A DC guard power supply system and a method for identifying the state of a battery circuit

Abstract

The present invention relates to a DC protection power supply system and a method for identifying the state of a battery circuit. The DC protection power supply system includes: a DC bus, an AC / DC power supply module, a battery pack, a bidirectional DC / DC conversion module, and a control unit; the method includes: obtaining the current of the battery pack before boosting the bidirectional DC / DC conversion module; controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack; obtaining the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack; judging the state of the battery pack circuit according to the current, current output current, and real-time current of the battery pack. The present invention can accurately identify the circuit state of the battery pack, and does not need to disconnect the AC for judgment and identification, and has high reliability and good safety.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply systems, and more specifically, to a direct current guard power supply system and a method for identifying the state of a battery circuit thereof. Background Art

[0002] The DC protection power supply system for electric power includes: AC / DC high-frequency switch module, 2 sets of AC / DC power supplies with two AC power supplies, the main purpose is to charge the battery pack and power the load when the AC is normal. When the AC is abnormal, the battery pack will power the load when the battery pack is normal. Bidirectional DC / DC power supply, when the AC is abnormal or there is a short circuit in the battery pack, the bidirectional DC / DC power supply will boost the voltage to power the load. And other control devices for monitoring this system, such as insulation monitor, switch status monitoring, DC monitoring, battery management, etc.

[0003] In the DC protection power supply system, the battery circuit (i.e., the circuit from the DC bus to the battery pack) generally has a switch, a current collection shunt, a fuse, and a battery pack. When the battery pack is inspected on site, the fuse needs to be removed at the beginning, and after the battery inspection is completed, it is easy to forget to restore the fuse. In this case, if the AC power is cut off, the battery pack cannot provide power to the DC bus, resulting in a loss of power to the DC bus, causing a serious accident. In addition, when the connection in the battery pack is broken (including caused by the failure of individual batteries or the disconnection of the connection strips between batteries), the battery pack will also be unable to provide power to the DC bus, resulting in a loss of power to the DC bus, causing a serious accident.

[0004] The existing solution is to adjust the DC output voltage of the AC / DC high-frequency switch module to be lower than the battery pack voltage, and the battery pack supplies power to the DC bus. If the battery replaces the DC bus, it means that the battery circuit is normal. However, in actual application, it is impossible for the AC / DC high-frequency switch module to disconnect the AC to determine the battery circuit. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a DC protection power supply system and a method for identifying the status of its battery circuit in view of the above-mentioned defects of the prior art.

[0006] The technical solution adopted by the present invention to solve the technical problem is: constructing a battery circuit state identification method for a DC protection power supply system, which is applied to the DC protection power supply system, wherein the DC protection power supply system comprises: a DC bus, an AC / DC power supply module, a battery pack, a bidirectional DC / DC conversion module and a control unit; the method comprises:

[0007] Before boosting the bidirectional DC / DC conversion module, obtaining the current of the battery pack;

[0008] Controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack;

[0009] Obtaining the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack;

[0010] The loop state of the battery pack is determined according to the current of the battery pack, the current output current and the real-time current.

[0011] In the battery circuit state identification method of the DC protection power supply system of the present invention, the battery pack includes: a plurality of sub-battery packs connected in series; the bidirectional DC / DC conversion module includes: a plurality of DC / DC sub-conversion modules arranged corresponding to the sub-battery packs;

[0012] The step of controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack comprises:

[0013] The plurality of DC / DC sub-conversion modules are controlled in sequence to perform voltage boosting so that the output voltages of the plurality of DC / DC sub-conversion modules are higher than the voltage of the battery pack.

[0014] In the battery circuit state identification method of the DC protection power supply system of the present invention, the obtaining of the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack includes:

[0015] sequentially acquiring real-time currents of the plurality of sub-battery groups connected in series;

[0016] The current output currents of the plurality of DC / DC sub-conversion modules are obtained in sequence.

[0017] In the method for identifying the battery circuit state of the DC protection power supply system of the present invention, judging the battery circuit state according to the current of the battery pack, the current output current and the real-time current includes:

[0018] The loop state of the battery pack is determined according to the current of the battery pack, the current output currents of the plurality of DC / DC sub-conversion modules, and the real-time currents of the plurality of sub-battery packs connected in series.

[0019] In the battery circuit state identification method of the DC guard power system of the present invention, the battery group includes: a first sub-battery group, a second sub-battery group, a third sub-battery group and a fourth sub-battery group, and the first sub-battery group, the second sub-battery group, the third sub-battery group and the fourth sub-battery group are connected in series in sequence;

[0020] The bidirectional DC / DC conversion module includes: a first DC / DC sub-conversion module, a second DC / DC sub-conversion module, a third DC / DC sub-conversion module and a fourth DC / DC sub-conversion module;

[0021] The step of controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack comprises:

[0022] sequentially controlling the first DC / DC sub-conversion module, the second DC / DC sub-conversion module, the third DC / DC sub-conversion module and the fourth DC / DC sub-conversion module to boost the voltage so that the voltage of the first DC / DC sub-conversion module, the second DC / DC sub-conversion module, the third DC / DC sub-conversion module and the fourth DC / DC sub-conversion module is higher than the voltage of the battery pack;

[0023] The obtaining of the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack comprises:

[0024] sequentially acquiring a first current output current of the first DC / DC sub-conversion module, a second current output current of the second DC / DC sub-conversion module, a third current output current of the third DC / DC sub-conversion module, and a fourth current output current of the fourth DC / DC sub-conversion module;

[0025] sequentially acquiring a first real-time current of the first sub-battery group, a second real-time current of the second sub-battery group, a third real-time current of the third sub-battery group, and a fourth real-time current of the fourth sub-battery group;

[0026] The determining of the battery pack circuit state according to the battery pack current, the current output current and the real-time current comprises:

[0027] The loop state of the battery pack is determined based on the current of the battery pack, the first current output current, the second current output current, the third current output current, the fourth current output current, the first real-time current, the second real-time current, the third real-time current and the fourth real-time current.

[0028] In the battery circuit state identification method of the DC guard power supply system of the present invention, judging the battery circuit state according to the current of the battery pack, the first current output current, the second current output current, the third current output current, the fourth current output current, the first real-time current, the second real-time current, the third real-time current and the fourth real-time current comprises:

[0029] If the current of the battery pack, the first real-time current, the second real-time current, the third real-time current, and the fourth real-time current are all equal, and any one of the first current output current, the second current output current, the third current output current, and the fourth current output current is equal to zero, then it is determined that the sub-battery pack corresponding to the DC / DC sub-conversion module with zero output current is open.

[0030] In the battery circuit state identification method of the DC protection power supply system of the present invention, controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack includes:

[0031] Any one of the plurality of DC / DC sub-conversion modules is controlled to perform voltage boosting so that an output voltage of the DC / DC sub-conversion module performing voltage boosting is higher than a voltage of the storage battery group.

[0032] In the battery circuit state identification method of the DC protection power supply system of the present invention, the obtaining of the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack includes:

[0033] Obtaining the current output current of the DC / DC sub-conversion module after the boost;

[0034] Obtaining the real-time current of the battery pack;

[0035] The determining of the battery pack circuit state according to the battery pack current, the current output current and the real-time current comprises:

[0036] If the current of the battery pack is less than the real-time current of the battery pack and the current output current of the boosted DC / DC sub-conversion module is equal to the real-time current of the battery pack, it is determined that the battery pack is disconnected from the DC bus.

[0037] In the battery circuit state identification method of the DC guard power supply system of the present invention, judging the battery circuit state according to the current of the battery pack, the current output current of the plurality of DC / DC sub-conversion modules and the real-time current of the plurality of sub-battery packs connected in series includes:

[0038] If the current of the battery pack is not equal to the real-time current of the plurality of serially connected sub-battery packs, and the current output currents of the plurality of DC / DC sub-conversion modules are not zero, it is determined that the battery pack circuit is normal.

[0039] The present invention also provides a DC protection power supply system, comprising: a DC bus, an AC / DC power supply module, a battery pack, a bidirectional DC / DC conversion module and a control unit;

[0040] The AC / DC power supply module is used to charge the battery pack and supply power to the load through the DC bus under normal AC state;

[0041] The battery pack is used to supply power to the load through the DC bus when the AC is abnormal;

[0042] The control unit is used for:

[0043] Before boosting the bidirectional DC / DC conversion module, obtaining the current of the battery pack;

[0044] Controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack;

[0045] Acquire the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack;

[0046] The loop state of the battery pack is determined according to the current of the battery pack, the current output current and the real-time current.

[0047] The implementation of the DC protection power supply system and the battery circuit status identification method of the present invention has the following beneficial effects: the DC protection power supply system includes: a DC bus, an AC / DC power supply module, a battery pack, a bidirectional DC / DC conversion module and a control unit; the method includes: obtaining the current of the battery pack before boosting the bidirectional DC / DC conversion module; controlling the bidirectional DC / DC conversion module to boost so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack; obtaining the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack; judging the battery pack circuit status according to the battery pack current, current output current and real-time current. The present invention can accurately identify the circuit status of the battery pack, and does not need to disconnect the AC for judgment and identification, with high reliability and good safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0049] Figure 1 is a schematic diagram of a DC protection power supply system provided by an embodiment of the present invention;

[0050] Figure 2 It is a flow chart of a method for identifying the state of a battery circuit of a DC protection power supply system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0052] refer to Figure 1 , which is a circuit diagram of the DC protection power supply system provided by the present invention.

[0053] like Figure 1 As shown, the DC protection power supply system includes: a DC bus 14, an AC / DC power supply module 11, a battery pack 12, a bidirectional DC / DC conversion module 13 and a control unit 15.

[0054] The AC / DC power supply module 11 is used to charge the battery pack 12 and supply power to the load through the DC bus 14 when the AC is in a normal state.

[0055] The battery pack 12 is used to supply power to the load via the DC bus 14 when the AC is abnormal.

[0056] The control unit 15 is used to: obtain the current of the battery pack 12 before boosting the bidirectional DC / DC conversion module 13; control the bidirectional DC / DC conversion module 13 to boost so that the output voltage of the bidirectional DC / DC conversion module 13 is higher than the voltage of the battery pack 12; obtain the current output current of the bidirectional DC / DC conversion module 13 and the real-time current of the battery pack 12; and determine the circuit state of the battery pack 12 according to the current of the battery pack 12, the current output current and the real-time current.

[0057] Furthermore, if Figure 1 As shown, the DC protection power supply system may further include: a first switch K1, the first switch K1 is used to control the on / off of the AC / DC power supply module 11 and the DC bus 14, that is, to control the connection or disconnection of the AC / DC power supply module 11.

[0058] Furthermore, if Figure 1 As shown, the DC protection power supply system may further include: a second switch K2, the second switch K2 is used to control the on-off of the battery pack 12 and the DC bus 14, that is, to control the connection or disconnection of the battery pack 12.

[0059] Optionally, in the embodiment of the present invention, the storage battery group 12 includes: a plurality of sub-battery groups connected in series. The bidirectional DC / DC conversion module 13 includes: a plurality of DC / DC sub-conversion modules arranged corresponding to the sub-battery groups.

[0060] In a specific embodiment, the battery pack 12 includes: a first sub-battery group (V1), a second sub-battery group (V2), a third sub-battery group (V3) and a fourth sub-battery group (V4), and the first sub-battery group, the second sub-battery group, the third sub-battery group and the fourth sub-battery group are connected in series in sequence. The bidirectional DC / DC conversion module 13 includes: a first DC / DC sub-conversion module (#1), a second DC / DC sub-conversion module (#2), a third DC / DC sub-conversion module (#3) and a fourth DC / DC sub-conversion module (#4). Among them, the first DC / DC sub-conversion module is arranged corresponding to the first sub-battery group, the second DC / DC sub-conversion module is arranged corresponding to the second sub-battery group, the third DC / DC sub-conversion module is arranged corresponding to the third sub-battery group, and the fourth DC / DC sub-conversion module is arranged corresponding to the fourth sub-battery group.

[0061] It can be understood that in the embodiment of the present invention, by adopting the DC guard power supply system, the circuit state of the battery pack 12 can be accurately identified, and there is no need to adjust the AC / DC power supply module 11, nor is there a need to disconnect the AC power, and the identification method is simple and reliable. Specifically, by controlling the bidirectional DC / DC conversion module 13 to boost, the output current of the bidirectional DC / DC conversion module 13 and the current of the battery pack 12 after boosting are measured at the same time, and the current of the battery pack 12 before boosting is measured, and then the circuit state of the battery pack 12 is identified based on the current of the battery pack 12 before boosting, the output current of the bidirectional DC / DC conversion module 13 after boosting, and the current of the battery pack 12 after boosting.

[0062] Specific identification method reference Figure 2 .

[0063] like Figure 2 As shown, the battery circuit state identification method of the DC guard power system includes:

[0064] Step S201 : before boosting the bidirectional DC / DC conversion module 13 , obtain the current of the battery pack 12 .

[0065] Step S202 , controlling the bidirectional DC / DC conversion module 13 to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module 13 is higher than the voltage of the battery pack 12 .

[0066] In some embodiments, controlling the bidirectional DC / DC conversion module 13 to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module 13 is higher than the voltage of the battery pack 12 includes: sequentially controlling multiple DC / DC sub-conversion modules to boost the voltage so that the output voltage of the multiple DC / DC sub-conversion modules is higher than the voltage of the battery pack 12.

[0067] Step S203 : obtaining the current output current of the bidirectional DC / DC conversion module 13 and the real-time current of the battery pack 12 .

[0068] In some embodiments, obtaining the current output current of the bidirectional DC / DC conversion module 13 and the real-time current of the battery pack 12 includes: sequentially obtaining the real-time currents of multiple series-connected sub-battery packs; and sequentially obtaining the current output currents of multiple DC / DC sub-conversion modules.

[0069] Step S204 , determining the circuit state of the battery pack 12 according to the current of the battery pack 12 , the current output current and the real-time current.

[0070] In some embodiments, judging the circuit status of the battery pack 12 based on the current, current output current and real-time current of the battery pack 12 includes: judging the circuit status of the battery pack 12 based on the current of the battery pack 12, the current output current of multiple DC / DC sub-conversion modules and the real-time current of multiple sub-battery packs connected in series.

[0071] In a specific embodiment, controlling the bidirectional DC / DC conversion module 13 to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module 13 is higher than the voltage of the battery pack 12 includes: sequentially controlling the first DC / DC sub-conversion module, the second DC / DC sub-conversion module, the third DC / DC sub-conversion module and the fourth DC / DC sub-conversion module to boost the voltage so that the voltages of the first DC / DC sub-conversion module, the second DC / DC sub-conversion module, the third DC / DC sub-conversion module and the fourth DC / DC sub-conversion module are higher than the voltage of the battery pack 12.

[0072] Sequentially obtain a first current output current of the first DC / DC sub-conversion module, a second current output current of the second DC / DC sub-conversion module, a third current output current of the third DC / DC sub-conversion module, and a fourth current output current of the fourth DC / DC sub-conversion module; sequentially obtain a first real-time current of the first sub-battery group, a second real-time current of the second sub-battery group, a third real-time current of the third sub-battery group, and a fourth real-time current of the fourth sub-battery group;

[0073] The circuit status of the battery pack 12 is determined based on the current of the battery pack 12, the first current output current, the second current output current, the third current output current, the fourth current output current, the first real-time current, the second real-time current, the third real-time current and the fourth real-time current.

[0074] Optionally, judging the circuit status of the battery group 12 according to the current of the battery group 12, the first current output current, the second current output current, the third current output current, the fourth current output current, the first real-time current, the second real-time current, the third real-time current and the fourth real-time current includes: if the current of the battery group 12, the first real-time current, the second real-time current, the third real-time current and the fourth real-time current are all equal, and any one of the first current output current, the second current output current, the third current output current and the fourth current output current is equal to zero, then judging that the sub-battery group corresponding to the DC / DC sub-conversion module with zero output current is open.

[0075] like Figure 1 As shown, the fourth sub-battery group (represented by V4) is open-circuited as an example for explanation. First, before performing the boost control, the current (Iz0) of the battery group 12 is measured first, and then the first DC / DC sub-conversion module is controlled to boost the voltage so that the output voltage of the first DC / DC sub-conversion module is higher than the voltage of the battery group 12. At this time, the first current output current (I1) of the first DC / DC sub-conversion module and the first real-time current (Iz1) of the battery group 12 are measured; then, the second DC / DC sub-conversion module is controlled to boost the voltage so that the output voltage of the second DC / DC sub-conversion module is higher than the voltage of the battery group 12. At this time, the second current output current (I2) of the second DC / DC sub-conversion module and the first real-time current (Iz1) of the battery group 12 are measured. The second real-time current (Iz2) of the battery pack 12 is measured; then, the third DC / DC sub-conversion module is controlled to perform a voltage boost so that the output voltage of the third DC / DC sub-conversion module is higher than the voltage of the battery pack 12. At this time, the third current output current (I3) of the third DC / DC sub-conversion module and the third real-time current (Iz3) of the battery pack 12 are measured; then, the fourth DC / DC sub-conversion module is controlled to perform a voltage boost so that the output voltage of the fourth DC / DC sub-conversion module is higher than the voltage of the battery pack 12. At this time, the fourth current output current (I4) of the fourth DC / DC sub-conversion module and the third real-time current (Iz4) of the battery pack 12 are measured. Finally, a judgment is made based on Iz0, Iz1, Iz2, Iz3, Iz4, I1, I2, I3, and I4.

[0076] If at this time, Iz0=Iz1=Iz2=Iz3=Iz4, and I1≠0, I2≠0, I3≠0, I4=0, it can be identified that at this time, the fourth sub-battery group is open circuit.

[0077] It can be understood that, since the fourth sub-battery group in the battery is open-circuited, the current of the battery group 12 does not change before and after the voltage is boosted.

[0078] Similarly, the open circuit status identification methods of other sub-battery groups are the same as the identification method of the fourth sub-battery group, and the present invention will not be repeated.

[0079] Furthermore, in some embodiments, controlling the bidirectional DC / DC conversion module 13 to perform boosting so that the output voltage of the bidirectional DC / DC conversion module 13 is higher than the voltage of the battery pack 12 includes: controlling any one of a plurality of DC / DC sub-conversion modules to perform boosting so that the output voltage of the DC / DC sub-conversion module performing the boosting is higher than the voltage of the battery pack 12.

[0080] In this embodiment, obtaining the current output current of the bidirectional DC / DC conversion module 13 and the real-time current of the battery pack 12 includes: obtaining the current output current of the DC / DC sub-conversion module after boosting; obtaining the real-time current of the battery pack 12; judging the loop state of the battery pack 12 according to the current, current output current and real-time current of the battery pack 12 includes: if the current of the battery pack 12 is less than the real-time current of the battery pack 12, and the current output current of the DC / DC sub-conversion module after boosting is equal to the real-time current of the battery pack 12, then judging that the battery pack 12 is disconnected from the DC bus 14.

[0081] By controlling any one of the multiple DC / DC sub-conversion modules to boost the voltage so that its output voltage is higher than the voltage of the battery pack 12, and measuring the current output current of the DC / DC sub-conversion module and the real-time current of the battery pack 12, if at this time, the current of the battery pack 12 is less than the real-time current of the battery pack 12, and the current output current of the DC / DC sub-conversion module after the boost is equal to the real-time current of the battery pack 12, it is determined that the battery pack 12 is disconnected from the DC bus 14. Figure 1 The second switch K2 in the bidirectional DC / DC conversion module 13 is in the disconnected state. It can be understood that, since the second switch K2 is disconnected, at this time, if any one of the DC / DC sub-conversion modules in the bidirectional DC / DC conversion module 13 is boosted, the bidirectional DC / DC conversion module 13 will reversely charge the battery pack 12, so that the current output current of the boosted DC / DC sub-conversion module is equal to the real-time current of the battery pack 12. Therefore, based on this condition, the connection state of the battery pack 12 and the DC bus 14 can be determined.

[0082] Furthermore, in some embodiments, judging the circuit status of the battery pack 12 based on the current of the battery pack 12, the current output current of multiple DC / DC sub-conversion modules and the real-time current of multiple sub-battery groups connected in series includes: if the current of the battery pack 12 is not equal to the real-time current of multiple sub-battery groups connected in series, and the current output current of multiple DC / DC sub-conversion modules is not zero, then judging that the circuit of the battery pack 12 is normal.

[0083] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0084] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0085] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot limit the scope of protection of the present invention. All equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for identifying the state of a battery circuit of a DC protection power supply system, applied to a DC protection power supply system, characterized in that: The DC protection power supply system includes: a DC bus, an AC / DC power supply module, a battery pack, a bidirectional DC / DC conversion module and a control unit; the battery pack includes: a plurality of sub-battery packs connected in series; the bidirectional DC / DC conversion module includes: a plurality of DC / DC sub-conversion modules arranged corresponding to the sub-battery packs; The method comprises: Before boosting the bidirectional DC / DC conversion module, obtaining the current of the battery pack; Controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack; controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack comprises: sequentially controlling the plurality of DC / DC sub-conversion modules to perform voltage boosting so that the output voltages of the plurality of DC / DC sub-conversion modules are higher than the voltage of the battery pack; Obtaining the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack; the obtaining the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack comprises: sequentially obtaining the real-time currents of the plurality of sub-battery packs connected in series; sequentially obtaining the current output currents of the plurality of DC / DC sub-conversion modules; The state of the battery pack circuit is determined according to the current of the battery pack, the current output current and the real-time current; the state of the battery pack circuit is determined according to the current of the battery pack, the current output current and the real-time current, including: determining the state of the battery pack circuit according to the current of the battery pack, the current output current of the plurality of DC / DC sub-conversion modules and the real-time current of the plurality of sub-batteries connected in series; The determining of the battery pack circuit state according to the battery pack current, the multiple DC / DC sub-conversion modules current output current and the multiple serially connected sub-battery packs real-time current comprises: If the current of the battery pack and the real-time current of the multiple sub-battery groups are equal, and any one of the current output currents of the multiple DC / DC sub-conversion modules is equal to zero, it is determined that the sub-battery group corresponding to the DC / DC sub-conversion module with zero output current is open.

2. The method for identifying the battery circuit status of a DC protection power supply system according to claim 1, characterized in that: The determining of the battery pack circuit state according to the battery pack current, the multiple DC / DC sub-conversion modules current output current and the multiple serially connected sub-battery packs real-time current comprises: If the current of the battery pack is not equal to the real-time current of the plurality of serially connected sub-battery packs, and the current output currents of the plurality of DC / DC sub-conversion modules are not zero, it is determined that the battery pack circuit is normal.

3. A method for identifying the state of a battery circuit of a DC protection power supply system, applied to a DC protection power supply system, characterized in that: The DC protection power supply system includes: a DC bus, an AC / DC power supply module, a battery pack, a bidirectional DC / DC conversion module and a control unit; the battery pack includes: a plurality of sub-battery packs connected in series; the bidirectional DC / DC conversion module includes: a plurality of DC / DC sub-conversion modules arranged corresponding to the sub-battery packs; The method comprises: Before boosting the bidirectional DC / DC conversion module, obtaining the current of the battery pack; Controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack; controlling the bidirectional DC / DC conversion module to boost the voltage so that the output voltage of the bidirectional DC / DC conversion module is higher than the voltage of the battery pack comprises: Controlling any one of the plurality of DC / DC sub-conversion modules to perform voltage boosting so that the output voltage of the DC / DC sub-conversion module performing voltage boosting is higher than the voltage of the battery pack; Acquire the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack; The obtaining of the current output current of the bidirectional DC / DC conversion module and the real-time current of the battery pack comprises: Obtaining the current output current of the DC / DC sub-conversion module after the boost; Obtaining the real-time current of the battery pack; Judging the state of the battery pack circuit according to the current of the battery pack, the current output current and the real-time current includes: If the current of the battery pack is less than the real-time current of the battery pack and the current output current of the boosted DC / DC sub-conversion module is equal to the real-time current of the battery pack, it is determined that the battery pack is disconnected from the DC bus.

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