Relay control surge current suppression and contact protection circuit

Abstract

The invention discloses a relay control surge current suppression and contact protection circuit which comprises a main circuit relay driving module, a bypass relay power-on delay driving module, a starting instant surge protection module, an alternating current load and a controller. The output end of the controller is electrically connected with a main circuit relay driving module and a bypass relay power-on delay driving module; through the combined action of the main circuit relay driving module, the bypass relay power-on delay driving module and the starting instant surge protection module, the purpose of protecting a relay contact at the starting instant of the relay control alternating current load circuit is achieved, and meanwhile the situation that the relay contact is damaged after the circuit runs for a long time is avoided. The temperature of the thermistor NTC rises, the resistance value of the thermistor NTC is reduced, the main circuit relay RY1 and the bypass relay RY2 are controlled by the same I / O port, the control mode is simple, no misoperation mode exists, and the reliability of the circuit is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of relays, and in particular to a relay control surge current suppression and contact protection circuit. Background Art

[0002] Relay is an automatic switching element with isolation function, which is widely used in telemetry, communication, remote control, mechatronics, power electronic equipment and automation control. Electromagnetic relays play an important role in voltage isolation, safety protection, automatic switching and other functions in circuits. Relay contacts will generate arcs during the switching process. Long-term use will cause problems such as contact wear, oxidation and adhesion, which will affect the normal operation of the relay. Especially in high-voltage and high-power control systems, transient overvoltage and overcurrent are easily generated at the moment of relay switching, which will cause transient arc erosion and adhesion of relay contacts, leading to control system failure and even serious accidents. In the existing relay contact protection circuit, the bypass control element and the main relay are controlled by two different I / O ports respectively. The time-sharing control of the two control elements is realized through the delay on the software. This contact protection circuit has the disadvantages of cumbersome control and easy to make mistakes. Therefore, a relay control surge current suppression and contact protection circuit is proposed. Summary of the invention

[0003] The object of the present invention is to provide a relay control surge current suppression and contact protection circuit to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions: a relay-controlled surge current suppression and contact protection circuit, comprising a main road relay driving module, a bypass relay power-on delay driving module, a startup instantaneous surge protection module, an AC load and a controller, the output end of the controller is electrically connected to the main road relay driving module and the bypass relay power-on delay driving module, the output end of the main road relay driving module is electrically connected to the main road relay RY1, the input end of the main road relay RY1 is electrically connected to the AC live wire ACL, the output end of the bypass relay power-on delay driving module is electrically connected to the bypass relay RY2, and the main road relay RY1 and the bypass relay RY2 are both electrically connected to the input end of the startup instantaneous surge protection module, the output end of the startup instantaneous surge protection module is electrically connected to the AC load, and the AC load is electrically connected to the AC neutral line ACN.

[0005] Preferably, the main road relay driving module includes a transistor Q1, a resistor R1, a resistor R2, and a fast recovery diode D1. The base of the transistor Q1 is connected in series with the resistor R1 and then connected to the output end of the controller. The base and emitter of the transistor Q1 are connected in series through the resistor R2. The emitter of the transistor Q1 is connected to GND. The collector of the transistor Q1 is connected in series with the fast recovery diode D1 and then connected to VCC. The fast recovery diode D1 is connected in parallel with the main road relay RY1.

[0006] Preferably, the model of the transistor Q1 is S8050, the model of the recovery diode D1 is FR107, and the resistance values ​​of the resistor R1 and the resistor R2 are both 10 kΩ.

[0007] Preferably, the cathode of the fast recovery diode D1 is connected to the positive pole of the coil of the main road relay RY1, the anode of the fast recovery diode D1 is connected to the negative pole of the coil of the main road relay RY1, the negative pole of the coil of the main road relay RY1 is connected to the collector of the transistor Q1, and the positive pole of the coil of the main road relay RY1 is connected to VCC.

[0008] Preferably, the bypass relay power-on delay drive module includes a transistor Q2, a transistor Q3, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a diode D2, a diode D3 and a fast recovery diode D4, the base of the transistor Q2 is connected in series with the resistor R4 and then connected to the output end of the controller, the base of the transistor Q2 is connected in series with the resistor R3 and then connected to VCC, the emitter of the transistor Q2 is connected to VCC, the collector of the transistor Q2 is connected to the resistor R5, the other end of the resistor R5 is connected to the resistor R6, the capacitor C1 and the anode of the diode D2, and the transistor Q2 is connected to the collector of the transistor Q2. The other ends of resistor R6 and capacitor C1 are connected to GND, and the cathode of diode D2 is connected to the anode of diode D3, the cathode of diode D3 is connected to the base of transistor Q3, the base and emitter of transistor Q3 are connected through resistor R7, the emitter of transistor Q3 is connected to GND, the collector of transistor Q3 is connected in series with the anode of recovery diode D4 and then connected to VCC, the recovery diode D4 is connected in parallel with bypass relay RY2, and the negative pole of the coil of bypass relay RY2 is connected to the collector of transistor Q3, and the positive pole of the coil of bypass relay RY2 is connected to the cathode of fast recovery diode D4.

[0009] Preferably, the model of the transistor Q2 is S8550, the model of the transistor Q3 is S8050, the model of the fast recovery diode D4 is FR107, the models of the diode D2 and the diode D3 are both 1N4148W, the resistance value of the resistor R3 is 4.99kΩ, the resistance values ​​of the resistors R4, R5, R6 and R7 are all 10kΩ, and the capacitance value of the capacitor C1 is 47uF.

[0010] Preferably, the startup instantaneous surge protection module includes a thermistor NTC, a fuse F1 and a varistor VDR, and the thermistor NTC, the fuse F1 and the varistor VDR are connected in series, the fuse F1 is connected to the AC load, the AC load is connected to 220VACN, the varistor VDR is connected to 220V ACL, the thermistor NTC is connected in parallel with the bypass relay RY2 contact, and the varistor VDR is connected in parallel with the main relay RY1 contact.

[0011] Preferably, the model of the thermistor NTC is MF73T-1, the model of the varistor VDR is 14D681K, and the parameters of the fuse F1 are 6A, 250V.

[0012] The invention provides a relay-controlled surge current suppression and contact protection circuit, which has the following advantages: the invention realizes the purpose of protecting the relay contacts at the moment of starting the relay-controlled AC load circuit through the joint action of a main relay driving module, a bypass relay power-on delay driving module and a startup instant surge protection module, while avoiding the temperature increase and resistance decrease of the thermistor NTC after the circuit has been running for a long time. The main relay RY1 and the bypass relay RY2 are controlled by the same I / O port, with a simple control method and error-free operation, which greatly improves the reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is the overall structural diagram of the present invention;

[0015] Figure 2 A circuit diagram of the present invention;

[0016] Figure 3 It is a schematic diagram of the connection relationship between the main relay RY1 and the bypass relay RY2 of the present invention.

[0017] In the figure: 1. Main line relay driver module; 2. Bypass relay power-on delay driver module; 3. Start-up instantaneous surge protection module; 4. AC load; 5. Controller. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Please see attached Figure 1 -Attached Figure 3An embodiment of the present invention is as follows: a relay-controlled surge current suppression and contact protection circuit, comprising a main relay driving module 1, a bypass relay power-on delay driving module 2, a startup instantaneous surge protection module 3, an AC load 4 and a controller 5, wherein the output end of the controller 5 is electrically connected to the main relay driving module 1 and the bypass relay power-on delay driving module 2, the output end of the main relay driving module 1 is electrically connected to the main relay RY1, the input end of the main relay RY1 is electrically connected to the AC live wire ACL, the output end of the bypass relay power-on delay driving module 2 is electrically connected to the bypass relay RY2, and the main relay RY1 and the bypass relay RY2 are both electrically connected to the startup instantaneous surge The input end of the surge protection module 3 is electrically connected, and the output end of the surge protection module 3 is electrically connected to the AC load 4 at the moment of startup, and the AC load 4 is electrically connected to the AC neutral line ACN; the main road relay driving module 1 includes a transistor Q1, a resistor R1, a resistor R2, and a fast recovery diode D1. The base of the transistor Q1 is connected in series with the resistor R1 and then connected to the output end of the controller 5. The base and emitter of the transistor Q1 are connected in series through the resistor R2, the emitter of the transistor Q1 is connected to GND, the collector of the transistor Q1 is connected in series with the fast recovery diode D1 and then connected to VCC, and the fast recovery diode D1 is connected in parallel with the main road relay RY1; the model of the transistor Q1 is S8050, the model of the recovery diode D1 is FR107, and the resistor R 1 and the resistance value of resistor R2 are both 10kΩ; the cathode of the fast recovery diode D1 is connected to the positive pole of the coil of the main road relay RY1, the anode of the fast recovery diode D1 is connected to the negative pole of the coil of the main road relay RY1, the negative pole of the coil of the main road relay RY1 is connected to the collector of the transistor Q1, and the positive pole of the coil of the main road relay RY1 is connected to VCC; the bypass relay power-on delay drive module 2 includes a transistor Q2, a transistor Q3, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a diode D2, a diode D3 and a fast recovery diode D4, the base of the transistor Q2 is connected in series with a resistor R4 to the output end of the controller 5, the base of the transistor Q2 is connected in series with a resistor R3 to VCC, and the transistor The emitter of transistor Q2 is connected to VCC, the collector of transistor Q2 is connected to resistor R5, the other end of resistor R5 is connected to resistor R6, capacitor C1 and the anode of diode D2, the other ends of resistor R6 and capacitor C1 are both connected to GND, the cathode of diode D2 is connected to the anode of diode D3, the cathode of diode D3 is connected to the base of transistor Q3, the base and emitter of transistor Q3 are connected through resistor R7, the emitter of transistor Q3 is connected to GND, the collector of transistor Q3 is connected in series with the anode of recovery diode D4 and then connected to VCC, the recovery diode D4 is connected in parallel with bypass relay RY2, the negative pole of the coil of bypass relay RY2 is connected to the collector of transistor Q3, the positive pole of the coil of bypass relay RY2 is connected to the cathode of fast recovery diode D4;The model of transistor Q2 is S8550, the model of transistor Q3 is S8050, the model of fast recovery diode D4 is FR107, the models of diode D2 and diode D3 are both 1N4148W, the resistance value of resistor R3 is 4.99kΩ, the resistance values ​​of resistors R4, R5, R6 and R7 are all 10kΩ, and the capacitance value of capacitor C1 is 47uF; the startup instantaneous surge protection module 3 includes a thermistor NTC, a fuse F1 and a varistor VDR, and the thermistor NTC, the fuse F1 and the varistor VDR are connected in series, the fuse F1 is connected to the AC load 4, the AC load 4 is connected to the 220V ACN, and the varistor VDR is connected to the 220V ACL, thermistor NTC is connected in parallel with the contact of bypass relay RY2, and the varistor VDR is connected in parallel with the contact of main relay RY1; the model of thermistor NTC is MF73T-1, the model of varistor VDR is 14D681K, and the parameter of fuse F1 is 6A, 250V. ;

[0020] Working principle: In the present invention, through the joint action of the main relay driving module 1, the bypass relay power-on delay driving module 2 and the startup instant surge protection module 3, the relay contacts are protected at the instant when the circuit of the AC load 4 controlled by the controller 5 starts, and at the same time, the problem of the temperature increase and resistance decrease of the thermistor NTC after the circuit runs for a long time is avoided. The controller 5 can control the interface I / O to output a high level or a low level through software. When the interface I / O outputs a high level, the main relay RY1 and the bypass relay RY2 are both in a closed state; when the interface I / O outputs a low level, the main relay RY1 and the bypass relay RY2 are both in a disconnected state; the main relay RY1 and bypass relay RY2 are controlled by the same I / O port. After the main relay RY1 is controlled to close, due to the action of the bypass relay power-on delay drive module 2, the bypass relay RY2 lags behind the main relay RY1 in closing, causing the thermistor NTC to short-circuit, preventing the temperature of the thermistor NTC from rising and the resistance from decreasing, causing excessive loss and heat dissipation to the circuit. When the main relay RY1 is controlled to close, due to the access of the thermistor NTC in the surge protection module 3 at the moment of startup, at the moment of closing, the temperature of the thermistor NTC is relatively low and the resistance is relatively large, which can well limit the surge current at the moment of closing, prevent the impact of large current on the relay contacts, and extend the service life of the contacts. At the same time, it can prevent the occurrence of overvoltage or overcurrent during the switching process when there are inductive components or capacitive loads in the circuit, causing damage to other electronic components.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these 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 invention.

Claims

1. A relay-controlled surge current suppression and contact protection circuit, comprising a main relay drive module (1), a bypass relay power-on delay drive module (2), a startup instantaneous surge protection module (3), an AC load (4) and a controller (5), characterized in that: The output end of the controller (5) is electrically connected to a main line relay driving module (1) and a bypass relay power-on delay driving module (2); the output end of the main line relay driving module (1) is electrically connected to a main line relay RY1; the input end of the main line relay RY1 is electrically connected to an AC live line ACL; the output end of the bypass relay power-on delay driving module (2) is electrically connected to a bypass relay RY2; the main line relay RY1 and the bypass relay RY2 are both electrically connected to the input end of a startup instantaneous surge protection module (3); the output end of the startup instantaneous surge protection module (3) is electrically connected to an AC load (4); and the AC load (4) is electrically connected to an AC neutral line ACN.

2. A relay control surge current suppression and contact protection circuit according to claim 1, characterized in that: The main line relay driving module (1) comprises a transistor Q1, a resistor R1, a resistor R2, and a fast recovery diode D1. The base of the transistor Q1 is connected in series with the resistor R1 and then connected to the output end of the controller (5). The base and emitter of the transistor Q1 are connected in series through the resistor R2. The emitter of the transistor Q1 is connected to GND. The collector of the transistor Q1 is connected in series with the fast recovery diode D1 and then connected to VCC. The fast recovery diode D1 is connected in parallel to the main line relay RY1.

3. A relay control surge current suppression and contact protection circuit according to claim 2, characterized in that: The model of the transistor Q1 is S8050, the model of the recovery diode D1 is FR107, and the resistance values ​​of the resistor R1 and the resistor R2 are both 10 kΩ.

4. A relay control surge current suppression and contact protection circuit according to claim 2, characterized in that: The cathode of the fast recovery diode D1 is connected to the positive pole of the coil of the main road relay RY1, the anode of the fast recovery diode D1 is connected to the negative pole of the coil of the main road relay RY1, the negative pole of the coil of the main road relay RY1 is connected to the collector of the transistor Q1, and the positive pole of the coil of the main road relay RY1 is connected to VCC.

5. A relay control surge current suppression and contact protection circuit according to claim 1, characterized in that: The bypass relay power-on delay driving module (2) comprises a transistor Q2, a transistor Q3, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a diode D2, a diode D3 and a fast recovery diode D4, the base of the transistor Q2 is connected in series with the resistor R4 and then connected to the output end of the controller (5), the base of the transistor Q2 is connected in series with the resistor R3 and then connected to VCC, the emitter of the transistor Q2 is connected to VCC, the collector of the transistor Q2 is connected to the resistor R5, the other end of the resistor R5 is connected to the resistor R6, the capacitor C1 and the anode of the diode D2, The other ends of resistor R6 and capacitor C1 are both connected to GND, and the cathode of diode D2 is connected to the anode of diode D3, the cathode of diode D3 is connected to the base of transistor Q3, the base and emitter of transistor Q3 are connected through resistor R7, the emitter of transistor Q3 is connected to GND, the collector of transistor Q3 is connected in series with the anode of recovery diode D4 and then connected to VCC, the recovery diode D4 is connected in parallel with bypass relay RY2, and the negative pole of the coil of bypass relay RY2 is connected to the collector of transistor Q3, and the positive pole of the coil of bypass relay RY2 is connected to the cathode of fast recovery diode D4.

6. A relay control surge current suppression and contact protection circuit according to claim 5, characterized in that: The model of the transistor Q2 is S8550, the model of the transistor Q3 is S8050, the model of the fast recovery diode D4 is FR107, the models of the diode D2 and the diode D3 are both 1N4148W, the resistance value of the resistor R3 is 4.99kΩ, the resistance values ​​of the resistors R4, R5, R6 and R7 are all 10kΩ, and the capacitance value of the capacitor C1 is 47uF.

7. A relay control surge current suppression and contact protection circuit according to claim 1, characterized in that: The startup instantaneous surge protection module (3) comprises a thermistor NTC, a fuse F1 and a varistor VDR, wherein the thermistor NTC, the fuse F1 and the varistor VDR are connected in series, the fuse F1 is connected to an AC load (4), the AC load (4) is connected to a 220V ACN, the varistor VDR is connected to a 220V ACL, the thermistor NTC is connected in parallel to a contact of a bypass relay RY2, and the varistor VDR is connected in parallel to a contact of a main relay RY1.

8. A relay control surge current suppression and contact protection circuit according to claim 7, characterized in that: The model of the thermistor NTC is MF73T-1, the model of the varistor VDR is 14D681K, and the parameters of the fuse F1 are 6A, 250V.

Images