Indicates the target AC voltage threshold.

3. The relay control circuit according to claim 1, characterized in that: The relay control circuit includes an A phase line, a B phase line and a C phase line, the load phase is the AB phase of the AC power supply, the leading phase is the CA phase of the AC power supply, the moving and static contacts of the relay are respectively connected to the A phase line and the B phase line, the input end of the isolation voltage threshold acquisition module is respectively connected to the A phase line and the C phase line, and the output end of the isolation voltage threshold is connected to the judgment module.

4. The relay control circuit according to claim 3, characterized in that: The isolation voltage threshold acquisition module includes an acquisition circuit and a buffer circuit. The acquisition circuit is signal-connected to the input end of the buffer circuit. The acquisition circuit is used to acquire the voltage value of the leading phase of the load phase connected to the relay and output a voltage signal. The buffer circuit is used to receive the voltage signal and process the voltage signal into an enable signal. The output end of the buffer circuit is signal-connected to the judgment module to output the enable signal to the judgment module.

5. The relay control circuit according to claim 4, characterized in that: The acquisition circuit includes a bidirectional optical coupler U3 and a filter circuit RC3, the input end of the bidirectional optical coupler U3 is connected to the A phase line and the C phase line, the output end of the bidirectional optical coupler U3 is connected to the filter circuit RC3, and the output end of the filter circuit RC3 is connected to the buffer circuit.

6. The relay control circuit according to claim 5, characterized in that: The on-state voltage of the bidirectional optical coupler U3 is equal to the target AC voltage threshold.

7. The relay control circuit according to claim 5, characterized in that: The filter circuit RC3 includes a resistor R12 and a capacitor C3, the input end of the resistor R12 is connected to the output end of the bidirectional optical coupler U3, the resistor R12 and the capacitor C3 are connected in parallel, and the parallel output end of the resistor R12 and the capacitor C3 is connected to the buffer circuit.

8. The relay control circuit according to claim 5, characterized in that: The buffer circuit includes a signal processing chip, which has three input ports, three output ports and a group of power ports. The three input ports are respectively connected to the AB phase circuit, CA phase circuit and BC phase circuit of the acquisition circuit, and the three output ports are connected to the judgment module.

9. The relay control circuit according to any one of claims 1 to 8, characterized in that: The judgment module includes a logic chip, a clock circuit, a reset circuit and a data circuit. The logic chip has a clock port, a reset port and a data port. The clock port is connected to the clock circuit, the reset port is connected to the reset circuit, and the data port is connected to the data circuit, the reset port and the data circuit port.

10. The relay control circuit according to any one of claims 1 to 8, characterized in that: The relay driving module includes a relay K1, a light emitting diode D2, a Schottky diode D1 and a MOS tube Q1. The relay K1, the light emitting diode D2 and the Schottky diode D1 are connected in parallel with each other. The source of the MOS tube Q1 is grounded, the drain of the MOS tube Q1 is connected to the parallel output end of the relay K1, the light emitting diode D2 and the Schottky diode D1, and the gate of the MOS tube Q1 is connected to the output end of the judgment module.

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