Anti-back electromotive force circuit

Abstract

The utility model provides an anti-counter electromotive force circuit, which comprises a power supply input end, a power supply output end, an anti-counter assembly, an absorption assembly, a release assembly, an anti-counter state switching 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 absorption assembly is used for absorbing the reverse electromotive force generated by the load. And the release assembly is used for releasing the reverse electromotive force in the absorption assembly. The anti-reverse state switching assembly is connected to the two ends of the anti-reverse assembly, the anti-reverse state switching assembly is in a normally-closed state when not powered on, and the power supply assembly is used for generating a power source to supply power to the anti-reverse state switching assembly when reverse electromotive force exists in a circuit. Therefore, when the load does not generate the reverse electromotive force or the reverse electromotive force is smaller than the output voltage of the power supply, the anti-reverse state switching assembly works in a normally-closed state, a short circuit is formed at the two ends of the anti-reverse state switching assembly, and then the situation that when the power supply works normally for a long time, the anti-reverse state switching assembly is connected into a loop, and consequently energy consumption is wasted is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic technical field, especially relate to a prevent reverse electromotive force circuit. BACKGROUND

[0002] In power electronic applications, motors as typical inductive loads are widely used in industrial automation, household appliances, transportation tools and many other fields. However, when the motor decelerates from high-speed operation to stop or suddenly loses power, the magnetic field in the coil will not disappear immediately, but according to Faraday's law of electromagnetic induction, a high-amplitude reverse electromotive force (Back-EMF) opposite to the power supply direction will be generated at both ends of the coil. This momentary high-voltage and high-current energy, if not properly handled, will be directly fed back to the power supply, posing a serious threat to the power supply system.

[0003] Traditional power supply design often lacks effective protection measures against such reverse electromotive force impact, resulting in overvoltage and overcurrent protection actions of the power supply when encountering such situations, and even direct damage to internal electronic components such as rectifier bridges and power switches. This not only increases the maintenance cost of the equipment, but also seriously affects the stability and efficiency of the system. In order to solve the above problems, some simple protection schemes have appeared on the market, such as adding passive components such as pressure-sensitive resistors and transient voltage suppression diodes (TVS) to absorb part of the reverse energy. For example, Chinese utility model patent CN218124309U discloses a method for protecting the power supply from the impact of reverse electromotive force by using diodes. However, the diodes are also connected to the circuit for a long time when no reverse electromotive force is generated, causing unnecessary consumption. UTILITY MODEL CONTENTS

[0004] To solve the above problems, the purpose of the utility model is to provide a reverse electromotive force protection circuit, which short-circuits the reverse protection component when no reverse electromotive force is generated in the circuit, thereby avoiding the problem of continuous energy consumption of the reverse protection component.

[0005] The utility model realizes the following technical scheme:

[0006] A reverse electromotive force protection circuit, comprising:

[0007] a power input terminal connected to a power supply;

[0008] a power output terminal for outputting power to supply power to a load;

[0009] a reverse protection component connected in series between the power input terminal and the power output terminal;

[0010] an absorption component, one end of which is connected between the reverse protection component and the power output terminal, and the other end is grounded;

[0011] a release component, one end of the release component is connected to two ends of the anti-reverse component respectively, and the other end of the release component is grounded;

[0012] an anti-reverse state switching component, connected to two ends of the anti-reverse component, the anti-reverse state switching component is in a normally closed state when not powered;

[0013] a power supply component, provided between the absorption component and the power supply output end, used to generate power for the anti-reverse state switching component when there is a reverse electromotive force in the circuit.

[0014] Further, the anti-reverse component includes a diode, an anode of the diode is connected to the power supply input end.

[0015] Further, the anti-reverse state switching component includes a relay, the relay is a normally closed relay, a common moving contact pin and a normally closed contact pin of the relay are connected to two ends of the anti-reverse component respectively, and a coil pin of the relay is connected to the power supply component.

[0016] Further, 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] Further, the release component includes a switch and a fourth resistor, one electrode end of the switch is connected to two ends of the anti-reverse component respectively, the other electrode end of the switch is connected in series with the fourth resistor, the other end of the fourth resistor is grounded, and a control end of the switch is connected to the power supply input end.

[0018] Further, the release component further includes a current-limiting resistor and a light-emitting diode connected in series with the other electrode end of the switch, and a cathode of the light-emitting diode is grounded.

[0019] Further, the power supply component includes a transformer, a primary coil of the transformer is connected in series between the absorption component and the power supply output end; one end of a secondary coil of the transformer is connected in series with a fifth diode, a cathode of the fifth diode is a positive output end of the power supply component, the other end of the secondary coil of the transformer is connected in series with a voltage stabilizing diode, a cathode of the voltage stabilizing diode is a negative output end of the power supply component; an anode end of the voltage stabilizing diode is grounded; and an electrolytic capacitor is further connected between the positive output end and the negative output end of the power supply component.

[0020] Further, the circuit further includes a working indication component, the working indication component includes a current-limiting resistor and a light-emitting diode connected in series, a cathode of the light-emitting diode is grounded, and the other end of the current-limiting resistor is connected between the absorption component and the power supply component.

[0021] Further, the circuit further comprises a storage component, one end of which is connected between the absorption component and the power supply component, and the other end is grounded.

[0022] Compared with the prior art, the technical scheme and beneficial effects of the utility model are as follows:

[0023] (1) The anti-reverse component is used for preventing the reverse electromotive force generated by the load from impacting the power supply, the absorption component absorbs the reverse electromotive force generated by the load, and the release component releases the reverse electromotive force in the absorption component, thereby playing a good protection role on the power supply. At the same time, when no reverse electromotive force or the reverse electromotive force is less than the output voltage of the power supply appears in the circuit, the anti-reverse component is short-circuited to reduce the energy consumption of the anti-reverse component.

[0024] (2) The release component of the utility model realizes the release of the reverse electromotive force through the voltage difference between the base and the emitter of the triode, and simultaneously realizes intuitive indication of the release process through the light-emitting diode.

[0025] (3) The power supply component of the utility model generates the power supply of the anti-reverse state switching component through induction of the reverse electromotive force, and accurately controls the working state of the anti-reverse state switching component through ingenious design. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of an anti-reverse electromotive force circuit provided by the utility model embodiment;

[0027] ILLUSTRATIVE DESCRIPTION

[0028] Power input end -10; power output end -20; anti-reverse component -30; absorption component -40; release component -50; anti-reverse state switching component -60; power supply component -70; working indication component -80; storage component -90. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the utility model embodiments clearer, the technical scheme in the utility model embodiments will be described clearly and completely in combination with the drawings in the utility model embodiments. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model, and are not used to limit the utility model. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the utility model.

[0030] Referring to Figure 1A reverse electromotive force prevention circuit comprises a power input terminal 10, a power output terminal 20, a reverse prevention component 30, an absorption component 40, a release component 50, a reverse prevention state switching component 60 and a power supply component 70. The power input terminal 10 is connected to a power source, and the power output terminal 20 is the final output terminal of the power source and supplies power to a load (not shown). The reverse prevention component 30 is connected in series between the power input terminal 10 and the power output terminal 20, and is used to prevent the reverse electromotive force generated by the load from impacting the power source. One end of the absorption component 40 is connected between the reverse prevention component 30 and the power output terminal 20, and the other end is grounded, and is used to absorb the reverse electromotive force generated by the load. One end of the release component 50 is connected to each of the two ends of the reverse prevention component 30, and the other end is grounded, and is used to release the reverse electromotive force in the absorption component 40.

[0031] The reverse prevention state switching component 60 is connected to the two ends of the reverse prevention component 30. When the reverse prevention state switching component 60 is not powered, it is in a normally closed state. The power supply component 70 is connected in series between the absorption component 40 and the power output terminal 20, and is used to supply power to the reverse prevention 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 supply power to the reverse prevention state switching component 60, and the reverse prevention state switching component 60 works in a normally closed state, thereby forming a short circuit between the two ends of the reverse prevention component, and avoiding the waste of energy caused by the reverse prevention component being connected to the circuit when the power source is working normally for a long time (without being impacted by a reverse electromotive force).

[0032] Continuing to refer to Figure 1 In this embodiment, the reverse prevention component 30 comprises a diode D1, and the anode of the diode D1 is connected to the power input terminal 10. The absorption component 40 comprises an electrolytic capacitor C1, and the positive electrode of the electrolytic capacitor C1 is connected to the cathode of the diode D1, and the negative electrode of the electrolytic capacitor C1 is grounded. The release component 50 comprises a switch Q1 and a resistor R4. The switch Q1 is a PNP triode, the emitter of the switch Q1 is connected to each of the two ends of the diode D1, the collector of the switch Q1 is connected in series with the resistor R4 and then grounded, and the base of the switch Q1 is connected to the power input terminal 10. In this embodiment, the release component 50 further comprises a current-limiting resistor R5 connected in series with the collector of the switch Q1 and a light-emitting diode D3, and the cathode of the light-emitting diode D3 is grounded. The working indication component 80 comprises a resistor R2 and a light-emitting diode D2 connected in series and connected in parallel to the two ends of the electrolytic capacitor C1, and the cathode of the light-emitting diode D2 is grounded.

[0033] When no back electromotive force is generated, or the back electromotive force is less than the output voltage of the power supply, the anode voltage of the diode Dl is always greater than the voltage of its cathode, the diode Dl is forward conducting, the electrolytic capacitor Cl functions as an energy storage filter, and the light emitting diode D2 connected in parallel across the electrolytic capacitor Cl is lit to indicate that the power supply is working normally. At this time, since the potential at point A is greater than the potential at point C, the EB electrode of the switch Ql is not conducting, i.e. the triode Ql is cut off, so the light emitting diode D3 is not lit.

[0034] When the back electromotive force exceeds the output voltage but does not exceed the reverse voltage of the diode Dl, the voltage at the anode B of the diode Dl is less than the voltage at the cathode C of the diode Dl at this time. At this time, due to the presence of the diode Dl, the reverse voltage will not reach the Vin+ of the power supply input to cause a reverse impact on the power supply product. Since in the normal case, the voltage across the electrolytic capacitor Cl is approximately the voltage at the input of the power supply, when the back electromotive force arrives, the energy electromotive force stored in the electrolytic capacitor Cl is less than the back electromotive force, so the back electromotive force charges the electrolytic capacitor Cl and is partially absorbed by the electrolytic capacitor Cl. When the voltage difference between the voltage at the electrolytic capacitor Cl and the voltage at point A is greater than the V BE on voltage of the switch Ql, the energy of the electrolytic capacitor Cl greater than the voltage at the input of the power supply is released to the ground through the I EC of the switch Ql, and at the same time, the light emitting diode D3 is also lit, and with the release process, the brightness of the light emitting diode D3 also changes from bright to dark, i.e. the light emitting diode D3 indicates the release process of the back electromotive force. When the energy stored in the electrolytic capacitor Cl is released to the voltage at the C terminal is less than the voltage at the A terminal, and the voltage difference is greater than the V BE on voltage of the switch Ql, the switch Ql is closed again, and thus the absorption and release process of the back electromotive force is completed.

[0035] Continuing to refer to Figure 1 , the anti-reverse state switching assembly 60 includes a relay KA, the relay KA is a normally closed relay, the common moving contact pin and the normally closed contact pin of the relay KA are connected across the diode Dl, and the coil pin of the relay KA is connected to the power supply assembly. When there is no back electromotive force in the power supply circuit, the power supply assembly does not generate power, the relay KA remains in the normally closed state, thereby short-circuiting the diode Dl, and further avoiding energy consumption of the diode Dl when the power supply is working normally for a long time.

[0036] The power supply assembly 70 comprises a transformer T2, a primary coil T2-1 of the transformer is connected in series between the current-limiting resistor R2 and the power output end 20. One end of a secondary coil T2-2 of the transformer is connected in series with a diode D5, the cathode of the diode D5 is the positive output end Vstart+ of the power supply assembly 70, the other end of the secondary coil T2-2 of the transformer is connected in series with a voltage stabilizing diode TVS, the cathode of the voltage stabilizing diode TVS is the negative output end Vstart- of the power supply assembly 70; the anode of the voltage stabilizing diode TVS is grounded. The positive output end Vstart+ and the negative output end Vstart- of the power supply assembly are further connected with an electrolytic capacitor C3.

[0037] When the direction electromotive force is greater than the power output voltage, the secondary coil T2-2 of the transformer will induce a reverse voltage on the primary coil T2-1 of the transformer to generate a power supply voltage, which drives the relay KA to act. When the reverse electromotive force reaches the protection threshold, the secondary coil T2-2 induces an electromotive force voltage on the primary coil T2-1 to reach the voltage required for the switching action of the relay KA. By selecting the transient voltage suppression diode TVS, the protection threshold of the circuit is set.

[0038] The circuit further comprises an energy storage assembly 90, which comprises an electrolytic capacitor C5, the positive electrode of the electrolytic capacitor C5 is arranged between the current-limiting resistor R2 and the transformer T2, and the negative electrode of the electrolytic capacitor C5 is grounded. The electrolytic capacitor C5 can enhance the delay of the reverse charging voltage to reach the moving contact of the relay KA to switch from the normally closed contact to the normally open contact, so that the diode D1 is normally connected to the circuit.

[0039] The above description shows and describes the preferred embodiments of the present application, it should be understood that the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the present application concept disclosed herein by the above teaching or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the claims of the present application.

Claims

1. A back EMF prevention circuit, characterized by, The application relates to a power supply device, which comprises the following components: a power input end connected with a power supply; a power output end for outputting power supply to a load; a reverse prevention component connected in series between the power input end and the power output end; an absorption component connected between the reverse prevention component and the power output end; a release component, one end of which is connected to both ends of the reverse prevention component, and the other end of which is grounded; a reverse prevention state switching component connected to both ends of the reverse prevention component, which is in a normally closed state when not powered; a power supply component arranged between the absorption component and the power output end, which is used for generating power supply for the reverse prevention state switching component when there is a reverse electromotive force in a circuit.

2. A back EMF prevention circuit according to claim 1, wherein, The reverse prevention component comprises a diode, the anode of which is connected with the power input end.

3. A back EMF prevention circuit according to claim 1, wherein, The reverse prevention state switching component comprises a relay, which is a normally closed relay, the common moving contact pin and the normally closed contact pin of the relay being connected to both ends of the reverse prevention component respectively, and the coil pin of the relay being connected with the power supply component.

4. A back EMF prevention circuit as defined in claim 1, wherein The absorption component comprises a first electrolytic capacitor, the positive pole of which is connected with the reverse prevention component, and the negative pole of which is grounded.

5. A back EMF prevention circuit as defined in claim 1, wherein, The release component comprises a switch and a fourth resistor, one electrode end of the switch being connected with both ends of the reverse prevention component respectively, the other electrode end of the switch being connected with the fourth resistor in series, the other end of the fourth resistor being grounded, and the control end of the switch being connected with the power input end.

6. A back EMF prevention circuit as claimed in claim 5, wherein, The release component further comprises a current-limiting resistor and a light-emitting diode connected with the other electrode end of the switch in series, and the cathode of the light-emitting diode is grounded.

7. A back EMF prevention circuit as defined in claim 1, wherein, The power supply component comprises a transformer, the primary coil of which is connected in series between the absorption component and the power output end; one end of the secondary coil of the transformer is connected with a fifth diode in series, the cathode of the fifth diode being the positive output end of the power supply component; the other end of the secondary coil of the transformer is connected with a voltage stabilizing diode in series, the cathode of the voltage stabilizing diode being the negative output end of the power supply component; the anode end of the voltage stabilizing diode is grounded; and an electrolytic capacitor is further connected between the positive output end and the negative output end of the power supply component.

8. A back EMF prevention circuit as defined in claim 1, wherein, The application further comprises a working indication component, which comprises a current-limiting resistor and a light-emitting diode connected in series, the cathode of the light-emitting diode being grounded, and the other end of the current-limiting resistor being connected between the absorption component and the power supply component.

9. A back EMF prevention circuit as defined in claim 1, wherein, The application further comprises an energy storage component, one end of which is connected between the absorption component and the power supply component, and the other end of which is grounded.

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