CN220672470U - Relay contact protection circuit - Google Patents
Relay contact protection circuit Download PDFInfo
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- CN220672470U CN220672470U CN202322060774.0U CN202322060774U CN220672470U CN 220672470 U CN220672470 U CN 220672470U CN 202322060774 U CN202322060774 U CN 202322060774U CN 220672470 U CN220672470 U CN 220672470U
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Abstract
The utility model provides a relay contact protection circuit which comprises a relay module, an MOS tube module, a relay driving module, an MOS tube driving module and an analog load module. The whole system is powered by a direct-current power supply, the relay module and the MOS tube module are in a parallel state and are connected in series between the positive electrode of the power supply and a load, and the load module is connected in series between the relay module and the negative electrode of the power supply. In the utility model, in the time period of relay contact attraction, the power supply starts to precharge the capacitor C1 through the MOS tube and the current limiting resistor, the charging time and effect can be regulated through the current limiting resistor R5, after the capacitor C1 is charged for a period of time, the attraction action of the relay is completed, at the moment, the C1 is close to the state of full charge, and the surge current can be effectively restrained within a reasonable range. After the relay is attracted, the MOS tube only acts in the action time period of the relay, and the matching of the power of the MOS tube and the power of an actual load is not needed to be considered in design.
Description
Technical Field
The utility model relates to the field of relays, in particular to a relay contact protection circuit.
Background
Relays have unique advantages as a very consumer switching device, such as: control-output high isolation, multi-path switching and the like can be realized. In practical use, however, the use of relays must be very careful, such as: in the direct current application, because of the uncertainty of the load, especially in the case that the load is a capacitive load, the surge current of the relay may reach tens or hundreds of amperes at the moment of the actuation of the relay, if the contact is not additionally protected or processed, the contact reed of the relay is extremely easy to burn out at the moment of the actuation, in this case, the problem can be solved only by changing the material of the reed of the relay, or selecting a larger-sized relay, so that the waste of resources and cost is caused, and because the surge resistance of the contact is not usually marked clearly when the relay manufacturer provides product data, a user needs to determine the reliability of the relay through a large number of experiments (selecting different loads and different relays) and cannot exhaust all the loads. It is therefore necessary to find a reliable unit circuit that solves the problem in principle of an anti-surge circuit.
Disclosure of Invention
The utility model provides a relay contact protection circuit to solve the problems in the prior art.
In order to achieve the above purpose, the present utility model proposes the following technical scheme: a relay contact protection circuit comprising:
the relay driving module is responsible for driving a switch of the relay and comprises a resistor R1, a resistor R2, a triode Q1 and a diode D2;
the MOS tube module is connected in parallel with the relay module and is also connected in series between the positive electrode of the power supply and the load, and the load module is connected in series between the relay module and the negative electrode of the power supply;
the MOS tube driving module is responsible for driving the switch of the MOS tube, and comprises a resistor R3, a resistor R4 and a voltage stabilizing tube D1, wherein the relay driving module and the MOS tube driving module are controlled by a CPU and share one CPU control pin, and are controlled by the CPU to be simultaneously opened or simultaneously closed;
the load module comprises a capacitor C1 and a resistor RL, wherein the positive electrode of the capacitor C1 is connected with a movable contact of the relay J1, the negative electrode of the capacitor C1 is grounded, and the resistor RL and the capacitor C1 are connected in parallel.
Further, in the utility model, the resistor R1, the resistor R2 and the triode Q1 form a triode switch circuit, the resistor R1 is connected with the base electrode and the MCU control pin of the triode Q1, the resistor R2 is connected with the base electrode and the emitter electrode of the triode Q1, the base electrode of the triode Q1 is grounded, the collector electrode of the triode Q1 is connected with one pin of the control coil of the relay, and the other pin of the relay coil is connected with a power supply;
the diode D2 forms a follow current circuit of the relay, the cathode of the diode D1 is connected with the anode of the power supply and the coil of the relay, and the anode of the diode D1 is connected with the other coil of the relay.
Furthermore, in the utility model, the resistor R3 and the short resistor R4 form a voltage dividing circuit, so as to divide a 10V power supply through a power supply voltage to supply power to the MOS tube, and the voltage stabilizing tube D1 provides protection for Vgs of the MOS tube;
one end of the resistor R3 is connected with the positive electrode of the power supply and the drain electrode D of the MOS tube, the other end of the resistor R3 is connected with the grid electrode G of the MOS tube, the resistor R4 is connected with the positive electrodes of the grid electrodes G and D2 of the MOS tube, the positive electrode of the voltage stabilizing tube D1 is connected with the grid electrode G of the MOS tube, and the negative electrode of the voltage stabilizing tube D1 is connected with the positive electrode of the power supply and the drain electrode D of the MOS tube.
Further, in the present utility model, the relay module includes a relay J1.
One end of a coil of the relay J1 is connected with the positive electrode of the power supply, the drain electrode D of the MOS tube Q2, the resistor R3 and the negative electrode of the voltage stabilizing tube D1, the other end of the coil of the relay J1 is connected with the collector electrode of the triode Q1, the positive electrode of the diode D2 and the resistor R4, a movable contact of the relay J1 is connected with the positive electrode of the load module, and a normally-open stationary contact of the relay J1 is connected with the positive electrode of the power supply.
Further, in the utility model, the MOS tube module comprises an N-MOS tube Q2 and a current limiting resistor R5;
the grid electrode G of the N-MOS tube Q2 is connected with the positive electrode of the voltage stabilizing tube, the source stage S of the N-MOS tube Q2 is connected with the resistor R5, the drain stage D of the N-MOS tube Q2 is connected with the positive electrode of the power supply, the resistor R3 and the negative electrode of the voltage stabilizing tube D1, and the resistor R5 is connected with the source stage S of the N-MOS tube Q2 and the movable contact of the relay J1.
The beneficial effect, the technical scheme of this application possesses following technical effect: in the utility model, in the time period of relay contact attraction, the power supply starts to precharge the capacitor C1 through the MOS tube and the current-limiting resistor, the charging time and effect can be regulated through the current-limiting resistor R5, and after the capacitor C1 is charged for a period of time, the attraction action of the relay is completed, and at the moment, the C1 is close to the state of full charge, so that the surge current can be effectively restrained within a reasonable range. In the on state: after the relay is attracted, the relay and the MOS tube (including the current-limiting resistor) are in a parallel state in fact, the conduction internal resistance (mΩ level) of the relay is far smaller than the resistance value (Ω level) of the current-limiting resistor, and the voltage drop between the stationary contact and the movable contact of the relay is extremely small, so that main current (more than 99%) passes through the relay contacts, at the moment, the MOS tube and the current-limiting resistor hardly generate power, so that the requirement on the MOS tube is low, the MOS tube only acts in the action time period of the relay, and the matching of the power of the MOS tube and the power of an actual load is not considered in design.
It should be understood that all combinations of the foregoing concepts, as well as additional concepts described in more detail below, may be considered a part of the inventive subject matter of the present disclosure as long as such concepts are not mutually inconsistent.
The foregoing and other aspects, embodiments, and features of the present teachings will be more fully understood from the following description, taken together with the accompanying drawings. Other additional aspects of the utility model, such as features and/or advantages of the exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of the embodiments according to the teachings of the utility model.
Drawings
The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the utility model will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of the system of the present utility model.
Fig. 2 is a circuit diagram of the present utility model.
Detailed Description
For a better understanding of the technical content of the present utility model, specific examples are set forth below, along with the accompanying drawings. Aspects of the utility model are described in this disclosure with reference to the drawings, in which are shown a number of illustrative embodiments. The embodiments of the present disclosure need not be defined to include all aspects of the present utility model. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, may be implemented in any of a number of ways, as the disclosed concepts and embodiments are not limited to any implementation. Additionally, some aspects of the disclosure may be used alone or in any suitable combination with other aspects of the disclosure.
1-2, a relay contact protection circuit comprises a relay module, a MOS tube module, a relay driving module, a MOS tube driving module and an analog load module. The whole system is powered by a direct-current power supply, the relay module and the MOS tube module are in a parallel state and are connected in series between the positive electrode of the power supply and a load, and the load module is connected in series between the relay module and the negative electrode of the power supply.
The relay driving module is used for driving the switch of the relay, the MOS tube driving module is used for driving the switch of the MOS tube, the load is an analog capacitive load (R+C), the relay driving module and the MOS tube driving module are controlled by a CPU, and 2 persons share one CPU control pin and are simultaneously opened and closed.
The relay driving module comprises a resistor R1, a resistor R2, a triode Q1 and a diode D2. Wherein: the resistor R1, the resistor R2 and the triode Q1 form a triode switch circuit, the resistor R1 is connected with the base electrode and the control pin (usually from an MCU) of the triode Q1, the resistor R2 is connected with the base electrode and the emitter electrode of the triode Q1, the base electrode of the triode Q1 is grounded, and the collector electrode of the triode Q1 is connected with one pin (the other pin of the relay coil is connected with a power supply) of the control coil of the relay.
The diode D2 constitutes a follow current circuit of the relay, the negative electrode of the diode D1 is connected to the positive electrode of the power supply and the coil of the relay (the coil connected to the positive electrode of the power supply), and the positive electrode of the diode D1 is connected to the other coil of the relay (the coil connected to the collector of the Q1).
By adopting the technical scheme, the relay can be reliably opened or closed, and the flywheel diode D1 can reliably release the residual energy of the relay coil when the relay is closed.
The MOS tube driving module comprises a resistor R3, a resistor R4 and a voltage stabilizing tube D1. Wherein: the resistor R3 and the resistor R4 form a voltage dividing circuit, so that proper voltage is separated through the power supply voltage to supply power to the Vgs of the MOS tube, and the voltage stabilizing tube D1 provides protection for the Vgs of the MOS tube.
One end of the resistor R3 is connected with the positive electrode of the power supply and the drain electrode D of the MOS tube, the other end of the resistor R3 is connected with the grid electrode G of the MOS tube, the resistor R4 is connected with the grid electrode G of the MOS tube and the positive electrode of the diode D2, the positive electrode of the voltage stabilizing tube D1 is connected with the grid electrode G of the MOS tube, and the negative electrode of the voltage stabilizing tube D1 is connected with the positive electrode of the power supply and the drain electrode D of the MOS tube.
By adopting the technical scheme, the relay driver and the MOS tube driver share the triode Q1, so that when the CPU controls the relay to be turned on/off, the MOS tube is turned on/off, thereby saving the CPU resource and hardware cost.
The relay module includes a relay J1. Wherein: one end of a coil of the relay J1 is connected with the positive electrode of the power supply, the drain electrode D of the MOS tube Q2, the resistor R3 and the negative electrode of the voltage stabilizing tube D1, the other end of the coil of the relay J1 is connected with the collector electrode of the triode Q1, the positive electrode of the diode D2 and the resistor R4, a movable contact of the relay J1 is connected with the positive electrode of the load module, and a normally-open stationary contact of the relay J1 is connected with the positive electrode of the power supply.
The MOS tube module comprises an N-MOS tube Q2 and a current limiting resistor R5, wherein: the grid electrode G of the N-MOS tube Q2 is connected with the positive electrode of the voltage stabilizing tube, the source stage S of the N-MOS tube Q2 is connected with the resistor R5, the drain stage D of the N-MOS tube Q2 is connected with the positive electrode of the power supply, the resistor R3 and the negative electrode of the voltage stabilizing tube D1, and the resistor R5 is connected with the source stage S of the N-MOS tube Q2 and the movable contact of the relay J1.
Under the condition that the MOS tube is firstly opened, the power supply charges the input capacitor of the load through the MOS tube and the R5, and the load is approximately in a state with 0 internal resistance at the moment of electrification due to uncertainty of the load, so that the MOS tube is prevented from being burnt out due to overlarge instant charging current, and therefore, the resistance value of the current-limiting resistor R5 is properly adjusted to enable the charging of the load capacitor to be gentle.
The load module is a structural diagram of an analog typical capacitive load, including a capacitor C1 and a resistor RL. Wherein: the positive pole of electric capacity C1 connects the movable contact of relay J1, and electric capacity C1's negative pole ground connection, resistance RL and electric capacity C1 are parallelly connected.
The working mode of the circuit is as follows: in the initial state: the relay and the MOS tube are in a closed state, the load module is in a non-working state, the capacity of the capacitor C1 is 0, and when the CPU provides an opening signal (high level) for R1, the Q1 is conducted, and the relay coil and the GS of the MOS tube are simultaneously electrified. Because the MOS is an electronic switch, the opening speed of the MOS is nanosecond level, the relay is a mechanical switch, and the time length of the relay is usually millisecond level when the relay is in suction, therefore, in the time period of the suction of the relay contacts, the power supply starts to precharge C1 through the MOS tube and the current limiting resistor, the charging time length and effect can be adjusted through the current limiting resistor R5, after the C1 is charged for a period of time, the suction action of the relay is completed, and at the moment, the C1 is close to the state of full charge, so that the surge current can be effectively restrained within a reasonable range.
In the on state: after the relay is attracted, the relay and the MOS tube (including the current-limiting resistor) are in a parallel state in fact, the conduction internal resistance (mΩ level) of the relay is far smaller than the resistance value (Ω level) of the current-limiting resistor, and the voltage drop between the stationary contact and the movable contact of the relay is extremely small, so that main current (more than 99%) passes through the relay contacts, at the moment, the MOS tube and the current-limiting resistor hardly generate power, so that the requirement on the MOS tube is low, the MOS tube only acts in the action time period of the relay, and the matching of the power of the MOS tube and the power of an actual load is not considered in design.
The standard parts used in the application file can be purchased from the market, and can be customized according to the description of the specification and the drawing, the specific connection modes of the parts adopt conventional means such as mature bolts, rivets and welding in the prior art, the machines, the parts and the equipment adopt conventional models in the prior art, the control mode is controlled automatically by a controller, a control circuit of the controller can be realized by simple programming of a person skilled in the art, the control method belongs to common knowledge in the art, and the application file is mainly used for protecting a mechanical device, so the control mode and circuit connection are not explained in detail.
While the utility model has been described with reference to preferred embodiments, it is not intended to be limiting. Those skilled in the art will appreciate that various modifications and adaptations can be made without departing from the spirit and scope of the present utility model. Accordingly, the scope of the utility model is defined by the appended claims.
Claims (5)
1. A relay contact protection circuit is characterized in that: comprising the following steps:
the relay driving module is responsible for driving a switch of the relay and comprises a resistor R1, a resistor R2, a triode Q1 and a diode D2;
the MOS tube module is connected in parallel with the relay module and is also connected in series between the positive electrode of the power supply and the load, and the load module is connected in series between the relay module and the negative electrode of the power supply;
the MOS tube driving module is responsible for driving the switch of the MOS tube, and comprises a resistor R3, a resistor R4 and a voltage stabilizing tube D1, wherein the relay driving module and the MOS tube driving module are controlled by a CPU and share one CPU control pin, and are controlled by the CPU to be simultaneously opened or simultaneously closed;
the load module comprises a capacitor C1 and a resistor RL, wherein the positive electrode of the capacitor C1 is connected with a movable contact of the relay J1, the negative electrode of the capacitor C1 is grounded, and the resistor RL and the capacitor C1 are connected in parallel.
2. A relay contact protection circuit according to claim 1, wherein: the resistor R1, the resistor R2 and the triode Q1 form a triode switch circuit, the resistor R1 is connected with the base electrode and the MCU control pin of the triode Q1, the resistor R2 is connected with the base electrode and the emitter electrode of the triode Q1, the base electrode of the triode Q1 is grounded, the collector electrode of the triode Q1 is connected with one pin of the control coil of the relay, and the other pin of the relay coil is connected with a power supply;
the diode D2 forms a follow current circuit of the relay, the cathode of the diode D1 is connected with the anode of the power supply and the coil of the relay, and the anode of the diode D1 is connected with the other coil of the relay.
3. A relay contact protection circuit according to claim 2, wherein: the resistor R3 and the short resistor R4 form a voltage dividing circuit, so that a 10V power supply is separated from a power supply voltage to supply power to the MOS tube, and the voltage stabilizing tube D1 provides protection for Vgs of the MOS tube;
one end of the resistor R3 is connected with the positive electrode of the power supply and the drain electrode D of the MOS tube, the other end of the resistor R3 is connected with the grid electrode G of the MOS tube, the resistor R4 is connected with the positive electrodes of the grid electrodes G and D2 of the MOS tube, the positive electrode of the voltage stabilizing tube D1 is connected with the grid electrode G of the MOS tube, and the negative electrode of the voltage stabilizing tube D1 is connected with the positive electrode of the power supply and the drain electrode D of the MOS tube.
4. A relay contact protection circuit according to claim 3, wherein: the relay module comprises a relay J1;
one end of a coil of the relay J1 is connected with the positive electrode of the power supply, the drain electrode D of the MOS tube Q2, the resistor R3 and the negative electrode of the voltage stabilizing tube D1, the other end of the coil of the relay J1 is connected with the collector electrode of the triode Q1, the positive electrode of the diode D2 and the resistor R4, a movable contact of the relay J1 is connected with the positive electrode of the load module, and a normally-open stationary contact of the relay J1 is connected with the positive electrode of the power supply.
5. A relay contact protection circuit according to claim 4, wherein: the MOS tube module comprises an N-MOS tube Q2 and a current limiting resistor R5;
the grid electrode G of the N-MOS tube Q2 is connected with the positive electrode of the voltage stabilizing tube, the source stage S of the N-MOS tube Q2 is connected with the resistor R5, the drain stage D of the N-MOS tube Q2 is connected with the positive electrode of the power supply, the resistor R3 and the negative electrode of the voltage stabilizing tube D1, and the resistor R5 is connected with the source stage S of the N-MOS tube Q2 and the movable contact of the relay J1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322060774.0U CN220672470U (en) | 2023-08-01 | 2023-08-01 | Relay contact protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322060774.0U CN220672470U (en) | 2023-08-01 | 2023-08-01 | Relay contact protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220672470U true CN220672470U (en) | 2024-03-26 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322060774.0U Active CN220672470U (en) | 2023-08-01 | 2023-08-01 | Relay contact protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220672470U (en) |
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2023
- 2023-08-01 CN CN202322060774.0U patent/CN220672470U/en active Active
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