Anti-back electromotive force circuit

Abstract

The invention provides a counter electromotive force prevention circuit which comprises a power input end, a power output end, a counter electromotive force prevention assembly, a counter electromotive force absorption assembly, a counter electromotive force prevention state switching assembly, an energy caching assembly, a counter electromotive force release assembly and a power supply assembly. And the anti-reverse assembly is used for preventing reverse electromotive force generated by the load from impacting the power supply. The back electromotive force absorption assembly is used for absorbing back electromotive force generated by the load. And the back electromotive force release assembly is used for releasing the back electromotive force in the absorption assembly. When no back electromotive force is recovered, a transient impact energy caching assembly in the energy caching assembly performs energy caching on an instantaneous large energy signal of the anti-reverse assembly, and a back electromotive force auxiliary caching assembly in the energy caching assembly performs auxiliary absorption on the back electromotive force; the transient impact energy caching assembly and the back electromotive force auxiliary caching assembly release cached energy and merge the cached energy into a main loop, so that sudden change energy interference in the protection process is effectively restrained, and meanwhile the part of energy is prevented from being wasted.

Description

Technical Field

[0001] The invention relates to the field of electronic technology, and in particular to a circuit for preventing back electromotive force. Background Art

[0002] In power electronics applications, motors are typical inductive loads and are widely used in industrial automation, home appliances, transportation and other fields. However, when the motor decelerates from high-speed operation to a stop or suddenly loses power, the magnetic field in its internal coil does not disappear immediately. Instead, according to Faraday's law of electromagnetic induction, a high-amplitude back electromotive force (Back-EMF) is generated at both ends of the coil in the opposite direction to the power supply. If this instantaneous high-voltage and high-current energy is not properly handled, it will be directly fed back to the power supply, posing a serious threat to the power supply system.

[0003] Traditional power supply designs often lack effective protection measures against such reverse electromotive force impacts, which makes the power supply prone to overvoltage and overcurrent protection actions when encountering such situations, and even directly damages the electronic components inside the power supply, such as the rectifier bridge, power switch tube, etc. This not only increases the maintenance cost of the equipment, but also seriously affects the stability and operating efficiency of the system. In order to solve the above problems, some simple protection solutions have appeared on the market, such as adding passive components such as varistors and transient suppression diodes (TVS) to absorb part of the reverse energy. For example, Chinese utility model patent CN218124309U discloses using a diode to protect the power supply from the impact of reverse electromotive force. However, when the reverse electromotive force is not generated, the diode is also connected to the circuit for a long time, causing unnecessary consumption, and when the reverse electromotive force arrives, the diode anode has a node impact because the instantaneous cathode voltage is greater than its anode, resulting in the energy not being able to be instantly transferred to the cathode. This impact is a transient large energy interference signal, thereby interfering with the circuit. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide an anti-reverse electromotive force circuit, which short-circuits the anti-reverse component when no reverse electromotive force is generated in the loop, thereby avoiding continuous energy consumption of the anti-reverse component, and suppresses and caches the transient high-energy interference signal when the circuit generates it for utilization.

[0005] The present invention is achieved through the following technical solutions:

[0006] A circuit for preventing back electromotive force, comprising:

[0007] An anti-reverse component is connected in series between the power input terminal and the power output terminal;

[0008] A back electromotive force absorption component, one end of which is connected between the anti-reverse component and the power supply output terminal, and the other end is grounded;

[0009] An anti-reverse state switching component has a common terminal, a normally closed contact and a normally open contact, wherein the common terminal and the normally closed contact are respectively connected to two ends of the anti-reverse component;

[0010] A transient impact energy buffer component, whose input end is connected to the normally open contact and whose output end is connected between the power input end and the anti-reverse component, is used to absorb the transient pulse energy of the anti-reverse component and release it to merge with the power input end;

[0011] A back electromotive force release component, one end of which is connected to the common end of the absorption component and the anti-reverse component, and the other end of which is grounded or is the transient impact energy buffer component;

[0012] A power supply component is arranged between the back electromotive force absorption component and the power output end, and is used to generate power to supply power to the anti-reverse state switching component when there is a back electromotive force in the circuit.

[0013] Furthermore, the anti-reverse component includes a diode or a unidirectional thyristor, the anode of the diode or the unidirectional thyristor is connected to the power input end; and the control end of the unidirectional thyristor is connected to the power supply component.

[0014] Furthermore, the anti-reverse state switching component includes a relay, which is a normally closed relay. The common moving contact pin and the normally closed contact pin of the relay are respectively connected to the two ends of the anti-reverse component, and the normally open contact pin of the relay is connected to the transient impact energy buffer component; the relay coil pin is connected to the power supply component.

[0015] Furthermore, the transient impact energy buffer component includes an energy storage capacitor and an anti-reverse diode, the anode of the anti-reverse diode and the energy storage capacitor are connected to the normally open contact of the anti-reverse state switching component, and the cathode of the anti-reverse diode is connected between the power input terminal and the anti-reverse component.

[0016] Furthermore, the absorption component includes a first electrolytic capacitor, a positive electrode of the first electrolytic capacitor is connected to the anti-reverse component, and a negative electrode thereof is grounded.

[0017] Furthermore, the back electromotive force release component includes a switch element and a fourth resistor, one electrode end of the switch element is respectively connected to the two ends of the anti-reverse component, the other electrode end of the switch element is connected in series with the fourth resistor, the other end of the fourth resistor is grounded, and the control end of the switch element is connected to the power input end.

[0018] Furthermore, the back electromotive force release component includes a switch element, one electrode end and a control end of the switch element are connected to an end of the back electromotive force absorption component away from the ground, and the other electrode end of the switch element is connected to the transient impact energy buffer component.

[0019] Furthermore, the back-electromotive force release component includes a unidirectional thyristor and a fourth resistor, the anode of the unidirectional thyristor is connected to the end of the back-electromotive force absorption component away from the ground, and the cathode of the unidirectional thyristor is grounded through the fourth resistor; the back-electromotive force release component also includes a ninth resistor and a sixth capacitor which are connected in series and then in parallel at both ends of the back-electromotive force absorption component, and the common end of the ninth resistor and the sixth capacitor is connected to the control end of the unidirectional thyristor.

[0020] Furthermore, the power supply component includes a transformer, and the primary coil of the transformer is connected in series between the energy storage component and the power supply output terminal; one end of the secondary coil of the transformer is connected in series with a fifth diode, and the cathode of the fifth diode is the positive output terminal of the power supply component; the other end of the secondary coil of the voltage regulator is connected in series with a Zener diode, and the cathode of the Zener diode is the negative output terminal of the power supply component; the anode end of the Zener diode is grounded; and an electrolytic capacitor is also connected between the positive output terminal and the negative output terminal of the power supply component.

[0021] Furthermore, the circuit also includes a work indication component, which includes a current limiting resistor and a light emitting diode connected in series, the cathode of the light emitting diode is grounded, and the other end of the current limiting resistor is connected between the energy storage component and the power supply component.

[0022] Compared with the prior art, the technical solution of the present invention and its beneficial effects are as follows:

[0023] (1) The present invention uses an anti-reverse component to prevent the reverse electromotive force generated by the load from impacting the power supply, an absorption component absorbs the reverse electromotive force generated by the load, and a release component releases the reverse electromotive force in the absorption component, thereby playing a good protective role on the power supply. At the same time, when there is no reverse electromotive force in the circuit or the reverse electromotive force is less than the output voltage of the power supply, the anti-reverse component is short-circuited to reduce the energy consumption of the anti-reverse component. At the same time, the transient impact energy cache component caches the instantaneous large energy signal of the anti-reverse component, and when the reverse electromotive force is restored, the transient impact energy cache component releases the cached energy into the main circuit, so that the sudden energy interference of the protection process is effectively suppressed, and at the same time, this part of the energy is avoided from being wasted; the auxiliary absorption of the back electromotive force by the back electromotive force auxiliary cache component improves the heat dissipation of the device on the one hand, and on the other hand, this part of the energy is absorbed and stored until the circuit system returns to normal and is used.

[0024] (2) The release component of the present invention realizes the release of the reverse electromotive force through the voltage difference between the base and the emitter of the transistor, and at the same time intuitively indicates the release process through the light emitting diode.

[0025] (3) The power supply component of the present invention generates power supply for the anti-reverse state switching component by inducing reverse electromotive force. The design is ingenious and the working state of the anti-reverse state switching component is precisely controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a principle block diagram of a back electromotive force protection circuit provided by an embodiment of the present invention;

[0027] Figure 2 is a circuit schematic diagram of a back electromotive force protection circuit provided by an embodiment of the present invention;

[0028] Figure 3 This is another circuit schematic diagram of a back electromotive force protection circuit provided by an embodiment of the present invention.

[0029] Illustration Description:

[0030] Power input terminal-10; power output terminal-20; anti-reverse component-30; back electromotive force absorption component-40; back electromotive force release component-50; anti-reverse state switching component-60; power supply component-70; work indication component-80; energy cache component-90. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] See also Figures 1 to 3, a back electromotive force prevention circuit, including a power input terminal 10, a power output terminal 20, an anti-reverse component 30, a back electromotive force absorption component 40, a back electromotive force release component 50, an anti-reverse state switching component 60, a power supply component 70, and an energy cache component 90, wherein the energy cache component 90 includes a transient impact energy cache component and a back electromotive force auxiliary cache component. The power input terminal 10 is connected to the power supply, and the power output terminal 20 is the final output terminal of the power supply, which supplies power to the load (not shown). The anti-reverse component 30 is connected in series between the power input terminal 10 and the power output terminal 20 to prevent the back electromotive force generated by the load from impacting the power supply. One end of the absorption component 40 is connected between the anti-reverse component 30 and the power output terminal 20, and the other end is grounded to absorb the back electromotive force generated by the load. One end of the release component 50 is respectively connected to one end of the anti-reverse component 30 away from the power input terminal 10, and the other end of the release component 50 is grounded to release the back electromotive force in the absorption component 40.

[0033] The anti-reverse state switching component 60 has two sets of common moving contacts, a normally closed contact and a normally open contact. The common end and the normally closed contact of the anti-reverse state switching component 60 are respectively connected to the two ends of the anti-reverse component 30. The input end of the transient impact energy buffer component is connected to one of the normally open contacts, and the output end is connected between the power input end and the anti-reverse component, which is used to absorb the transient pulse energy of the anti-reverse component and release it to the main circuit. The input end of the back electromotive force auxiliary buffer component is connected to the other of the normally open contacts, and the output end is connected between the back electromotive force absorption component and the power output end, which is used to assist in absorbing the back electromotive force and release it to the main circuit. The anti-reverse state switching component 60 is in a normally closed state when it is not powered on. A power supply component 70 is connected in series between the back electromotive force absorption component 40 and the power output end 20, which is used to generate a power supply to supply power to the anti-reverse state switching component 60 when there is a reverse electromotive force in the circuit. That is, when the load does not generate a reverse electromotive force, the power supply component 70 does not generate a power supply for the anti-reverse state switching component 60, and the anti-reverse state switching component 60 works in a normally closed state, thereby forming a short circuit at both ends of the anti-reverse component 30, thereby avoiding the waste of energy caused by the anti-reverse component 30 being connected to the circuit when the power supply is working normally for a long time (when it is not impacted by the reverse electromotive force). When the load generates a large reverse electromotive force, the power supply component 70 generates a power supply for the anti-reverse state switching component 60, and the anti-reverse state switching component 60 switches to a normally open contact, so that the transient impact energy buffer component and the reverse electromotive force auxiliary buffer component are connected to the circuit, which are used to absorb transient impact energy and reverse electromotive force respectively, and after the circuit returns to the forward direction, the absorbed energy is released to the main circuit, thereby avoiding energy waste.

[0034] Continue reading Figure 1In this embodiment, the anti-reverse component 30 adopts a unidirectional thyristor Q1, the anode of the unidirectional thyristor Q1 is connected to the power input terminal 10, the cathode of the unidirectional thyristor Q1 is connected to the positive electrode of the capacitor C1, and the control end of the unidirectional thyristor Q1 is connected to the power supply component 70. When there is a reverse electromotive force in the circuit, a power supply is generated to control the unidirectional thyristor Q1 to be forward-conducted.

[0035] In another embodiment, the anti-reverse component 30 may also include a diode D1 , and an anode of the diode D1 is connected to the power input terminal 10 .

[0036] The back electromotive force absorption component 40 includes an electrolytic capacitor C1 , a positive electrode of the electrolytic capacitor C1 is connected to the cathode of the unidirectional thyristor Q1 , and a negative electrode of the electrolytic capacitor C1 is grounded.

[0037] The back electromotive force release component 50 includes a unidirectional thyristor Q2 and a fourth resistor R4, wherein the anode of the unidirectional thyristor Q2 is connected to an end of the electrolytic capacitor C1 away from the ground, and the cathode of the unidirectional thyristor Q2 is grounded through the resistor R4. The back electromotive force release component 50 also includes a resistor R9 connected in series and then connected in parallel at both ends of the electrolytic capacitor C1, a voltage stabilizing diode ZD2 and an electrolytic capacitor C6, wherein the common end of the anode of the voltage stabilizing diode ZD2 and the positive electrode of the electrolytic capacitor C6 is connected to the control end of the unidirectional thyristor Q2, and the negative electrode of the electrolytic capacitor C6 is grounded. In the present embodiment, the back electromotive force release component 50 also includes a current limiting resistor R5 and a light emitting diode D3 connected in parallel at both ends of the resistor R4, and the cathode of the light emitting diode D3 is grounded.

[0038] When the back electromotive force in the electrolytic capacitor C1 is greater than the voltage parameter of the Zener diode ZD2, the Zener diode ZD2 is turned on to charge the electrolytic capacitor C6. The electrolytic capacitor C6 gives a start-up current signal to the control end of the unidirectional thyristor Q2, so that the AK end of the unidirectional thyristor Q2 can be turned on, and then the electromotive force energy stored in C1 is released to GND through the unidirectional thyristor Q2 and the resistor R4. A light-emitting diode D3 is connected in parallel at both ends of the resistor R4. During the process of release from the beginning to the end, the light-emitting diode D3 indicates the brightness from bright to dark due to the change of the shunt current from large to small. The voltage parameter of the Zener diode ZD2 is the same as the input voltage. .

[0039] When there is no reverse electromotive force, or the reverse electromotive force is less than the output voltage of the power supply, the voltage at the anode end of the diode D1 is always greater than the voltage at the cathode end, the diode D1 is forward-conducted, the electrolytic capacitor C1 plays the role of energy storage and filtering, and the light-emitting diode D2 connected in parallel at both ends of the electrolytic capacitor C1 lights up, indicating that the power supply is working normally. At this time, since the unidirectional thyristor Q1 is not turned on, the light-emitting diode D3 is not lit.

[0040] Continue reading Figure 2 and Figure 3The anti-reverse state switching component 60 includes a relay KA, which is a normally closed relay. The relay KA has at least two groups of common moving contacts, normally closed contacts, and normally open contacts. For ease of representation, in this embodiment, the first group of common moving contacts is recorded as pin 1, the first group of normally closed contacts is pin 2, the first group of normally open contacts is pin 3, the second group of common moving contacts is pin 4, the second group of normally closed contacts is pin 5, and the second group of normally open contacts is pin 6. Pin 1 of the common moving contact of the relay is connected between the anti-reverse component 30 and the power input terminal 10, and pin 2 of the normally closed contact of the relay is connected to the other end of the anti-reverse component 30.

[0041] When there is no reverse electromotive force in the power supply circuit, the power supply component does not generate power, and the relay KA remains in a normally closed state, thereby short-circuiting the diode D1, thereby preventing the diode D1 from consuming energy when the power supply works normally for a long time. Alternatively, the unidirectional thyristor Q1 is short-circuited, thereby preventing the main circuit from being unable to work due to the unidirectional thyristor Q1 not being turned on when the power supply works normally for a long time (sufficient reverse electromotive force enables the power supply component to generate power to supply power to the unidirectional thyristor Q1).

[0042] The common moving contact pin 4 of the relay is connected to the normally closed contact pin 2, and the normally closed contact pin 5 of the relay is connected to the common moving contact pin 1. In the normally closed state, the common moving contact pin 4 and the normally closed contact pin 5 also short-circuit the anti-party component 30.

[0043] The normally open contact pin 3 of the relay is connected to the transient impact energy buffer component, the normally open contact pin 6 of the relay is connected to the back electromotive force auxiliary buffer component, and the relay coil pin is connected to the power supply component 70.

[0044] Continue reading Figure 2 The transient impact energy buffer component includes a storage capacitor C4 and a diode D4. The anode of the diode D4 and the diode D4 are connected to the normally open contact 3 of the relay. The cathode of the diode D4 is connected between the power input terminal 10 and the anti-reverse component 30, that is, connected to the main circuit.

[0045] The electromotive force auxiliary buffer component includes a storage capacitor C7, a diode D10 and a diode D9, the anode of the diode D10 is connected to the normally open contact 6 pin of the relay, the common end of the anodes of the diode D10 and the diode D9 is connected to the cathode of the diode D10, and the cathode of the diode D9 is connected between the back electromotive force absorption component 40 and the power supply component 70.

[0046] When there is a reverse electromotive force in the power supply circuit, the power supply component 70 generates power, and the relay KA switches to the normally open contact to conduct. The anode of the diode D1 or the thyristor Q1 is connected to the transient impact energy buffer component, and the cathode of the diode D1 or the thyristor Q1 is connected to the reverse electromotive force auxiliary buffer component.

[0047] When there is a reverse electromotive force in the power supply circuit, that is, when the diode D1 or the thyristor Q1 is in the protection state, the anode of the diode D1 or the thyristor Q1 will also have a node impact instantly because the cathode voltage is greater than its anode, resulting in the energy not being able to be transferred to the cathode instantly. This impact is a transient large-energy interference signal, which will be absorbed and temporarily stored by the energy storage capacitor C4 (at this time, the relay has been activated and the relay switch has been turned to the normally open contacts 3 and 6). When there is no reverse electromotive force, the relay KA resumes the normally closed contact conduction. At this time, the energy temporarily stored on the energy storage capacitor C4 is turned on again through the diode D4 and merged into the Vin+ output branch, so that the sudden energy interference of the protection process is effectively suppressed, and at the same time, this part of the energy is prevented from being wasted. The diode D4 uses the unidirectional conduction characteristics of the diode to effectively isolate the energy storage capacitor C4 from being charged when there is no reverse electromotive force, so that the energy storage capacitor C4 is only prepared to absorb the anode interference of the diode D1 or the thyristor Q1 when preventing reverse charging.

[0048] When there is a reverse electromotive force in the power supply circuit, the electrolytic capacitor C1 mainly absorbs and stores energy. At the same time, the reverse electromotive force at point K is also conducted through the common moving contact pin 4 to the normally open contact pin 6, and then absorbed by the energy storage capacitor C7 after passing through the diode D10. After the system returns to a state without reverse electromotive force, the temporarily stored energy in the energy storage capacitor C7 will be released and returned to the output main circuit through the diode D9. Adding a reverse electromotive force auxiliary buffer component will have better heat dissipation than a single method that completely relies on the electrolytic capacitor C1 to absorb and consume, because part of the reverse electromotive force energy can be absorbed and stored until it is used when the circuit system returns to normal.

[0049] The power supply component 70 includes a transformer T2, and the primary coil T2-1 of the transformer is connected in series between the current limiting resistor R2 and the power supply output terminal 20. One end of the secondary coil T2-2 of the transformer is connected in series with a diode D5, and the cathode of the diode D5 is the positive output terminal Vstart+ of the power supply component 70. The other end of the secondary coil T2-2 of the transformer is connected in series with a voltage regulator diode TVS, and the cathode of the voltage regulator diode TVS is the negative output terminal Vstart- of the power supply component 70; the anode end of the voltage regulator diode TVS is grounded. An electrolytic capacitor C3 is also connected between the positive output terminal Vstart+ and the negative output terminal Vstart- of the power supply component.

[0050] When the reverse electromotive force is greater than the power supply output voltage, the secondary coil T2-2 of the transformer will sense the reverse voltage of the primary coil T2-1 of the transformer and generate a supply voltage, which drives the relay KA to operate. When the reverse electromotive force reaches the protection threshold, the electromotive force voltage sensed by the secondary coil T2-2 on the primary coil T2-1 reaches the voltage required for the relay KA to switch. The circuit protection threshold can be set by selecting the transient voltage suppression diode TVS.

[0051] The power supply component 70 further includes a resistor R7 connected to the cathode of the diode D5, that is, the positive output terminal Vstart+ of the power supply component 70. The other end of the resistor R7 is connected to the control terminal of the unidirectional thyristor Q1. The end of the resistor R7 away from the unidirectional thyristor Q1 is also connected to a voltage stabilizing diode ZD1. The voltage stabilizing diode ZD1 can stabilize the positive output terminal Vstart+ of the power supply component 70 and stabilize the voltage at the control terminal of the unidirectional thyristor Q1.

[0052] The circuit is also provided with an energy storage component, which includes an electrolytic capacitor C5, the positive electrode of which is provided between the current limiting resistor R2 and the transformer T2, and the negative electrode of which is grounded. The electrolytic capacitor C5 can enhance the delay of the reverse charging voltage reaching the moving contact of the relay KA to switch from the normally closed contact to the normally open contact, thereby allowing the diode D1 or the unidirectional thyristor Q1 to be normally connected to the circuit.

[0053] The above description shows and describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept of this article through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall be within the scope of protection of the claims attached to the present invention without departing from the spirit and scope of the present invention.

Claims

1. A circuit for preventing back electromotive force, characterized in that: include: The anti-reverse component is connected in series between the power input terminal and the power output terminal; A back electromotive force absorption component, one end of which is connected between the anti-reverse component and the power supply output terminal, and the other end is grounded; The anti-reverse state switching component has at least two groups of common moving contacts, a normally closed contact and a normally open contact, wherein the common moving contact and the normally closed contact are respectively connected to the two ends of the anti-reverse component; the anti-reverse state switching component is in a normally closed state when not powered on; An energy buffer component, comprising a transient impact energy buffer component and a back electromotive force auxiliary buffer component, wherein the input end of the transient impact energy buffer component is connected to one of the normally open contacts, and the output end is connected between the power input end and the anti-reverse component, and is used to absorb the transient pulse energy of the anti-reverse component and release it to the main circuit; the input end of the back electromotive force auxiliary buffer component is connected to the other of the normally open contacts, and the output end is connected between the back electromotive force absorption component and the power output end, and is used to assist in absorbing the back electromotive force and release it to the main circuit; A back electromotive force release component, one end of which is connected to the common end of the absorption component and the anti-reverse component, and the other end of which is grounded or connected to the transient impact energy buffer component; A power supply component is arranged between the back electromotive force absorption component and the power output end, and is used to generate power to supply power to the anti-reverse state switching component when there is a reverse electromotive force in the circuit.

2. The anti-back electromotive force circuit according to claim 1, characterized in that: The anti-reverse component includes a diode or a unidirectional thyristor, the anode of the diode or the unidirectional thyristor is connected to the power input end; the control end of the unidirectional thyristor is connected to the power supply component.

3. The anti-back electromotive force circuit according to claim 1, characterized in that: The anti-reverse state switching component includes a relay, a first group of common moving contacts of the relay is connected between the anti-reverse component and the power input terminal, a first group of normally closed contacts of the relay is connected to the other end of the anti-reverse component, and a first group of normally open contacts of the relay is connected to the transient impact energy buffer component; The second group of common moving contacts of the relay is connected to the first group of normally closed contacts, the second group of normally closed contacts of the relay is connected to the first group of common moving contacts, and the second group of normally open contacts of the relay is connected to the back electromotive force auxiliary buffer component; The relay is a normally closed relay; the relay coil pin is connected to the power supply component.

4. The anti-back electromotive force circuit according to claim 3, characterized in that: The transient impact energy buffer component includes a fourth energy storage capacitor and a fourth diode, the anode of the fourth diode and the fourth energy storage capacitor are connected to the first group of normally open contacts of the relay, and the cathode of the fourth diode is connected between the power input terminal and the anti-reverse component.

5. The anti-back electromotive force circuit according to claim 3, characterized in that: The back-electromotive force auxiliary buffer component includes a seventh energy storage capacitor, a tenth diode and a ninth diode, the anode of the tenth diode is connected to the second group of normally open contacts of the relay, the common end of the anode of the seventh energy storage capacitor and the ninth diode is connected to the cathode of the tenth diode, and the cathode of the ninth diode is connected between the back-electromotive force absorption component and the power supply component.

6. The anti-back electromotive force circuit according to claim 1, characterized in that: The back electromotive force absorption component includes a first electrolytic capacitor, the positive electrode of the first electrolytic capacitor is connected to the anti-reverse component, and the negative electrode of the first electrolytic capacitor is grounded.

7. The anti-back electromotive force circuit according to claim 1, characterized in that: The back electromotive force release component comprises a unidirectional thyristor and a fourth resistor, the anode of the unidirectional thyristor is connected to the end of the back electromotive force absorption component away from the ground, and the cathode of the unidirectional thyristor is grounded through the fourth resistor; The back electromotive force release component also includes a ninth resistor, a voltage-stabilizing diode and a sixth electrolytic capacitor which are connected in series and then in parallel at both ends of the back electromotive force absorption component. The common end of the anode of the voltage-stabilizing diode and the positive electrode of the sixth electrolytic capacitor is connected to the control end of the unidirectional thyristor, and the negative electrode of the sixth capacitor is grounded.

8. The anti-back electromotive force circuit according to claim 1, characterized in that: The power supply component includes a transformer, and the primary coil of the transformer is connected in series between the energy storage component and the power supply output terminal; one end of the secondary coil of the transformer is connected in series with a fifth diode, and the cathode of the fifth diode is the positive output terminal of the power supply component; the other end of the secondary coil of the voltage regulator is connected in series with a voltage regulator diode, and the cathode of the voltage regulator diode is the negative output terminal of the power supply component; the anode end of the voltage regulator diode is grounded; and an electrolytic capacitor is also connected between the positive output terminal and the negative output terminal of the power supply component.

9. The anti-back electromotive force circuit according to claim 1, characterized in that: It also includes a work indication component, which includes a current limiting resistor and a light emitting diode connected in series, the cathode of the light emitting diode is grounded, and the other end of the current limiting resistor is connected between the energy storage component and the power supply component.

10. The anti-back electromotive force circuit according to claim 1, characterized in that: It also includes an energy storage component, one end of which is connected to one end of the power output end of the power supply component, and the other end of the energy storage component is grounded.

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