CN214045135U

CN214045135U - Three-phase UPS charging control circuit with central line

Info

Publication number: CN214045135U
Application number: CN202023138673.3U
Authority: CN
Inventors: 徐权文; 周玉坤; 魏亚海; 王亮
Original assignee: Guangzhou Baoshi New Energy Co ltd
Current assignee: Guangzhou Baoshi New Energy Co ltd
Priority date: 2020-12-22
Filing date: 2020-12-22
Publication date: 2021-08-24
Anticipated expiration: 2030-12-22

Abstract

The utility model provides a take central line three-phase UPS charge control circuit, including battery management system BMS, lithium cell group and take central line three-phase UPS circuit, take central line three-phase UPS circuit includes UPS circuit, positive phase circuit, negative phase circuit and line center end, the input of positive phase circuit, negative phase circuit and line center end are connected with the output end circuit of UPS circuit respectively, the output of positive phase circuit and battery management system BMS's input end circuit connection, the output of battery management system BMS with the positive pole circuit connection of lithium cell group; the output end of the negative phase circuit is connected with the negative circuit of the lithium battery pack, and the middle line end is connected with the middle circuit of the lithium battery pack. The utility model discloses can avoid the unbalanced electric quantity that load A, B, C unbalanced three phase brought, let the lithium cell group once be full of the electricity and all can resume lithium cell group total capacity once.

Description

Three-phase UPS charging control circuit with central line

Technical Field

The utility model relates to a UPS charge control circuit technical field, concretely relates to take central line three-phase UPS charge control circuit.

Background

In the three-phase UPS of area central line discharge process, because of the A, B, C unbalanced three phase of load end can lead to UPS central line current to change greatly, finally lead to positive half battery group (being the well end of lithium cell group to the lithium cell group positive pole) inconsistent with the capacity of the half battery of negative group (being the well end of lithium cell group to the lithium cell group negative pole), and UPS charges simultaneously for positive and negative half battery group and can not be full of positive and negative half battery group capacity simultaneously, consequently make whole lithium cell group capacity depend on half group of minimum capacity, make the capacity of lithium cell group can't reach the saturated condition.

SUMMERY OF THE UTILITY MODEL

The utility model provides a not enough to prior art, the utility model provides a take central line three-phase UPS charge control circuit can avoid the unbalanced electric quantity that load A, B, C unbalanced-phase brought, lets the lithium cell group all can resume lithium cell group total capacity once through being full of the electricity once.

In order to achieve the purpose, the utility model discloses a three-phase UPS charging control circuit with central line, including battery management system BMS, lithium cell group and three-phase UPS circuit with central line, three-phase UPS circuit with central line includes UPS circuit, positive phase circuit, negative phase circuit and neutral conductor end, the input and the neutral conductor end of positive phase circuit, negative phase circuit are respectively with the output end circuit connection of UPS circuit, the output of positive phase circuit is connected with battery management system BMS's input end circuit, the output of battery management system BMS with the positive circuit connection of lithium cell group; the output end of the negative phase circuit is connected with the negative circuit of the lithium battery pack, and the middle line end is connected with the middle circuit of the lithium battery pack.

Further, the positive phase circuit comprises an insulated gate bipolar transistor Su7, an inductor Lu1 and a thyristor Su9, the drain D of the insulated gate bipolar transistor Su7 is electrically connected with the output end of the UPS circuit, the source of the insulated gate bipolar transistor Su7 is electrically connected with one end of the inductor Lu1, the other end of the inductor Lu1 is electrically connected with the anode of the thyristor Su9, and the cathode of the thyristor Su9 is electrically connected with the input end of the battery management system BMS.

Further, the positive phase circuit further comprises a transient diode Du1, a capacitor Cu1 and a resistor Ru1, wherein the cathode of the transient diode Du1 is connected with the source circuit of the igbt Su7, one end of the capacitor Cu1 is connected with the anode circuit of the thyristor Su9, one end of the resistor Ru1 is connected with the anode circuit of the thyristor Su9, and the anode of the transient diode Du1, the other end of the capacitor Cu1 and the other end of the resistor Ru1 are respectively connected with the neutral line circuit.

Further, the negative phase circuit comprises an insulated gate bipolar transistor Su8, an inductor Lu2 and a thyristor Su10, the drain D of the insulated gate bipolar transistor Su8 is electrically connected with the output end of the UPS circuit, the source of the insulated gate bipolar transistor Su8 is electrically connected with one end of the inductor Lu2, the other end of the inductor Lu2 is electrically connected with the cathode of the thyristor Su10, and the anode of the thyristor Su9 is electrically connected with the input end of the battery management system BMS.

Furthermore, the negative phase circuit further comprises a transient diode Du2, a capacitor Cu2 and a resistor Ru2, wherein the anode of the transient diode Du2 is connected with the source circuit of the igbt Su8, one end of the capacitor Cu2 is connected with the cathode circuit of the thyristor Su10, one end of the resistor Ru2 is connected with the cathode circuit of the thyristor Su10, and the cathode of the transient diode Du2, the other end of the capacitor Cu2 and the other end of the resistor Ru2 are respectively connected with the neutral line circuit.

Further, a fuse Fu1 is arranged between the positive phase circuit and the output end of the UPS circuit, and a fuse Fu2 is arranged between the negative phase circuit and the output end of the UPS circuit.

Further, the battery management system BMS includes a pre-charge relay S1, a pre-charge resistor R1, a total positive relay S2, a charge positive relay S3, a total negative relay S7, a charge negative relay S8, a wake-up key K1, a DC internal relay S4, an air switch S5, a switching power supply DCDC, a switching power supply ACDC, a diode D1, a diode D2, and a diode D3, wherein the pre-charge relay S1, the total positive relay S2, the charge positive relay S3, the DC internal relay S4, a neutral relay S6, the total negative relay S7, and the charge negative relay S8 are respectively controlled by the BCU main controller;

the cathode of the diode D1 and one end of the charging positive relay S3 are collected at the node a, and the anode of the UPS is connected with the node a in a circuit; the other end of the charging positive relay S3, the anode of the diode D1, one end of the main positive relay S2 and one end of the pre-charging resistor R1 are gathered at a node b, the other end of the pre-charging resistor R1 is in circuit connection with one end of the pre-charging relay S1, the other end of the pre-charging relay S1, the other end of the main positive relay S2, one end of the awakening key K1 and one end of the DC internal relay S4 are gathered at a node C, and the anode of the lithium battery pack is in circuit connection with the node C;

the other end of the DC internal relay S4 and the other end of the wake-up switch K1 are respectively connected with an input positive electrode circuit of a switch power supply DCDC, an output positive electrode of the switch power supply DCDC is connected with a positive electrode circuit of a diode D2, a negative electrode of the diode D2 and one end of an idle switch S5 are respectively connected with an output positive electrode circuit of a switch power supply ACDC, an output negative electrode of the switch power supply DCDC is connected with an output negative electrode circuit of the switch power supply ACDC, and an input end of the switch power supply ACDC is connected with an alternating current circuit;

one end of the charging negative relay S8 and the anode of the diode D3 are collected at a node D, and the cathode of the UPS is in circuit connection with the node D; the other end of the charging negative relay S8, the negative electrode of the diode D3 and one end of the total negative relay S7 are gathered at a node e, the other end of the total negative relay S7 and the input negative electrode of the switching power supply DCDC are gathered at a node f, and the negative electrode of the lithium battery pack is in circuit connection with the node f;

the neutral terminal of the UPS is connected to the battery' S neutral circuit through neutral relay S6.

Compared with the prior art, the utility model has the advantages of it is following: the utility model discloses in, the three-phase UPS circuit of area central line includes the UPS circuit, positive phase circuit, negative phase circuit and well line end, when charging lithium cell group, through the control of battery management system BMS, positive phase circuit and negative phase circuit can be respectively positive half battery group simultaneously, negative half battery group charges, independent disconnection when corresponding half battery group is full of, thereby realize avoiding the positive half battery group of electric quantity and the unbalanced problem of negative half battery group of the lithium cell group that the load A, B, C unbalanced three-phase brought, let the lithium cell group every through once full charge can resume lithium cell group total capacity, and the UPS that has still kept original design is equipped with the electric time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, 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 inventive exercise.

Fig. 1 is a schematic circuit diagram of a three-phase UPS charging control circuit with a neutral line according to the present invention;

FIG. 2 is a schematic diagram of a three-phase UPS circuit with neutral line;

fig. 3 is a flow chart of a control method of the three-phase UPS charging control circuit with neutral line.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Referring to fig. 1, the embodiment of the utility model discloses a three-phase UPS charging control circuit with neutral line, including battery management system BMS, lithium cell group and three-phase UPS circuit with neutral line, three-phase UPS circuit with neutral line includes UPS circuit, positive phase circuit, negative phase circuit and neutral line end, the input and neutral line end of positive phase circuit, negative phase circuit are respectively with the output end circuit connection of UPS circuit, the output of positive phase circuit is connected with the input circuit of battery management system BMS, the output of battery management system BMS is connected with the positive circuit of lithium cell group; the output end of the negative phase circuit is connected with the negative circuit of the lithium battery pack, and the middle line end is connected with the middle circuit of the lithium battery pack. The middle end of the lithium battery pack divides the lithium battery pack into a positive half battery pack and a negative half battery pack, and the battery capacities of the positive half battery pack and the negative half battery pack are the same.

The positive-phase circuit comprises an insulated gate bipolar transistor Su7, an inductor Lu1 and a thyristor Su9, the drain D of the insulated gate bipolar transistor Su7 is connected with the output end circuit of the UPS circuit, the source of the insulated gate bipolar transistor Su7 is connected with one end circuit of the inductor Lu1, the other end of the inductor Lu1 is connected with the anode circuit of the thyristor Su9, and the cathode of the thyristor Su9 is connected with the input end circuit of the battery management system BMS.

The negative phase circuit comprises an insulated gate bipolar transistor Su8, an inductor Lu2 and a thyristor Su10, the drain D of the insulated gate bipolar transistor Su8 is connected with the output end circuit of the UPS circuit, the source of the insulated gate bipolar transistor Su8 is connected with one end circuit of the inductor Lu2, the other end of the inductor Lu2 is connected with the cathode circuit of the thyristor Su10, and the anode of the thyristor Su9 is connected with the input end circuit of the battery management system BMS.

Further, a fuse Fu1 is arranged between the positive phase circuit and the output end of the UPS circuit, and a fuse Fu2 is arranged between the negative phase circuit and the output end of the UPS circuit, and is used for protecting the negative phase circuit and the positive phase circuit respectively.

In this embodiment, the negative phase circuit and the positive phase circuit are symmetrically arranged, and when the lithium battery pack is used, mains supply is input from the input end of the UPS, and after filtering by the filter and rectification by the rectifier in sequence, the lithium battery pack is charged by the negative phase circuit, the positive phase circuit and the neutral terminal respectively. Specifically, the positive phase circuit and the negative phase circuit charge the positive half battery pack and the negative half battery pack respectively at the same time, and when the positive half battery pack or the negative half battery pack is detected to be fully charged, the path of the corresponding battery pack is cut off until the positive half battery pack and the negative half battery pack are fully charged respectively. For example, in the process of simultaneously charging the positive half pack and the negative half pack, respectively, when it is detected that the positive half pack is fully charged, the battery management system BMS opens the switches S1, S2, S3, thereby cutting off the charging loop of the positive half pack, while the negative half pack continues to charge the negative half pack since it is not fully charged. When the positive phase circuit charges the positive half battery, the current direction is as follows: fu1- > Su7 is switched on and off in a PWM mode- > passes through Lu1- > Su9 open- > UPS positive pole- > battery management system BMS- > lithium battery pack- > middle end of the battery- > S6 in- > UPS neutral line; when the negative phase circuit charges the negative half-group battery, the current direction is as follows: the neutral line end- > S6 in- > battery neutral line- > battery pack- > battery cathode- > battery management system BMS- > UPS cathode- > Su10 in- > Lu2- > Su8 is switched on and off- > Fu2 in a PWM mode.

In this embodiment, in the circuit structure of the positive phase circuit and the negative phase circuit, the igbt turns on and off in a PWM mode, the inductor turns on and off in a PWM mode, the thyristor is a switch, and the instantaneous diode is turned on by the instantaneous diode when there is an instantaneous high voltage between the positive electrode centering line and the negative electrode centering line, so as to protect other devices, the capacitor functions to stabilize voltage, and the resistor functions to discharge capacitance when the system is turned off. The structure setting of positive phase circuit and negative phase circuit in this embodiment can open simultaneously respectively just half battery pack and the half group of burden and charge, mutually noninterfere to independently break off when half battery pack that corresponds is full of, avoid the unbalanced electric quantity that load A, B, C three-phase imbalance brought, let the lithium cell group all can resume total capacity through once being full of the electricity, but also kept the UPS of former design time of being prepared for the electricity.

Specifically, the battery management system BMS includes a pre-charge relay S1, a pre-charge resistor R1, a total positive relay S2, a charge positive relay S3, a total negative relay S7, a charge negative relay S8, a wake-up key K1, a DC internal relay S4, an idle switch S5, a switching power supply DCDC, a switching power supply ACDC, a diode D1, a diode D2, and a diode D3, wherein the pre-charge relay S1, the total positive relay S2, the charge positive relay S3, the DC internal relay S4, a neutral relay S6, the total negative relay S7, and the charge negative relay S8 are respectively controlled by a BCU main controller;

In this embodiment, the battery management system BMS is configured to perform charging and discharging protection on the lithium battery pack during charging and discharging of the lithium battery pack, so as to prevent overcharge or overdischarge of the lithium battery; under normal operating condition, realize data transmission through RS485 interface respectively between battery management system BMS, UPS, the lithium cell group, information such as the voltage, electric current, temperature, the trouble of transmission battery, the charge of real-time adjustment battery, discharge power.

Wherein the battery management system BMS has the following states:

(1) in an initial state, the relays S1, S2, S3, S4, S5, S6, S7 and S8 are in an open state;

(2) when the battery management system is started manually, the air switch S5 is closed manually, the wake-up switch K1 is pressed, the switch power supply DCDC works to provide a 12V power supply for the battery management system BMS, the battery management system BMS performs self-checking (namely whether the voltage, the temperature and the total pressure of a battery cell are normal or not are detected), if the self-checking is not successful, a fault is reported, and if the self-checking is successful, the main negative relay S7, the charging positive relay S3 and the DC internal relay S4 are closed by the BCU main controller for pre-charging; at the moment, the battery charges the Cu1 and the Cu2 of the UPS, and the current direction is as follows: s1- > R1- > S3; when the outer total pressure is detected to be 90% of the inner total pressure, the BCU master controller closes the total positive relay S2 and the neutral line relay S6, and simultaneously opens the pre-charging relay S1, and the current direction is as follows: s2- > S3.

(3) When the mains supply is started, the air switch S5 is closed, the mains supply is connected, the switch power supply ACDC converts 220V external alternating current into 12V direct current to provide 12V power for the battery management system BMS, the battery management system BMS performs self-checking (namely whether the voltage, the temperature and the total pressure of a battery monomer are normal or not is detected), if the self-checking is not successful, a fault is reported, and if the self-checking is successful, the BCU main controller closes the total negative relay S7, the charging positive relay S3 and the DC internal relay S4 to perform pre-charging; when the outer total pressure is detected to be 90% of the inner total pressure, the BCU master controller closes the total positive relay S2 and the neutral line relay S6, and simultaneously opens the pre-charging relay S1, and the current direction is as follows: s2- > S3.

(4) In a charging state, commercial power is input from the input end of the UPS, and after filter filtering and rectifier rectification are sequentially carried out, the lithium battery pack is charged through the negative phase circuit, the positive phase circuit and the neutral line terminal respectively. Specifically, the positive phase circuit and the negative phase circuit charge the positive half-pack battery and the negative half-pack battery, respectively, at the same time, and are independently disconnected when the corresponding half-pack battery is fully charged. Specifically, the method comprises the following steps:

i) when the positive phase circuit charges the positive half battery, the current direction is as follows: fu1- > Su7 is switched on and off in a PWM mode- > passes through Lu1- > Su9 open- > UPS positive pole- > S3 combined- > S2 combined- > lithium battery pack- > middle end of the battery- > S6 combined- > UPS neutral line;

ii) when the negative phase circuit charges the negative half battery, the current direction is as follows: the neutral line terminal- > S6 in- > battery neutral line- > battery pack- > battery negative electrode- > S7- > S8- > UPS negative electrode- > Su10 in- > Lu2- > Su8 is switched on and off- > Fu2 in a PWM mode.

In the charged state, the battery management system BMS also has a charge protection function. When the positive half battery pack is fully charged, the BCU main controller disconnects the charging positive relay S3, switches the charging loop of the positive half battery pack, namely disconnects the charging of the positive half battery pack, and closes the charging positive relay S3 after the highest cell voltage of the positive half battery pack is lower than the set recovery voltage; when the negative half battery pack is fully charged, the BCU main controller disconnects the charging negative relay S8, switches the charging loop of the negative half battery pack, namely disconnects the charging of the negative half battery pack, and closes the charging negative relay S8 after the highest cell voltage of the negative half battery pack is lower than the set recovery voltage.

(5) In the discharge state, the current direction is: the battery positive pole, the middle end and the negative pole- > the UPS inverter- > Su5- > Su6- > output switch, and the battery discharges. Similarly, under the discharge state, the battery management system BMS still has the discharge protection function, when the battery management system BMS detects that the highest cell voltage of positive and negative half group is lower than the set recovery voltage, the BCU main controller disconnects the total positive relay S2 and the total negative relay S7, and cuts off the discharge loop until the highest cell voltage of positive and negative half group is higher than the set recovery voltage, the BCU main controller closes the total positive relay S2 and the total negative relay S7, and the lithium battery pack continues to discharge.

(6) When the power-off operation is performed without using the lithium battery, the BCU main controller disconnects S2, S3, S4, S6, S7 and S8, a switching power supply circuit is cut off, and the BMS enters a power-off state.

On the other hand, the embodiment of the utility model provides a still provides a take central line three-phase UPS charge control circuit's control method, including following step:

step 1, a battery management system BMS controls and closes a path between a positive phase circuit and a lithium battery pack and a path between a negative phase circuit and the lithium battery pack, so that the positive phase circuit and the negative phase circuit charge a positive half battery pack and a negative half battery pack of the lithium battery pack at the same time;

and 2, detecting the electric quantity of the positive half battery pack and the negative half battery pack of the lithium battery pack in real time in the charging process, and independently disconnecting the positive half battery pack and the negative half battery pack when the corresponding half battery packs are fully charged.

During the charging process of the lithium battery pack, whether the positive half battery pack and the negative half battery pack are fully charged or not is detected in real time, after the positive half battery pack and the negative half battery pack are fully charged, the corresponding half battery packs are independently disconnected when fully charged, namely, the battery management system BMS controls to disconnect a path between the positive phase circuit and the lithium battery pack and/or controls to disconnect a path between the negative phase circuit and the lithium battery pack.

In this embodiment, the middle end of the lithium battery pack divides the lithium battery pack into a positive half battery pack and a negative half battery pack, and the battery capacities of the positive half battery pack and the negative half battery pack are the same; when charging, battery management system BMS simultaneous control UPS is respectively to half the assembled battery well, half the assembled battery of burden charges, when half the assembled battery that corresponds is full of, independent disconnection when being full of, can guarantee through half the assembled battery of positive after once charging, half the assembled battery of burden can both be full of the electricity to the unbalanced problem of electric quantity that load A, B, C unbalanced three-phase brought has been avoided, let the lithium cell group can all resume the lithium cell group total capacity after every through once being full of the electricity, and the UPS reserve electricity time of original design has still been kept.

Specifically, in step 1, the step of controlling the closed path between the positive phase circuit and the lithium battery pack and the closed path between the negative phase circuit and the lithium battery pack by the battery management system BMS specifically includes: the battery management system BMS closes the charging positive relay S3, the master positive relay S2, the neutral relay S6, and the battery management system BMS closes the master negative relay S7, the charging negative relay S8.

Specifically, in step 2, the step of independently disconnecting when the corresponding half pack battery is fully charged includes: when detecting that the positive half group battery is fully charged, the battery management system BMS turns off the charging positive relay S3 and the total positive relay S2; when the negative half pack is detected to be fully charged, the battery management system BMS turns off the master negative relay S7, the charging negative relay S8.

To sum up, the utility model discloses in, the three-phase UPS circuit of area central line includes the UPS circuit, positive phase circuit, negative phase circuit and line mid-end, when charging lithium cell group, through the control of battery management system BMS, positive phase circuit and negative phase circuit can be respectively just half the assembled battery simultaneously, half the assembled battery of burden charges, independent disconnection when half the assembled battery that corresponds is full of, thereby realize avoiding the unbalanced half assembled battery and the unbalanced problem of half the assembled battery of the electric quantity of the lithium cell group that brings of load A, B, C three-phase, let the lithium cell group every through once full of the electricity all can resume the group total capacity of lithium cell, and the UPS that has still kept original design is equipped with the electric time.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-phase UPS charging control circuit with a neutral line is characterized by comprising a battery management system BMS, a lithium battery pack and a three-phase UPS circuit with a neutral line, wherein the three-phase UPS circuit with the neutral line comprises a UPS circuit, a positive phase circuit, a negative phase circuit and a neutral line end, the input ends of the positive phase circuit and the negative phase circuit and the neutral line end are respectively connected with the output end circuit of the UPS circuit, the output end of the positive phase circuit is connected with the input end circuit of the battery management system BMS, and the output end of the battery management system BMS is connected with the positive electrode circuit of the lithium battery pack; the output end of the negative phase circuit is connected with the negative circuit of the lithium battery pack, and the middle line end is connected with the middle circuit of the lithium battery pack.

2. The three-phase UPS charging control circuit with the neutral wire of claim 1, wherein the positive phase circuit comprises an insulated gate bipolar transistor Su7, an inductor Lu1 and a thyristor Su9, the drain D of the insulated gate bipolar transistor Su7 is electrically connected with the output end of the UPS circuit, the source of the insulated gate bipolar transistor Su7 is electrically connected with one end of the inductor Lu1, the other end of the inductor Lu1 is electrically connected with the anode of the thyristor Su9, and the cathode of the thyristor Su9 is electrically connected with the input end of the BMS.

3. The three-phase UPS charging control circuit with the neutral wire of claim 2, wherein the positive phase circuit further comprises a transient diode Du1, a capacitor Cu1 and a resistor Ru1, the cathode of the transient diode Du1 is connected with the source circuit of the IGBT Su7, one end of the capacitor Cu1 is connected with the anode circuit of the thyristor Su9, one end of the resistor Ru1 is connected with the anode circuit of the thyristor Su9, and the anode of the transient diode Du1, the other end of the capacitor Cu1 and the other end of the resistor Ru1 are respectively connected with the neutral wire circuit.

4. The three-phase UPS charging control circuit with the neutral wire of claim 3, wherein the negative phase circuit comprises an insulated gate bipolar transistor Su8, an inductor Lu2 and a thyristor Su10, the drain D of the insulated gate bipolar transistor Su8 is electrically connected with the output end of the UPS circuit, the source of the insulated gate bipolar transistor Su8 is electrically connected with one end of the inductor Lu2, the other end of the inductor Lu2 is electrically connected with the cathode of the thyristor Su10, and the anode of the thyristor Su9 is electrically connected with the input end of the battery management system BMS.

5. The three-phase UPS charging control circuit with the neutral wire of claim 4, wherein the negative phase circuit further comprises a transient diode Du2, a capacitor Cu2 and a resistor Ru2, the anode of the transient diode Du2 is connected with the source circuit of the IGBT Su8, one end of the capacitor Cu2 is connected with the cathode circuit of the thyristor Su10, one end of the resistor Ru2 is connected with the cathode circuit of the thyristor Su10, and the cathode of the transient diode Du2, the other end of the capacitor Cu2 and the other end of the resistor Ru2 are respectively connected with the neutral wire circuit.

6. The three-phase UPS charging control circuit with neutral according to claim 1, wherein a fuse Fu1 is disposed between the positive phase circuit and the output of the UPS circuit, and a fuse Fu2 is disposed between the negative phase circuit and the output of the UPS circuit.

7. The neutral three-phase UPS charging control circuit of claim 1, wherein the battery management system BMS comprises a pre-charging relay S1, a pre-charging resistor R1, a total positive relay S2, a charging positive relay S3, a total negative relay S7, a charging negative relay S8, a wake-up key K1, a DC internal relay S4, an idle switch S5, a switching power supply DCDC, a switching power supply ACDC, a diode D1, a diode D2 and a diode D3, wherein the pre-charging relay S1, the total positive relay S2, the charging positive relay S3, the DC internal relay S4, the neutral relay S6, the total negative relay S7 and the charging negative relay S8 are respectively controlled by a BCU main controller;