CN117277261B

CN117277261B - Low-voltage direct-current bidirectional power supply communication circuit and power supply method thereof

Info

Publication number: CN117277261B
Application number: CN202311558562.3A
Authority: CN
Inventors: 刘振锋; 黄广建
Original assignee: Zhuhai Digital Power Technology Co ltd
Current assignee: Zhuhai Digital Power Technology Co ltd
Priority date: 2023-11-22
Filing date: 2023-11-22
Publication date: 2024-03-15
Anticipated expiration: 2043-11-22
Also published as: CN117277261A

Abstract

The invention discloses a low-voltage direct-current bidirectional power supply communication circuit and a power supply method thereof, wherein the bidirectional power supply communication circuit is electrically connected with a local main control circuit to form a branch, and the low-voltage direct-current bidirectional power supply communication circuits of different branches are electrically connected in a positive-negative bidirectional manner through two lines; at least one branch is connected with an external power supply system through a low-voltage direct-current bidirectional power supply communication circuit; the low-voltage direct-current bidirectional power supply communication circuit comprises: the device comprises an external power supply input module, a rectifying module, a local power supply module, a positive power supply driving module, a negative power supply driving module, a power competition prevention module and an input/output interface module; the power supply competition preventing module is used for competing the power supply of all the external power supply systems when at least two external power supply systems exist, the competition loser can close the power supply outwards, and the competition winner can supply power to the other party besides the local power supply. The two wires for power supply and communication can be not divided into positive and negative poles, and can be simultaneously powered at multiple ends.

Description

Low-voltage direct-current bidirectional power supply communication circuit and power supply method thereof

Technical Field

The invention relates to the technical field of electronic circuits, in particular to a low-voltage direct-current bidirectional power supply communication circuit and a power supply method thereof.

Background

In the prior art, two (or more) machines are powered and communicated through two wires, but in order to solve the problem of positive and negative power supply, the positive and negative poles of the two wires which are generally interconnected cannot be exchanged, and once the two wires which are interconnected are connected and the two ends are powered, the power supplies at the two ends can be short-circuited, and the power supplies and the whole system can be burnt; or two wires which are connected with each other can exchange the positive electrode and the negative electrode but can not supply power at the two ends simultaneously, namely, the power supply is fixed on one machine, and the other machine can not supply power; typically, single ended power supply systems operate properly. However, if the power supply and communication line is too long or the wire diameter is too small, the voltage drop on the wire is too large, and the power must be supplied at two ends; yet another condition is human inattention. Therefore, the common installation specifications in the industry all require that the two wires for power supply and communication be installed according to the condition of positive connection, but when a person is negligent, the power supply and the system can be damaged if the connection is reversed and the two ends are connected with the power supply.

In summary, there is an urgent need in the industry to develop a low-voltage direct-current bidirectional power supply communication circuit capable of switching between power supply and communication without separating positive and negative poles.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a low-voltage direct-current bidirectional power supply communication circuit which is capable of supplying power to multiple ends simultaneously and has the advantages that two wires of power supply communication are not divided into positive and negative electrodes and can be exchanged, and a power supply method thereof.

The aim of the invention is achieved by the following technical scheme:

the low-voltage direct-current bidirectional power supply communication circuit is electrically connected with the local main control circuit to form a branch, and the low-voltage direct-current bidirectional power supply communication circuits of different branches are electrically connected through two wires without dividing positive and negative directions; at least one branch is connected with an external power supply system through a low-voltage direct-current bidirectional power supply communication circuit; the low-voltage direct-current bidirectional power supply communication circuit comprises: the device comprises an external power supply input module, a rectifying module, a local power supply module, a positive power supply driving module, a negative power supply driving module, a power competition prevention module and an input/output interface module; the external power supply input module is used for externally inputting power supply; the rectification module is used for rectifying a power supply, and the rectified voltage is input to the local power supply module and the external power supply input module, wherein the power supply does not divide positive and negative polarities; the local power supply module is used for supplying power to the low-voltage direct-current bidirectional power supply communication circuit and the local main control circuit; the positive power supply driving module is used for inputting local power supply to the power supply input and output positive end; the negative power supply driving module is used for inputting local power supply to the power supply input and output negative terminal; the power supply competition preventing module is used for carrying out competition release on power supply of all external power supply systems when at least two external power supply systems exist, a competition loser can close the outward power supply, and a competition winner can supply power to the other party besides the local power supply.

Preferably, the external power input module includes: diode D1, the second pin of the anodal connecting plug J1 of diode D1, the first pin of plug J1 is connected to ground, and rectifier module includes: the anodes of the diode D4 and the diode D5 are connected to the ground, the cathode of the diode D4 is connected with the cathode of the diode D1 through the diode D2, and the cathode of the diode D5 is connected with the cathode of the diode D1 through the diode D3 (LOCAL power supply end LOCAL_VCC); the local power supply module includes: the positive electrode of the capacitor TC1 is connected with the LOCAL power supply terminal LOCAL_VCC and is also the negative electrode of the diode D1.

Preferably, the positive power supply driving module comprises: MOS pipe Q1, MOS pipe Q1 is P channel enhancement mode MOSFET, MOS pipe Q1's grid passes through resistance R1 to be connected diode D2's negative pole, MOS pipe Q1's grid still passes through resistance C1 to be connected diode D2's negative pole, MOS pipe Q1's grid still passes through resistance R2 to be connected triode Q2's collecting electrode, triode Q2's projecting pole passes through resistance R6 to be connected to ground, MOS pipe Q1's source connection diode D2's negative pole, diode D2's positive pole is connected to MOS pipe Q1's drain electrode, MOS pipe Q1's drain electrode still connects the power input and output positive terminal, MOS pipe Q1's drain electrode still passes through resistance R7 in proper order, resistance R8 connects power competition prevention module, triode Q2's projecting pole still passes through resistance R3 and connects capacitor C1's one end, triode Q2's base passes through resistance R5 in proper order, diode D6 connects resistance R7 and resistance R8's tie point, resistance R5's one end is passed through respectively to the resistance C2, resistance R5's the other end still is as triode Q2 drive signal end.

Preferably, the negative supply power driving module includes: MOS pipe Q3, MOS pipe Q3 is N channel enhancement mode MOSFET, and MOS pipe Q3's drain electrode is connected power input and output negative terminal through recoverable insurance tube F1, and MOS pipe Q3's grid is connected to ground through resistance R10, electric capacity C3 respectively, and MOS pipe Q3's grid still passes through resistance R9 and connects resistance R5's one end, and MOS pipe Q3's source electrode ground.

Preferably, the power contention prevention module includes: the triode Q4, the power input and output negative terminal is connected through resistance R13 to triode Q4's projecting pole, triode Q4's base is connected to MOS pipe Q3's drain electrode NMOS_D, resistance R14 connects triode Q4's projecting pole and base, triode Q4's collecting electrode passes through electric capacity C4 to be connected to ground, triode Q4's collecting electrode still passes through resistance R12 to be connected triode Q5's base, triode Q5's projecting pole is connected to ground, triode Q5's collecting electrode connecting resistance R8 and resistance R9's tie point, opto-coupler U1's transmitting terminal positive pole passes through resistance R11 and connects power input and output negative terminal, opto-coupler U1's transmitting terminal negative pole passes through diode D6 and connects the power input and output positive terminal, opto-coupler U1's receiving terminal C extremely connecting resistance R8 and resistance R9's tie point, opto-coupler U1's receiving terminal E extremely is connected to ground, input and output interface module includes: plug J2, the second pin of plug J2 passes through inductance L1 and connects power input output positive terminal, and the second pin of plug J2 still carries out first communication end connection with local main control circuit through electric capacity C5, and the first pin of plug J2 passes through inductance L2 and connects power input output negative terminal, and the first pin of plug J2 still carries out the second communication end connection with local main control circuit through electric capacity C6.

Preferably, the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected in a positive connection or reverse connection mode, wherein the positive connection is the connection between the power input and output positive ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches, and the connection between the power input and output negative ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches; the reverse connection is that the power input and output positive ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected with the power input and output negative ends of the low-voltage direct-current bidirectional power supply communication circuits of other branches.

The power supply method based on the low-voltage direct current bidirectional power supply communication circuit, only one branch is connected with an external power supply system through the low-voltage direct current bidirectional power supply communication circuit, the branch connected with the external power supply system is used as a first branch, the branch not connected with the external power supply system is used as a second branch, the number of the second branches is at least 1, the low-voltage direct current bidirectional power supply communication circuits of the first branch and the second branch are positively connected, and then the power supply method comprises the following steps: for the first branch, the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module of the first branch, an MOS tube Q1 of the positive power supply driving module and an MOS tube Q3 of the negative power supply driving module are both conducted, and a power supply input and output positive end and a power supply input and output negative end supply power; for the second branch, as the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected in a forward direction, the power supply input output positive end and the power supply input output negative end of the second branch are powered on, the LOCAL power supply end local_VCC is powered through the rectifying module, after the LOCAL power supply end local_VCC obtains power, the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are both conducted, and the LOCAL power supply end local_VCC is powered on; the positive power input and output ends of the first branch and the second branch are positive, and the negative power input and output ends of the first branch and the second branch are negative.

The power supply method based on the low-voltage direct current bidirectional power supply communication circuit, only one branch is connected with an external power supply system through the low-voltage direct current bidirectional power supply communication circuit, the branch connected with the external power supply system is used as a third branch, the branch not connected with the external power supply system is used as a fourth branch, the number of the fourth branches is at least 1, and the low-voltage direct current bidirectional power supply communication circuits of the third branch and the fourth branch are reversely connected, so that the power supply method comprises the following steps: for the third branch, the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module of the third branch, the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are both conducted, and the power supply input and output positive end and the power supply input and output negative end supply power; for the fourth branch, because the low-voltage direct current bidirectional power supply communication circuits of different branches are reversely connected, the power input/output positive end of the fourth branch inputs negative electricity and the power input/output negative end of the fourth branch inputs positive electricity, the LOCAL power supply end local_VCC is supplied with power through the rectifying module, after the LOCAL power supply end local_VCC is supplied with power, the power competition prevention module starts protection because the power input/output positive end inputs negative electricity and the power input/output negative end inputs positive electricity, and the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are cut off.

The power supply method based on the low-voltage direct-current bidirectional power supply communication circuit comprises the following steps that all branches are connected with an external power supply system through the respective low-voltage direct-current bidirectional power supply communication circuit, all the low-voltage direct-current bidirectional power supply communication circuits of all the branches are connected in a forward direction, and then the power supply method comprises the following steps: the power supply system with high voltage in the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module of a branch, an MOS tube Q1 of the positive power supply driving module and an MOS tube Q3 of the negative power supply driving module are both conducted, and a power supply input and output positive end and a power supply input and output negative end supply power; wherein, the positive power input and output ends of the branches are positive, and the negative power input and output ends are negative; or the voltage difference of the external power supply systems is smaller than the voltage difference of the MOS tube Q1 of the positive power supply driving module in different branches, all the external power supply systems supply power to the LOCAL power supply end LOCAL_VCC through the external power supply input modules of the branches, the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are both conducted, and the power supply input and output positive end and the power supply input and output negative end supply power; the positive power input and output ends of the branches are positive, and the negative power input and output ends of the branches are negative.

The power supply method based on the low-voltage direct-current bidirectional power supply communication circuit comprises the following steps that all branches are connected with an external power supply system through the respective low-voltage direct-current bidirectional power supply communication circuit, and all the low-voltage direct-current bidirectional power supply communication circuits of all the branches are connected in reverse, so that the power supply method comprises the following steps: all the low-voltage direct-current bidirectional power supply communication circuits of all the branches are reversely connected, all the branches compete, and one party wins power competition; the competition failure party can close the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module which are powered outwards, so that the system damage caused by short circuit is avoided; the competing winner supplies power to the LOCAL power supply end local_vcc of the branch circuit and also supplies power to the LOCAL power supply ends local_vcc of the other branch circuits; comparing the self-power supply voltage of the competing failure party with the voltage of the competing failure party after voltage drop, and supplying power to a power supply end local_VCC of the competing failure party by the party with high voltage, wherein the difference value obtained by subtracting the line voltage drop from the voltage of the competing failure party is subtracted by the voltage drop of the rectifying bridge voltage to be used as the voltage of the competing failure party after voltage drop.

Compared with the prior art, the invention has the following advantages:

When only one branch is connected with external power supply, the other branches are only used as power receiving parties, and the branches with external power supply are connected positively or reversely, and the power supply can be sent out no matter the branches are connected positively or reversely. The other branches can obtain local_VCC no matter the positive connection or the negative connection because of the rectification circuit. The whole system can be powered by electricity. When a plurality of branches are supplied with external power and are connected in positive connection, the transmission power has no logic conflict because of no conflict of positive and negative electrodes. The MOS transistors Q1 and Q3 of all branches are conducted. The direction of the current looks at the magnitude of the external power supply voltage, and the power supply with large power supply voltage flows the current to the branch circuit with small power supply voltage. When a plurality of branches are provided with external power supply and are connected in reverse, the power supply competition prevention module releases competition for the power supply of all external power supply systems, a competition failure party can close the external power supply, a competition winner party supplies power to the other party except for local power supply, and the problem that a plurality of external power supplies are short-circuited due to the conflict of positive and negative polarities is avoided. Therefore, the two lines of power supply and communication in the application can be not divided into positive and negative poles (arbitrary connection), and can be supplied with power at multiple ends at the same time, and the power supply at multiple ends can be any one side or can be supplied with power at the same time.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:

fig. 1 is a system block diagram formed by electrically connecting a low-voltage direct-current bidirectional power supply communication circuit with a local main control circuit.

Fig. 2 is a circuit diagram of a low voltage dc bi-directional power supply communication circuit of the present invention.

Fig. 3 is a circuit diagram of a power contention model of the source contention prevention module according to the present invention.

Detailed Description

The invention is further described below with reference to the drawings and examples.

The low-voltage direct-current bidirectional power supply communication circuit is electrically connected with the local main control circuit to form a branch, and the low-voltage direct-current bidirectional power supply communication circuits of different branches are electrically connected through two wires without dividing positive and negative directions; at least one branch is connected with an external power supply system through a low-voltage direct-current bidirectional power supply communication circuit; the low-voltage direct-current bidirectional power supply communication circuit comprises: an external power supply input module 1, a rectifying module 2, a local power supply module 3, a positive power supply driving module 4, a negative power supply driving module 5, a power competition prevention module 6 and an input/output interface module 7; the external power supply input module 1 is used for externally inputting power supply; the rectification module 2 is used for rectifying a power supply, and the rectified voltage is input to the external power supply input module 1 and the local power supply module 3, wherein the power supply does not divide positive and negative polarities; the local power supply module 3 is used for supplying power to the low-voltage direct-current bidirectional power supply communication circuit and the local main control circuit; the positive power supply driving module 4 is used for inputting local power supply to the positive power supply input and output end; the negative power supply driving module 5 is used for inputting local power supply to the negative input and output end of the power supply; the power competition preventing module 6 is configured to, when at least two external power supply systems exist, release competition for power supply of all the external power supply systems, and the competing loser will close the power supply to the outside, and the competing winner supplies power to the other party in addition to the local power supply.

The two wires of power supply and communication connected between the low-voltage direct-current two-way power supply communication circuits of all the branches are not divided into positive and negative poles and can be exchanged. The power supply can be performed at the host computer or the slave computer, namely any external power supply system can supply power, or all external power supply systems can supply power, namely bidirectional power supply is performed. And the common circuit is divided into an anode and a cathode by two lines for power supply and communication, and once the two lines are connected and both ends are powered, the power supplies at both ends can be short-circuited, and the power supply and the whole system can be burnt. The invention overcomes the condition of damaging the power supply and the system under the extreme condition, and ensures that the system is safe and can work normally.

In this embodiment, a low-voltage direct-current bidirectional power supply communication circuit will be described by taking two branches (two devices) as an example. The present application focuses on the power section and the communication section is not in the scope of discussion. In this embodiment, the two low-voltage direct-current bidirectional power supply communication circuits are connected in a positive or reverse connection manner, wherein the positive connection is a connection between power input and output positive ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches, and the connection between power input and output negative ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches is performed; fig. 2 is a circuit diagram of a low voltage dc bi-directional power supply communication circuit of the present invention. As shown in fig. 2, pin 2 of plug J2 of the first leg is connected to pin 2 of J2 of the second leg; the pin 1 of the plug J2 of the first branch is connected with the pin 1 of the plug J2 of the second branch. I.e., VIN/out+ of the two machines (via inductances L1 and J2); i.e., VIN/OUT-connection (via inductances L2 and J2) of the two machines. The reverse connection is that the power input and output positive ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected with the power input and output negative ends of the low-voltage direct-current bidirectional power supply communication circuits of other branches. Pin 2 of plug J2 of the first leg is connected to pin 1 of plug J2 of the second leg as shown in fig. 2; the pin 1 of the plug J2 of the first branch is connected with the pin 2 of the plug J2 of the second branch. I.e., the VIN/OUT+ of the first leg is connected to the VIN/OUT+ of the second leg; the VIN/OUT-of the first branch is connected (via inductors L1/L2 and J2) to the VIN/OUT+ of the second branch. Plug J1 and plug J2 are board-to-wire connectors.

In the present embodiment, the external power supply input module 1 includes: diode D1, the positive pole of diode D1 connects the second pin of plug J1, the first pin of plug J1 connects to ground. The diode D1 prevents reverse connection of the external power supply. The rectifying module 2 includes: the anodes of the diode D2, the diode D3, the diode D4 and the diode D5 are connected to the ground, the cathode of the diode D4 is connected with the cathode of the diode D1 (namely a LOCAL power supply end LOCAL_VCC) through the diode D2, and the cathode of the diode D5 is connected with the cathode of the diode D1 through the diode D3, so that the positive power supply driving module 4 and the negative power supply driving module 5 are powered by the positive power supply; the power from the positive power input/output terminal VIN/OUT+ and the negative power input/output terminal VIN/OUT-is supplied to the LOCAL power supply terminal LOCAL_VCC after passing through the rectifying circuit. The rectifying action can be executed without dividing the positive polarity of the power input/output positive terminal VIN/OUT+ and the power input/output negative terminal VIN/OUT-.

The local power supply module 3 includes: the positive electrode of the capacitor TC1 is connected with a LOCAL power supply end LOCAL_VCC, the LOCAL power supply module 3 is used for providing LOCAL power supply through the LOCAL power supply end LOCAL_VCC, the LOCAL power supply end LOCAL_VCC voltage can come from an external power supply input module 1, a rectifying module 2, a positive power supply driving module 4 and a negative power supply driving module 5, and finally the LOCAL power supply is provided by a module with high voltage in the external power supply input module 1, the rectifying module 2, the LOCAL power supply module 3, the positive power supply driving module 4 and the negative power supply driving module 5 through the LOCAL power supply end LOCAL_VCC.

In this embodiment, the positive power supply driving module 4 includes: the MOS tube Q1, the MOS tube Q1 is a P channel enhancement MOSFET, as shown in FIG. 2, the 3 pin of the MOS tube Q1 is the G pole, the 4 pin is the S pole, and the 1/2/5/6 pin is the D pole. The grid of the MOS tube Q1 is connected with the cathode of the diode D2 through a resistor R1, the grid of the MOS tube Q1 is also connected with the cathode of the diode D2 through a capacitor C1, the grid of the MOS tube Q1 is also connected with the collector of the triode Q2 through a resistor R2, the emitter of the triode Q2 is connected to the ground through a resistor R6, and the triode Q2 is an NPN triode. The source electrode of the MOS tube Q1 is connected with the cathode of the diode D2, the drain electrode of the MOS tube Q1 is connected with the anode of the diode D2, the drain electrode of the MOS tube Q1 is also connected with the power input and output positive end, the drain electrode of the MOS tube Q1 is also connected with the power competition prevention module 6 through a resistor R7 and a resistor R8 in sequence, the emitter electrode of the triode Q2 is also connected with one end of a capacitor C1 through a resistor R3, the base electrode of the triode Q2 is connected with a connection point of the resistor R7 and the resistor R8 through a resistor R5 and a diode D6 in sequence, one end of the capacitor C1 is connected with one end of the resistor R5 through a resistor R4 and a capacitor C2 respectively, and the other end of the resistor R5 is also used as a triode driving signal end (MOS_DRV); the LOCAL power supply terminal local_VCC voltage drives the triode Q2 through the resistor R4, the capacitor C2 and the resistor R5, the triode Q2 is conducted, the resistor R1, the capacitor C1 and the resistor R2 are driven to conduct current, voltage drop exists on the resistor R1, vgs negative voltage is provided by the voltage drop, after the voltage exceeds the threshold value of the Vgs of the MOS tube Q1, the MOS tube Q1 is conducted, and the LOCAL power supply terminal local_VCC voltage is conducted to VIN/OUT+. Resistor R3 and resistor R6 provide voltage bias to the emitter of transistor Q2, enabling transistor Q2 to be turned off more reliably when it is desired to turn off. The capacitor C2 is used to better enable the transistor driving signal terminal mos_drv to be quickly powered on in the initial stage of the LOCAL power supply terminal local_vcc voltage power-on, so as to ensure the reliable conduction of the transistor Q2.

In the present embodiment, the negative power supply driving module 5 includes: MOS pipe Q3, MOS pipe Q3 is N channel enhancement mode MOSFET, and MOS pipe Q3' S3 foot is the G utmost point, and 4 foot is the S utmost point, and 1/2/5/6 foot is the D utmost point. The drain electrode of the MOS tube Q3 is connected with the power input and output negative terminal through a recoverable fuse tube F1, the grid electrode of the MOS tube Q3 is connected to the ground through a resistor R10 and a capacitor C3 respectively, the MOS tube Q3 is also connected with one end of a resistor R5 through a resistor R9, F1 is a recoverable fuse tube, is a positive temperature coefficient thermistor, and the higher the temperature is, the larger the resistance is. The triode driving signal end MOS_DRV provides positive voltage for the G pole of the MOS tube Q3 through a resistor R9, a resistor R10 and a capacitor C3, and when the voltage of Vgs exceeds a threshold value, the MOS tube Q3 is conducted, and VIN/OUT-is conducted to the ground.

In the present embodiment, the power contention prevention module 6 includes: transistor Q4, transistor Q4 is a PNP transistor. The emitter of triode Q4 passes through resistance R13 connection power input output negative terminal, the drain electrode of MOS pipe Q2 is connected to triode Q4's base, resistance R14 connects triode Q4's emitter and base, triode Q4's collecting electrode passes through electric capacity C4 and is connected to ground, triode Q4's collecting electrode still passes through resistance R12 and connects triode Q5's base, triode Q5's emitter is connected to ground, triode Q5's collecting electrode connecting resistance R8 and resistance R9's tie point (MOS_DRV), triode Q5 is NPN triode. The positive pole of the transmitting terminal of opto-coupler U1 connects the power input output negative terminal (VIN/OUT-), the transmitting terminal negative pole of opto-coupler U1 connects the power input output positive terminal (VIN/OUT+), the receiving terminal C of opto-coupler U1 connects the junction point of resistance R8 and resistance R9, the receiving terminal E of opto-coupler U1 connects to ground, input/output interface module 7 includes: the second pin of plug J2 passes through inductance L1 and connects power input output positive terminal, the second pin of plug J2 still carries OUT first communication end connection with local main control circuit through electric capacity C5, the first pin of plug J2 passes through inductance L2 and connects power input output negative terminal, the first pin of plug J2 still carries OUT second communication end connection with local main control circuit through electric capacity C6, the voltage of power input output positive terminal VIN/OUT+ is the positive voltage that is switched on by MOS pipe Q1 under the normal condition, power input output negative terminal VIN/OUT-voltage is the negative voltage that MOS pipe Q3 led to ground.

If the two-wire bidirectional power supply and communication are reversely connected, opposite voltage is introduced from the opposite machine, so that the negative terminal VIN/OUT-of the power supply input and output is possibly positive voltage, the positive terminal VIN/OUT+ of the power supply input and output is possibly negative voltage, at the moment, the optocoupler U1 is driven to be conducted, the voltage of the triode driving signal terminal MOS_DRV is pulled down to the ground by the optocoupler output electrode, the triode Q2 is turned off, the MOS tube Q1 is further turned off, and the MOS tube Q3 is turned off because the G electrode has no voltage. The MOS tube Q1 and the MOS tube Q3 are all cut off, so that the isolation of the positive voltage of the local_VCC and the negative voltage of the positive end VIN/OUT+ of the power input and output is protected, and the isolation of the positive voltage of the negative end VIN/OUT-of the power input and output and the ground is protected.

When the power input/output positive terminal VIN/OUT+ is negative voltage, the diode D6 and the resistor R7 also discharge the voltage of the triode driving signal terminal MOS_DRV to the power input/output positive terminal VIN/OUT+, so that the MOS tube Q1 and the MOS tube Q3 are closed. VIN/out+ is positive and the path consisting of diode D6 and resistor R7 is not active.

The positive power input/output terminal VIN/OUT+ is positive voltage, and the optocoupler U1 is cut off when the negative power input/output terminal VIN/OUT-is negative voltage.

In addition, because the U1 optocoupler is started with a driving voltage threshold, in order to provide protection even if the voltage difference between the power input/output negative terminal VIN/OUT-and the power input/output positive terminal VIN/OUT+ is smaller than the threshold, the application also designs another protection which consists of a resistor R13, a resistor R14, a triode Q4, a resistor R12, a capacitor C4 and a triode Q5.

The resistor R13 and the resistor R14 are connected to two ends of the recoverable insurance F1, when the current of the recoverable insurance F1 is increased, the pressure difference between the two ends of the recoverable insurance F1 is increased, when the pressure difference between the two ends of the resistor R14 drives the triode Q4 to be conducted, the capacitor C4 drives the triode Q5 to be conducted through the resistor R12, the C electrode of the triode Q5 conducts MOS_DRV to the ground, so that the MOS tube Q1 and the MOS tube Q3 are cut off, and the protection action is executed.

In summary, as long as the positive terminal VIN/out+ of the power input/output is a negative voltage, the negative terminal VIN/OUT-of the power input/output is a positive voltage, the power contention prevention module 6 starts protection, and the circuit formed by the resistor R13, the resistor R14, the triode Q4, the resistor R12, the capacitor C4 and the triode Q5 is protected at the beginning, when the voltage difference between the positive terminal VIN/out+ of the power input/output and the negative terminal VIN/out+ of the power input/output reaches the starting threshold of the optocoupler U1, the circuit is started to protect by the optocoupler U1 and the diode d6+ resistor R7, and the stable state of protection can be maintained.

The power supply competition is divided into the following cases:

(1) The two external power systems have different power-on times, and the machine powered on first wins competition.

(2) If the power-up times of the two external power systems are the same, and the rising slope can be analyzed by the model of fig. 3 as well:

The power competition model is shown in fig. 3, and is a case that 'two-wire bidirectional power supply+communication' is reversely connected, and the first branch and the second branch are externally powered.

V1 is the external power supply of the first branch, V2 is the external power supply of the second branch, VIN/OUT+1/VIN/OUT-1 is VIN/OUT+/VIN/OUT-, VIN/OUT+2/VIN/OUT-2 is VIN/OUT+/VIN/OUT-of the second branch. F1 is the fuse of the first branch and F2 is the fuse of the second branch. Equivalent to connecting two power supplies in series through two recoverable fuses (F1, F2). F1 F2 is a recoverable fuse, a positive temperature coefficient thermistor, and the higher the temperature, the greater the impedance.

The pressure drop across F1 is VF1 and the pressure drop across F2 is VF2, VIN/out+1-VIN/OUT-1=vdiff1, VIN/out+2-VIN/OUT-2=vdiff2.

Vdiff1=v1-v1-v2+v2, if v1=v2, then it reduces to: vdiff1=vf2-VF 1.

Vdiff2=v2-v2-v1+v1, if v1=v2, then it reduces to: vdiff2=vf1-vf2.

It can be seen that vdiff1= -Vdiff2, the two voltages are in opposite relationship, one positive and the other must be negative, the positive voltage is the competing victory and the negative voltage is the losing one.

Because of the small difference between the parameters of F1 and F2, or the master/slave selects F1 and F2 with different parameters, at the same current, VF1 and VF2 always have the difference at the same time.

The voltages of V1, V2 are also different and the load capacities are also different, which can also lead to variations in Vdiff1, vdiff 2.

When Vdiff1 or Vdiff2 reaches the starting voltage of the optocoupler, the MOS tube Q1 of the loser is lost, and the MOS tube Q3 is closed. Before the starting voltage of the optocoupler U1 is not reached, the protection circuit consisting of the recoverable fuse F1, the triode Q4 and the triode Q5 is used for preventing the short-circuit current of the circuit from being overlarge.

In the present embodiment, the input-output interface module 7 includes: the second pin of plug J2 passes through inductance L1 and connects power input output positive terminal, the second pin of plug J2 still carries out first communication end connection with local main control circuit through electric capacity C5, the first pin of plug J2 passes through inductance L2 and connects power input output negative terminal, the first pin of plug J2 still carries out second communication end connection with local main control circuit through electric capacity C6, communication_signal1/communication_signal2 is connected to "local main control circuit" of FIG. 1, be "local communication" signal of FIG. 1, be received J2 through electric capacity C5/C6 respectively. The power input/output of this circuit: VIN/OUT+ and VIN/OUT-are connected to J2 through inductors L1 and L2, respectively. The J2 plug-in wire is connected to J2 of another machine to complete power supply and communication.

The working modes of the low-voltage direct-current bidirectional power supply communication circuit are four, namely:

1. as shown in fig. 1, only one of the "first external power supply system" and the "second external power supply system" is employed. The two-wire bidirectional power supply and communication adopts positive connection.

2. As shown in fig. 1, only one of the "first external power supply system" and the "second external power supply system" is employed. The two-wire bidirectional power supply and communication adopts reverse connection.

3. As shown in fig. 1, both the "first external power supply system" and the "second external power supply system" are connected. The two-wire bidirectional power supply and communication adopts positive connection.

4. As shown in fig. 1, both the "first external power supply system" and the "second external power supply system" are connected. The two-wire bidirectional power supply and communication adopts reverse connection.

The four working modes are specifically as follows:

(1) Only one branch is connected with an external power supply system through a low-voltage direct-current bidirectional power supply communication circuit, the branch connected with the external power supply system is used as a first branch, the branch not connected with the external power supply system is used as a second branch, and the number of the second branches is 1; the low-voltage direct current bidirectional power supply communication circuits of the first branch and the second branch are connected in a forward direction, and the power supply method comprises the following steps:

For the first branch (one with an external power supply), the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module 1 of the first branch, a MOS tube Q1 of a positive power supply driving module 4 and a MOS tube Q3 of a negative power supply driving module 5 are both conducted, and a power supply input/output positive end (positive power) and a power supply input/output negative end (negative power) supply; thus, the power supply sequence of the first branch: the external power supply system, the LOCAL power supply end LOCAL_VCC, the MOS tube Q1 and the MOS tube Q3 are conducted, and the power supply input and output positive end outputs positive points and the power supply input and output negative end outputs negative electricity.

For the second branch (one without external power supply), as the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected in a forward direction, the power input/output positive end and the power input/output negative end of the second branch are powered on, the LOCAL power supply end LOCAL_VCC is powered through the rectifying module 2, after the LOCAL power supply end LOCAL_VCC obtains power, the MOS tube Q1 of the positive power supply driving module 4 and the MOS tube Q3 of the negative power supply driving module 5 are both conducted, and the LOCAL power supply end LOCAL_VCC is powered on more directly, namely, after the MOS tube Q1 and the MOS tube Q3 are conducted, the voltage drop of the MOS tube is smaller than that of the rectifying diode. Therefore, after the MOS transistor Q1 and the MOS transistor Q3 are conducted, the rectifying module does not work (is bypassed by the MOS transistor Q1 and the MOS transistor Q3). After the MOS tube Q1 and the MOS tube Q3 are conducted, the voltage drop between the power input/output positive terminal VIN/OUT+ and the power input/output negative terminal VIN/OUT-conducted to the LOCAL power supply terminal LOCAL_VCC is smaller than that of the rectifying circuit, so that the direct power supply is realized. The positive power input and output ends of the first branch and the second branch are positive, and the negative power input and output ends of the first branch and the second branch are negative. Because the two-wire bidirectional power supply and communication are positive, the VIN/OUT+ of the two parties are positive, the VIN/OUT-of the two parties are negative, the power competition prevention module 6 cannot start protection, and no power competition exists. Thus, the power supply sequence of the second branch: the power input/output positive end inputs positive points and the power input/output negative end inputs negative electricity, the rectifying module is connected with the LOCAL supply local_VCC-MOS tube Q1 and the MOS tube Q3, the power input/output positive end is connected to the local_VCC through the MOS tube Q1, and the power input/output negative end is connected to the ground through the MOS tube Q3.

(2) Only one branch is connected with an external power supply system through a low-voltage direct-current bidirectional power supply communication circuit, the branch connected with the external power supply system is taken as a third branch, the branch not connected with the external power supply system is taken as a fourth branch, the number of the fourth branches is 1, and the low-voltage direct-current bidirectional power supply communication circuits of the third branch and the fourth branch are reversely connected, so that the power supply method comprises the following steps:

for the third branch (one with external power supply), the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module 1 of the third branch, a MOS tube Q1 of a positive power supply driving module 4 and a MOS tube Q3 of a negative power supply driving module 5 are both conducted, and a positive power supply input/output end outputs positive power and a negative power supply input/output end outputs negative power;

for the fourth branch (one without external power supply), because the low-voltage direct current two-way power supply communication circuits of different branches are reversely connected, the power input/output positive end of the fourth branch inputs negative electricity and the power input/output negative end inputs positive electricity, the LOCAL power supply end local_vcc is supplied with power through the rectifying module 2, after the LOCAL power supply end local_vcc is supplied with power, the power competition prevention module 6 starts protection, and the MOS tube Q1 of the positive power supply driving module 4 and the MOS tube Q3 of the negative power supply driving module 5 are cut off. In this case, although the LOCAL power supply terminal local_vcc of the side without the external power supply is powered, the voltage drops across the rectifying module 2, which is lower. The voltage drop of the MOS transistor Q1 and the MOS transistor Q3 in the first working mode is smaller than that of the rectifying module 2. In this case too, there is no power competition.

(3) All the branches are connected with an external power supply system through respective low-voltage direct-current bidirectional power supply communication circuits, and all the low-voltage direct-current bidirectional power supply communication circuits of all the branches are connected in a forward direction, so that the power supply method comprises the following steps:

the power supply system with high voltage in the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module 1 of a branch, an MOS tube Q1 of a positive power supply driving module 4 and an MOS tube Q3 of a negative power supply driving module 5 are both conducted, and a power supply input positive end, a power supply input negative end and a power supply input negative end supply power; wherein, the positive power input and output ends of all the branches are positive, and the negative power input and output ends are negative; because the two-wire bidirectional power supply and communication are connected positively, namely the positive power input and output ends VIN/OUT+ of the two are connected together, the negative power input and output ends VIN/OUT-are connected together, and the polarities of the power supplies are the same, the situation of power supply conflict competition does not exist.

Or alternatively

Both local_vcc's supply power by who sees who of these two external power sources is high in voltage and supplies the entire system with high voltage. If the voltage difference of the external power supply systems is smaller than the voltage difference of the MOS tube Q1 of the positive power supply driving module 4 in different branches, the two groups of external power supply systems supply power to the LOCAL power supply end LOCAL_VCC through the external power supply input module 1 of each branch, the MOS tube Q1 of the positive power supply driving module 4 and the MOS tube Q3 of the negative power supply driving module 5 are both conducted, and the power supply input and output positive end and the power supply input and output negative end supply power; the two-wire bidirectional power supply and communication line only plays a role in communication and does not participate in power supply. The positive power input/output ends of all the branches are positive, the negative power input/output ends of all the branches are negative, the power competition prevention module 6 cannot start protection, and no power competition exists.

(4) All the branches are connected with an external power supply system through respective low-voltage direct-current bidirectional power supply communication circuits, and all the low-voltage direct-current bidirectional power supply communication circuits of all the branches are reversely connected, so that the power supply method comprises the following steps:

the external power supply of the first branch will supply power to local_VCC through D1, and after local_VCC gets power, Q1 is turned on, Q3 supplies positive power to VIN/OUT+, and negative power to VIN/OUT-.

Similarly, the second external power supply will supply power to local_VCC through D1, and local_VCC is powered to turn on Q1, Q3 to supply positive power to VIN/OUT+ and negative power to VIN/OUT-.

Because the two-wire bidirectional power supply and communication adopts reverse connection, the VIN/OUT+ of the first branch is connected with the VIN/OUT+ of the second branch, and the VIN/OUT+ of the first branch is connected with the VIN/OUT+ of the second branch, namely the short circuit phenomenon can occur. Therefore, the low-voltage direct-current bidirectional power supply communication circuits of all the branches are reversely connected, all the branches compete, and one party can win power competition; the competition failure party can close the MOS tube Q1 of the positive power supply driving module 4 and the MOS tube Q3 of the negative power supply driving module 5 which are powered outwards, so that the damage of the system caused by short circuit is avoided; the competing winner supplies power to the LOCAL power supply end local_vcc of the branch circuit and also supplies power to the LOCAL power supply ends local_vcc of the other branch circuits; comparing the self-power supply voltage of the competing failure party with the voltage of the competing failure party after voltage drop, and supplying power to a power supply end local_VCC of the competing failure party by the party with high voltage, wherein the difference value obtained by subtracting the line voltage drop from the voltage of the competing failure party is subtracted by the voltage drop of the rectifying bridge voltage to be used as the voltage of the competing failure party after voltage drop.

Therefore, in the above (1) and (2), only one branch is connected with external power supply, and the other branches are only used as power receivers. When the power supply is connected in the positive or reverse direction, the branch circuit with external power supply can send out power supply no matter the power supply is connected in the positive or reverse direction. The other branches can obtain local_VCC no matter the positive connection or the negative connection because of the rectification circuit. The whole system can be powered by electricity. When the MOS tube Q1 and the MOS tube Q3 are connected in the forward direction, the voltage drop of the power receiving branch circuit is smaller (the voltage drop of the MOS tube is smaller than the voltage drop of diode rectification), and when the MOS tube Q1 and the MOS tube Q3 are connected in the reverse direction, the voltage drop is larger. In the above (3), there are a plurality of branches with external power supply, and the connection is positive. There is no logical collision of the transmitted power since there is no collision of the positive and negative electrodes. The MOS transistors Q1 and Q3 of all branches are conducted. The direction of the current looks at the magnitude of the external power supply voltage, and the power supply with large power supply voltage flows the current to the branch circuit with small power supply voltage. In the above (4), there are a plurality of branches with external power supply, and the connection is reverse connection. Because of the conflict of positive and negative polarities, a plurality of external power sources may be short-circuited as shown in fig. 3.

The whole system is to be released from the short circuit by two ways:

A) The power supply which is powered on first wins power competition due to different power-on time of the external power supply. According to the simulation, the competition is won as long as the power supply leads the other power supply by 0.1 mS. This situation applies to most cases. In the case of 220V AC power supplied simultaneously by the same power supply, the time for dc power to come out is typically several mS to several tens of mS.

B) In extreme cases, the DC voltages of the external power supply are powered up completely simultaneously (power up interval is less than 0.1 mS). Then the action is to be taken by the reinstatement insurance. The recoverable insurance is an element with positive temperature coefficient, namely, the higher the current is, the higher the temperature is, the higher the impedance is, and when the insurance impedance of different branches at the same time has a difference of a plurality of ohms, the time sequence of the power supply competition protection circuit operation is caused, and the branch which does not operate wins competition. The protection circuit of the first-acting branch circuit can close the MOS transistors Q1 and Q3 to stop short circuit and stop power competition, and the state can be kept all the time.

In the case of the other extreme, the impedance of the fuse is consistent at the same time when the fuse is short-circuited at the beginning, the circuit can enter an oscillation state, namely Q1 and Q3 are repeatedly opened and closed, the fuse is repeatedly heated and cooled, and the impedance is repeatedly changed from small to large and from large to small. In the process, due to heat dissipation of the PCB, the performance and other factors of the external power supply are not exactly the same, namely, the impedance of the fuse is different after oscillation for a period of time, and the competition state can be broken when the impedance is different.

The proper recoverable insurance parameters and parameters of the MOS tube are selected, the device is not damaged even if the device is repeatedly oscillated, and experiments prove that each branch is directly short-circuited with the 1,2 pins (the permanent short circuit) of the J2, the power supply and the system are not damaged (the recoverable insurance can always generate heat, but cannot be damaged).

In addition, in order to avoid oscillation, the master and slave branches can select fuses with slightly different characteristics, so that the impedance of the recoverable fuses is different when short circuit is started.

In sum, this application has realized communication + power supply with two lines, and two cables do not divide positive negative pole, and convenient construction avoids wiring error to cause the accident. The power can be supplied to two ends under the condition of not dividing the anode and the cathode so as to adapt to the condition of insufficient power supply of a single power supply in actual engineering. Therefore, even if the two wires are reversely connected under the condition of human negligence, the power supply and the system cannot be damaged under the condition of supplying power to the two ends, and the device can be normally used.

The above embodiments are preferred examples of the present invention, and the present invention is not limited thereto, and any other modifications or equivalent substitutions made without departing from the technical aspects of the present invention are included in the scope of the present invention.

Claims

1. The low-voltage direct-current bidirectional power supply communication circuit is characterized in that the low-voltage direct-current bidirectional power supply communication circuit is electrically connected with a local main control circuit to form a branch, and the low-voltage direct-current bidirectional power supply communication circuits of different branches are electrically connected through two wires without dividing positive and negative directions; at least one branch is connected with an external power supply system through a low-voltage direct-current bidirectional power supply communication circuit;

the low-voltage direct-current bidirectional power supply communication circuit comprises: the device comprises an external power supply input module, a rectifying module, a local power supply module, a positive power supply driving module, a negative power supply driving module, a power competition prevention module and an input/output interface module;

the external power supply input module is used for externally inputting power supply;

the rectification module is used for rectifying a power supply, and the rectified voltage is input to the local power supply module and the external power supply input module, wherein the power supply does not divide positive and negative polarities;

the local power supply module is used for supplying power to the low-voltage direct-current bidirectional power supply communication circuit and the local main control circuit;

the positive power supply driving module is used for inputting local power supply to the power supply input and output positive end;

the negative power supply driving module is used for inputting local power supply to the power supply input and output negative terminal;

The power supply competition prevention module is used for carrying out competition elimination on power supply of all external power supply systems when at least two external power supply systems exist, a competition loser can close the outward power supply, and a competition winner can supply power to the other party besides the local power supply;

the positive power supply driving module comprises: the MOS transistor Q1 is a P-channel enhancement MOSFET, the grid electrode of the MOS transistor Q1 is connected with the cathode of the diode D2 through the resistor R1, the grid electrode of the MOS transistor Q1 is also connected with the cathode of the diode D2 through the capacitor C1, the grid electrode of the MOS transistor Q1 is also connected with the collector of the triode Q2 through the resistor R2, the emitter of the triode Q2 is connected to the ground through the resistor R6, the source of the MOS transistor Q1 is connected with the cathode of the diode D2, the drain of the MOS transistor Q1 is also connected with the anode of the diode D2, the drain of the MOS transistor Q1 is also connected with the power input and output positive end, the drain of the MOS transistor Q1 is also connected with the power competition prevention module through the resistor R7 and the resistor R8 in sequence, the base of the triode Q2 is also connected with the connecting point of the resistor R7 and the resistor R8 through the resistor R4 and the capacitor C2 respectively, and the other end of the resistor R5 is also used as the triode driving signal end;

The negative power supply driving module includes: the MOS tube Q3 is an N-channel enhanced MOSFET, the drain electrode of the MOS tube Q3 is connected with the power input and output negative terminal through the restorable fuse tube F1, the grid electrode of the MOS tube Q3 is connected to the ground through the resistor R10 and the capacitor C3 respectively, the grid electrode of the MOS tube Q3 is also connected with one end of the resistor R5 through the resistor R9, and the source electrode of the MOS tube Q3 is grounded;

the power contention prevention module includes: the triode Q4, the power input and output negative terminal is connected through resistance R13 to triode Q4's projecting pole, triode Q4's base is connected to MOS pipe Q3's drain electrode NMOS_D, resistance R14 connects triode Q4's projecting pole and base, triode Q4's collecting electrode passes through electric capacity C4 to be connected to ground, triode Q4's collecting electrode still passes through resistance R12 to be connected triode Q5's base, triode Q5's projecting pole is connected to ground, triode Q5's collecting electrode connecting resistance R8 and resistance R9's tie point, opto-coupler U1's transmitting terminal positive pole passes through resistance R11 and connects power input and output negative terminal, opto-coupler U1's transmitting terminal negative pole passes through diode D6 and connects the power input and output positive terminal, opto-coupler U1's receiving terminal C extremely connecting resistance R8 and resistance R9's tie point, opto-coupler U1's receiving terminal E extremely is connected to ground.

2. The low voltage dc bi-directional power supply communication circuit of claim 1 wherein the external power supply input module comprises: diode D1, the positive pole of diode D1 being connected to the second pin of plug J1, the first pin of plug J1 being connected to ground,

The rectification module includes: the anodes of the diode D4 and the diode D5 are connected to the ground, the cathode of the diode D4 is connected with the cathode of the diode D1 through the diode D2, and the cathode of the diode D5 is connected with the LOCAL power supply end LOCAL_VCC through the diode D3;

the local power supply module includes: and the positive electrode of the capacitor TC1 is connected with the LOCAL power supply terminal LOCAL_VCC.

3. The low voltage direct current bi-directional power supply communication circuit of claim 2 wherein,

the input/output interface module includes: plug J2, the second pin of plug J2 passes through inductance L1 and connects power input output positive terminal, and the second pin of plug J2 still carries out first communication end connection with local main control circuit through electric capacity C5, and the first pin of plug J2 passes through inductance L2 and connects power input output negative terminal, and the first pin of plug J2 still carries out the second communication end connection with local main control circuit through electric capacity C6.

4. The low-voltage direct-current bidirectional power supply communication circuit according to claim 1, wherein the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected in a positive connection or a reverse connection mode, wherein the positive connection is used for connecting power input and output positive ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches, and the power input and output negative ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected; the reverse connection is that the power input and output positive ends of the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected with the power input and output negative ends of the low-voltage direct-current bidirectional power supply communication circuits of other branches.

5. A power supply method based on a low voltage DC bi-directional power supply communication circuit as claimed in any one of claims 1-4, characterized in that only one branch is connected to an external power supply system via the low voltage DC bi-directional power supply communication circuit, the branch connected to the external power supply system is taken as a first branch, the branch not connected to the external power supply system is taken as a second branch, the number of the second branches is at least 1,

the low-voltage direct current bidirectional power supply communication circuits of the first branch and the second branch are connected in a forward direction, and the power supply method comprises the following steps:

for the first branch, the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module of the first branch, an MOS tube Q1 of the positive power supply driving module and an MOS tube Q3 of the negative power supply driving module are both conducted, and a power supply input and output positive end and a power supply input and output negative end supply power;

for the second branch, as the low-voltage direct-current bidirectional power supply communication circuits of different branches are connected in a forward direction, the power input and output positive end and the power input and output negative end of the second branch are powered on, the LOCAL power supply end local_VCC is powered on through the rectifying module, and after the LOCAL power supply end local_VCC is powered on, the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are both conducted to supply power to the LOCAL power supply end local_VCC; the power input and output positive ends of the first branch and the second branch are positive, and the power input and output negative ends of the first branch and the second branch are negative;

the rectifying module includes: the anodes of the diode D4 and the diode D5 are connected to the ground, the cathode of the diode D4 is connected with the cathode of the diode D1 through the diode D2, and the cathode of the diode D5 is connected with the LOCAL power supply end LOCAL_VCC through the diode D3;

the local power supply module includes: the positive electrode of the capacitor TC1 is connected with the LOCAL power supply end LOCAL_VCC;

The negative power supply driving module includes: MOS pipe Q3, MOS pipe Q3 is N channel enhancement mode MOSFET, and MOS pipe Q3's drain electrode is connected power input and output negative terminal through recoverable insurance tube F1, and MOS pipe Q3's grid is connected to ground through resistance R10, electric capacity C3 respectively, and MOS pipe Q3's grid still passes through resistance R9 and connects resistance R5's one end, and MOS pipe Q3's source ground.

6. A power supply method based on the low-voltage direct current bi-directional power supply communication circuit as claimed in any one of claims 1 to 4, characterized in that only one branch is connected with the external power supply system through the low-voltage direct current bi-directional power supply communication circuit, the branch connected with the external power supply system is taken as a third branch, the branch not connected with the external power supply system is taken as a fourth branch, the number of the fourth branches is at least 1,

the low-voltage direct current bidirectional power supply communication circuit of the third branch and the fourth branch is reversely connected, and then the power supply method comprises the following steps:

for the third branch, the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module of the third branch, the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are both conducted, and the power supply input and output positive end and the power supply input and output negative end supply power;

For the fourth branch, because the low-voltage direct-current bidirectional power supply communication circuits of different branches are reversely connected, the power supply input/output positive end of the fourth branch inputs negative electricity and the power supply input/output negative end of the fourth branch inputs positive electricity, the LOCAL power supply end local_VCC is supplied with power through the rectifying module, and after the LOCAL power supply end local_VCC is supplied with power, the power supply competition prevention module starts protection because the power supply input/output positive end inputs negative electricity and the power supply input/output negative end inputs positive electricity, and the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module are cut off;

7. A power supply method based on the low-voltage direct current bi-directional power supply communication circuit according to any one of claims 1 to 4, characterized in that all branches are connected to an external power supply system through respective low-voltage direct current bi-directional power supply communication circuits, and all branches are forward connected between the low-voltage direct current bi-directional power supply communication circuits, and the power supply method comprises:

the power supply system with high voltage in the external power supply system supplies power to a LOCAL power supply end LOCAL_VCC through an external power supply input module of a branch, an MOS tube Q1 of the positive power supply driving module and an MOS tube Q3 of the negative power supply driving module are both conducted, and a power supply input and output positive end and a power supply input and output negative end supply power; wherein, the positive power input and output ends of the branches are positive, and the negative power input and output ends are negative; or alternatively

The voltage difference of the external power supply systems is smaller than the voltage difference of MOS (metal oxide semiconductor) transistors Q1 of the positive power supply driving modules in different branches, all the external power supply systems are supplied to a LOCAL power supply end LOCAL_VCC through the external power supply input modules of the branches, the MOS transistors Q1 of the positive power supply driving modules and the MOS transistors Q3 of the negative power supply driving modules are all conducted, and the power supply input output positive ends and the power supply input output negative ends are all supplied; wherein, the positive power input and output ends of the branches are positive, and the negative power input and output ends are negative;

8. A power supply method based on the low-voltage direct current bi-directional power supply communication circuit according to any one of claims 1 to 4, characterized in that all branches are connected to an external power supply system through respective low-voltage direct current bi-directional power supply communication circuits, and all branches are connected in reverse directions between the low-voltage direct current bi-directional power supply communication circuits, and the power supply method comprises:

all the low-voltage direct-current bidirectional power supply communication circuits of all the branches are reversely connected, all the branches compete, and one party wins power competition; the competition failure party can close the MOS tube Q1 of the positive power supply driving module and the MOS tube Q3 of the negative power supply driving module which are powered outwards, so that the system damage caused by short circuit is avoided; the competing winner supplies power to the LOCAL power supply end local_vcc of the branch circuit and also supplies power to the LOCAL power supply ends local_vcc of the other branch circuits; comparing the self-power supply voltage of the competing failure party with the voltage of the competing failure party after voltage drop, and supplying power to a power supply end local_VCC of the competing failure party by the party with high voltage, wherein the voltage difference obtained by subtracting the voltage drop of the line voltage from the voltage of the competing failure party is subtracted from the voltage drop of the rectifying bridge voltage to serve as the voltage of the competing failure party after voltage drop.