CN109494120B - Relay control circuit - Google Patents

Abstract

The invention relates to a relay control circuit, comprising: the switching module is used for receiving the first control signal or the second control signal, and when receiving the first control signal, the switching module controls the relay coil to be powered off so that the relay coil does not work; when receiving the second control signal, switch module relay coil circular telegram work, detection module detects the relay circular telegram, and output signal control delay module output delay voltage to reduce the pressure drop at relay coil both ends, can reduce relay coil's actual power through reducing relay coil both ends voltage, and then can reduce relay's consumption.

Description

Relay control circuit

Technical Field

The present invention relates to the field of relays, and in particular to a relay control circuit.

Background technique

An electromagnetic relay is an electronic device that uses a low-voltage control circuit to control the operation of a high-voltage working circuit. It is commonly used in various electronic circuits. Usually, an electromagnetic relay consists of a coil, an armature, a contact spring, etc. When current flows through the coil, the armature will be attracted to the coil under the action of the electromagnetic effect, and then the moving contact and the static contact will contact. By making the moving contact and the static contact contact and disconnect the control circuit, it is easy to use. When using traditional relays, the inventor found that the relay power consumption is high during use.

Summary of the invention

Based on this, it is necessary to provide a relay control circuit to address the problem of high power consumption of traditional relays.

A relay control circuit, comprising:

A relay coil, wherein a first end of the relay coil is connected to a power source;

a switching module connected to the second end of the relay coil, the switching module being used to receive a first control signal or a second control signal, wherein when the switching module receives the first control signal, the switching module controls the relay coil to be powered off and outputs a high level signal, and when the switching module receives the second control signal, the switching module controls the relay coil to be powered on and outputs a low level signal;

A detection module, used for detecting a level signal, when the level signal is detected to be the low level signal, the detection module outputs a first state signal, when the level signal is detected to be the high level signal, the detection module outputs a second state signal;

The delay module is used to receive the first state signal or the second state signal. When the delay module receives the first state signal, the delay module controls the switching module to disconnect so that the relay coil is continuously powered off. When the delay module receives the second state signal, the delay module controls the switching module to turn on and outputs a delay voltage to the second end of the relay coil through the switching module to reduce the voltage drop across the relay coil.

In one of the embodiments, the switching module includes a first switch unit and a protection unit;

The first end of the first switch unit is used to input the first control signal or the second control signal, the second end of the first switch unit is respectively connected to one end of the relay coil and one end of the protection unit, the first switch unit is used to be disconnected under the action of the first control signal to de-energize the relay coil, and the second end of the first switch unit outputs the high level signal, or the first switch unit is used to be turned on under the action of the second control signal to energize the relay coil, and the second end of the first switch unit outputs the low level signal;

The other end of the protection unit is connected to the first end of the relay coil and the power supply, and is used to eliminate the induced voltage of the relay coil.

In one of the embodiments, the detection module includes a comparison unit and a voltage division unit;

The comparison unit includes a first input end, a second input end and an output end, the first input end is respectively connected to the second end of the first switch unit and the second end of the relay coil, and is used to receive the high level signal or the low level signal output by the first switch unit, the second input end is connected to the voltage divider unit, and is used to receive the fixed voltage signal output by the voltage divider unit, and the output end is connected to the delay module;

The comparison unit is used to compare the size of the high-level signal or the low-level signal with the fixed voltage signal. When the comparison unit receives the high-level signal, the comparison unit outputs the first state signal to the delay module. When the comparison unit receives the low-level signal, the comparison unit outputs the second state signal to the delay module.

In one of the embodiments, the delay module includes a second switch unit and a voltage stabilizing unit;

The first end of the second switch unit is connected to the output end of the comparison unit, and is used to receive the first state signal or the second state signal; the second end of the second switch unit is respectively connected to one end of the voltage stabilizing unit and the third end of the first switch unit; the third end of the second switch unit is connected to the other end of the voltage stabilizing unit and ground;

When the second switch unit receives the first state signal, the second switch unit controls the first switch unit to be continuously disconnected so that the relay coil remains de-energized. When the second switch unit receives the second state signal, the second switch unit is disconnected so that the voltage stabilizing unit is connected to the circuit. The voltage stabilizing unit outputs the delayed voltage to the second end of the relay coil through the first switch unit to reduce the voltage drop across the relay coil.

In one of the embodiments, the delay module further includes a charge and discharge unit;

One end of the charge-discharge unit is respectively connected to the first end of the second switch unit and the output end of the comparison unit, and the other end of the charge-discharge unit is respectively connected to the third end of the second switch unit and the ground;

When the comparison unit outputs the first state signal, the comparison unit charges the charge-discharge unit. When the comparison unit outputs the second state signal, the charge-discharge unit charges the second switch unit to delay disconnection of the second switch unit.

In one embodiment, the first switch unit includes a transistor T1, and the protection unit includes a diode D1;

The base of the transistor T1 is used to receive the first control signal or the second control signal, the collector of the transistor T1 is respectively connected to one end of the relay coil, the cathode of the diode D1 and the first input end of the detection module, the anode of the diode D1 is respectively connected to the first end of the relay coil and the power supply, the emitter of the transistor T1 is connected to the second end of the delay module, when the transistor T1 receives the first control signal, the transistor T1 is disconnected to de-energize the relay coil; when the transistor T1 receives the second control signal, the transistor T1 is turned on to energize the relay coil.

In one embodiment, the comparison unit includes an operational amplifier U1, and the voltage dividing unit includes a resistor R1 and a resistor R2;

The operational amplifier U1 includes a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is respectively connected to the collector of the transistor T1, the second terminal of the relay coil and the anode of the diode D1; the output terminal is connected to the first terminal of the second switch unit;

One end of the resistor R1 is connected to the power supply, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the second input end, and the other end of the resistor R2 is grounded.

In one embodiment, the charging and discharging unit includes a capacitor C1, one end of the capacitor C1 is respectively connected to the output end of the operational amplifier U1 and the first end of the second switch unit, and the other end of the capacitor C1 is grounded.

In one embodiment, the second switch unit includes a transistor T2, the base of the transistor T2 is connected to the output end of the operational amplifier U1 and one end of the capacitor C1, the collector of the transistor T2 is respectively connected to one end of the voltage stabilizing unit and the emitter of the transistor T1, and the emitter of the transistor T2 is respectively connected to the other end of the voltage stabilizing unit and the ground.

In one embodiment, the voltage stabilizing unit includes a voltage stabilizing diode ZD1, an anode of the voltage stabilizing diode ZD1 is respectively connected to the emitter of the transistor T1 and the collector of the transistor T2, and a cathode of the voltage stabilizing diode ZD1 is respectively connected to the emitter of the transistor T2 and ground.

The above-mentioned relay control circuit, when receiving a first control signal, controls the relay coil to cut off the power so that the relay coil does not work. When receiving a second control signal, the relay coil is energized to work. By adopting a delay module to output a delay voltage, the voltage drop across the relay coil can be reduced. By reducing the voltage drop, the actual power of the relay coil can be reduced, thereby reducing the power consumption of the relay.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a relay control circuit module provided by an embodiment of the present application;

FIG2 is a schematic diagram of a relay control circuit module provided in yet another embodiment of the present application;

FIG3 is a schematic diagram of the structure of a relay control circuit provided in one embodiment of the present application.

Detailed ways

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

Please refer to FIG. 1 . An embodiment of the present application provides a relay control circuit, comprising: a switching module 100, a detection module 200, a delay module 300 and a relay coil 400. The first end of the relay coil 400 is connected to a power source, and the second end is connected to the switching module 100. The switching module 100 is used to receive a first control signal or a second control signal. When the switching module 100 receives the first control signal, the switching module 100 controls the relay coil 400 to be powered off and output a high level signal; when the switching module 100 receives the second control signal, the switching module 100 controls the relay coil 400 to be powered on and output a low level signal. The detection module 200 is used to receive a low level signal or a high level signal. When the detection module 200 receives a low level signal, the detection module 200 outputs a first state signal; when the detection module 200 receives a high level signal, the detection module 200 outputs a second state signal. The delay module 300 is used to receive a first state signal or a second state signal. When the delay module 300 receives a first state signal, the delay module 300 controls the switching module 100 to disconnect so that the relay coil 400 is continuously powered off; when the delay module 300 receives a second state signal, the delay module 300 controls the switching module 100 to turn on and outputs a delay voltage to the second end of the relay coil 400 through the switching module 100 to reduce the voltage drop across the relay coil 400.

Specifically, the relay control circuit provided in the embodiment of the present application can be used in various electrical tools. The switching module 100 is connected to the main control module in the electrical tool, and the main control module outputs the first control signal or the second control signal to the input end of the switching module 100. In this embodiment, the first control signal and the second control signal can both be voltage signals, wherein the first control signal can be a low voltage and the second control signal can be a high voltage.

The first end of the relay coil 400 is connected to the power supply, the second end of the relay coil 400 is connected to the switching module 100, and the moving contact and the static contact of the relay are connected to the working circuit of the electric tool to control the on and off of the working circuit. The switching module 100 can be disconnected under the action of the first control signal, then there is no voltage drop at both ends of the relay coil 400 connected to the switching module 100, and the switching module 100 outputs a high-level signal. The detection module 200 receives the high-level signal output by the switching module 100, and by processing the signal, it can detect that the current relay coil 400 is not powered on, and then outputs a first state signal. The delay module 300 controls the switching module 100 to remain disconnected after processing the received first state signal, so that the relay coil 400 is continuously powered off. That is, when the switching module 100 receives the first control signal, the relay coil 400 does not work.

When the switching module 100 receives the second control signal, the switching module 100 is turned on under the action of the second control signal, and the relay coil 400 connected to the switching module 100 is energized, and the switching module 100 outputs a low voltage signal. The detection module 200 processes the detected low voltage signal to determine that the current relay coil 400 is in the energized state, and the detection module 200 outputs the second state signal. After the delay module 300 processes the received second state signal, it controls the switching module 100 to continue to be turned on, and outputs the delay voltage to the second end of the relay coil 400 through the switching module 100 to reduce the voltage drop across the relay coil 400.

The above-mentioned relay control circuit, when receiving a first control signal, controls the relay coil 400 to cut off the power so that the relay coil does not work. When receiving a second control signal, the relay coil 400 is powered on to work. By adopting a delay module to output a delay voltage, the voltage drop across the relay coil 400 can be reduced. By reducing the voltage drop, the actual power of the relay coil 400 can be reduced, thereby reducing the power consumption of the relay.

Please refer to FIG. 2 . In one embodiment, the switching module 100 includes a first switch unit 110 and a protection unit 120. The first switch unit 110 includes a first end, a second end, and a third end. The first end of the first switch unit 110 is used to input a first control signal or a second control signal, the second end is respectively connected to the second end of the relay coil 400 and one end of the protection unit 120, the third end is connected to the delay module 300, and the other end of the protection unit 120 and the first end of the relay coil 400 are connected to a power supply. The first switch unit 110 is used to disconnect under the action of the first control signal to de-energize the relay coil 400, and at this time, the second end of the first switch unit 110 outputs a high level signal. Or the first switch unit 110 is used to conduct under the action of the second control signal to energize the relay coil 400, and at this time, the second end of the first switch unit 110 outputs a low level signal.

In this embodiment, the first switch unit 110 can be turned on or off under the control of voltage, specifically, it can be turned off under the action of a low level and turned on under the action of a high level, thereby de-energizing or energizing the relay coil 400. The protection unit 120 is connected in parallel to both ends of the relay coil 400 to eliminate the influence of the induced voltage generated when the relay coil 400 is energized.

The detection module 200 includes a comparison unit 210 and a voltage divider unit 220. The comparison unit 210 includes a first input terminal, a second input terminal and an output terminal. The first input terminal is connected to a common connection point of the second terminal of the first switch unit 110, the first terminal of the relay coil 400 and one end of the protection unit 120, and is used to receive a high level signal or a low level signal output by the second terminal of the first switch unit 110. The second input terminal is connected to the voltage divider unit 220, and is used to receive a fixed voltage signal of the voltage divider unit 220. The output terminal is connected to the delay module 300.

The comparison unit 210 is used to compare the voltage output by the first switch unit 110 and the fixed voltage output by the voltage divider unit 220, and judge whether the relay coil 400 is in the power-on state or the power-off state according to the comparison result. When the signal received by the comparison unit 210 is a high-level signal, the comparison unit 210 compares and processes the high-level signal and the fixed voltage signal, and judges that the relay coil 400 is in the power-off state according to the processing result, then the comparison unit 210 outputs a first state signal to the delay module 300. When the signal received by the comparison unit 210 is a low-level signal, the comparison unit 210 compares and processes the low-level signal and the fixed voltage signal, and judges that the relay coil 400 is in the power-on state according to the processing result, then the comparison unit 210 outputs a second state signal to the delay module 300. In this embodiment, the first state signal may be a high-level signal, and the second state signal may be a low-level signal.

The delay module 300 includes a second switch unit 310, a voltage stabilizing unit 320 and a charge-discharge unit 330. One end of the charge-discharge unit 330 is respectively connected to the first end of the second switch unit 310 and the output end of the comparison unit 210, and the other end of the charge-discharge unit 330 is respectively connected to the third end of the second switch unit 310 and the ground.

When the comparison unit 210 outputs the first state signal, i.e., a high level signal, the comparison unit 210 charges the charge-discharge unit 330. At the same time, the second switch unit 310 is turned on under the action of the first state signal, and the second switch unit 310 controls the first switch unit 110 to be continuously turned off, so that the relay coil 400 remains de-energized and the relay does not work.

When the comparison unit 210 outputs the second state signal, i.e., the low level signal, the comparison unit 210 no longer charges the charge-discharge unit 330. The second switch unit 310 is about to be cut off under the action of the second state signal. At this time, the charge-discharge unit 330 discharges and charges the second switch unit 310. The second switch unit 310 will continue to be turned on under the action of the energy storage and discharge of the charge-discharge unit 330. The second switch unit 310 delays turning off to ensure that the first switch unit 110 is effectively turned on. When the energy storage of the charge-discharge unit 330 is exhausted, the second switch unit 310 is disconnected. At this time, the voltage stabilizing unit 320 is connected to the circuit. The voltage stabilizing unit 320 outputs a delayed voltage to the second end of the relay coil 400 through the first switch unit 110 to reduce the voltage drop across the two ends of the relay coil 400, thereby reducing the actual power of the relay coil 400, and further reducing the power consumption of the relay.

Please refer to FIG. 3 , in one embodiment, the first switch unit 110 includes a transistor T1, and the protection unit 120 includes a diode D1. The base of the transistor T1 is the first end of the first switch unit 110, which is used to receive the first control signal or the second control signal. The collector of the transistor T1 is the second end of the switch unit 110, which is respectively connected to the second end of the relay coil 400, the cathode of the diode D1 and the first input end of the detection module. The anode of the diode D1 is respectively connected to the first end of the relay coil 400 and the power supply. The emitter of the transistor T1 is also the third end of the first switch unit 110, which is connected to the second end of the delay module 300. When the transistor T1 receives the first control signal, the transistor T1 is disconnected to de-energize the relay coil 400. When the transistor T1 receives the second control signal, the transistor T1 is turned on to energize the relay coil 400.

In this embodiment, the transistor T1 can be an NPN transistor, the first control signal is a low level, the second control signal is a high level, the transistor T1 can be cut off under the action of the first control signal, and turned on under the action of the second control signal. Of course, the transistor T1 can also be a PNP transistor, in which case the first control signal is a high level and the second control signal is a low level.

The comparison unit 210 includes an operational amplifier U1, and the voltage divider unit 220 includes a resistor R1 and a resistor R2. The operational amplifier U1 includes a first input terminal, a second input terminal and an output terminal. The first input terminal is respectively connected to the collector of the transistor T1, the second end of the relay coil 400 and the common connection point A of the anode of the diode D1, and the output terminal is connected to the first end of the second switch unit and one end of the charge and discharge unit. One end of the resistor R1 is connected to the power supply, and the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the second input terminal, the common connection point of the resistor R1 and the resistor R2 is point B, and the other end of the resistor R2 is grounded. The comparison unit 210 may also include a feedback resistor R3, one end of the feedback resistor R3 is connected to the output terminal of the operational amplifier U1, and the other end is connected to one end of the resistor R1 and the power supply.

In this embodiment, the first input terminal of the amplifier U1 is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

The second switch unit 310 includes a transistor T2, the voltage stabilizing unit 320 includes a voltage stabilizing diode ZD1, and the charge-discharge unit 330 includes a capacitor C1. One end of the capacitor C1 is connected to the output end of the operational amplifier U1 and the base of the transistor T2, respectively, and the other end of the capacitor C1 is grounded. The collector of the transistor T2 is connected to the anode of the voltage stabilizing diode ZD1 and the emitter of the transistor T1, respectively, and their common connection point is point C, and the emitter of the transistor T2 is connected to the cathode of the voltage stabilizing diode ZD1 and the ground, respectively.

In this embodiment, the type of transistor T2 is the same as that of transistor T1, both of which are NPN transistors. At this time, the first state signal is a high level, and the second state signal is a low level. Of course, transistor T2 can also be a PNP transistor, then the first state signal is a low level, and the second state signal is a high level.

Next, the working principle of the circuit diagram shown in Figure 3 is explained:

For the convenience of principle description, the rated working voltage of the relay coil 400 is first defined as V ₀ , the rated power is defined as P ₀ , and the resistance of the relay coil 400 is defined as _RL . The actual working voltage of the relay coil 400 is defined as V ₁ , and the actual power of the relay coil 400 is defined as P ₁ . In the circuit provided in this embodiment, the power supply voltage Vcc is set to be equal to the rated working voltage V ₀ of the relay, the rated voltage V _Z of the Zener diode ZD1 is set to be 1/4 of the rated working voltage V ₀ of the relay, that is, V _Z =1/4V ₀ , and the resistance value of the resistor R1 is twice the resistance value of the resistor R2, that is: R1 =2R2.

When the base of transistor T1 inputs the first control signal, i.e., a low level, transistor T1 does not obtain a forward bias voltage and is in an open circuit state, and the relay coil 400 does not obtain a voltage and does not work. At this time, the voltage V _A = Vcc = V ₀ at the common connection point A of the collector of transistor T1 and the relay coil 400. The voltage at the common connection point B of the resistor R1 and the resistor R2 is divided by a voltage:

Therefore, _VA > _VB , that is, the voltage at the non-inverting input terminal of the operational amplifier U1 is higher than the voltage at the inverting input terminal of the operational amplifier U1, and the output terminal of the operational amplifier U1 outputs the first state signal, that is, a high level. The output terminal of the operational amplifier U1 charges the capacitor C1. The capacitor C1 is an electrolytic capacitor, the positive electrode of the capacitor C1 is connected to the output terminal of the operational amplifier U1 and the base of the transistor T2, and the negative electrode is grounded. When the positive electrode voltage of the capacitor C1 reaches the conduction threshold voltage of the transistor T2, the transistor T2 is forward biased and turned on, the voltage regulator diode ZD1 is short-circuited, and the voltage at the common connection point C is close to 0V, that is, the emitter of the transistor T1 is grounded, so the relay coil 400 remains in the power-off state.

When the base of transistor T1 inputs the second control signal, i.e., a high level, transistor T1 is forward biased and turned on, and the relay coil 400 is voltaged and turned on. At this time, since transistor T1 is turned on, the collector and emitter voltages of the transistor are approximately equal, i.e., the voltage at the common connection point A is infinitely close to the voltage at the common connection point C, and the voltage at point C is close to 0V, so V _A ≈ 0V. The voltage at point B is V _B ＝1/3V ₀ , so V _A ＜V _B , the voltage at the in-phase input terminal of operational amplifier U1 is lower than the voltage at the inverting input terminal, and the output terminal of operational amplifier U1 outputs a low level. Transistor T2 will be turned off, but since the energy storage discharge of capacitor C1 can keep transistor T2 turned on, transistor T2 will be turned off with a delay, and the delay generated in this way will ensure that the relay coil 400 is reliably turned on. When the charge of capacitor C1 is released to a level that is not enough to keep transistor T2 turned on, transistor T2 is turned off. At this time, Zener diode ZD1 is connected to the circuit, and the voltage at the common connection point C is the rated voltage of Zener diode ZD1, i.e. 1/4V ₀ . At the same time, the voltage at point A is also 1/4V ₀ , thereby reducing the voltage across relay coil 400 from V ₀ to 3/4V ₀ , i.e., the actual working voltage of the relay V1 = 3/4V ₀ .

The rated power of the relay is:

The actual working power of the relay is:

Therefore, by reducing the operating voltage across the relay coil 400, the current passing through the relay coil 400 will be reduced accordingly, so the actual working power is reduced, and the purpose of reducing the power consumption of the relay is finally achieved.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims (8)

1. A relay control circuit, comprising: A relay coil, wherein a first end of the relay coil is connected to a power source; A switching module connected to the second end of the relay coil, the switching module is used to receive a first control signal or a second control signal, when the switching module receives the first control signal, the switching module controls the relay coil to be powered off and outputs a high level signal, when the switching module receives the second control signal, the switching module controls the relay coil to be powered on and outputs a low level signal; wherein the switching module comprises a first switch unit, the first end of the first switch unit is used to input the first control signal or the second control signal, and the second end of the first switch unit is respectively connected to the first end of the relay coil and one end of the protection unit; A detection module, used for detecting a level signal, when the level signal is detected to be the low level signal, the detection module outputs a first state signal, when the level signal is detected to be the high level signal, the detection module outputs a second state signal; wherein, the detection module comprises a comparison unit and a voltage divider unit, the comparison unit outputs the first state signal or the second state signal, the comparison unit comprises a first input end, a second input end and an output end, the first input end is respectively connected to the second end of the first switch unit and the second end of the relay coil, for receiving the high level signal or the low level signal output by the first switch unit, the second input end is connected to the voltage divider unit, for receiving the fixed voltage signal output by the voltage divider unit, and the output end is connected to a delay module; A delay module, used for receiving the first state signal or the second state signal, when the delay module receives the first state signal, the delay module controls the switching module to be disconnected so that the relay coil is continuously powered off, when the delay module receives the second state signal, the delay module controls the switching module to be turned on and outputs a delay voltage to the second end of the relay coil through the switching module to reduce the voltage drop across the relay coil; the delay module includes a second switch unit, a voltage stabilizing unit and a charge-discharge unit, the voltage stabilizing unit and the comparison unit are both connected to the second switch unit, the second switch unit and the comparison unit are both also connected to the charge-discharge unit, and the second switch unit receives the first state signal or the second state signal; When the comparison unit outputs the first state signal, the comparison unit charges the charge-discharge unit, and when the comparison unit outputs the second state signal, the charge-discharge unit charges the second switch unit, so that the second switch unit is disconnected with a delayed time; When the second switch unit receives the first state signal, the second switch unit controls the first switch unit to be continuously disconnected so that the relay coil remains de-energized; when the second switch unit receives the second state signal, the second switch unit is disconnected so that the voltage stabilizing unit is connected to the circuit; the voltage stabilizing unit outputs the delayed voltage to the second end of the relay coil through the first switch unit so as to reduce the voltage drop across the relay coil; The first end of the second switch unit is connected to the output end of the comparison unit for receiving the first state signal or the second state signal, the second end of the second switch unit is respectively connected to one end of the voltage stabilizing unit and the third end of the first switch unit, and the third end of the second switch unit is respectively connected to the other end of the voltage stabilizing unit and the ground; one end of the charge and discharge unit is respectively connected to the first end of the second switch unit and the output end of the comparison unit, and the other end of the charge and discharge unit is respectively connected to the third end of the second switch unit and the ground. 2. The relay control circuit according to claim 1, characterized in that the switching module includes a protection unit; The first switch unit is used to be disconnected under the action of the first control signal to de-energize the relay coil, and the second end of the first switch unit outputs the high level signal, or the first switch unit is used to be turned on under the action of the second control signal to energize the relay coil, and the second end of the first switch unit outputs the low level signal; The other end of the protection unit is connected to the first end of the relay coil and the power supply, and is used to eliminate the induced voltage of the relay coil. 3. The relay control circuit according to claim 2 is characterized in that the comparison unit is used to compare the size of the high level signal or the low level signal with the fixed voltage signal, and when the comparison unit receives the high level signal, the comparison unit outputs the first state signal to the delay module, and when the comparison unit receives the low level signal, the comparison unit outputs the second state signal to the delay module. 4. The relay control circuit according to any one of claims 2 to 3, characterized in that the first switch unit comprises a transistor T1, and the protection unit comprises a diode D1; The base of the transistor T1 is used to receive the first control signal or the second control signal, the collector of the transistor T1 is respectively connected to one end of the relay coil, the cathode of the diode D1 and the first input end of the comparison unit in the detection module, the anode of the diode D1 is respectively connected to the first end of the relay coil and the power supply, the emitter of the transistor T1 is connected to the second end of the delay module, when the transistor T1 receives the first control signal, the transistor T1 is disconnected to de-energize the relay coil; when the transistor T1 receives the second control signal, the transistor T1 is turned on to energize the relay coil. 5. The relay control circuit according to claim 4, characterized in that the comparison unit comprises an operational amplifier U1, and the voltage dividing unit comprises a resistor R1 and a resistor R2; The operational amplifier U1 includes a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is respectively connected to the collector of the transistor T1, the second terminal of the relay coil and the anode of the diode D1; the output terminal is connected to the first terminal of the second switch unit; One end of the resistor R1 is connected to the power supply, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the second input end, and the other end of the resistor R2 is grounded. 6 . The relay control circuit according to claim 5 , wherein the charge and discharge unit comprises a capacitor C1 , one end of the capacitor C1 is respectively connected to the output end of the operational amplifier U1 and the first end of the second switch unit, and the other end of the capacitor C1 is grounded. 7. The relay control circuit according to claim 6 is characterized in that the second switch unit includes a transistor T2, the base of the transistor T2 is connected to the output end of the operational amplifier U1 and one end of the capacitor C1, the collector of the transistor T2 is respectively connected to one end of the voltage stabilizing unit and the emitter of the transistor T1, and the emitter of the transistor T2 is respectively connected to the other end of the voltage stabilizing unit and the ground. 8. The relay control circuit according to claim 7 is characterized in that the voltage stabilizing unit comprises a voltage stabilizing diode ZD1, an anode of the voltage stabilizing diode ZD1 is respectively connected to the emitter of the transistor T1 and the collector of the transistor T2, and a cathode of the voltage stabilizing diode ZD1 is respectively connected to the emitter of the transistor T2 and ground.