Relay contact protection circuit

Abstract

The utility model provides a relay contact protection circuit. The relay contact protection circuit comprises an alternating current positive voltage step-down circuit and an alternating current negative voltage step-down circuit, the alternating current positive voltage step-down circuit is provided with a first switch module, and the alternating current negative voltage step-down circuit is provided with a second switch module. The first switch module and the second switch module are arranged in parallel between the first contact and the second contact. A first switch module and a second switch module are arranged in parallel between a first contact and a second contact; when the first contact and the second contact are attracted or disconnected, because the first switch module and the second switch module which are connected in parallel can be conducted, the generated voltage drop is very small, the voltage between the first contact and the second contact can be effectively reduced, the effect of voltage reduction protection on the contacts is achieved, the service life of the contacts is prolonged, and the cost is saved.

Description

Technical Field

[0001] The present application belongs to the technical field of relays, and in particular, relates to a relay contact protection circuit. Background Art

[0002] When the relay is closed and opened, the voltage between the contacts is relatively large, which causes serious damage to the contacts. In the related art, the solution is to connect a bypass relay in parallel to the bypass of the protected relay. Although it can extinguish the arc, the cost is high and the circuit volume is large due to the need for an additional bypass relay, and the contacts of the bypass relay are also prone to failure. Utility Model Content

[0003] The purpose of the present application is to provide a relay contact protection circuit, aiming to solve the problems of high cost and large size existing in traditional relay protection circuits.

[0004] In a first aspect of an embodiment of the present application, a relay contact protection circuit is provided, wherein the relay comprises at least a coil, and a first contact and a second contact that are in contact with or disconnected from each other when the coil is energized;

[0005] The relay contact protection circuit includes: an AC positive voltage step-down circuit and an AC negative voltage step-down circuit;

[0006] The AC positive voltage step-down circuit is provided with a first switch module, and the AC negative voltage step-down circuit is provided with a second switch module;

[0007] The first contact is respectively connected to the first end of the alternating current, the input end of the first switch module and the input end of the second switch module;

[0008] The second contact is respectively connected to the first end of the load, the output end of the first switch module, and the output end of the second switch module;

[0009] The control end of the first switch module, the control end of the second switch module and the second end of the load are connected to the second end of the alternating current;

[0010] The first switch module and the second switch module are arranged in parallel between the first contact and the second contact;

[0011] The voltage drop when the first contact and the second contact are in contact with or disconnected from each other is the voltage drop after the first switch module and / or the second switch module is turned on.

[0012] The beneficial effects of the embodiments of the present application compared with the prior art are: in the above-mentioned technical solution of the present application, the first switch module and the second switch module are arranged in parallel between the first contact and the second contact; when the first contact and the second contact are attracted, or disconnected, since the parallel first switch module and the second switch module will be turned on, the voltage drop generated by themselves is very small, which can effectively reduce the voltage between the first contact and the second contact, play a role in protecting the contacts, and is beneficial to improving the life of the contacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of the structure of a relay provided in one embodiment of the present application;

[0014] Figure 2 A schematic diagram of the structure of a relay contact protection circuit provided in one embodiment of the present application;

[0015] Figure 3 A schematic diagram of another relay contact protection structure provided in an embodiment of the present application;

[0016] Figure 4 Another relay contact protection circuit provided by an embodiment of the present application;

[0017] Figure 5 A capacitor voltage and contact voltage waveform diagram provided in one embodiment of the present application.

[0018] Description of Reference Numerals

[0019] 1-AC positive voltage step-down circuit; 2-AC negative voltage step-down circuit; 11-first switch module; 12-first diode; 13-voltage division acquisition module; 14-first optical coupler; 15-second diode; 21-second switch module; 22-third diode; 23-second voltage division acquisition module; 24-second optical coupler; 25-fourth diode; 131-first resistor; 132-second resistor; 133-first capacitor; 231-fourth resistor; 232-third resistor; 233-second capacitor. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application 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 application and are not used to limit the present application.

[0021] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0022] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0024] Figure 1 A structural schematic diagram of a relay is shown, wherein the relay comprises a relay coil and a plurality of contacts.

[0025] When the relay coil is powered on, the first contact and the second contact are closed, and the power load circuit can be connected, and the power supply can supply power to the load. When the relay coil is powered off, the first contact and the second contact are disconnected. A switch device can be provided on the circuit where the coil is located. When the switch device is closed, the coil is powered, and when the switch device is disconnected, the coil is powered off.

[0026] Figure 2 The structure diagram of the relay contact protection circuit provided by an embodiment of the present application is shown. For the convenience of explanation, only the part related to the present embodiment is shown, which is described in detail as follows:

[0027] The present application proposes a relay contact protection circuit. The relay at least comprises a coil, and a first contact and a second contact that are in contact with or disconnected from each other when the coil is energized.

[0028] The relay contact protection circuit comprises: an alternating current positive voltage step-down circuit 1 and an alternating current negative voltage step-down circuit 2.

[0029] The AC positive voltage step-down circuit 1 is provided with a first switch module 11 , and the AC negative voltage step-down circuit 2 is provided with a second switch module 21 .

[0030] The first contact is respectively connected to a first end of the alternating current, an input end of the first switch module 11 and an input end of the second switch module 21 .

[0031] The second contact is respectively connected to the first end of the load, the output end of the first switch module 11 and the output end of the second switch module 21 .

[0032] The control end of the first switch module 11, the control end of the second switch module 21 and the second end of the load are connected to the second end of the alternating current;

[0033] The first switch module 11 and the second switch module 21 are arranged in parallel between the first contact and the second contact.

[0034] The voltage drop at the moment when the first contact and the second contact are in contact or disconnected with each other is the voltage drop after the first switch module 11 and / or the second switch module 21 is turned on.

[0035] In the above-mentioned technical solution of the present application, the first switch module and the second switch module are arranged in parallel between the first contact and the second contact; when the first contact and the second contact are energized, or disconnected, since the parallel first switch module and the second switch module will be turned on, the voltage drop generated by themselves is very small, which can effectively reduce the voltage between the first contact and the second contact, plays a role in protecting the contacts, and is beneficial to improving the life of the contacts.

[0036] In some embodiments, the first switch module 11 includes a metal oxide semiconductor field effect transistor and / or the second switch module 21 includes a metal oxide semiconductor field effect transistor.

[0037] See attached Figure 4 , the metal oxide semiconductor field effect transistor Q2 is an N-channel MOS tube, and the metal oxide semiconductor field effect transistor 3 is a P-channel MOS tube.

[0038] In this embodiment, after the metal oxide semiconductor field effect transistor is turned on, the voltage drop generated between the source S and the drain D is very small. By utilizing the above characteristics, the first switch module and the second switch module are connected in parallel between the first contact and the second contact. When the first contact and the second contact are closed or disconnected, the first switch module and the second switch module are turned on. After being turned on, the voltage drop generated between the source S and the drain D is very small. In this way, the voltage between the first contact and the second contact is effectively reduced, which plays a role in voltage reduction protection and is beneficial to improving the life of the contacts. Instead of using a relatively high-cost relay, a low-cost metal oxide semiconductor field effect transistor can be used to achieve the function of voltage reduction protection for the contacts.

[0039] See also Figure 3The AC positive voltage step-down circuit 1 also includes: a first diode 12 , an anode of the first diode 12 is respectively connected to the first contact of the relay and the first end of the AC power, and a cathode is connected to the input end of the first switch module 11 .

[0040] In this embodiment, the first diode 12 is set in such a way that when the power supply is a forward voltage, the first diode 12 is turned on, and when the power supply is a negative voltage, the first diode 12 is turned off, thereby preventing the negative voltage from flowing into the AC positive voltage step-down circuit 1.

[0041] When the power supply is a forward AC voltage, the first diode 12 is turned on, and after the first switch module 11 is controlled to be turned on, the forward AC voltage is applied to the load.

[0042] In this embodiment, the first switch module 11 is provided with a control terminal, and a high level input to the control terminal can trigger the first switch module 11 to be turned on.

[0043] In some embodiments, the relay contact protection circuit may further include:

[0044] The first voltage division acquisition module 13 has a first end connected to the cathode of the first diode 12 and the input end of the first switch module 11 , a second end connected to the second end of the alternating current, and a voltage division output end connected to the control end of the first switch module 11 .

[0045] The first voltage division acquisition module 13 is used to collect the first voltage at the input end of the first switch module 11. Based on the voltage value, the voltage division output end outputs a second voltage related to the first voltage to the control end of the first switch module 11 to drive the first switch module 11 to be turned on or off.

[0046] In this embodiment, the first voltage-dividing acquisition module 13 at least includes a first voltage-dividing acquisition submodule and a second voltage-dividing acquisition submodule connected in series, wherein the first voltage-dividing acquisition submodule and the second voltage-dividing acquisition submodule can be respectively formed by one or more resistors connected in series or in parallel.

[0047] In one embodiment, the first voltage-dividing acquisition module 13 at least includes a first resistor 131, a second resistor 132 and a first capacitor 133. The second resistor 132 and the first capacitor 133 are connected in parallel. The first end of the first capacitor 133 and the second resistor 132 connected in parallel serves as the first end of the first voltage-dividing acquisition module. The second end of the first capacitor 133 and the second resistor 132 connected in parallel is connected to the first end of the first resistor 131, and the second end of the first resistor 131 serves as the second end of the first voltage-dividing acquisition module.

[0048] When a positive voltage is input to the first end of the alternating current, the first capacitor 133 is charged, and when a negative voltage is input to the first end of the alternating current, the first capacitor 133 is discharged; when the voltage across the first capacitor 133 is greater than or equal to the turn-on voltage threshold of the first switch module 11, the first switch module 11 is turned on. When the voltage across the first capacitor 133 is less than the turn-on voltage threshold of the first switch module 11, the first switch module 11 is turned off.

[0049] In some embodiments, a first photocoupler 14 is further provided between the second end of the first voltage-dividing acquisition module 13 and the second end of the alternating current. The first end of the first photocoupler 14 is connected to the second end of the first voltage-dividing acquisition module 13, and the second end of the first photocoupler 14 is connected to the second end of the alternating current.

[0050] In this embodiment, when the first photocoupler 14 receives the first control signal and turns on, the loop in which the first photocoupler 14 is located is turned on, and when the voltage across the first capacitor 133 is greater than the turn-on voltage of the first switch module, the first switch module 11 is turned on.

[0051] When the first photoelectric coupler 14 is disconnected, the voltage-divided output terminal of the first voltage-divided acquisition module 13 does not output the second voltage to the control terminal of the first switch module, thereby keeping the first switch module 11 in the disconnected state.

[0052] In some embodiments, a second diode 15 is provided between the second end of the first voltage division acquisition module 13 and the second end of the alternating current, and the anode of the second diode 15 is connected to the second end of the first voltage division acquisition module 13 , and the cathode is connected to the second end of the alternating current.

[0053] In this embodiment, the second diode 15 is arranged in the same direction as the first diode 12. After the first diode 12 and the second diode 15 are turned on, a current path is formed. The second diode 15 also has the function of blocking negative voltage.

[0054] In some embodiments, the cathode of the second diode 15 is connected to the first end of the first photocoupler 14 , and the anode of the second diode 15 is connected to the second end of the first voltage division acquisition module 13 .

[0055] In some embodiments, the AC negative voltage step-down circuit 2 may further include: a third diode 22 , wherein the cathode of the third diode 22 is connected to the first contact of the relay, and the anode of the third diode 22 is connected to the input end of the second switch module 21 .

[0056] The output end of the second switch module 21 is connected to the second contact and the first end of the load respectively, and the second end of the load is connected to the second end of the alternating current.

[0057] When a negative AC voltage is input, the third diode 22 is turned on, and the second switch module 21 is controlled to be turned on, the third diode 22 and the second switch module 21 are connected in series between the first contact of the relay and the second contact of the relay, and the voltage drop between the first contact of the relay and the second contact of the relay is the sum of the voltage drops of the third diode 22 and the second switch module 21.

[0058] In some embodiments, a second voltage division acquisition module 23 may be further included, wherein the first end of the second voltage division acquisition module 23 is respectively connected to the anode of the third diode 22 and the input end of the second switch module 21, the second end is connected to the second end of the alternating current, and the voltage division output end is connected to the control end of the second switch module 21.

[0059] The second voltage division acquisition module 23 is used to collect the third voltage at the input end of the second switch module 21, and the voltage division output end outputs a fourth voltage related to the third voltage to the control end of the second switch module 21 to drive the second switch module 21 to open and close.

[0060] In this embodiment, the second voltage division acquisition module 23 may further include a fourth resistor 231 , a third resistor 232 and a second capacitor 233 .

[0061] The third resistor 232 is connected in parallel with the second capacitor 233. The first end of the second capacitor 233 and the third resistor 232 connected in parallel serves as the first end of the second voltage division acquisition module.

[0062] The second end of the second capacitor 233 and the third resistor 232 connected in parallel is connected to the first end of the fourth resistor 231 , and the second end of the fourth resistor 231 serves as the second end of the second voltage division acquisition module.

[0063] In some embodiments, a second photoelectric coupler 24 is further provided between the second end of the second voltage division acquisition module 23 and the second end of the alternating current.

[0064] The first end of the second photoelectric coupler 24 is connected to the second end of the second voltage-dividing acquisition module 23, and the second end of the second photoelectric coupler 24 is connected to the second end of the AC power. In addition to being able to control the on-off of the circuit, the second photoelectric coupler 24 can also effectively isolate the weak current driving signal and the strong current step-down circuit.

[0065] In some embodiments, a fourth diode 25 is provided between the second end of the second voltage division acquisition module 23 and the second end of the alternating current, and the anode of the fourth diode 25 is connected to the second end of the alternating current, and the cathode is connected to the second end of the second voltage division acquisition module 23 .

[0066] In this embodiment, the fourth diode 25 has a function of blocking forward voltage. The anode of the fourth diode 25 is connected to the first end of the second photocoupler 24 , and the cathode of the fourth diode 25 is connected to the second end of the fourth resistor 231 .

[0067] See attached Figure 4 MOS tube Q2 is an N-channel, which is turned on when the G pole is at a high level and cut off when the G pole is at a low level. MOS tube Q3 is a P-channel, which is turned on when the G pole is at a low level and cut off when the G pole is at a high level.

[0068] When the voltage value of the first end of the resistor R4 is a positive voltage value, the MOS tube Q3 is not turned on, so as to prevent the positive voltage from flowing into the AC negative voltage step-down circuit.

[0069] When the voltage value of the first end of the resistor R5 is a negative voltage value, the MOS tube Q2 is not turned on, so as to prevent the negative voltage from flowing into the AC positive voltage step-down circuit.

[0070] The positive pressure circuit includes: a diode D1, a resistor R2, a resistor R4, a diode D3, and an optocoupler G1.

[0071] The anode of the diode D1 is connected to the first contact and the power supply L, and the cathode of the diode D1 is respectively connected to the S terminal of Q3, the first terminal of the resistor R2, and the first terminal of the capacitor C1, wherein the resistor R2 and the capacitor C1 are connected in parallel; the second terminal of the resistor R2 and the second terminal of the capacitor C1 are connected together as the parallel first terminal; the first terminal of the resistor R2 and the first terminal of the capacitor C1 are connected together as the parallel second terminal. The above-mentioned parallel second terminal is respectively connected to the G pole of the MOS tube Q3 and the first terminal of the resistor R4; the second terminal of the resistor R4 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to the first terminal 4 of the optical coupler G1, the second terminal 3 of the optical coupler G1 is respectively connected to the second terminal of the load and the power supply N, the third terminal 1 of the optical coupler G1 is connected to the GPIO2 pin, and the fourth terminal 2 is grounded.

[0072] The negative pressure circuit includes: a diode D2, a resistor R3, a resistor R5, a diode D4, and an optocoupler G2.

[0073] The anode of the diode D2 is connected to the first contact and the power supply L, and the anode of the diode D2 is respectively connected to the S terminal of Q3, the first terminal of the resistor R3, and the first terminal of the capacitor C2, wherein the resistor R3 and the capacitor C2 are connected in parallel; the second terminal of the resistor R3 and the second terminal of the capacitor C2 are connected together as the parallel first terminal; the first terminal of the resistor R3 and the first terminal of the capacitor C2 are connected together as the parallel second terminal. The above-mentioned parallel second terminal is respectively connected to the G pole of the MOS tube Q2 and the first terminal of the resistor R5; the second terminal of the resistor R5 is connected to the anode of the diode D4, the anode of the diode D4 is connected to the first terminal 3 of the optical coupler G2, the second terminal 4 of the optical coupler G2 is respectively connected to the second terminal of the load and the power supply N, the third terminal 1 of the optical coupler G2 is connected to the GPIO2 pin, and the fourth terminal 2 is grounded.

[0074] The anode of the diode D1 is connected to the first contact point and the neutral line L, respectively, and the cathode of the diode D2 is connected to the first contact point and the neutral line L, respectively.

[0075] The second contact is connected to the D end of the MOS transistor Q2 and the D end of the MOS transistor Q3 respectively. In the first series circuit composed of the MOS transistor Q2 and the diode D2, one end of the first series circuit is connected to the first contact, and the other end of the first series circuit is connected to the second contact. In the second series circuit composed of the MOS transistor Q3 and the diode D1, one end of the second series circuit is connected to the first contact, and the other end of the second series circuit is connected to the second contact.

[0076] The coil of the relay is connected in series with a transistor Q1, the base of the transistor is connected to the first end of the resistor R1, and the second end of the resistor R1 is connected to the GPI01 pin. The transistor Q1 can be an NPN transistor or a PNP transistor. The base of the NPN transistor is triggered to turn on when a high level is input, and the base of the PNP transistor is triggered to turn on when a low level is input.

[0077] Taking the PNP transistor as an example, when the GPIO1 pin is at a low level, the transistor Q1 is turned on, the relay coil is energized, and the relay is turned on. When the GPIO1 pin is at a high level, the transistor is cut off, the relay coil is de-energized, and disconnected.

[0078] Taking the NPN transistor as an example, when the GPIO1 pin is at a high level, the transistor Q1 is turned on, the relay coil is energized, and the relay is turned on. When the GPIO1 pin is at a low level, the transistor is cut off, the relay coil is de-energized, and disconnected.

[0079] Before the GPIO1 pin controls the relay to turn on / off, the GPOI2 pin is first controlled to output a high level, so that the above-mentioned step-down circuit performs the above-mentioned step-down process, and the MOS tube Q2 and the MOS tube Q3 are stably turned on, so that the voltage between the two contacts is the sum of the VDS of the MOS tube and the VF of the diode, thereby achieving step-down. After the relay is turned on, the GPIO2 pin can be controlled to be turned off to reduce the power consumption of the circuit. Before controlling the relay to turn off / on, the GPIO2 pin is first controlled to be turned on.

[0080] See attached Figure 5 The capacitor charging and discharging voltage waveforms and the contact voltage waveforms are shown.

[0081] Curve 1 is the voltage waveform of capacitor C1. Curve 2 is the voltage waveform between contacts, where the voltage between contacts is stable between positive and negative 2 volts. Curve 3 is the voltage waveform of capacitor C2.

[0082] The dynamic process of the entire system is described in detail below. When the first photoelectric coupler 14 and the second photoelectric coupler 24 are controlled to be turned on, the loops where the first photoelectric coupler 14 and the second photoelectric coupler 24 are located are turned on respectively.

[0083] When the external power source is positive AC, the first capacitor 133 is charged and the second capacitor 233 is discharged. When the external power source is negative AC, the first capacitor 133 is discharged and the second capacitor 233 is charged.

[0084] The charging and discharging process of the first capacitor 133 and the second capacitor 233 and the conduction process of the first switch module 11 and the second switch module 21 are as follows: in the first few cycles of the sinusoidal alternating current of the external power supply, when the alternating current is positive, the positive voltage step-down circuit 1 of the alternating current is turned on, the negative voltage step-down circuit 2 of the alternating current is turned off, the first capacitor 133 is charged, and the second capacitor 233 is discharged.

[0085] When the external power source outputs a sinusoidal alternating current negative voltage, the alternating current negative voltage step-down circuit 2 is turned on, the alternating current positive voltage step-down circuit 1 is turned off, the second capacitor 233 is charged, and the first capacitor 133 is discharged.

[0086] In the first few cycles of the sinusoidal alternating current, the charging of the first capacitor 133 is greater than the discharging, and the minimum capacitance voltage of the first capacitor 133 gradually increases, but is less than the conduction voltage of the first switch module 11, and the first switch module 11 is not turned on.

[0087] Similarly, in the first few cycles of the sinusoidal alternating current, the charging of the second capacitor 233 is greater than the discharging, and the minimum capacitance voltage of the second capacitor 233 gradually increases, but is less than the conduction voltage of the second switch module 21, and the second switch module 21 is not turned on.

[0088] After the first few cycles of the input sinusoidal alternating current, after the above-mentioned alternating current positive voltage step-down circuit 1 and the alternating current negative voltage step-down circuit 2 are turned on for several cycles, the charging of the first capacitor 133 and the second capacitor 233 are equal to the discharging, and the minimum capacitor voltage of the first capacitor 133 and the minimum capacitor voltage of the second capacitor 233 are respectively greater than the turn-on voltages of the first switch module 11 and the second switch module 21, so that the first switch module 11 and the second switch module 21 are turned on.

[0089] The voltage fluctuation of the capacitor charge and discharge cycle is controlled by the voltage divider resistor. As the voltage divider resistor increases, the voltage fluctuation of the capacitor decreases, but it takes longer to reach the charge and discharge equilibrium state.

[0090] See also Figure 5 The waveform diagram of the capacitor voltage and the contact voltage is shown in FIG. In the figure, the middle curve is the contact voltage, and the amplitude of the contact voltage is within the range of plus or minus 2 volts, which plays a good role in voltage reduction protection. The bottom curve is the capacitor voltage, and the top curve is the capacitor voltage after the voltage divider resistance is increased by 10 times.

[0091] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0092] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0093] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0094] In the embodiments provided in the present application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0095] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0096] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0097] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A relay contact protection circuit, characterized in that: The relay comprises at least a coil, and a first contact and a second contact which are in contact with or disconnected from each other when the coil is energized; The relay contact protection circuit comprises: an alternating current positive voltage step-down circuit and an alternating current negative voltage step-down circuit; The AC positive voltage step-down circuit is provided with a first switch module, and the AC negative voltage step-down circuit is provided with a second switch module; The first contact is respectively connected to a first end of the alternating current, an input end of the first switch module, and an input end of the second switch module; The second contact is respectively connected to the first end of the load, the output end of the first switch module and the output end of the second switch module; The control end of the first switch module, the control end of the second switch module and the second end of the load are connected to the second end of the alternating current; The voltage drop when the first contact and the second contact are in contact with or disconnected from each other is the voltage drop after the first switch module and / or the second switch module is turned on.

2. The relay contact protection circuit according to claim 1, characterized in that: The first switch module includes a metal oxide semiconductor field effect transistor and / or the second switch module includes a metal oxide semiconductor field effect transistor.

3. The relay contact protection circuit according to claim 1, characterized in that: The AC positive voltage step-down circuit further includes: a first diode, wherein an anode of the first diode is respectively connected to the first contact and the first end of the AC power, and a cathode of the first diode is connected to an input end of the first switch module.

4. The relay contact protection circuit according to claim 3, characterized in that: The AC positive voltage step-down circuit also includes: A first voltage-dividing acquisition module, wherein a first end of the first voltage-dividing acquisition module is respectively connected to the cathode of the first diode and the input end of the first switch module, a second end is connected to the second end of the alternating current, and a voltage-dividing output end is connected to the control end of the first switch module; The first voltage division acquisition module is used to collect the first voltage at the input end of the first switch module, and the voltage division output end outputs a second voltage related to the first voltage to the control end of the first switch module to drive the first switch module to be turned on or off.

5. The relay contact protection circuit according to claim 4, characterized in that: The first voltage division acquisition module at least includes a first resistor, a second resistor and a first capacitor; The second resistor is connected in parallel with the first capacitor; a first end of the first capacitor and the second resistor connected in parallel serves as a first end of the first voltage division acquisition module; The second end of the first capacitor and the second resistor connected in parallel is connected to the first end of the first resistor, and the second end of the first resistor serves as the second end of the first voltage division acquisition module; When a positive voltage is input to the first end of the alternating current, the first capacitor is charged, and when a negative voltage is input to the first end of the alternating current, the first capacitor is discharged; when the voltage across the first capacitor is greater than the turn-on voltage threshold of the first switch module, the first switch module is turned on.

6. The relay contact protection circuit according to claim 4, characterized in that: A first photoelectric coupler is further provided between the second end of the first voltage division acquisition module and the second end of the alternating current; The second end of the first photoelectric coupler is connected to the second end of the alternating current, and the first end of the first photoelectric coupler is connected to the second end of the first voltage division acquisition module.

7. The relay contact protection circuit according to claim 4, characterized in that: A second diode is provided between the second end of the first voltage division acquisition module and the second end of the alternating current, wherein the anode of the second diode is connected to the second end of the first voltage division acquisition module, and the cathode of the second diode is connected to the second end of the alternating current.

8. The relay contact protection circuit according to claim 1, characterized in that: The AC negative voltage step-down circuit further includes: a third diode, a cathode of the third diode being connected to the first contact of the relay and the first end of the AC power respectively, and an anode of the third diode being connected to the input end of the second switch module.

9. The relay contact protection circuit according to claim 8, characterized in that: The AC negative voltage step-down circuit also includes: A second voltage-dividing acquisition module, wherein a first end of the second voltage-dividing acquisition module is respectively connected to the anode of the third diode and the input end of the second switch module, a second end is grounded, and a voltage-dividing output end is connected to the control end of the second switch module; The second voltage division acquisition module is used to collect the third voltage at the input end of the second switch module, and the voltage division output end outputs a fourth voltage related to the third voltage to the control end of the second switch module to control the opening and closing of the second switch module.

10. The relay contact protection circuit according to claim 9, characterized in that: The second voltage division acquisition module at least includes a fourth resistor, a third resistor and a second capacitor; The third resistor and the second capacitor are connected in parallel; the first end of the second capacitor and the third resistor connected in parallel serves as the first end of the second voltage division acquisition module; The second end of the second capacitor and the third resistor connected in parallel is connected to the first end of the fourth resistor, and the second end of the fourth resistor serves as the second end of the second voltage division acquisition module; When a negative voltage is input to the first end of the alternating current, the second capacitor is charged, and when a positive voltage is input to the first end of the alternating current, the second capacitor is discharged; when the voltage across the second capacitor is greater than the turn-on voltage threshold of the second switch module, the second switch module is turned on.

11. The relay contact protection circuit according to claim 9, characterized in that: A second photoelectric coupler is further provided between the second end of the second voltage division acquisition module and the second end of the alternating current; The first end of the second photoelectric coupler is connected to the second end of the second voltage division acquisition module, and the second end of the second photoelectric coupler is connected to the second end of the alternating current.

12. The relay contact protection circuit according to claim 9, characterized in that: A fourth diode is provided between the second end of the second voltage division acquisition module and the second end of the alternating current, wherein the anode of the fourth diode is connected to the second end of the alternating current, and the cathode of the fourth diode is connected to the second end of the second voltage division acquisition module.

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