CN113285436A

CN113285436A - Reverse electromotive force active discharge protection circuit and active arc extinguishing method

Info

Publication number: CN113285436A
Application number: CN202110668181.5A
Authority: CN
Inventors: 赵佩云; 朱忠芳; 朱蝶; 郑瑞象
Original assignee: Zhejiang Nanjing Electric Co ltd
Current assignee: Zhejiang Nanjing Electric Co ltd
Priority date: 2021-06-16
Filing date: 2021-06-16
Publication date: 2021-08-20

Abstract

The invention relates to the field of direct current system protection, in particular to a reverse electromotive force active discharge protection circuit which comprises a signal processing circuit, a discharge driving circuit, a discharge resistor and a polarity switching circuit, wherein one end of the discharge resistor is electrically connected with the polarity switching circuit, the other end of the discharge resistor is electrically connected with the discharge driving circuit, both the polarity switching circuit and the signal processing circuit are electrically connected with the discharge driving circuit, the polarity switching circuit is provided with two discharge interfaces for connecting a direct current load in parallel, and the signal processing circuit outputs a load driving signal for controlling the direct current load and a discharge control signal for controlling the discharge driving circuit. The invention provides a reverse electromotive force active discharge protection circuit, which can actively extinguish arc and solve the problem that a switch or a relay contact is damaged by reverse electromotive force generated by an inductive device.

Description

Reverse electromotive force active discharge protection circuit and active arc extinguishing method

Technical Field

The invention relates to the technical field of direct current system protection, in particular to a reverse electromotive force active discharge protection circuit and an active arc extinguishing method.

Background

When a switch or a relay is powered off by inductive devices such as a motor, an electromagnet and the like, reverse electromotive force often causes an arc discharge phenomenon on a contact, the contact is burnt, and finally circuit faults are caused.

The existing solution is to connect elements such as a resistance-capacitance absorption circuit, a thermistor, and a transient voltage-stabilizing tube in parallel at two ends of a switch or a relay contact to absorb the reverse electromotive force, but the passive elements have limited protection effect, or too high residual voltage, or limited absorption, or low speed, etc., which have disadvantages. The present invention improves upon the above-mentioned deficiencies.

Disclosure of Invention

In order to overcome the defects of the background art, the invention provides a reverse electromotive force active discharge protection circuit which can actively extinguish arc and solve the problem that a switch or a relay contact is damaged by reverse electromotive force generated by an inductive device.

The technical scheme adopted by the invention is as follows: the utility model provides a protection circuit is initiatively released to reverse electromotive force, is including signal processing circuit, the drive circuit that releases, discharge resistance and polarity switching circuit, the one end electricity of discharge resistance is connected polarity switching circuit, and the other end electricity is connected the drive circuit that releases, polarity switching circuit with the equal electricity of signal processing circuit is connected the drive circuit that releases, polarity switching circuit is equipped with two interfaces that release that are used for parallelly connected direct current load, signal processing circuit output is used for controlling direct current load's load drive signal and is used for control the control signal that releases of drive circuit's the control signal that releases.

Preferably, the polarity switching circuit adopts a rectifying circuit, and the signal processing circuit adopts a processor.

Preferably, the bleeder drive circuit comprises a first NMOS transistor, a second resistor, a fourth resistor, a fifth resistor, a first capacitor, a voltage regulator tube and a photoelectric coupler, a positive output end of the rectifier circuit is electrically connected with one end of the discharge resistor, a negative output end of the rectifier circuit is electrically connected with an S pole of the first NMOS transistor, a D pole of the first NMOS transistor and one end of the second resistor are electrically connected with the other end of the discharge resistor, the other end of the second resistor is electrically connected with a negative pole of the voltage regulator tube, one end of the fifth resistor and one end of the first capacitor are electrically connected with a G pole of the first NMOS transistor, a positive pole of the voltage regulator tube, the other end of the fifth resistor and the other end of the first capacitor are electrically connected with the S pole of the first NMOS transistor, a first input pin of the photoelectric coupler is electrically connected with one end of the fourth resistor, and the other end of the fourth resistor is electrically connected with an output end of the processor, and a second input pin of the photoelectric coupler is grounded, a first output pin of the photoelectric coupler is electrically connected with the negative electrode of the voltage stabilizing tube, and a second output pin of the photoelectric coupler is electrically connected with the G electrode of the first NMOS tube.

Preferably, the rectifying circuit adopts a bridge rectifier.

Preferably, the photocoupler adopts LTV-357T.

The application circuit comprises a load control circuit, the load control circuit comprises a common relay, the common relay is provided with a relay coil and a relay contact, the signal processing circuit outputs a load driving signal to switch on and off the relay coil, two ends of the direct current load are respectively and electrically connected with two discharging interfaces of the polarity switching circuit, and the direct current load is also connected with the relay contact in series.

Preferably, direct current load is high voltage direct current motor, load control circuit is including first ordinary relay and second NMOS pipe, first ordinary relay has first relay coil and first relay contact, and first relay contact is normally open contact, DC12V is inserted to the one end of first relay coil, and the other end electricity is connected the D utmost point of second NMOS pipe, the S utmost point ground connection of second NMOS pipe, the G utmost point electric connection of second NMOS pipe the output of signal processing circuit, DC220V power positive pole is connected to high voltage direct current motor 'S positive terminal electricity, high voltage direct current motor' S negative terminal electricity is connected the one end of first relay contact, and DC220V power negative pole is connected to the other end electricity of first relay contact.

An active arc extinguishing method of the reverse electromotive force active discharge protection circuit based on the technical scheme comprises the following steps:

(1) the processor outputs a bleeding control signal when receiving a load turn-off request from the outside;

(2) delaying, after the first NMOS tube is conducted, enabling the first NMOS tube, the discharge resistor, the rectifying circuit and the direct current load to form a discharge loop;

(3) the processor outputs a load driving signal to control the switch or the relay to turn off the load, and the time is delayed to wait for the end of discharging;

(4) the processor stops outputting the discharge control signal, the first NMOS tube is cut off to disconnect the discharge loop, and the load turn-off action is completed.

In conclusion, the beneficial effects of the invention are as follows:

1. according to the technical scheme, the reverse electromotive force harmful to the circuit is processed in an active and early intervention mode, and the actual requirement can be better met;

2. the application circuit based on the reverse electromotive force active discharge protection circuit is designed by adding the reverse electromotive force active discharge protection circuit into a cheap common relay to replace a high-voltage direct-current relay, so that the actual installation space can be effectively saved, the cost is reduced, and the actual requirement can be better met;

3. the active arc extinguishing method based on the reverse electromotive force active discharge protection circuit treats the reverse electromotive force harmful to the circuit in an active and advanced intervention mode.

The invention is further described with reference to the following figures and detailed description.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a block diagram of the circuit of the present invention;

FIG. 2 is a circuit diagram of a first embodiment of an application circuit of the present invention;

FIG. 3 is a circuit diagram of a second embodiment of the application circuit of the present invention;

fig. 4 is a schematic view of a work flow of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 4 in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the implementation objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention.

As shown in fig. 1 to 4, the reverse electromotive force active leakage protection circuit disclosed in this embodiment includes a signal processing circuit, a leakage driving circuit, a discharge resistor R1, and a polarity switching circuit, one end of the discharge resistor R1 is electrically connected to the polarity switching circuit, the other end is electrically connected to the leakage driving circuit, both the polarity switching circuit and the signal processing circuit are electrically connected to the leakage driving circuit, the polarity switching circuit is provided with two leakage interfaces for connecting a dc load in parallel, and the signal processing circuit outputs a load driving signal for controlling the dc load and a leakage control signal for controlling the leakage driving circuit. In the technical scheme, the circuit mainly comprises a signal processing circuit, a discharge driving circuit, a discharge resistor R1 and a polarity switching circuit, wherein the signal processing circuit is responsible for outputting a load driving signal for controlling the start and stop of the direct current load and outputting a discharge control signal before the direct current load is disconnected, the discharge driving circuit is controlled by the discharge control signal, the discharge resistor R1 is connected in parallel to the direct current load in time after receiving the discharge control signal, the discharge resistor R1 is responsible for discharging residual electric energy on the direct current load to a safe voltage as soon as possible, the discharge resistor R1 can convert the residual electric energy into heat energy, and the polarity switching circuit is used for switching the direct current load with unknown polarity into the polarity required by the circuit. In specific implementation, the direct current load mainly comprises inductive devices such as a motor and an electromagnet.

Preferably, the polarity switching circuit is a rectifying circuit, and the signal processing circuit is a processor. The polarity switching circuit adopts a rectification circuit to conveniently switch a direct current load with unknown polarity into the polarity required by the circuit, the signal processing circuit adopts a processor, the processor adopts a single chip microcomputer during specific implementation, the single chip microcomputer receives control demand signals such as positive and negative rotation and stalling of an external motor and then drives the motor control circuit to work according to the demand, and when a reversing or stalling signal is received, a release control signal is output in advance to release the reverse electromotive force of the motor so as to reduce the relay arcing phenomenon caused by the reverse electromotive force. The processor is in the prior art and will not be described in detail here.

As a preferable technical solution, the bleeder drive circuit includes a first NMOS transistor Q1, a second resistor R2, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a voltage regulator diode D1 and a photo coupler OP1, a positive output terminal of the rectifying circuit is electrically connected to one end of the discharge resistor R1, a negative output terminal is electrically connected to an S pole of the first NMOS transistor Q1, a D pole of the first NMOS transistor Q1 and one end of the second resistor R2 are both electrically connected to the other end of the discharge resistor R1, the other end of the second resistor R2 is electrically connected to a negative pole of the voltage regulator diode D1, one end of the fifth resistor R5 and one end of the first capacitor C1 are both electrically connected to a G pole of the first NMOS transistor Q1, a positive pole of the photo coupler D1, the other end of the fifth resistor R5 and the other end of the first capacitor C1 are all electrically connected to an S pole of the first NMOS transistor Q1, and the first input pin of the photo coupler OP 4, the other end of the fourth resistor R4 is electrically connected to the output end of the processor, the second input pin of the photoelectric coupler OP1 is grounded, the first output pin of the photoelectric coupler OP1 is electrically connected to the negative electrode of the voltage regulator tube D1, and the second output pin of the photoelectric coupler OP1 is electrically connected to the G pole of the first NMOS tube Q1. In the above technical solution, the first NMOS transistor Q1 is a switching transistor, and is used for connecting the discharge resistor R1 to a discharge loop for discharging; the second resistor R2 is a current-limiting resistor, the voltage regulator tube D1 adopts a 10V voltage regulator tube D1, and the second resistor R2 and the voltage regulator tube D1 form a 10V voltage regulator circuit; the fourth resistor R4 is a current-limiting resistor of the photocoupler OP1, and is used for protecting the photocoupler OP 1; the fifth resistor R5 is used for ensuring that the first NMOS transistor Q1 is turned off quickly; the first capacitor C1 plays a role in stabilizing the gate voltage of the first NMOS transistor Q1; the photoelectric coupler OP1 plays a role in isolating a high-voltage circuit from a low-voltage circuit and controlling the first NMOS tube Q1 to be switched on or switched off. The NMOS transistor, the resistor, the capacitor, the voltage regulator D1, and the photoelectric coupler OP1 all belong to the prior art, and are not specifically described herein.

Preferably, the rectifier circuit adopts a rectifier bridge stack BD 1. The rectifier circuit adopts a rectifier bridge stack BD1, consists of four diodes and has four leading-out pins, and can well switch a direct current load with unknown polarity into the polarity required by the circuit. The bridge rectifier BD1 is prior art and will not be described in detail herein.

Preferably, the photocoupler OP1 adopts LTV-357T. In specific implementation, the photoelectric coupler OP1 comprises but is not limited to LTV-357T, and the LTV-357T can well play a role in optical coupling isolation of a high-voltage circuit and a low-voltage circuit, and can control the conduction of the first NMOS tube Q1 when the processor outputs a discharge control signal, so that a discharge loop is formed. The LTV-357T belongs to the prior art and is not further described herein.

The application circuit is additionally provided with a load control circuit on the basis of the reverse electromotive force active discharge protection circuit, the load control circuit comprises a common relay, the common relay is provided with a relay coil and a relay contact, a signal processing circuit outputs a load driving signal to switch on and off the relay coil, two ends of a direct current load are respectively and electrically connected with two discharge interfaces of a polarity switching circuit, and the direct current load is also connected with the relay contact in series. The reverse electromotive force active discharge protection circuit is an active arc extinguishing circuit, the load control circuit adopts a common relay to realize the turn-off of a direct current load, the common relay is used for switching off the power supply of the direct current load, the reverse electromotive force often causes an arc discharge phenomenon on a contact, the contact burning is caused, the circuit fault is easily caused, the active arc extinguishing circuit of the reverse electromotive force active discharge protection circuit is applied, a discharge resistor R1 can be timely merged into the direct current load before the direct current load is switched off, the discharge resistor R1 can discharge the reverse electromotive force to a safe voltage range, the active arc extinguishing effect can be effectively realized, and the circuit protection circuit is better protected. The design of the application circuit is that a cheap common relay is added with a reverse electromotive force active discharge protection circuit to replace a high-voltage direct-current relay, so that the actual installation space can be effectively saved and the cost can be reduced. The high-voltage direct-current relay performs arc extinction through a permanent magnet arc extinction technology or inert gas, and is large in size and high in cost. The common relay and the high-voltage direct-current relay both belong to the prior art, and are not specifically described herein.

As an embodiment of the above application circuit, the DC load is a high voltage DC motor, the load control circuit includes a first normal relay J1 and a second NMOS tube Q2, the first normal relay J1 has a first relay coil and a first relay contact, the first relay contact is a normally open contact, one end of the first relay coil is connected to DC12V, the other end of the first relay coil is electrically connected to the D pole of the second NMOS tube Q2, the S pole of the second NMOS tube Q2 is grounded, the G pole of the second NMOS tube Q2 is electrically connected to the output end of the signal processing circuit, the positive terminal of the high voltage DC motor is electrically connected to the positive terminal of the DC220V power supply, the negative terminal of the high voltage DC motor is electrically connected to one end of the first relay contact, and the other end of the first relay contact is electrically connected to the negative terminal of the DC220V power supply. The embodiment is used for protecting the start-stop control circuit of the high-voltage direct-current motor, the processor receives a motor start-stop control signal from the outside, when the motor needs to be started, the processor sends a load driving signal to enable the second NMOS tube Q2 to be conducted, the second NMOS tube Q2 is conducted to enable the first relay coil to be electrified, when the coil is electrified, the first relay contact is closed to enable the negative terminal of the high-voltage direct-current motor to be connected to the negative pole of a DC220V power supply, the motor starts to operate, when the processor receives an external motor stop request, the processor outputs a release control signal to conduct the first NMOS tube Q1, the first NMOS tube Q1 is conducted to enable the first NMOS tube Q1, the discharge resistor R1, the rectifier bridge stack BD1 and the motor to form a discharge loop, damage to the relay contact caused by arc discharge can be eliminated, then the processor sends a load driving signal to enable the second NMOS tube Q2 to be stopped, and the first relay coil is powered off when the second NMOS tube Q2 is stopped, when the coil is powered off, the contact of the first relay is disconnected, so that the negative terminal of the high-voltage direct-current motor is disconnected with the negative electrode of a DC220V power supply, the motor stops rotating, and due to the addition of the active arc extinguishing circuit, the reverse electromotive force can be thoroughly discharged completely by the discharge resistor R1, so that the circuit can be better protected. The high-voltage direct current motor belongs to the prior art and is not specifically described herein. Fig. 2 may be specifically referred to in this embodiment.

The invention also provides another embodiment of the application circuit, which is used for protecting the forward and reverse rotation control circuit of the high-voltage direct-current motor, the load control circuit adopts two common relays to realize forward and reverse rotation control during implementation, the two common relays are respectively a second common relay J2 and a third common relay J3, relay coils of the second common relay J2 and the third common relay J3 are electrically connected with the output end of the processor, the processor receives external motor start-stop and steering control signals and respectively outputs load driving signals to the second common relay J2 and the third common relay J3, and due to the addition of the active arc extinguishing circuit, in the process of controlling the high-voltage direct-current motor to realize forward and reverse rotation, the discharge resistor R1 can thoroughly release reverse electromotive force generated when the motor stops rotating, so that the circuit can be better protected. Fig. 3 may be specifically referred to in this embodiment.

The present embodiment provides an active arc extinguishing method based on a back electromotive force active bleeding protection circuit by taking motor control as an example, which includes the following steps:

(1) the processor outputs a discharge control signal to the discharge driving circuit when receiving an external motor stalling request;

(2) delaying, when the first NMOS tube Q1 is conducted, and the first NMOS tube Q1 is conducted, the first NMOS tube Q1, the discharge resistor R1, the rectifier bridge stack BD1 and the motor form a discharge loop, and damage of arc discharge to relay contacts is eliminated;

(3) the processor outputs a load driving signal to control the relay to break a contact, and the time delay waits for the end of discharge;

(4) the processor stops outputting the discharge control signal, and the first NMOS tube Q1 cuts off the discharge loop to complete the motor stalling action.

The present invention deals with the counter emf that is harmful to the circuit in an active and proactive intervention. The specific steps are that a discharging resistor R1 is incorporated into the load in advance when the contact needs to be disconnected, then the contact is disconnected, and the discharging resistor R1 is removed after the discharging resistor R1 discharges the reverse electromotive force to a safe voltage range or discharges light. The operations of the steps are all finished by prestored program codes of the single chip microcomputer. In specific implementation, the discharge resistor R1 can be connected to the discharge loop in a continuous or intermittent manner to adapt to different discharge speed requirements. The method has the advantages that the back electromotive force can be thoroughly discharged, the problem of residual voltage is solved, and the speed problem is solved because of the intervention in advance.

The skilled person should understand that: although the invention has been described in terms of the above specific embodiments, the inventive concept is not limited thereto and any modification applying the inventive concept is intended to be included within the scope of the patent claims.

Claims

1. The utility model provides a protection circuit is released voluntarily to back electromotive force which characterized in that: including signal processing circuit, the drive circuit that releases, discharge resistance and polarity switching circuit, the one end electricity of discharge resistance is connected polarity switching circuit, and the other end electricity is connected the drive circuit that releases, polarity switching circuit with signal processing circuit all connects the drive circuit that releases, polarity switching circuit is equipped with two interfaces that release that are used for parallelly connected direct current load, signal processing circuit output is used for controlling direct current load's load drive signal and is used for control drive circuit's the control signal that releases.

2. The active reverse-emf bleeder protection circuit of claim 1, wherein: the polarity switching circuit adopts a rectifying circuit, and the signal processing circuit adopts a processor.

3. The back-emf active bleed-off protection circuit of claim 2, wherein: the bleeder driving circuit comprises a first NMOS tube, a second resistor, a fourth resistor, a fifth resistor, a first capacitor, a voltage regulator tube and a photoelectric coupler, wherein the positive output end of the rectifying circuit is electrically connected with one end of the discharge resistor, the negative output end of the rectifying circuit is electrically connected with the S pole of the first NMOS tube, the D pole of the first NMOS tube and one end of the second resistor are electrically connected with the other end of the discharge resistor, the other end of the second resistor is electrically connected with the negative pole of the voltage regulator tube, one end of the fifth resistor and one end of the first capacitor are electrically connected with the G pole of the first NMOS tube, the positive pole of the voltage regulator tube, the other end of the fifth resistor and the other end of the first capacitor are electrically connected with the S pole of the first NMOS tube, a first input pin of the photoelectric coupler is electrically connected with one end of the fourth resistor, and the other end of the fourth resistor is electrically connected with the output end of the processor, and a second input pin of the photoelectric coupler is grounded, a first output pin of the photoelectric coupler is electrically connected with the negative electrode of the voltage stabilizing tube, and a second output pin of the photoelectric coupler is electrically connected with the G electrode of the first NMOS tube.

4. The active reverse-emf bleeder protection circuit of claim 3, wherein: the rectifying circuit adopts a bridge rectifier.

5. The active reverse-emf bleeder protection circuit of claim 4, wherein: the photoelectric coupler adopts LTV-357T.

6. An application circuit based on the back electromotive force active leakage protection circuit of any one of claims 1 to 5, characterized in that: the direct current load circuit is characterized by further comprising a load control circuit, the load control circuit comprises a common relay, the common relay is provided with a relay coil and a relay contact, the signal processing circuit outputs a load driving signal to switch on and off the relay coil, two ends of the direct current load are respectively and electrically connected with two discharging interfaces of the polarity switching circuit, and the direct current load is further connected with the relay contact in series.

7. An application circuit according to claim 6, wherein: the direct current load is high voltage direct current motor, load control circuit is including first ordinary relay and second NMOS pipe, first ordinary relay has first relay coil and first relay contact, and first relay contact is normally open contact, DC12V is inserted to the one end of first relay coil, and the other end electricity is connected the D utmost point of second NMOS pipe, the S utmost point ground connection of second NMOS pipe, the G utmost point electric connection of second NMOS pipe the output of signal processing circuit, DC220V power positive pole is connected to the positive wiring end electricity of high voltage direct current motor, and the negative wiring end electricity of high voltage direct current motor is connected the one end of first relay contact, and the other end electricity of first relay contact is connected DC220V power negative pole.

8. An active arc extinguishing method based on the back electromotive force active discharge protection circuit of any one of claims 3 to 5, comprising the steps of: