Relay disconnection arc discharge prevention circuit

Abstract

The utility model discloses a relay disconnection arc discharge prevention circuit comprising a DC power supply having a positive electrode Vin + and a negative electrode Vin-; one end of the relay is connected between the positive electrode Vin + and a resistor, and the other end of the relay is connected with a load and used for controlling on-off of power supply of the load; one end of the resistor is connected with the anode Vin +, the other end is connected with the anode of a capacitor, and the resistor is used for limiting the charging current of the capacitor when the relay is closed; the anode of the capacitor is connected with the anode of the diode and one end of the resistor; according to the utility model, effective arc discharge prevention can be realized, the generation of electric arc when the relay contact is disconnected can be greatly reduced, the service life of the relay is prolonged, and the stability and reliability of the whole circuit system are improved.

Description

Technical Field

[0001] This utility model relates to the field of electrical technology, specifically a relay disconnect anti-arc circuit. Background Technology

[0002] A relay is a commonly used power switching control device. Relay contacts are prone to generating an electric arc when they operate, especially when the relay's closed contacts open. The conditions for arc generation are: a circuit voltage of not less than 10-20V, a current of not less than 80-100mA, and the size of the contact gap. When the relay's closed contacts just separate, the gap is extremely small, and the circuit voltage is applied between the contacts, creating a very strong electric field (E=U / d). When the electric field strength exceeds 3×10⁶ V / m, electrons on the cathode surface are pulled out by the electric field force, forming free electrons in the contact space. These free electrons escape from the cathode and rush towards the anode, becoming strong electric field emission. The high-speed movement of these electrons collide with neutral gas molecules, ionizing them. After ionization, the positive ions move towards the cathode, colliding with the cathode surface and raising its temperature, leading to thermionic emission. These thermionic electrons then participate in further collisional ionization, thus forming a large number of charged particles between the electrodes, making the gas conductive and creating a hot electron flow, i.e., an electric arc.

[0003] The generation of electric arcs can cause a series of serious problems, such as shortening the service life of relay contacts, causing contact surface ablation and wear, and affecting their normal conduction and disconnection functions; at the same time, the high temperature and electromagnetic interference generated by the electric arc may damage surrounding electronic components, affecting the stability and reliability of the entire circuit system. Utility Model Content

[0004] This utility model discloses a relay disconnection anti-arc circuit, which can effectively prevent arcing, greatly reduce the generation of electric arc when the relay contacts are disconnected, extend the service life of the relay, and improve the stability and reliability of the entire circuit system.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] This utility model discloses a relay disconnect anti-arc circuit, comprising:

[0007] A DC power supply with a positive terminal Vin+ and a negative terminal Vin-;

[0008] A relay, with one end connected between the positive terminal Vin+ and a resistor, and the other end connected to the load, is used to control the power supply to the load.

[0009] A resistor, with one end connected to the positive terminal Vin+ and the other end connected to the positive terminal of a capacitor, is used to limit the charging current to the capacitor when the relay is closed.

[0010] A capacitor, whose positive terminal is connected to the anode of a diode and one end of a resistor;

[0011] A diode, whose cathode is connected to the load.

[0012] Furthermore, the resistance value is determined based on the voltage of the DC power supply and the maximum allowable charging current. The calculation formula is: resistance value = input voltage / maximum charging current. The selected resistor has a power rating that satisfies P = I²R, where I is the actual charging current and P is greater than the calculated power value.

[0013] Furthermore, the capacitor's withstand voltage is greater than the input voltage of the DC power supply.

[0014] Furthermore, the precharge drive circuit is used to control the precharge MOSFET to turn on before the first MOSFET is fully turned on, so as to precharge the load.

[0015] Furthermore, the reverse withstand voltage of the diode is greater than the maximum reverse voltage that may occur in the circuit, and the maximum forward current is greater than the maximum current that may pass through when the capacitor discharges.

[0016] Furthermore, an inductor is installed between the relay and the load.

[0017] The beneficial effects of this utility model are:

[0018] This invention features a simple structure, consisting of only a few basic components. Compared to some traditional complex absorption circuits, its structure is concise, clear, and easy to understand and implement. This simple structure not only reduces the difficulty of circuit design but also reduces potential failure points caused by an excessive number of components, thereby improving circuit reliability.

[0019] This invention exhibits significant anti-arc effect, effectively controlling the voltage rise rate between contacts when the relay disconnects, ensuring it remains below the voltage value corresponding to the critical electric field strength required to generate an arc, thus successfully preventing arcing. It significantly reduces arcing when relay contacts disconnect, extends relay lifespan, and improves the stability and reliability of the circuit system. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a circuit diagram of an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the capacitor C charging circuit when the relay is closed according to an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the discharge circuit of capacitor C when the relay is disconnected according to an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] As shown in the figure, this utility model discloses a relay disconnect anti-arc circuit, comprising:

[0026] A DC power supply with a positive terminal Vin+ and a negative terminal Vin-;

[0027] Relay K, one end of which is connected between the positive terminal Vin+ and a resistor R, and the other end of which is connected to the load ZL, is used to control the power supply to the load.

[0028] Resistor R is connected at one end to the positive terminal Vin+ and at the other end to the positive terminal of capacitor C. It is used to limit the charging current to capacitor C when relay K is closed.

[0029] Capacitor C has its positive terminal connected to the anode of diode D and one end of resistor R. When relay K is closed, it charges through resistor R; when relay K is open, it discharges through diode D to the load ZL, with a discharge voltage V. C =Vin-i(t) / C*t, where i(t) is the discharge current.

[0030] like Figure 3 As shown, the voltage V between the contacts of relay K is... K1 =Vin-V C =i(t) / C*t, which is inversely proportional to the capacitance C and gradually increases from zero with time;

[0031] Diode D, with its cathode connected to the load ZL, provides a unidirectional path for capacitor C to discharge to the load ZL when relay K is disconnected. By selecting a capacitor C with an appropriate capacitance value, the electric field strength E between the contacts is made equal to V when VK1 rises to the minimum arc-generating voltage of 10-20V. K1 / d1<3×106V / m, thus preventing the generation of electric arc, where d1 is the contact spacing at this time.

[0032] In one embodiment of this utility model, the resistance value of the resistor R is determined based on the voltage of the DC power supply and the maximum allowable charging current. The calculation formula is R = Vin / maximum charging current, and the selected resistor has a power that satisfies P = I²R, where I is the actual charging current and P is greater than the calculated power value.

[0033] Choose a DC power supply with an appropriate voltage value based on the requirements of the actual application scenario. Common DC power supply voltages include 5V, 12V, and 24V. For example, in industrial control equipment and communication equipment, 24V or higher voltage DC power supplies may be used.

[0034] In one embodiment of this utility model, the withstand voltage of the capacitor C is greater than the input voltage Vin of the DC power supply.

[0035] like Figure 3 As shown, as long as the capacitor C is of appropriate capacitance, arcing can be prevented. This invention is simple and effective.

[0036] In one embodiment of this utility model, the reverse withstand voltage of the diode is greater than the maximum reverse voltage that may occur in the circuit, and the maximum forward current is greater than the maximum current that may pass through when the capacitor discharges.

[0037] In one embodiment of this utility model, the charging current of capacitor C is not greater than the ratio of input voltage Vin to resistance R.

[0038] When relay K is disconnected, the discharge circuit of capacitor C is as follows: the positive terminal of capacitor C discharges to the load ZL through diode D. The current flows out from the positive terminal of capacitor C, through diode D to the load ZL, and then returns from the load ZL to the negative terminal of capacitor C, forming a discharge circuit.

[0039] The charging circuit is as follows: starting from the DC power supply Vin+, the current flows through the resistor R to the positive terminal of the capacitor C, and then returns from the negative terminal of the capacitor C to the DC power supply Vin-, forming a complete charging circuit.

[0040] In one embodiment of this utility model, an inductor L is installed between the relay K and the load ZL.

[0041] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A relay opening anti-pulling arc circuit characterized by comprising: include: A DC power supply with a positive terminal Vin+ and a negative terminal Vin-; A relay, with one end connected between the positive terminal Vin+ and a resistor, and the other end connected to the load, is used to control the power supply to the load. A resistor, with one end connected to the positive terminal Vin+ and the other end connected to the positive terminal of a capacitor, is used to limit the charging current to the capacitor when the relay is closed. A capacitor, whose positive terminal is connected to the anode of a diode and one end of a resistor; A diode, whose cathode is connected to the load.

2. The relay opening anti-pulling arc circuit according to claim 1, characterized in that, The resistance value is determined based on the DC power supply voltage and the maximum allowable charging current. The calculation formula is: resistance value = input voltage / maximum charging current. The selected resistor has a power rating that satisfies P = I²R, where I is the actual charging current and P is greater than the calculated power value.

3. The relay opening anti-pulling arc circuit according to claim 1, characterized in that, The voltage rating of the capacitor C is greater than the input voltage of the DC power supply.

4. The relay opening anti-pulling arc circuit according to claim 1, characterized in that, The reverse withstand voltage of the diode is greater than the maximum reverse voltage that may occur in the circuit, and the maximum forward current is greater than the maximum current that may pass through when the capacitor discharges.

5. The relay opening anti-pulling arc circuit according to claim 1, characterized in that, The charging current of the capacitor should not exceed the ratio of the input voltage to the resistance.

6. The relay opening anti-pulling arc circuit according to claim 1, characterized in that, An inductor is installed between the relay and the load.

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