Relay drive circuit and relay control device

Abstract

The utility model provides a relay drive circuit and a relay control device, and relates to the technical field of relays, the circuit comprises a power supply, a diode, a first current limiting unit, a second current limiting unit and a relay body, the power supply is respectively connected with the relay body and the cathode of the diode; the first current limiting unit is connected with the anode of the diode, the second current limiting unit, the relay body and the control unit. The second current limiting unit is respectively connected with the positive electrode of the diode, the relay body and the control unit, and the second current limiting unit is grounded; and the control unit is used for lowering the working current flowing through the relay body on the basis of a first control signal corresponding to the first current limiting unit and a second control signal corresponding to the second current limiting unit under the condition of maintaining the working state of the relay body. The relay can save energy, reduce consumption, prolong the service life of the relay body and improve the reliability of related equipment.

Description

Technical Field

[0001] The utility model relates to the technical field of relays, in particular to a relay driving circuit and a relay control device. Background Art

[0002] Relays are widely used in various industrial fields. The working principle of a relay is to control the on-off of the relay switch by controlling the current in the relay coil.

[0003] However, the current in the relay coil will generate a large amount of heat, with high energy consumption. Moreover, when working for a long time, or in harsh environments such as high temperature or airtight spaces, the generated heat will greatly affect the lifespan of the relay, and thus affect the reliability of related equipment. Summary of the Utility Model

[0004] The utility model provides a relay driving circuit and a relay control device to solve the defect in the prior art that the high energy consumption of the relay affects the lifespan of the relay and the reliability of related equipment, save energy and reduce consumption, and improve the lifespan of the relay body and the reliability of related equipment.

[0005] The utility model provides a relay driving circuit, including: a power supply, a diode, a first current limiting unit, a second current limiting unit, and a relay body, where:

[0006] The power supply is respectively connected to the relay body and the negative electrode of the diode, and the power supply is used to provide working current for the relay body;

[0007] The first current limiting unit is respectively connected to the positive electrode of the diode, the second current limiting unit, the relay body, and a control unit; the second current limiting unit is respectively connected to the positive electrode of the diode, the relay body, and the control unit, and the second current limiting unit is grounded;

[0008] The control unit is used to generate a first control signal corresponding to the first current limiting unit and a second control signal corresponding to the second current limiting unit, and based on the first control signal and the second control signal, while maintaining the working state of the relay body, reduce the working current flowing through the relay body; the first control signal is used to control the on-off state of the first current limiting unit, and the second control signal is used to control the on-off state of the second current limiting unit.

[0009] According to the relay driving circuit provided by the present utility model, the first end of the first current limiting unit is connected to the first control end of the control unit, the second end of the first current limiting unit is respectively connected to the second control end of the control unit and the first end of the second current limiting unit, the third end of the first current limiting unit is respectively connected to the positive electrode of the diode and the third end of the second current limiting unit, and the second end of the second current limiting unit is grounded.

[0010] According to the relay driving circuit provided by the present utility model, the first current limiting unit includes a first constant current circuit or a first switching circuit;

[0011] The first end corresponding to the first constant current circuit or the first switching circuit serves as the first end of the first current limiting unit, the second end corresponding to the first constant current circuit or the first switching circuit serves as the second end of the first current limiting unit, and the third end corresponding to the first constant current circuit or the first switching circuit serves as the third end of the first current limiting unit.

[0012] According to the relay driving circuit provided by the present utility model, the first constant current circuit includes a first constant current switching tube, a first resistor, and a first switching tube, wherein:

[0013] The first end of the first constant current switching tube is respectively connected to the second end of the first constant current switching tube and the first end of the first switching tube, and the first end of the first constant current switching tube serves as the first end of the first constant current circuit. The third end of the first constant current switching tube is connected to one end of the first resistor, and the third end of the first constant current switching tube serves as the third end of the first constant current circuit. The other end of the first resistor is connected to the third end of the first switching tube, and the second end of the first switching tube serves as the second end of the first constant current circuit.

[0014] According to the relay driving circuit provided by the present utility model, the first switching circuit includes a second resistor and a second switching tube, wherein:

[0015] The first end of the second switching tube serves as the first end of the first switching circuit, the second end of the second switching tube serves as the second end of the first switching circuit, the third end of the second switching tube is connected to one end of the second resistor, and the other end of the second resistor serves as the third end of the first switching circuit.

[0016] According to the relay driving circuit provided by the present utility model, the second current limiting unit includes a second constant current circuit or a second switching circuit;

[0017] The first end corresponding to the second constant current circuit or the second switching circuit serves as the first end of the second current limiting unit, the second end corresponding to the second constant current circuit or the second switching circuit serves as the second end of the second current limiting unit, and the third end corresponding to the second constant current circuit or the second switching circuit serves as the third end of the second current limiting unit.

[0018] According to the relay driving circuit provided by the present invention, the second constant current circuit has the same structure as the first constant current circuit.

[0019] According to the relay driving circuit provided by the present invention, the second switching circuit has the same structure as the first switching circuit.

[0020] According to the relay driving circuit provided by the present invention, it further includes a first current limiting resistor and a second current limiting resistor. The first current limiting resistor is connected in series between the first control end of the control unit and the first end of the first current limiting unit; the second current limiting resistor is connected in series between the second control end of the control unit and the first end of the second current limiting unit.

[0021] The present invention further provides a relay control device, including: a control unit and the relay driving circuit as described in any one of the above.

[0022] For the relay driving circuit and the relay control device provided by the present invention, the power supply is respectively connected to the relay body and the negative electrode of the diode. The first current limiting unit is respectively connected to the positive electrode of the diode, the second current limiting unit, the relay body and the control unit; the second current limiting unit is respectively connected to the relay body and the control unit, and the second current limiting unit is grounded. After the power supply provides a working current for the relay body, the control unit generates a first control signal corresponding to the first current limiting unit and a second control signal corresponding to the second current limiting unit. After adjusting the working current based on the first control signal and the second control signal to make the relay body in a working state, when controlling the relay body to maintain the working state according to the second control signal, the working current flowing through the relay body is reduced by the first control signal, which not only ensures the working state of the relay body, but also saves energy and reduces consumption, reduces the heat generation of the relay coil in the relay body, and further improves the life of the relay body and the reliability of related equipment. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of a relay driving circuit provided by an embodiment of the present invention.

[0025] Figure 2 It is a schematic structural diagram of a first constant current circuit provided by an embodiment of the present invention.

[0026] Figure 3 It is a schematic structural diagram of a first switch circuit provided by an embodiment of the present invention.

[0027] Figure 4 It is a schematic structural diagram of a second constant current circuit provided by an embodiment of the present invention.

[0028] Figure 5 It is a schematic structural diagram of a second switch circuit provided by an embodiment of the present invention.

[0029] Figure 6 It is a schematic diagram of an example circuit of a relay driving circuit provided by an embodiment of the present invention.

[0030] Figure 7 It is a schematic structural diagram of a relay control device provided by an embodiment of the present invention.

[0031] Reference numerals:

[0032] 100: Relay driving circuit; 110: First current limiting unit; 111: First constant current circuit; 112: First switch circuit; 120: Second current limiting unit; 121: Second constant current circuit; 122: Second switch circuit; 200: Control unit. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0034] Aiming at the problem in the prior art that the high energy consumption of the relay affects the service life of the relay and the reliability of related equipment, an embodiment of the present invention provides a relay driving circuit. Figure 1 It is a schematic structural diagram of a relay driving circuit provided by an embodiment of the present invention. As Figure 1 shown, the relay driving circuit 100 includes: a power supply VCC, a diode D1, a first current limiting unit 110, a second current limiting unit 120, and a relay body K1.

[0035] The power supply VCC is respectively connected to the negative electrodes of the relay body K1 and the diode D1, and the power supply VCC is used to provide operating current for the relay body K1.

[0036] The first current limiting unit 110 is respectively connected to the positive electrode of the diode D1, the second current limiting unit 120, the relay body K1, and the control unit 200; the second current limiting unit 120 is respectively connected to the positive electrode of the diode D1, the relay body K1, and the control unit 200, and the second current limiting unit 120 is grounded.

[0037] The control unit 200 is used to generate a first control signal CTL1 corresponding to the first current limiting unit 110 and a second control signal CTL2 corresponding to the second current limiting unit 120, and based on the first control signal CTL1 and the second control signal CTL2, while maintaining the operating state of the relay body K1, reduce the operating current flowing through the relay body K1; the first control signal CTL1 is used to control the on / off state of the first current limiting unit 110, and the second control signal CTL2 is used to control the on / off state of the second current limiting unit 120.

[0038] Specifically, the relay body K1 includes a relay coil and a relay switch. The power supply VCC is connected to the relay coil in the relay body K1 to provide operating current for the relay coil. After the relay coil is powered on, according to the principle of electromagnetic induction, the relay coil will generate a magnetic field. When the magnetic field is large enough, it attracts the relay switch to act, controlling the separation or closing of the contacts in the relay switch to achieve the on-off control of the relay switch. However, the operating current in the relay coil will generate a large amount of heat, resulting in a relatively high power consumption of the relay body K1. Therefore, in the embodiment of the present invention, when the relay body K1 needs to work and the power supply VCC provides operating current for the relay body K1, first, the control unit 200 generates a first control signal CTL1 corresponding to the first current limiting unit 110 and a second control signal CTL2 corresponding to the second current limiting unit 120. The first current limiting unit 110 is controlled to conduct through the first control signal CTL1, and the second current limiting unit 120 is controlled to conduct through the second control signal CTL2. At this time, since the relay body K1 is on the main path, while the first current limiting unit 110 and the second current limiting unit 120 are respectively on two branch paths, therefore, according to the connection relationship of the relay body K1, the first current limiting unit 110, and the second current limiting unit 120, it can be known that the operating current of the relay coil is the sum of the currents corresponding to the first current limiting unit 110 and the second current limiting unit 120 respectively. Through the conducting first current limiting unit 110 and second current limiting unit 120, the operating current flowing through the relay coil can be adjusted to reach the starting current, so that the magnetic field generated by the relay coil attracts the relay switch, making the relay body K1 in the working state. After the relay text works stably, the control unit 200 generates the first control signal CTL1 again, and the first current limiting circuit is controlled to turn off through the first control signal CTL1 generated for the second time. At this time, the operating current in the relay coil is adjusted to the holding current through the second current limiting unit 120. The current value of the holding current is lower than the rated current value of the starting current. While maintaining the working state of the relay body K1 through the holding current, the operating current in the relay coil is reduced, the heat generation is reduced, energy is saved and consumption is reduced, and the service life of the relay body K1 and the reliability of the equipment corresponding to the relay body K1 are improved.

[0039] Exemplarily, when the first control signal CTL1 is a low-level signal, the first current limiting unit 110 is controlled to conduct, and when the first control signal CTL1 is a high-level signal, the first current limiting unit 110 is controlled to turn off. When the second control signal CTL2 is a high-level signal, the second current limiting unit 120 is controlled to conduct, and when the second control signal CTL2 is a low-level signal, the second current limiting unit 120 is controlled to turn off.

[0040] It should be noted that the level state of the first control signal CTL1 generated for the second time is different from that of the first control signal CTL1 generated for the first time. For example, when the first control signal CTL1 generated for the first time is a low-level signal, the first control signal CTL1 generated for the second time is a high-level signal.

[0041] Optionally, the control unit 200 may be an MCU (Micro Controller Unit, micro control unit 200), a PLC (Programmable Logic Controller, programmable logic controller), a single-chip microcomputer, etc., and the embodiments of the present invention do not limit this.

[0042] Further, as Figure 1 shown, the first end of the first current limiting unit 110 is connected to the first control end of the control unit 200, the second end of the first current limiting unit 110 is respectively connected to the second control end of the control unit 200 and the first end of the second current limiting unit 120, the third end of the first current limiting unit 110 is respectively connected to the positive electrode of the diode D1 and the third end of the second current limiting unit 120, and the second end of the second current limiting unit 120 is grounded.

[0043] Further, the first current limiting unit 110 includes a first constant current circuit 111 or a first switching circuit 112;

[0044] The first end corresponding to the first constant current circuit 111 or the first switching circuit 112 serves as the first end of the first current limiting unit 110, the second end corresponding to the first constant current circuit 111 or the first switching circuit 112 serves as the second end of the first current limiting unit 110, and the third end corresponding to the first constant current circuit 111 or the first switching circuit 112 serves as the third end of the first current limiting unit 110.

[0045] Further, Figure 2 is a schematic structural diagram of the first constant current circuit provided by the embodiments of the present invention. As Figure 2 shown, the first constant current circuit 111 includes a first constant current switching transistor QH1, a first resistor R1, and a first switching transistor QK1, where:

[0046] The first end of the first constant-current switching transistor QH1 is respectively connected to the second end of the first constant-current switching transistor QH1 and the first end of the first switching transistor QK1, and the first end of the first constant-current switching transistor QH1 serves as the first end of the first constant-current circuit 111. The third end of the first constant-current switching transistor QH1 is connected to one end of the first resistor R1, and the third end of the first constant-current switching transistor QH1 serves as the third end of the first constant-current circuit 111. The other end of the first resistor R1 is connected to the third end of the first switching transistor QK1, and the second end of the first switching transistor QK1 serves as the second end of the first constant-current circuit 111.

[0047] Specifically, after the first end and the second end of the first constant-current switching transistor QH1 are connected, a constant-current semiconductor device is formed. The dynamic resistance corresponding to this constant-current semiconductor device is relatively large, generally in the order of megohms, and the current in the constant-current region corresponding to this constant-current semiconductor device is relatively small. Therefore, the first switching transistor QK1 is used to amplify the current flowing into the first constant-current circuit 111, thereby adjusting the current flowing into the first constant-current circuit 111. It can be Figure 2 seen that according to Kirchhoff's current law, the current flowing into the first constant-current circuit 111 is , where represents the constant current flowing through the first constant-current switching transistor QH1, and represents the current flowing through the first switching transistor QK1. According to the amplification principle of the first switching transistor QK1, , where represents the amplification factor of the first switching transistor QK1. It can be seen that the current flowing into the first constant-current circuit 111 can also be expressed as . When the amplification factor of the first switching transistor QK1 is much greater than 1, the current flowing through the first constant-current switching transistor QH1 can be ignored. Then the current flowing into the first constant-current circuit 111 can also be expressed as , that is, the current flowing through the first constant-current circuit 111

[0048] is approximately the current flowing through the first switching transistor QK1.

[0049] It should be noted that the current in the constant-current region corresponding to the constant-current semiconductor device generally remains between 0 and 10 mA, preferably between 5 and 6 mA. After the current is amplified by the first switching transistor QK1, it can reach 50 to 60 mA, or even a larger current value, and the amplified current value depends on the magnitude of the holding current corresponding to the relay coil.

[0050] Furthermore, Figure 3 is a schematic structural diagram of the first switching circuit provided by an embodiment of the present invention. As Figure 3 shown, the first switching circuit 112 includes a second resistor R2 and a second switching transistor QK2, where:

[0051] The first end of the second switching transistor QK2 serves as the first end of the first switching circuit 112, the second end of the second switching transistor QK2 serves as the second end of the first switching circuit 112, the third end of the second switching transistor QK2 is connected to one end of the second resistor R2, and the other end of the second resistor R2 serves as the third end of the first switching circuit 112.

[0052] Specifically, in the first switching circuit 112, the second resistor R2 is connected in series with the second switching transistor QK2. Therefore, the current flowing into the first switching circuit 112, the current flowing through the second resistor R2, and the current flowing through the second switching transistor QK2 are equal. At the same time, the on / off state of the first switching circuit 112 depends on the on / off state of the second switching transistor QK2. That is, when the signal at the first end of the second switching transistor QK2 is a high-level signal, the second switching transistor QK2 is turned on, and then the first switching circuit 112 is turned on. On the contrary, when the signal at the first end of the second switching transistor QK2 is a low-level signal, the second switching transistor QK2 is turned off, and then the first switching circuit 112 is turned off.

[0053] It should be noted that the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2 can be a JFET (Junction Field Effect Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), an IGBT (Insulate-Gate Bipolar Transistor), or a triode. The types of the first constant-current switching transistor QH1, the first switching transistor QK1, and the second switching transistor QK2 can be the same or different, and the embodiments of the present invention do not limit this. When the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2 is a JFET, a MOSFET, or an IGBT, the gate of the JFET, MOSFET, or IGBT serves as the first end of the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2, the source of the JFET, MOSFET, or IGBT serves as the second end of the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2, and the drain of the JFET, MOSFET, or IGBT serves as the third end of the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2. When the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2 is a triode, the base of the triode serves as the first end of the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2, the emitter of the triode serves as the second end of the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2, and the collector of the triode serves as the third end of the first constant-current switching transistor QH1, the first switching transistor QK1, or the second switching transistor QK2.

[0054] Further, the second current-limiting unit 120 includes a second constant-current circuit 121 or a second switching circuit 122;

[0055] The corresponding first ends of the second constant-current circuit 121 or the second switching circuit 122 serve as the first end of the second current-limiting unit 120, the corresponding second ends of the second constant-current circuit 121 or the second switching circuit 122 serve as the second end of the second current-limiting unit 120, and the corresponding third ends of the second constant-current circuit 121 or the second switching circuit 122 serve as the third end of the second current-limiting unit 120.

[0056] Specifically, when the first current limiting unit 110 includes the first constant current circuit 111 or the first switch circuit 112, and the second current limiting unit 120 includes the second constant current circuit 121 or the second switch circuit 122, there are four combinations of the first current limiting unit 110 and the second current limiting unit 120, which are: the first current limiting unit 110 is the first constant current circuit 111, and the second current limiting unit 120 is the second constant current circuit 121; the first current limiting unit 110 is the first constant current circuit 111, and the second current limiting unit 120 is the second switch circuit 122; the first current limiting unit 110 is the first switch circuit 112, and the second current limiting unit 120 is the second constant current circuit 121; the first current limiting unit 110 is the first switch circuit 112, and the second current limiting unit 120 is the second switch circuit 122.

[0057] Further, the second constant current circuit 121 has the same structure as the first constant current circuit 111.

[0058] Specifically, Figure 4 is a schematic structural diagram of the second constant current circuit provided by an embodiment of the present invention. As Figure 4 shown, the second constant current tube includes a second constant current switching tube QH2, a third resistor R3, and a third switching tube QK3, where: the first end of the second constant current switching tube QH2 is respectively connected to the second end of the second constant current switching tube QH2 and the first end of the third switching tube QK3, and the first end of the second constant current switching tube QH2 serves as the first end of the second constant current circuit 121. The third end of the second constant current switching tube QH2 is connected to one end of the third resistor R3, and the third end of the second constant current switching tube QH2 serves as the third end of the second constant current circuit 121. The other end of the third resistor R3 is connected to the third end of the third switching tube QK3, and the second end of the third switching tube QK3 serves as the second end of the second constant current circuit 121. Since the second constant current circuit 121 has the same structure as the first constant current circuit 111, the second constant current circuit 121 has the same characteristics as the first constant current circuit 111. For example, in the second constant current circuit 121, when the amplification factor of the third switching tube QK3 is much greater than 1, the current flowing into the second constant current switching tube QH2 can be ignored, and the current flowing into the second constant current circuit 121 is approximately the current flowing through the third switching tube QK3. Another example is that the on / off state of the second constant current circuit 121 depends on the on / off state of the third switching tube QK3. That is, when the signal at the first end of the third switching tube QK3 is a low-level signal, the third switching tube QK3 is turned on, and the second constant current circuit 121 is turned on. Conversely, when the signal at the first end of the third switching tube QK3 is a high-level signal, the third switching tube QK3 is turned off, and the second constant current circuit 121 is turned off.

[0059] Further, the second switch circuit 122 has the same structure as the first switch circuit 112.

[0060] Specifically,Figure 5 is a schematic structural diagram of a second switch circuit provided by an embodiment of the present invention. As Figure 5 shown, the second switch circuit 122 includes a fourth resistor R4 and a fourth switching transistor QK4, where: the first end of the fourth switching transistor QK4 serves as the first end of the second switch circuit 122, the second end of the fourth switching transistor QK4 serves as the second end of the second switch circuit 122, the third end of the fourth switching transistor QK4 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 serves as the third end of the second switch circuit 122. In the second switch circuit 122, the fourth resistor R4 is in series with the fourth switching transistor QK4. Therefore, the current flowing into the second switch circuit 122, the current flowing through the fourth resistor R4, and the current flowing through the fourth switching transistor QK4 are equal. At the same time, the on / off state of the second switch circuit 122 depends on the on / off state of the fourth switching transistor QK4, that is, when the signal at the first end of the fourth switching transistor QK4 is a high-level signal, the fourth switching transistor QK4 is turned on, and then the second switch circuit 122 is turned on. Conversely, when the signal at the first end of the fourth switching transistor QK4 is a low-level signal, the fourth switching transistor QK4 is turned off, and then the second switch circuit 122 is turned off.

[0061] In addition, the on / off state of the relay body K1 depends on the on / off state of the third switching transistor QK3 in the second constant current circuit 121 in the second current limiting unit 120 or the on / off state of the fourth switching transistor QK4 in the second switch circuit 122. The on / off state of the relay body K1 is used to indicate whether the relay coil is energized. When the second current limiting unit 120 includes the second constant current circuit 121, if the third switching transistor QK3 is turned on, the second constant current circuit 121 is turned on, the relay coil in the relay body K1 is energized, and the relay switch may be closed; if the third switching transistor QK3 is turned off, the second constant current circuit 121 is turned off, the relay coil is de-energized, and the relay switch is opened. Similarly, when the second current limiting unit 120 includes the second switch circuit 122, if the fourth switching transistor QK4 is turned on, the second switch circuit 122 is turned on, the relay coil in the relay body K1 is energized, and the relay switch may be closed; if the fourth switching transistor QK4 is turned off, the second switch circuit 122 is turned off, the relay coil is de-energized, and the relay switch is opened.

[0062] It should be noted that the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4 can be a JFET, a MOSFET, an IGBT or a triode. The types of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4 can be the same or different, and the embodiments of the present invention do not limit this. When the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4 is a JFET, a MOSFET or an IGBT, the gate of the JFET, the MOSFET or the IGBT serves as the first end of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4, the source of the JFET, the MOSFET or the IGBT serves as the second end of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4, and the drain of the JFET, the MOSFET or the IGBT serves as the third end of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4. When the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4 is a triode, the base of the triode serves as the first end of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4, the emitter of the triode serves as the second end of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4, and the collector of the triode serves as the third end of the second constant-current switching transistor QH2, the third switching transistor QK3 or the fourth switching transistor QK4.

[0063] It should be noted that according to Kirchhoff's current law, the working current flowing through the relay coil is the sum of the currents flowing through the first current-limiting unit 110 and the second current-limiting unit 120, that is, , where I represents the working current flowing through the relay coil, represents the current flowing through the first current-limiting unit 110, represents the current flowing through the second current-limiting unit 120. When the working current I flowing through the relay coil is the holding current of the relay body K1, the relay body K1 can be started to work. Based on this, can be determined. When the first current-limiting unit 110 is turned off, then , and the relay body K1 is connected in series with the second current-limiting unit 120. Since the resistance values of the third switching transistor QK3 or the fourth switching transistor QK4 in the second current-limiting unit 120 are small and can be ignored, the first equivalent resistance corresponding to the second current-limiting unit 120 can be the third resistor R3 in the second constant-current circuit 121 or the fourth resistor R4 in the second switching circuit 122. At this time, when the impedance of the relay coil in the relay body K1 is known as and the output voltage of the power supply VCC is U, can be determined, where Represents the first equivalent resistance corresponding to the second current limiting unit 120. According to the calculation formula of the output voltage of the power supply VCC, the first equivalent resistance in the second current limiting unit 120 can be determined. The resistance value of can be . This first equivalent resistance can ensure that the on-off state of the second current limiting unit 120 can determine the on-off state of the relay body K1. When only the second current limiting unit 120 is conducting, or both the second current limiting unit 120 and the first current limiting unit 110 are conducting, the relay body K1 can be started. And if the second current limiting unit 120 is turned off, since the working current is directly less than the starting current, the relay body K1 is turned off.

[0064] Furthermore, the relay driving circuit 100 further includes a first current limiting resistor RX1 and a second current limiting resistor RX2. The first current limiting resistor RX1 is connected in series between the first control end of the control unit 200 and the first end of the first current limiting unit 110; the second current limiting resistor RX2 is connected in series between the second control end of the control unit 200 and the first end of the second current limiting unit 120.

[0065] It should be noted that the first current limiting resistor RX1 plays a current limiting role and is used to protect the first switching tube QK1 in the first constant current circuit 111 or the second switching tube QK2 in the first switching circuit 112 in the first current limiting unit 110 during overcurrent. The second current limiting resistor RX2 plays a current limiting role and is used to protect the third switching tube QK3 in the second constant current circuit 121 or the fourth switching tube QK4 in the second switching circuit 122 in the second current limiting unit 120 during overcurrent.

[0066] It should be noted that after the relay coil is powered off, a too high impact current may be generated. The diode can be used to protect the first switching tube QK1 in the first constant current circuit 111 or the second switching tube QK2 in the first switching circuit 112 in the first current limiting unit 110 from the impact of the impact current.

[0067] Exemplarily, taking the first current limiting unit 110 including the first constant current circuit 111 and the second current limiting unit 120 including the second switching circuit 122 as an example, Figure 6 is an example circuit schematic diagram of the relay driving circuit provided by the embodiment of the present invention. As Figure 6 shown, the working principle of the relay driving circuit 100 is as follows.

[0068] When the relay body K1 needs to work, the first control signal CTL1 generated by the control unit 200 is a low-level signal. This first control signal CTL1 controls the first switching transistor QK1 to conduct, so as to conduct the first current-limiting unit 110. At the same time, the second control signal CTL2 generated by the control unit 200 is a high-level signal. This second control signal CTL2 controls the second switching transistor QK2 to conduct, so as to conduct the second current-limiting unit 120.

[0069] (2)After the second current-limiting unit 120 is conducted, the power supply VCC, the relay body K1, and the second current-limiting unit 120 form a closed loop. The power supply VCC provides a working current for the relay coil in the relay body K1. Based on the fourth resistor R4 in the second current-limiting unit 120, the working current in the relay coil can be adjusted to reach the holding current. Based on the first resistor R1 in the first current-limiting unit 110, on the basis of the holding current, the working current in the relay coil can be further adjusted to reach the starting current, so as to energize the relay coil and generate a magnetic field, attract the relay switch, and make the relay body K1 in a working state.

[0070] (3)After the relay switch is stably attracted, the first control signal CTL1 generated by the control unit 200 for the second time is a high-level signal. The first control signal CTL1 generated for the second time controls the first switching transistor QK1 to turn off, so as to turn off the first current-limiting unit 110. At the same time, the control unit 200 controls the second current-limiting unit 120 to remain in the conducting state. Based on the presence of the fourth resistor R4 in the second current-limiting unit 120, it can be ensured that the current in the relay coil reaches the holding current, maintaining the existing working state. And the holding current at this time is lower than the starting current. By reducing the working current, the heat generation of the relay coil is reduced, saving energy and reducing consumption.

[0071] In the relay driving circuit provided by the embodiment of the present invention, the power supply is connected to the relay body. The first current-limiting unit is connected in parallel with the second current-limiting unit, and after being connected in parallel, it is connected in series with the relay body. After the power supply provides a working current for the relay body, by generating a first control signal corresponding to the first current-limiting unit and a second control signal corresponding to the second current-limiting unit by the control unit, after adjusting the working current based on the first control signal and the second control signal to make the relay body in a working state, when controlling the relay body to maintain the working state according to the second control signal, the working current flowing through the relay body is reduced by the first control signal, which not only ensures the working state of the relay body, but also saves energy and reduces consumption, reduces the heat generation of the relay coil in the relay body, and further improves the service life of the relay body and the reliability of related equipment.

[0072] The embodiment of the present invention also provides a relay control device. Figure 7 It is a schematic structural diagram of the relay control device provided by the embodiment of the present invention, asFigure 7 As shown, the relay control device includes: a control unit 200 and a relay drive circuit 100 as described in any one of the above.

[0073] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A relay drive circuit, characterized in that: include: A power supply, a diode, a first current limiting unit, a second current limiting unit and a relay body, wherein: The power supply is connected to the relay body and the cathode of the diode respectively, and the power supply is used to provide working current for the relay body; The first current limiting unit is respectively connected to the anode of the diode, the second current limiting unit, the relay body and the control unit; the second current limiting unit is respectively connected to the anode of the diode, the relay body and the control unit, and the second current limiting unit is grounded; The control unit is used to generate a first control signal corresponding to the first current limiting unit and a second control signal corresponding to the second current limiting unit, and based on the first control signal and the second control signal, reduce the working current flowing through the relay body while maintaining the working state of the relay body; the first control signal is used to control the on-off state of the first current limiting unit, and the second control signal is used to control the on-off state of the second current limiting unit.

2. The relay drive circuit according to claim 1, characterized in that: The first end of the first current limiting unit is connected to the first control end of the control unit, the second end of the first current limiting unit is respectively connected to the second control end of the control unit and the first end of the second current limiting unit, the third end of the first current limiting unit is respectively connected to the positive electrode of the diode and the third end of the second current limiting unit, and the second end of the second current limiting unit is grounded.

3. The relay drive circuit according to claim 2, characterized in that: The first current limiting unit includes a first constant current circuit or a first switch circuit; The first end corresponding to the first constant current circuit or the first switch circuit serves as the first end of the first current limiting unit, the second end corresponding to the first constant current circuit or the first switch circuit serves as the second end of the first current limiting unit, and the third end corresponding to the first constant current circuit or the first switch circuit serves as the third end of the first current limiting unit.

4. The relay drive circuit according to claim 3, characterized in that: The first constant current circuit includes a first constant current switch tube, a first resistor and a first switch tube, wherein: The first end of the first constant current switch tube is respectively connected to the second end of the first constant current switch tube and the first end of the first switch tube, and the first end of the first constant current switch tube serves as the first end of the first constant current circuit, the third end of the first constant current switch tube is connected to one end of the first resistor, and the third end of the first constant current switch tube serves as the third end of the first constant current circuit, the other end of the first resistor is connected to the third end of the first switch tube, and the second end of the first switch tube serves as the second end of the first constant current circuit.

5. The relay drive circuit according to claim 4, characterized in that: The first switch circuit includes a second resistor and a second switch tube, wherein: The first end of the second switch tube serves as the first end of the first switch circuit, the second end of the second switch tube serves as the second end of the first switch circuit, the third end of the second switch tube is connected to one end of the second resistor, and the other end of the second resistor serves as the third end of the first switch circuit.

6. The relay drive circuit according to any one of claims 3 to 5, characterized in that: The second current limiting unit includes a second constant current circuit or a second switch circuit; The first end corresponding to the second constant current circuit or the second switch circuit serves as the first end of the second current limiting unit, the second end corresponding to the second constant current circuit or the second switch circuit serves as the second end of the second current limiting unit, and the third end corresponding to the second constant current circuit or the second switch circuit serves as the third end of the second current limiting unit.

7. The relay drive circuit according to claim 6, characterized in that: The second constant current circuit has the same structure as the first constant current circuit.

8. The relay drive circuit according to claim 6, characterized in that: The second switch circuit has the same structure as the first switch circuit.

9. The relay drive circuit according to any one of claims 1 to 5, characterized in that: It also includes a first current limiting resistor and a second current limiting resistor, the first current limiting resistor is connected in series between the first control end of the control unit and the first end of the first current limiting unit; the second current limiting resistor is connected in series between the second control end of the control unit and the first end of the second current limiting unit.

10. A relay control device, characterized in that: include: A control unit and a relay drive circuit as claimed in any one of claims 1 to 9.

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