Cable fault detection method, energy storage converter and energy storage system

Abstract

The invention discloses a cable fault detection method, an energy storage converter and an energy storage system.The cable fault detection method is applied to the energy storage converter in the energy storage system, the energy storage system further comprises N battery packs connected with the energy storage converter in parallel, and the method comprises the steps that when each battery pack is in a working state, N is a positive integer greater than or equal to 1; obtaining the port voltage of the energy storage converter and the port voltage and working current of each battery pack; determining the voltage, current and impedance of each power connection cable in the energy storage system according to the port voltage of the energy storage converter, the port voltage of each battery pack and the working current of each battery pack; power connection cables in the energy storage system comprise a power connection cable between the energy storage converter and the battery packs and a power connection cable between any two battery packs; and according to the voltage, the current and the impedance of each power connection cable in the energy storage system, determining whether each power connection cable in the energy storage system has a fault. In this way, whether the power connection cable breaks down or not can be detected in real time.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of cable fault detection, and particularly relate to a cable fault detection method, an energy storage converter and an energy storage system. BACKGROUND

[0002] Portable energy storage products are defined as small mobile energy devices with lithium batteries as the main energy storage carrier, which have the advantages of no noise, zero emission, easy to carry, etc. The market is growing rapidly. With the higher demand of users for the portability and large capacity of products, more and more products are designed in the form of host plus external battery pack (battery modular stacking design) to increase the system energy storage capacity to meet longer endurance while realizing plug and play to meet the portability requirements. This also puts higher requirements on the power connection cable of the battery pack. Due to plug and play, the power connection cable will be frequently plugged and unplugged. If the connection reliability of the power connection cable cannot be detected in time, it may cause the system to not work properly, and even cause safety risks. SUMMARY

[0003] Embodiments of the present application provide a cable fault detection method, an energy storage converter and an energy storage system, which can detect whether the power connection cable fails in real time.

[0004] In a first aspect, embodiments of the present application provide a cable fault detection method applied to an energy storage converter in an energy storage system, the energy storage system further comprising N battery packs, the energy storage converter being connected in parallel with the N battery packs, wherein N is a positive integer, and the method comprises: acquiring a port voltage of the energy storage converter and a port voltage and a working current of each battery pack when the battery packs are in a working state, wherein the working state is a charging state or a discharging state, and the working current is a charging current or a discharging current; determining a voltage, a current and an impedance of each power connection cable in the energy storage system according to the port voltage of the energy storage converter, the port voltage of each battery pack and the working current of each battery pack, wherein the power connection cables in the energy storage system include power connection cables between the energy storage converter and the battery packs and power connection cables between any two battery packs; and determining whether each power connection cable in the energy storage system fails according to the voltage, the current and the impedance of each power connection cable in the energy storage system.

[0005] In one or more embodiments, determining the voltage, current and impedance of each power connection cable in the energy storage system according to the port voltage of the energy storage converter, the port voltage of each battery pack and the operating current of each battery pack comprises: determining the voltage of the power connection cable between any two adjacent devices according to the absolute value of the difference between the port voltages of the two adjacent devices, wherein the devices include the energy storage converter and the battery pack; determining the current of the power connection cable between the Nth battery pack and the (N-1)th battery pack according to the operating current of the Nth battery pack, and determining the current of the power connection cable between the Ith device and the (I-1)th device according to the absolute value of the difference between the current of the power connection cable between the Ith device and the (I+1)th device and the operating current of the Ith device, wherein I is a positive integer less than or equal to N-1; and determining the impedance of each power connection cable according to the ratio between the voltage and the current of each power connection cable in the energy storage system.

[0006] In one or more embodiments, determining whether a fault occurs in each power connection cable in the energy storage system according to the voltage, current and impedance of each power connection cable in the energy storage system comprises: determining that the Kth power connection cable in the energy storage system is broken when the voltage of the Kth power connection cable is greater than a first preset voltage threshold and the difference between the current of the Kth power connection cable and zero is less than a preset current threshold, wherein the Kth power connection cable is any power connection cable in the energy storage system and K is a positive integer.

[0007] In one or more embodiments, determining whether a fault occurs in each power connection cable in the energy storage system according to the voltage, current and impedance of each power connection cable in the energy storage system comprises: determining that the Mth power connection cable in the energy storage system has a high resistance fault when the impedance of the Mth power connection cable is greater than or equal to a first preset impedance threshold, wherein the Mth power connection cable is any power connection cable in the energy storage system and M is a positive integer.

[0008] In one or more embodiments, determining whether a fault occurs in each power connection cable in the energy storage system according to the voltage, current and impedance of each power connection cable in the energy storage system comprises: when the impedance of the Jth power connection cable in the energy storage system is less than a first preset impedance threshold and greater than or equal to a second preset impedance threshold, determining the heat generated by the Jth power connection cable according to the current of the Jth power connection cable, wherein the Jth power connection cable is any power connection cable in the energy storage system and J is a positive integer, and the first preset impedance threshold is greater than the second preset impedance threshold; and determining that the Jth power connection cable has a high resistance fault when the heat generated by the Jth power connection cable is greater than the heat dissipation power of the Jth power connection cable.

[0009] In one or more embodiments, the energy storage system further comprises a temperature sensor arranged at each power connection cable; and determining whether a fault occurs in each power connection cable in the energy storage system according to a voltage, a current and an impedance of each power connection cable in the energy storage system comprises: when an impedance of an Tth power connection cable in the energy storage system is less than a first preset impedance threshold and greater than or equal to a second preset impedance threshold, performing the following steps: determining heat generated by the Tth power connection cable according to an output signal of the temperature sensor, wherein the Tth power connection cable is any power connection cable in the energy storage system, T is a positive integer, and the first preset impedance threshold is greater than the second preset impedance threshold; and determining that the Tth power connection cable has a high-impedance fault when the heat generated by the Tth power connection cable is greater than a heat dissipation power of the Tth power connection cable.

[0010] In one or more embodiments, the battery pack comprises a controller, a cell module and a voltage conversion circuit, the cell module comprises at least one cell, and the voltage conversion circuit is electrically connected with the controller and the cell module respectively, and is configured to operate in response to a pulse width modulation signal output by the controller to step down or step up a voltage of the cell module; the method further comprises: obtaining a port voltage of the battery pack when the voltage conversion circuit operates; and determining that a power connection cable electrically connected with the battery pack is short-circuited if the port voltage of the battery pack is less than a second preset voltage threshold within a preset time length.

[0011] In one or more embodiments, the battery pack comprises a controller, a cell module, a charging switch and a discharging switch, the cell module comprises at least one cell, the charging switch and the discharging switch are connected in series between a positive electrode of the cell module and a positive port of the battery pack, or the charging switch and the discharging switch are connected in series between a negative electrode of the cell module and a negative port of the battery pack, and the controller is electrically connected with the charging switch and the discharging switch respectively; the method further comprises: obtaining a port voltage of each battery pack and a voltage of the cell module in each battery pack when each battery pack is not in a working state; and outputting a control signal to the controller to make the controller control the charging switch and the discharging switch to be closed, so that the battery pack is in the working state, if an absolute value of a difference between the port voltage of any battery pack and the voltage of the cell module in the battery pack is less than a third preset voltage threshold.

[0012] In a second aspect, the embodiments of the present application provide an energy storage converter, comprising: at least one processor and a memory; the memory is coupled with the processor, and is configured to store instructions or programs, which, when executed by the at least one processor, cause the at least one processor to perform the cable fault detection method as described above.

[0013] In a third aspect, the embodiments of the present application provide an energy storage system, comprising: N battery packs, wherein N is a positive integer; and the energy storage converter as described above, which is connected in parallel with the N battery packs.

[0014] The beneficial effects of the present application are: the cable fault detection method of the present application is applied to the energy storage converter in the energy storage system, the energy storage system further includes N battery packs, and the energy storage converter is connected in parallel with the N battery packs. The method comprises: acquiring the port voltage of the energy storage converter and the port voltage and working current of each battery pack when each battery pack is in a working state, wherein the working state is a charging state or a discharging state, and the working current is a charging current or a discharging current; determining the voltage, current and impedance of each power connection cable in the energy storage system according to the port voltage of the energy storage converter, the port voltage of each battery pack and the working current of each battery pack, wherein the power connection cable in the energy storage system includes the power connection cable between the energy storage converter and the battery pack and the power connection cable between any two battery packs; and determining whether each power connection cable in the energy storage system has a fault according to the voltage, current and impedance of each power connection cable in the energy storage system. In the foregoing manner, the electrical signals related to each power connection cable can be acquired, and then whether each power connection cable has a fault can be determined based on the electrical signals related to each power connection cable. BRIEF DESCRIPTION OF DRAWINGS

[0015] One or more embodiments are illustrated by way of example in the figures that are included in the disclosure and which are illustrative of examples only. Identical reference numbers in the figures represent similar elements.

[0016] Figure 1 is a schematic diagram of an energy storage system provided by an embodiment of the present application; Figure 2 is a schematic diagram of an energy storage converter provided by an embodiment of the present application; Figure 3 is a schematic diagram of a battery pack provided by an embodiment of the present application; Figure 4 is a flow of a cable fault detection method provided by an embodiment of the present application Figure 1 ; Figure 5 is a flow of a cable fault detection method provided by an embodiment of the present application Figure 2 ; Figure 6 is a flow of a cable fault detection method provided by an embodiment of the present application Figure 3 ; Figure 7 is a flow of a cable fault detection method provided by an embodiment of the present application Figure 4 ; Figure 8 is a flow of a cable fault detection method provided by an embodiment of the present application Figure 5 ; Figure 9 is a flow of a cable fault detection method provided by an embodiment of the present applicationFigure 6 ; Figure 10 This is the flowchart of the cable fault detection method provided in the embodiments of this application. Figure 7 ; Figure 11 This is the flowchart of the cable fault detection method provided in the embodiments of this application. Figure 8 . Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0018] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements between them.

[0019] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0020] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the composition of an energy storage system provided in an embodiment of this application. Figure 1 As shown, the energy storage system 100 includes an energy storage converter 10 and N battery packs, where N is a positive integer.

[0021] The energy storage converter 10 is used to realize bidirectional conversion and control of electrical energy. Specifically, when the battery pack is in charging mode, the energy storage converter 10 converts the alternating current (AC) output from the grid or photovoltaic inverter into direct current (DC) suitable for charging the battery pack; when the battery pack is in discharging mode, the energy storage converter 10 converts the DC released by the battery pack into alternating current (AC) that meets the requirements of the grid or load.

[0022] In some embodiments, such as Figure 2 As shown, the energy storage converter 10 includes at least one processor 101 and a memory 102. The memory 102 can be built into the energy storage converter 10 or externally placed outside the energy storage converter 10. The memory 102 can also be a remotely configured memory connected to the energy storage converter 10 via a network.

[0023] The memory 102, as a non-volatile computer readable storage medium, can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 102 can include a program storage area and a data storage area, wherein the program storage area can store an operating system and at least one application required by a function; the data storage area can store data created according to the use of the terminal, etc. In addition, the memory 102 can include a high-speed random access memory, and can also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state memory device. In some embodiments, the memory 102 can optionally include a memory remotely arranged with respect to the processor 101, which can be connected to the terminal through a network. Examples of the above network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0024] The processor 101 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 102 and calling data stored in the memory 102, thereby performing overall monitoring of the terminal, such as implementing the cable fault detection method described in any embodiment of the present application.

[0025] The processor 101 can be one or more, Figure 2 The processor 101 is taken as an example. The processor 101 and the memory 102 can be connected through a bus or other means. The processor 101 can include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, etc. The processor 101 can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0026] Please refer back to Figure 1 The N battery packs include a first battery pack B1, a second battery pack B2, …, and an Nth battery pack BN. The first battery pack B1, the second battery pack B2, …, and the Nth battery pack BN are connected in parallel with the energy storage converter 10. The first battery pack B1, the second battery pack B2, …, and the Nth battery pack BN are also in communication connection with the energy storage converter 10, so that the energy storage converter 10 can obtain information related to the first battery pack B1, the second battery pack B2, …, and the Nth battery pack BN (such as the port voltage and working current of each battery pack); the energy storage converter 10 can also issue control instructions to each battery pack to make each battery pack perform corresponding operations, such as the energy storage converter 10 issuing instructions to close the charging switch and the discharging switch to each battery pack to make each battery pack close the corresponding charging switch and discharging switch.

[0027] Figure 3 An example shows a structure of a battery pack, wherein, Figure 3 Taking the first battery pack B1 as an example, other battery packs have the same structure as the first battery pack B1. As shown in the figure, Figure 3 The first battery pack B1 includes a battery cell module B1_1, a voltage conversion circuit B1_2, and a controller B1_3.

[0028] The battery module 12 includes a plurality of battery cells connected in parallel, series, or mixed connection, for storing and providing electric energy, and the mixed connection includes series connection and parallel connection. The voltage conversion circuit B1_2 is electrically connected to the controller B1_3 and the battery cell module B1_1, respectively, and is used to operate in response to the pulse width modulation signal output by the controller B1_3 to step down or step up the voltage of the battery cell module B1_1.

[0029] In some embodiments, the voltage conversion circuit B1_2 includes a first switch tube K1, a first diode D1, and a first inductor L2. The gate of the first switch tube K1 is electrically connected to the controller B1_3, the source of the first switch tube K1 is electrically connected to the anode of the first diode D1 and the first end of the first inductor L1, respectively, the drain of the first switch tube K1 is electrically connected to the negative electrode B- of the battery cell module B1_1, the cathode of the first diode D1 is electrically connected to the positive electrode B+ of the battery cell module B1_1, and the second end of the first inductor L1 is electrically connected to the negative electrode port P- of the first battery pack B1. The first switch tube K1 is controlled by the pulse width modulation signal to alternately turn on and off to step down the voltage of the battery cell module B1_1.

[0030] It can be understood that this embodiment only exemplarily shows a circuit structure of the voltage conversion circuit B1_2, and in other embodiments, the voltage conversion circuit B1_2 can also adopt other circuit structures, such as the circuit structure of a boost circuit. Secondly, in this embodiment, the first switch tube K1 is taken as an example of an NMOS tube, and in other embodiments, the first switch tube K1 can be set as other controllable switching elements In some embodiments, the first battery pack B1 includes a discharge switch Q1 and a charging switch Q2, wherein the discharge switch Q1 and the charging switch Q2 are connected in series between the negative electrode B- of the battery cell module B1_1 and the negative electrode port P- of the first battery pack B1, and the discharge switch Q1 and the charging switch Q2 are also electrically connected to the controller B1_3. The discharge switch Q1 and the charging switch Q2 are controlled by the controller B1_3 to turn on or off.

[0031] It can be understood that the embodiment takes the example that the discharge switch Q1 and the charging switch Q2 are connected in series between the negative electrode B- of the battery cell module B1_1 and the negative electrode port P- of the first battery pack B1, in other embodiments, the discharge switch Q1 and the charging switch Q2 can also be connected in series between the positive electrode B+ of the battery cell module B1_1 and the positive electrode port P+ of the first battery pack B1, and in this case, the two ends of the voltage conversion circuit B1_2 electrically connected to the negative electrode B- of the battery cell module B1_1 and the negative electrode port P- of the first battery pack B1 should also be adjusted to be electrically connected to the positive electrode B+ of the battery cell module B1_1 and the positive electrode port P+ of the first battery pack B1 respectively, that is, the circuit after the discharge switch Q1 and the charging switch Q2 are connected in series remains in a parallel state with the voltage conversion circuit B1_2. Secondly, in this embodiment, the discharge switch Q1 and the charging switch Q2 are both NMOS tubes, in other embodiments, the discharge switch Q1 and / or the charging switch Q2 can be set as other controllable switching elements.

[0032] It should be noted that the hardware structure of the energy storage system 100 shown in Figure 1 and the hardware structure of the battery pack shown in Figure 3 are only one example, and the energy storage system 100 and the battery pack can have more or fewer components than those shown in the figure, can combine two or more components, or can have a different component configuration, and various components shown in the figure can be implemented in hardware, software, or a combination of hardware and software including one or more signal processing and / or application specific integrated circuits.

[0033] For example, in some embodiments, the energy storage system 100 further includes a temperature sensor (not shown in the figure) arranged at each power connection cable. The temperature sensor can output a corresponding signal according to the heat generated by the corresponding power connection cable, and transmit the signal to the energy storage converter 10, so that the energy storage converter 10 determines the heat generated by each power connection cable in real time according to the received signal. In a specific embodiment, the temperature sensor includes a thermistor, which is a negative temperature coefficient thermistor (NTC) or a positive temperature coefficient thermistor (PTC).

[0034] Please refer to Figure 4 , Figure 4 The flowchart of the cable fault detection method provided by the embodiment of the present application. The cable fault detection method is applied to an energy storage converter in an energy storage system, and the energy storage system further includes N battery packs, and the energy storage converter is connected in parallel with the N battery packs, where N is a positive integer. In some embodiments, the energy storage system herein can be implemented as shown inFigure 1 The structure shown is implemented in detail in the above embodiments and will not be repeated here. Figure 4 As shown, the cable fault detection method includes the following steps S410 to S430.

[0035] Step S410: When each battery pack is in the working state, obtain the port voltage of the energy storage converter and the port voltage and operating current of each battery pack, wherein the working state is the charging state or the discharging state, and the operating current is the charging current or the discharging current.

[0036] by Figure 1 For example, the port voltage of energy storage converter 10 is V. P The port voltage of the first battery pack B1 is V. P1 The port voltage of the second battery pack B1 is V. P2 The port voltage of the Nth battery pack BN is V. PN Among them, such as Figure 3 As shown, the port voltage V of the first battery pack B1 is... P1 Let P be the voltage between the positive terminal P+ and the negative terminal P- of the first battery pack B1. The operating current of the first battery pack B1 is I. B1 The operating current of the second battery pack B1 is I. B2 The operating current of the Nth battery pack BN is I. BN .

[0037] When each battery pack is in the charging state, the port voltage of the energy storage converter and the port voltage and charging current of each battery pack are obtained.

[0038] In some embodiments, such as Figure 5 As shown, before each battery pack enters the working state, the cable fault detection method further includes the following steps S510 to S520.

[0039] Step S510: When each battery pack is not in operation, acquire the port voltage of each battery pack and the voltage of the cell module in each battery pack.

[0040] Step S520: If the absolute value of the difference between the port voltage of any battery pack and the voltage of the cell module in the battery pack is less than the third preset voltage threshold, a control signal is output to the controller so that the controller controls the charging switch and the discharging switch to close, thereby putting the battery pack into working state.

[0041] Specifically, the port voltage of each battery pack is the voltage between the positive and negative terminals of that battery pack. Figure 3The port voltage of the first battery pack B1 is the voltage between the positive port P+ and the negative port P- of the first battery pack B1.

[0042] The voltage of the cell module in each battery pack is the voltage between the positive electrode and the negative electrode of the cell module. For example, Figure 3 The voltage of the cell module B1_1 in the first battery pack B1 is the voltage between the positive electrode B+ and the negative electrode B- of the cell module B1_1.

[0043] The absolute value of the difference between the port voltage and the voltage of the cell module in any battery pack is less than the third preset voltage threshold, which means that the difference between the port voltage and the voltage of the cell module is small for the battery pack, and the closing of the charging switch and the discharging switch will not cause the battery pack to overcurrent, which is beneficial to protect the battery pack and reduce the risk of damage. For example, Figure 1 The third preset voltage threshold is a voltage threshold set in advance, which can be set based on the actual application scenario, and the embodiments of the present application do not make specific limitations thereto. For example, in a specific embodiment, the third preset voltage threshold is set to 2V. Figure 3 The first battery pack B1 is taken as an example. If the absolute value of the difference between the port voltage of the first battery pack B1 and the voltage of the cell module B1_1 is less than the third preset voltage threshold, the energy storage converter 10 outputs a control signal to the controller B1_3 to control the controller B1_3 to close the charging switch Q1 and the discharging switch Q2, so that the first battery pack B1 is in a working state. After the charging switch and the discharging switch in the first battery pack B1, the second battery pack B2, …, and the Nth battery pack BN are closed, step S410 and subsequent steps can be performed.

[0044] It can be understood that the third preset voltage threshold is a voltage threshold set in advance, which can be set based on the actual application scenario, and the embodiments of the present application do not make specific limitations thereto. For example, in a specific embodiment, the third preset voltage threshold is set to 2V.

[0045] In some embodiments, as Figure 6 As shown, the cable fault detection method further includes steps S610 to S620.

[0046] Step S610: obtaining the port voltage of the battery pack when the voltage conversion circuit is running.

[0047] Step S620: If the port voltage of the battery pack is less than the second preset voltage threshold within a preset time period, it is determined that the power connection cable connected to the battery pack is short-circuited.

[0048] Specifically, the first battery pack B1 is taken as an example. If the absolute value of the difference between the port voltage of the first battery pack B1 and the voltage of the cell module B1_1 is less than the third preset voltage threshold, the energy storage converter 10 outputs a control signal to the controller B1_3 to control the controller B1_3 to close the charging switch Q1 and the discharging switch Q2, so that the first battery pack B1 is in a working state. After the charging switch and the discharging switch in the first battery pack B1, the second battery pack B2, …, and the Nth battery pack BN are closed, step S410 and subsequent steps can be performed. Figure 3As shown in the first battery pack B1, the first battery pack B1 controls the voltage conversion circuit B1_2 to operate, that is, the controller B1_3 outputs a pulse width modulation signal to control the first switch tube K1 to be turned on or turned off, so as to reduce the voltage of the battery cell module B1_1. In this case, the voltage between the positive port P+ and the negative port P- of the first battery pack B1, that is, the port voltage of the first battery pack B1, is obtained.

[0049] If the port voltage of the first battery pack B1 remains less than the second preset voltage threshold value within the preset time length, it is determined that the power connection cable electrically connected with the first battery pack B1 is short-circuited, that is, the positive port P+ and the negative port P- of the first battery pack B1 are short-circuited. Correspondingly, the power connection cable electrically connected with each battery pack is short-circuited, and the positive port and the negative port of each battery pack are short-circuited. Of course, if the port voltage of the first battery pack B1 does not remain less than the second preset voltage threshold value within the preset time length, it is determined that the power connection cable electrically connected with the first battery pack B1 is not short-circuited. Thus, the process of detecting whether each power connection cable is short-circuited is realized.

[0050] It can be understood that the preset time length is a preset time length, and the second preset voltage threshold value is a preset voltage threshold value. The preset time length and the second preset voltage threshold value can be set based on actual application scenarios, and the embodiments of the present application do not make specific limitations thereto. For example, in a specific embodiment, the preset time length is set to 500 ms, and the second preset voltage threshold value is set to 2 V.

[0051] Step S420: determining the voltage, current and impedance of each power connection cable in the energy storage system according to the port voltage of the energy storage converter, the port voltage of each battery pack and the working current of each battery pack, wherein the power connection cable in the energy storage system includes the power connection cable between the energy storage converter and the battery pack and the power connection cable between any two battery packs.

[0052] Specifically, the electrical signals related to each power connection cable can be determined through step S420, and then whether each power connection cable is faulty can be determined based on the electrical signals related to each power connection cable.

[0053] In some embodiments, as shown in Figure 7 The specific implementation process of step S420 can include the following steps S710 to S730.

[0054] Step S710: determining the voltage of the power connection cable between two adjacent devices according to the absolute value of the difference between the port voltages of the two adjacent devices, wherein the devices include the energy storage converter and the battery pack.

[0055] Specifically, the voltage of the power connection cable between the two adjacent devices is determined according to the absolute value of the difference between the port voltages of the two adjacent devices. Figure 1The energy storage system 100 shown is an example. Based on the port voltage V of the energy storage converter 10... P The port voltage V of the first battery pack B1 P1 The difference is used to determine the voltage (denoted as V) of the power connection cable between the energy storage converter 10 and the first battery pack B1. L1 ), that is, V L1 =|V P -V P1 |;According to the port voltage V of the first battery pack B1 P1 The port voltage V of the second battery pack B2 P2 The difference is used to determine the voltage (denoted as V) of the power connection cable between the first battery pack B1 and the second battery pack B2. L2 ), that is, V L2 =|V P1 -V P2 |;…;According to the port voltage V of the (N-1)th battery pack BN-1 PN-1 The port voltage V of the Nth battery pack BN PN The difference is used to determine the voltage (denoted as V) of the power connection cable between the (N-1)th battery pack BN-1 and the Nth battery pack BN. LN ), that is, V LN =|V PN-1 -V PN |

[0056] Step S720: Based on the operating current of the Nth battery pack, determine the current of the power connection cable between the Nth battery pack and the (N-1)th battery pack. Based on the absolute value of the difference between the current of the power connection cable between the Ith device and the (I+1)th device and the operating current of the Ith device, determine the current of the power connection cable between the Ith device and the (I-1)th device, where I is a positive integer less than or equal to N-1.

[0057] Specifically, with Figure 1 The energy storage system 100 shown is an example. Based on the operating current I of the Nth battery pack BN... BN Determine the current I of the power connection cable between the Nth battery pack BN and the (N-1)th battery pack BN-1. LN , that is I LN =I BN Based on the current I in the power connection cable between the (N-1)th battery pack and the Nth battery pack. LN The operating current IB of the (N-1)th battery pack N-1 The absolute value of the difference is used to determine the current (denoted as I) in the power connection cable between the (N-1)th and (N-2)th battery packs. LN-1 ), i.e. I LN-1 =|I LN -IB N-1|;Based on the current I of the power connection cable between the (N-2)th battery pack and the (N-1)th battery pack. LN-1 The operating current IB of the (N-2)th battery pack N-2 The absolute value of the difference is used to determine the current (denoted as I) in the power connection cable between the (N-2)th and (N-3)th battery packs. LN-2 ), i.e. I LN-2 =|I LN-1 -IB N-2 |;…;Based on the current I of the power connection cable between the first and second battery packs L2 The absolute value of the difference between the operating current IB1 of the first battery pack and the current of the power connection cable between the first battery pack and the energy storage converter 10 is used to determine the current (denoted as I). L1 ), i.e. I L1 =|I L2 -IB1|.

[0058] Step S730: Determine the impedance of each power connection cable based on the ratio between the voltage and current of each power connection cable in the energy storage system.

[0059] Specifically, with Figure 1 The energy storage system 100 shown is an example. Based on the voltage V of the power connection cable between the energy storage converter 10 and the first battery pack B1... L1 With current I L1 Determine the impedance (denoted as R) of the power connection cable between the energy storage converter 10 and the first battery pack B1. L1 ), that is, R L1 =V L1 / I L1 According to the voltage V of the power connection cable between the first battery pack B2 and the second battery pack B2 L2 With current I L2 Determine the impedance (denoted as R) of the power connection cable between the first battery pack B2 and the second battery pack B2. L2 ), that is, R L2 =V L2 / I L2 ...; Based on the voltage V of the power connection cable between the (N-1)th battery pack BN-1 and the Nth battery pack BN LN With current I LN Determine the impedance (denoted as R) of the power connection cable between the (N-1)th battery pack BN-1 and the Nth battery pack BN. LN ), that is, R LN =V LN / I LN .

[0060] Step S430: Determine whether any power connection cable in the energy storage system is faulty based on the voltage, current, and impedance of each power connection cable in the energy storage system.

[0061] In some embodiments, such as Figure 8 As shown, the specific implementation process of step S430 includes the following step S810.

[0062] Step S810: When the voltage of the Kth power connection cable in the energy storage system is greater than the first preset voltage threshold and the difference between the current of the Kth power connection cable and zero is less than the preset current threshold, it is determined that the Kth power connection cable has a disconnection fault. Here, the Kth power connection cable is any power connection cable in the energy storage system and K is a positive integer.

[0063] Specifically, with Figure 1 The energy storage system 100 shown is an example. When K>1, the Kth power connection cable is the power connection cable between the Kth battery pack BK and the (K-1)th battery pack BK-1; when K=1, the Kth power connection cable is the power connection cable between the energy storage converter 10 and the first battery pack B1.

[0064] Based on the foregoing explanation, the voltage of the Kth power connection cable is V. LK The current in the Kth power connection cable is I. LK , where V LK A voltage greater than the first preset voltage threshold means that the voltage of the Kth power connection cable is too high; simultaneously, I LK The difference between the current and zero is less than the preset current threshold, meaning the current in the Kth power connection cable is close to or equal to 0. This can be understood as follows: when the power connection cable is functioning correctly, its impedance is low, resulting in a small voltage drop and thus a small voltage difference between adjacent devices. Conversely, a break in the connection leads to a larger voltage difference between adjacent devices, resulting in a higher voltage in the power connection cable. Furthermore, during battery pack charging or discharging, the current flowing through the power connection cable is the charging or discharging current; therefore, the current in the Kth power connection cable should have a significant difference from 0. Thus, when V... LK Greater than the first preset voltage threshold, and I LK When the difference between the current and zero is less than the preset current threshold, it can be determined that the Kth power connection cable has a broken wire fault.

[0065] It is understood that the first preset voltage threshold is a pre-set voltage threshold, which can be set based on the actual application scenario. This application embodiment does not impose specific limitations on this. For example, in a specific embodiment, the first preset voltage threshold is set to 0.5V.

[0066] In some embodiments, as shown in FIG. 9, the specific implementation process of step S430 includes the following step S910. Figure 9

[0067] Step S910: determining that the Mth power connection cable in the energy storage system has a high-impedance fault when the impedance of the Mth power connection cable is greater than or equal to a first preset impedance threshold, where the Mth power connection cable is any power connection cable in the energy storage system, and M is a positive integer.

[0068] Specifically, taking the energy storage system 100 shown in FIG. 1 as an example. When M > 1, the Mth power connection cable is the power connection cable between the Mth battery pack BM and the (M-1)th battery pack BM-1; when M = 1, the Mth power connection cable is the power connection cable between the energy storage converter 10 and the first battery pack B1. Figure 1 According to the foregoing, the impedance of the Mth power connection cable is R LM . R LM greater than or equal to the first preset impedance threshold means that R LM is too high, so that it can be determined that the Mth power connection cable has a high-impedance fault (i.e., an impedance-too-high fault). It can be understood that, according to the formula P = I 2 R of Joule heat, if the impedance of the Mth power connection cable is too high, the Joule heat is also too high, which can cause a local high temperature, thereby triggering a fire of the surrounding combustible materials. Based on this, by determining in real time whether the Mth power connection cable has a high-impedance fault, it is possible to prevent abnormal situations such as high temperature and even fire in time.

[0069] It can be understood that the first preset impedance threshold is a preset impedance threshold, which can be set based on actual application scenarios, and the embodiments of the present application do not make specific limitations thereon. For example, in a specific embodiment, the first preset impedance threshold is set to 0.1 Ω.

[0070] In some embodiments, the specific implementation process of step S430 includes the following steps: when the impedance of the Jth power connection cable in the energy storage system is less than the first preset impedance threshold and greater than or equal to a second preset impedance threshold, performing steps S1010 to S1020 as shown in FIG. 10.

[0071] Figure 10 Step S1010: determining the heat generated by the Jth power connection cable according to the current of the Jth power connection cable, where the Jth power connection cable is any power connection cable in the energy storage system, J is a positive integer, and the first preset impedance threshold is greater than the second preset impedance threshold.

[0072]

[0073] ​​​Step S1020: When the heat generated by the J-th power connection cable is greater than the heat dissipation power of the J-th power connection cable, it is determined that the J-th power connection cable has a high resistance fault.

[0074] Specifically, with Figure 1 The energy storage system 100 shown is an example. When J>1, the Jth power connection cable is the power connection cable between the Jth battery pack BJ and the J-1th battery pack BJ-1; when J=1, the Mth power connection cable is the power connection cable between the energy storage converter 10 and the first battery pack B1.

[0075] Based on the foregoing, the impedance of the J-th power connection cable is R. LJ The impedance R of the J-th power connection cable in the energy storage system. LJ If the impedance is less than the first preset impedance threshold but greater than or equal to the second preset impedance threshold, it means that the J-th power connection cable may or may not have experienced a high-resistance fault. This can be determined by the relationship between the heat generated by the J-th power connection cable and its heat dissipation power. The formula for the Joule heat of the J-th power connection cable is P=IJ. 2 R represents the heat generated by the J-th power connection cable. If the heat generated by the J-th power connection cable is greater than its heat dissipation power, it means the heat release power is greater than the heat dissipation power, and the temperature will tend to rise over time. This could potentially cause localized high temperatures, which could then ignite nearby flammable materials. Therefore, when the heat generated by the J-th power connection cable is greater than its heat dissipation power, a high-resistance fault is determined to have occurred in the J-th power connection cable. Conversely, if the heat generated by the J-th power connection cable is less than or equal to its heat dissipation power, it means the heat release power is less than or equal to the heat dissipation power, and the temperature will tend to remain constant or decrease over time, without causing localized high temperatures. Therefore, when the heat generated by the J-th power connection cable is less than or equal to its heat dissipation power, a high-resistance fault is determined to have occurred in the J-th power connection cable.

[0076] It is understood that the second preset impedance threshold is a pre-set impedance threshold, which can be set based on the actual application scenario. This application embodiment does not impose specific limitations on this. For example, in a specific embodiment, the second preset impedance threshold is set to 0.05Ω. Secondly, the heat dissipation power of the Jth power connection cable is based on actual test data according to the size and material of the power connection cable; this data is obtained through pre-testing.

[0077] In some embodiments, the specific implementation process of step S430 includes the following steps: when the impedance of the T-th power connection cable in the energy storage system is less than a first preset impedance threshold and greater than or equal to a second preset impedance threshold, perform the following... Figure 11The steps S1110 to S1120 are shown.

[0078] Step S1110: determining the heat generated by the Tth power connection cable according to the output signal of the temperature sensor, wherein the Tth power connection cable is any power connection cable in the energy storage system, T is a positive integer, and the first preset impedance threshold is greater than the second preset impedance threshold.

[0079] Step S1120: determining that the Tth power connection cable has a high-impedance fault when the heat generated by the Tth power connection cable is greater than the heat dissipation power of the Tth power connection cable.

[0080] Specifically, the energy storage system 100 is taken as an example. Figure 1 When T>1, the Tth power connection cable is the power connection cable between the Tth battery pack BT and the (T-1)th battery pack BT-1; when T=1, the Mth power connection cable is the power connection cable between the energy storage converter 10 and the first battery pack B1.

[0081] According to the foregoing, the impedance of the Tth power connection cable is R LT The impedance R LT of the Tth power connection cable in the energy storage system is less than the first preset impedance threshold and greater than or equal to the second preset impedance threshold, which means that the Tth power connection cable may have a high-impedance fault or may not have a high-impedance fault, which can be determined by the size between the heat generated by the Tth power connection cable and the heat dissipation power of the Tth power connection cable. The heat generated by the Tth power connection cable is directly determined according to the output signal of the temperature sensor. If the heat generated by the Tth power connection cable is greater than the heat dissipation power of the Tth power connection cable, it means that the heat release power is greater than the heat dissipation power, and the temperature will show an upward trend over time, which may also cause local high temperature and thus cause the surrounding combustible materials to catch fire. Therefore, when the heat generated by the Tth power connection cable is greater than the heat dissipation power of the Tth power connection cable, it is determined that the Tth power connection cable has a high-impedance fault. Conversely, if the heat generated by the Tth power connection cable is less than or equal to the heat dissipation power of the Tth power connection cable, it means that the heat release power is less than or equal to the heat dissipation power, and the temperature will show a trend of keeping unchanged or decreasing over time, which will not cause abnormal conditions such as local high temperature. Therefore, when the heat generated by the Tth power connection cable is less than or equal to the heat dissipation power of the Tth power connection cable, it is determined that the Tth power connection cable does not have a high-impedance fault.

[0082] In conclusion, in the embodiments of the present application, it can be quickly and effectively judged whether short circuit fault, disconnection fault and high resistance fault of each power connection cable in the energy storage system 100 occurs. Meanwhile, the cable fault detection method provided by the present application can be used to detect in real time during the operation of the energy storage system 100, without presetting test conditions, which is more friendly to users, and can be applied to portable and plug-and-play products.

[0083] The above is only the embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent flow transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

[0084] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that the technical solutions recorded in the above embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of cable fault detection, characterized by, The application relates to a storage energy converter applied to a storage energy system, wherein the storage energy system further comprises N battery packs, the storage energy converter is connected in parallel with the N battery packs, N is a positive integer, and the method comprises the following steps: When each battery pack is in a working state, the port voltage of the storage energy converter and the port voltage and working current of each battery pack are acquired, wherein the working state is a charging state or a discharging state, and the working current is a charging current or a discharging current; According to the port voltage of the storage energy converter, the port voltage of each battery pack and the working current of each battery pack, the voltage, current and impedance of each power connection cable in the storage energy system are determined, wherein the power connection cables in the storage energy system comprise power connection cables between the storage energy converter and the battery packs and power connection cables between any two battery packs; According to the voltage, current and impedance of each power connection cable in the storage energy system, it is determined whether a fault occurs in each power connection cable in the storage energy system.

2. The cable fault detection method of claim 1, wherein, The determination of the voltage, current and impedance of each power connection cable in the storage energy system according to the port voltage of the storage energy converter, the port voltage of each battery pack and the working current of each battery pack comprises the following steps: According to the absolute value of the difference between the port voltages of any two adjacent devices, the voltage of the power connection cable between the two adjacent devices is determined, wherein the devices comprise the storage energy converter and the battery packs; According to the working current of the Nth battery pack, the current of the power connection cable between the Nth battery pack and the N-1th battery pack is determined, and according to the absolute value of the difference between the current of the power connection cable between the Ith device and the I+1th device and the working current of the Ith device, the current of the power connection cable between the Ith device and the I-1th device is determined, wherein I is a positive integer less than or equal to N-1; According to the ratio between the voltage and the current of each power connection cable in the storage energy system, the impedance of each power connection cable is determined.

3. The cable fault detection method according to claim 1 or 2, characterized by, The determination of whether a fault occurs in each power connection cable in the storage energy system according to the voltage, current and impedance of each power connection cable in the storage energy system comprises the following steps: When the voltage of the Kth power connection cable in the storage energy system is greater than a first preset voltage threshold, and the difference between the current of the Kth power connection cable and zero is less than a preset current threshold, it is determined that the Kth power connection cable has a wire breakage fault, wherein the Kth power connection cable is any power connection cable in the storage energy system, and K is a positive integer.

4. The cable fault detection method according to claim 1 or 2, characterized by, The determination of whether a fault occurs in each power connection cable in the storage energy system according to the voltage, current and impedance of each power connection cable in the storage energy system comprises the following steps: When the impedance of the Mth power connection cable in the storage energy system is greater than or equal to a first preset impedance threshold, it is determined that the Mth power connection cable has a high resistance fault, wherein the Mth power connection cable is any power connection cable in the storage energy system, and M is a positive integer.

5. The cable fault detection method of claim 4, wherein, The determination of whether a fault occurs in each power connection cable in the storage energy system according to the voltage, current and impedance of each power connection cable in the storage energy system comprises the following steps: When the impedance of the Jth power connection cable in the energy storage system is less than the first preset impedance threshold and greater than or equal to the second preset impedance threshold, the following steps are performed: According to the current of the Jth power connection cable, the heat generated by the Jth power connection cable is determined, wherein the Jth power connection cable is any power connection cable in the energy storage system, J is a positive integer, and the first preset impedance threshold is greater than the second preset impedance threshold; When the heat generated by the Jth power connection cable is greater than the heat dissipation power of the Jth power connection cable, it is determined that the Jth power connection cable has a high-impedance fault.

6. The cable fault detection method of claim 4, wherein, The energy storage system further comprises a temperature sensor arranged on each power connection cable; The method further comprises: When the impedance of the Tth power connection cable in the energy storage system is less than the first preset impedance threshold and greater than or equal to the second preset impedance threshold, the following steps are performed: According to the output signal of the temperature sensor, the heat generated by the Tth power connection cable is determined, wherein the Tth power connection cable is any power connection cable in the energy storage system, T is a positive integer, and the first preset impedance threshold is greater than the second preset impedance threshold; When the heat generated by the Tth power connection cable is greater than the heat dissipation power of the Tth power connection cable, it is determined that the Tth power connection cable has a high-impedance fault.

7. The cable fault detection method of claim 1, wherein, The battery pack comprises a controller, a cell module, and a voltage conversion circuit, the cell module comprises at least one cell, the voltage conversion circuit is electrically connected with the controller and the cell module respectively, and the voltage conversion circuit is used to operate in response to a pulse width modulation signal output by the controller to step down or step up the voltage of the cell module; The method further comprises: When the voltage conversion circuit operates, the port voltage of the battery pack is obtained; If the port voltage of the battery pack is less than a second preset voltage threshold within a preset time period, it is determined that the power connection cable electrically connected with the battery pack is short-circuited.

8. The cable fault detection method of claim 1, wherein, The battery pack comprises a controller, a cell module, a charging switch, and a discharging switch, the cell module comprises at least one cell, the charging switch and the discharging switch are connected in series between the positive electrode of the cell module and the positive electrode port of the battery pack, or the charging switch and the discharging switch are connected in series between the negative electrode of the cell module and the negative electrode port of the battery pack, and the controller is electrically connected with the charging switch and the discharging switch respectively; The method further comprises: When each battery pack is not in the working state, the port voltage of each battery pack and the voltage of the cell module in each battery pack are obtained; If the absolute value of the difference between the port voltage of any battery pack and the voltage of the cell module in the battery pack is less than a third preset voltage threshold, a control signal is output to the controller to make the controller control the charging switch and the discharging switch to be closed, so that the battery pack is in the working state.

9. An energy storage converter, characterized by The battery pack comprises: At least one processor and a memory; The battery pack comprises: The memory is coupled with the processor, and is configured to store instructions or programs, which, when executed by the at least one processor, cause the at least one processor to perform the cable fault detection method according to any one of claims 1-8.

10. An energy storage system characterized by, Comprise: N battery packs, wherein N is a positive integer; And the energy storage converter according to claim 9, the energy storage converter is connected in parallel with N battery packs.

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