Controllable high-voltage protection circuit for controlling relay coil
By designing a controllable high-voltage protection circuit including a switching module, a freewheeling diode, a composite transistor and a third switch tube, the problem of contact adhesion under high voltage of the traditional relay coil power supply scheme is solved, and the effective protection and normal operation of the relay are achieved.
Patent Information
- Application Number
- CN202421568131.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-03
- Publication Date
- 2025-05-09
- Estimated Expiration
- 2034-07-03
AI Technical Summary
Traditional direct control relay coil power supply schemes can easily lead to adhesion of relay contacts under high voltage conditions, affecting their normal operation and life.
A controllable high-voltage protection circuit is designed, including a relay, a switching module, a freewheeling diode, a composite transistor, a third switch tube and a controller. By disconnecting the connection between the power supply and the relay under high voltage, and using the freewheeling diode to absorb the negative voltage at the moment of power failure, preventing contacts from sticking.
It effectively prevents the relay contacts from sticking, protects the normal operation and life of the relay. At the same time, through the combination of the voltage stabilization tube and the composite transistor, overvoltage protection and negative pressure absorption under high pressure are achieved.
Smart Images
Figure CN222851333U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of relay protection circuits, and in particular to a controllable high-voltage protection circuit for controlling a relay coil. Background Art
[0002] With the widespread application of relays in various electronic devices, their ability to drive load motors has received more and more attention.
[0003] Reference Figure 1 The figure shows a direct control relay coil power supply circuit composed of an anti-reverse diode D2, which includes an anti-reverse diode and a twin relay. The power supply +B directly supplies power to the relay coil through the anti-reverse diode D2. When the power supply voltage +B becomes high instantly (above 18V), the relay contacts are switched at this time. The moving contact will bring the voltage of the normally open contact (greater than 18V) to the normally closed contact, and arcing can easily cause the relay contacts to stick.
[0004] However, in the traditional direct control relay coil power supply solution, when the power supply becomes high instantly, such as reaching 18V or above, switching the relay contacts will cause the moving contact to bring the voltage of the normally open contact to the normally closed contact, thereby causing arcing and causing the risk of relay contact adhesion. This adhesion phenomenon seriously affects the normal operation and life of the relay. Therefore, a solution that can effectively protect the relay and prevent contact adhesion under high voltage conditions is urgently needed. Utility Model Content
[0005] In order to solve the contact sticking problem caused by switching relays under high voltage in the traditional direct control relay coil power supply solution, the present application provides a controllable high-voltage protection circuit for controlling the relay coil.
[0006] The present application provides a controllable high-voltage protection circuit for controlling a relay coil, which adopts the following technical solution:
[0007] A controllable high-voltage protection circuit for controlling a relay coil comprises a relay, a switch module, a freewheeling diode, a composite triode, a third switch tube and a controller, wherein the composite triode comprises a first switch tube and a second switch tube, the output end of the controller is connected to the control end of the first switch tube, the input end of the first switch tube is connected to the control end of the second switch tube, the input end of the second switch tube is used to be connected to a power supply, the output end of the second switch tube is connected to a relay, the input end of the third switch tube is connected to the control end of the first switch tube, the output end of the third switch tube is grounded, a pin at one end of the switch module is used to be connected to a power supply, a pin at the other end of the switch module is grounded, the control end of the third switch tube is connected between the switch module and the ground end, the switch module is used to control the third switch tube to be turned on when the power supply is higher than a limit value, the cathode of the freewheeling diode is connected between the relay and the output end of the second switch tube, and the anode of the freewheeling diode is grounded.
[0008] By adopting the above technical solution, during the operation of the relay, the power supply supplies power to the relay through the second switch tube. When the power supply becomes high instantly and is higher than the limit value (such as above 18V), the switch module is turned on, and the third switch tube is turned on, and the first switch tube is turned off, triggering the second switch tube to turn off, thereby disconnecting the connection between the power supply and the relay. At this time, since the relay coil is an inductive load, the relay coil is de-energized under high voltage, and the freewheeling diode is used to absorb the instantaneous negative pressure of the power failure, which effectively prevents the relay contacts from sticking, thereby protecting the relay.
[0009] Preferably, the switch module comprises a voltage regulator tube, a cathode of the voltage regulator tube is used to be connected to a power source, an anode of the voltage regulator tube is grounded, and a control end of the third switch tube is connected between the switch module and the ground end.
[0010] By adopting the above technical solution, the voltage regulator tube as a part of the switch module can play the role of overvoltage protection. When the power supply is higher than the set limit value, the voltage regulator tube will start to work, thereby realizing the conduction of the third switch tube.
[0011] Preferably, the first switch tube is an NPN transistor, and the second switch tube is a PNP transistor.
[0012] By adopting the above technical solution, the two poles of the composite transistor are PNP transistor and NPN transistor respectively, and complementary operation can be achieved by using NPN and PNP transistors. The working modes of NPN and PNP transistors are complementary. When one is turned on, the other is usually in the cut-off state, which allows them to be used well together. In this way, the on and off states of the circuit can be controlled more flexibly; in addition, NPN and PNP transistors usually have a good balance in power handling capacity. NPN transistors are usually used to drive loads to ground, while PNP transistors are usually used to drive loads to power supplies. Therefore, by using NPN and PNP transistors at the same time, the load can be better distributed and the power handling capacity and stability of the circuit can be improved.
[0013] Preferably, the third switch tube is an NPN transistor.
[0014] By adopting the above technical solution, NPN transistor is one of the commonly used transistor types and is widely used in electronic devices. Therefore, using NPN transistor as the third switch tube can easily find suitable models and suppliers, thereby improving the versatility and accessibility of the circuit; in addition, the base of the NPN transistor is the control terminal, which can be controlled to be turned on and off by the signal output by the controller. The control signal has strong adaptability, and the state of the third switch tube can be adjusted according to the signal output by the controller, thereby realizing the control function of the circuit.
[0015] Preferably, the anode of the voltage regulator is connected to a first resistor, and the other end of the first resistor is grounded.
[0016] By adopting the above technical solution, the influence of power supply fluctuation on circuit stability can be reduced through the voltage dividing effect of the first resistor.
[0017] Preferably, a second resistor is provided between the anode of the voltage regulator tube and the control end of the third switch tube.
[0018] By adopting the above technical solution, a second resistor is set between the anode of the voltage stabilizing diode and the control terminal of the third switch tube, which can limit the flow of the control signal and ensure the stable operation of the voltage stabilizing diode. This helps to control the on and off states of the third switch tube and improve the stability and reliability of the circuit.
[0019] Preferably, the output end of the controller is connected to a third resistor, and the other end of the third resistor is connected between the input end of the third switch tube and the control end of the first switch tube.
[0020] By adopting the above technical solution, the third resistor plays a role in limiting the current, thereby protecting the controller.
[0021] Preferably, a fourth resistor is connected between the input end of the first switch tube and the control end of the second switch tube.
[0022] By adopting the above technical solution, a fourth resistor is connected between the input end of the first switch tube and the control end of the second switch tube, which can limit the current and thus protect the switch tube.
[0023] In summary, the present application includes at least one of the following beneficial technical effects:
[0024] 1. During the operation of the relay, the power supply supplies power to the relay through the second switch tube. When the power supply instantly becomes higher and higher than the limit value (such as above 18V), the switch module is turned on, and the third switch tube is turned on, the first switch tube is turned off, triggering the second switch tube to turn off, thereby disconnecting the connection between the power supply and the relay. At this time, since the relay coil is an inductive load, the relay coil is powered off under high voltage, and the freewheeling diode absorbs the instantaneous negative pressure of power failure, which effectively prevents the relay contacts from sticking, thereby protecting the relay;
[0025] 2. As part of the switch module, the voltage regulator can play the role of overvoltage protection. When the power supply is higher than the set limit value, the voltage regulator will start to work, thereby realizing the conduction of the third switch tube;
[0026] 3. The two poles of the composite transistor are PNP transistor and NPN transistor. Complementary operation can be achieved by using NPN and PNP transistors. The working modes of NPN and PNP transistors are complementary. When one is turned on, the other is usually in the off state, which makes them work well together. In this way, the on and off states of the circuit can be controlled more flexibly. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a schematic diagram of the electrical principle of the traditional direct control relay coil power supply circuit.
[0028] Figure 2 The utility model is a schematic diagram of the electrical principle of a controllable high-voltage protection circuit for powering a control relay coil. DETAILED DESCRIPTION
[0029] The present application is further described in detail below in conjunction with the accompanying drawings.
[0030] The present application embodiment discloses a controllable high voltage protection circuit for controlling a relay coil. Figure 2 A controllable high-voltage protection circuit for controlling a relay coil includes a relay K1, a switch module, a freewheeling diode D1, a composite triode Q1, a third switch tube Q2 and a controller MCU.
[0031] The composite triode is a semiconductor device with multiple PN junctions interconnected. The internal structure is generally formed by alternating and stacking multiple P-type and N-type material layers. The composite triode has 6 pins. In this embodiment, the composite triode includes a first switch tube and a second switch tube, wherein the first switch tube adopts an NPN triode, and the second switch tube adopts a PNP triode. The emitter of the first switch tube is 1 pin, the collector of the first switch tube is 6 pins, the base electrode of the first switch tube is 2 pins, the base electrode of the second switch tube is 5 pins, the emitter of the second switch tube is 4 pins, the relay has 8 pins, the collector of the second switch tube is 3 pins, the controller adopts a single-chip microcomputer, the IO port of the controller is connected to the base electrode of the first switch tube through the third resistor R3, the emitter of the first switch tube is grounded, the collector of the first switch tube is connected to the base electrode of the second switch tube through the fourth switch tube R4, the emitter of the second switch tube is connected to the power supply +B pin, and the collector of the second switch tube is connected to the 5 pin of the relay.
[0032] The switch module includes a Zener tube Z1, which adopts the BZX84-C18 model. The cathode of the Zener tube is connected to the power supply, and the anode of the Zener tube is grounded through the first resistor R1. The third switch tube adopts an NPN transistor, and the base of the third switch tube is connected between the anode of the Zener tube and the ground terminal through the second resistor R2. The emitter of the third switch tube is grounded, and the collector of the third switch tube is connected to the base electrode of the first switch tube. When the power supply becomes high instantly and is higher than the limit value, the Zener tube is turned on to turn on the third switch tube. The limit value in this embodiment is 18V.
[0033] The cathode of the freewheeling diode is connected between the relay and the collector of the second switching tube, the anode of the freewheeling diode is grounded, and contact 1 of the relay is connected to the +12V_UP port of the power supply to power the relay. The other contacts of the relay can be connected to the load driving circuit to realize the switching of the driving circuit.
[0034] The implementation principle of a controllable high-voltage protection circuit for controlling a relay coil in an embodiment of the present application is as follows: when in use, the MCU_IO control port outputs 5V, the NPN tube in the composite triode Q1 is turned on, the 6th pin is low, the PNP tube is turned on, and the +12V_UP power supply supplies power to the relay coil. When the power supply +B becomes high instantly (above 18V), the voltage regulator tube Z1 is turned on, at this time the third switch tube Q2 is turned on, the 3rd pin is low, and finally the composite triode Q1 is cut off, the hardware turns off the controllable +12V_UP, and the relay coil is powered off. Since the relay coil is an inductive load, a negative pressure will be generated at +12V_UP at the moment of power failure, and the negative pressure is absorbed by the freewheeling diode D1. The controllable high-voltage protection circuit for powering the relay coil in this embodiment uses a combination of a 18V voltage regulator tube and a controllable circuit to power off the relay coil under high voltage conditions, and cooperate with the freewheeling diode to absorb the negative pressure at the moment of power failure, effectively preventing the relay contacts from sticking, thereby protecting the relay.
[0035] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. A controllable high voltage protection circuit for controlling a relay coil, comprising a relay, characterized in that: It also includes a switch module, a freewheeling diode, a composite triode, a third switch tube and a controller. The composite triode includes a first switch tube and a second switch tube. The output end of the controller is connected to the control end of the first switch tube, the input end of the first switch tube is connected to the control end of the second switch tube, the input end of the second switch tube is used to connect to a power supply, the output end of the second switch tube is connected to a relay, the input end of the third switch tube is connected to the control end of the first switch tube, the output end of the third switch tube is grounded, a pin at one end of the switch module is used to connect to a power supply, a pin at the other end of the switch module is grounded, the control end of the third switch tube is connected between the switch module and the ground end, the switch module is used to control the third switch tube to conduct when the power supply is higher than a limit value, the cathode of the freewheeling diode is connected between the relay and the output end of the second switch tube, and the anode of the freewheeling diode is grounded.
2. A controllable high voltage protection circuit for controlling a relay coil according to claim 1, characterized in that: The switch module comprises a voltage regulator tube, a cathode of the voltage regulator tube is used to be connected to a power source, and an anode of the voltage regulator tube is grounded.
3. The controllable high voltage protection circuit for controlling a relay coil according to claim 1, characterized in that: The first switch tube is an NPN transistor, and the second switch tube is a PNP transistor.
4. The controllable high voltage protection circuit for controlling a relay coil according to claim 1, characterized in that: The third switch tube is an NPN transistor.
5. The controllable high voltage protection circuit for controlling a relay coil according to claim 2, characterized in that: The anode of the voltage regulator is connected to a first resistor, and the other end of the first resistor is grounded.
6. The controllable high voltage protection circuit for controlling a relay coil according to claim 2, characterized in that: A second resistor is arranged between the anode of the voltage regulator tube and the control end of the third switch tube.
7. The controllable high voltage protection circuit for controlling a relay coil according to claim 1, characterized in that: The output end of the controller is connected to a third resistor, and the other end of the third resistor is connected between the input end of the third switch tube and the control end of the first switch tube.
8. The controllable high voltage protection circuit for controlling a relay coil according to claim 1, characterized in that: A fourth resistor is connected between the input end of the first switch tube and the control end of the second switch tube.