Battery on-line monitoring method, device and standby power supply system

Abstract

The application provides a battery online monitoring method and device and a standby power supply system. A bidirectional direct current conversion module is connected between a direct current bus and a battery. The bidirectional direct current conversion module is electrically connected with the direct current bus through a first direct current terminal group and is electrically connected with a battery cell group in the battery through a second direct current terminal group. The battery cell group comprises a plurality of series-connected battery cells. The method comprises the following steps: detecting whether a main power supply of the direct current bus is powered off in real time; detecting whether the battery cell group connected with the second direct current terminal group is abnormal; when the battery cell group connected with the second direct current terminal group is abnormal and the main power supply of the direct current bus is powered off, controlling the bidirectional direct current conversion module to step down the voltage of the first direct current terminal group to the voltage corresponding to the battery cell group connected with the second direct current terminal group and outputting through the second direct current terminal group. The application can protect the battery while reducing the overall cost of the backup power supply.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery protection, and more particularly to a battery online monitoring method, device and standby power supply system. BACKGROUND

[0002] To ensure the continuity and reliability of power supply, backup power supplies are used in places such as substations, communication base stations, UPS machine rooms, data centers, etc. These backup power supplies can provide power immediately to maintain the operation of critical equipment when the main power supply fails or is interrupted. Most of the current backup power supplies use batteries, which are usually composed of multiple battery units connected in series.

[0003] To avoid the situation that the battery cannot provide power protection for the main circuit (i.e. the DC bus) due to abnormality of part of the battery units, the multiple battery units in the battery are usually divided into multiple battery unit groups, and each battery unit group is connected to the DC bus through a DC-DC module. In this way, when any battery unit group is abnormal and the main circuit is powered off, the DC-DC module will convert the power of the normal battery units and supply power to the main circuit. However, since the voltage and power of the main circuit are much larger than those of the battery unit group, in order to ensure normal power supply of the main circuit, the DC-DC module needs to use relatively high-specification cables to connect the battery unit group and the main circuit, which is relatively high in cost. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a battery online monitoring method, device and standby power supply system to solve the problem of relatively high cost of the above-mentioned backup power supply.

[0005] The technical solution for solving the above-mentioned technical problem is to provide a battery online monitoring method for online monitoring of a battery serving as a backup power supply for a DC bus, wherein the battery includes N battery units connected in series between the positive and negative electrodes of the DC bus, the DC bus is connected with a main power supply, N is an integer greater than 2, a bidirectional DC-DC module is connected between the DC bus and the battery, the bidirectional DC-DC module is electrically connected with the DC bus through a first DC terminal group and electrically connected with one battery unit group in the battery through a second DC terminal group, the battery unit group includes M battery units connected in series, M is an integer greater than or equal to 1 and less than N; and the method comprises:

[0006] real-time detection of whether the main power supply of the DC bus is powered off;

[0007] detection of whether the battery unit group electrically connected with the second DC terminal group is abnormal;

[0008] When the battery unit group connected to the second DC terminal group is abnormal and the main power supply of the DC bus is powered off, the bidirectional DC conversion module is controlled to step down the voltage of the first DC terminal group to the voltage corresponding to the battery unit group connected to the second DC terminal group, and output through the second DC terminal group, and then the remaining battery unit in the battery is connected in series with the second DC terminal group of the bidirectional DC conversion module to supply power to the DC bus.

[0009] As a further improvement of the application, the battery comprises P battery unit groups, P being an integer greater than or equal to 2 and less than or equal to N; a contactor array is connected between the second DC terminal group of the bidirectional DC conversion module and the battery, the contactor array comprises a first wiring terminal group, P second wiring terminal groups and a contactor group for electrically connecting the first wiring terminal group and any second wiring terminal group, and the first wiring terminal group is electrically connected to the second DC terminal group of the bidirectional DC conversion module, and the P second wiring terminal groups are respectively electrically connected to the P battery unit groups of the battery; the method comprises:

[0010] When a preset time is reached or a preset instruction is received, the contactor group is controlled to electrically connect the P second wiring terminal groups to the first wiring terminal group in turn, and the battery unit groups electrically connected to the second DC terminal group are detected in turn;

[0011] After all the battery unit groups are detected, the contactor group is controlled to electrically connect the first wiring terminal group to the second wiring terminal connected to the abnormal battery unit group in the battery.

[0012] As a further improvement of the application, the battery is connected to the DC bus via a diode group, and a normally closed switch is connected in parallel across the diode group;

[0013] The detection of whether the battery unit group electrically connected to the second DC terminal group is abnormal comprises:

[0014] When a preset time is reached or a preset instruction is received, the normally closed switch is controlled to be opened;

[0015] The bidirectional DC conversion module is controlled to discharge the battery unit group connected to the second DC terminal group at a preset discharge current, and the preset discharge current is less than or equal to 0.1C;

[0016] The electrical parameters of the battery unit group connected to the second DC terminal group are detected, and whether the battery unit group connected to the second DC terminal group is abnormal is determined according to the electrical parameters.

[0017] As a further improvement of the application, the control of the bidirectional DC conversion module to discharge the battery unit group connected to the second DC terminal group at a preset discharge current comprises:

[0018] The bidirectional DC conversion module converts the voltage of the battery unit group connected to the second DC terminal group into a voltage corresponding to the DC bus voltage and outputs to the DC bus through the first DC terminal group;

[0019] When the preset discharge cutoff condition is reached, the bidirectional DC conversion module stops working.

[0020] As a further improvement of the application, the discharge cutoff condition is one of the following: the voltage of the battery unit group is lower than a first preset voltage, the voltage of each battery unit in the battery unit group is lower than a second preset voltage, and the discharge duration reaches a first preset duration, which is not less than the duration for completely emptying the battery unit group.

[0021] The detection of the electrical parameters of the battery unit group connected to the second DC terminal group and the determination of whether the battery unit group connected to the second DC terminal group is abnormal based on the electrical parameters include:

[0022] The discharge voltage and discharge current of the battery unit group connected to the second DC terminal group during the working process of the bidirectional DC conversion module are obtained.

[0023] After the bidirectional DC conversion module stops working, the total discharge amount is calculated based on the integral of the discharge voltage and discharge current, and the battery unit group connected to the second DC terminal group is determined to be abnormal when the total discharge amount is less than 80% of the rated capacity of the battery unit group.

[0024] As a further improvement of the application, the method includes:

[0025] When the detection of each battery unit group is completed and the battery unit group is normal, the bidirectional DC conversion module charges the battery unit group to the rated capacity, and the battery unit group is normal when the ratio of the full charge capacity to the rated capacity of the battery unit group is greater than or equal to a preset value.

[0026] After the discharge and charge of all battery unit groups are completed, the normally closed switch is closed.

[0027] As a further improvement of the application, the discharge cutoff condition is that the discharge duration reaches a second preset duration, which is less than one-tenth of the duration for completely emptying the battery unit group.

[0028] The detection of the electrical parameters of the battery unit group connected to the second DC terminal group and the determination of whether the battery unit group connected to the second DC terminal group is abnormal based on the electrical parameters include:

[0029] During the operation of the bidirectional DC-DC converter module, the output current of the battery cell group connected to the second DC terminal group is detected, and if the output current is lower than a preset current threshold, it is confirmed that the battery cell group connected to the second DC terminal group is abnormal; or...

[0030] After the bidirectional DC-DC converter module stops working, the voltage of the battery cell group connected to the second DC terminal group is detected, and if the voltage of the battery cell group is lower than a preset voltage threshold, it is confirmed that the battery cell group connected to the second DC terminal group is abnormal.

[0031] As a further improvement of the present invention, the method includes:

[0032] After all battery cell groups have been tested, the normally closed switch is closed, and the current in the circuit containing the battery is detected.

[0033] An alarm signal is output when the current in the circuit containing the battery is abnormal.

[0034] When the current in the circuit where the battery is located is normal, the normally closed switch is opened, and the contactor group is controlled to make P second terminal groups electrically connected to the first terminal group in sequence, so that the bidirectional DC-DC converter module charges P battery cell groups to their rated capacity in sequence.

[0035] After all battery cell groups have finished charging, the normally closed switch is closed.

[0036] This invention also provides an online monitoring device for a storage battery used for online monitoring of a storage battery serving as a backup power source. The storage battery comprises N battery cells connected in series to a DC bus. A main power supply and a load are connected to the DC bus, where N is an integer greater than 2. The online monitoring device includes:

[0037] A bidirectional DC-DC converter module includes an energy storage capacitor, a first DC terminal group, and a second DC terminal group. The bidirectional DC-DC converter module is electrically connected to a DC bus through the first DC terminal group and electrically connected to a battery cell group in a battery through the second DC terminal group. The battery cell group includes M battery cells connected in series, where M is an integer greater than or equal to 1 and less than N.

[0038] The control module is electrically connected to the DC bus and the bidirectional DC-DC converter module, respectively. The control module includes a storage unit and a control chip. The storage unit is integrated into the control chip or connected to the control chip. The storage unit stores a computer program that can be executed on the control chip. When the control chip executes the computer program, it implements the steps of the battery online monitoring method as described above.

[0039] The present invention also provides a backup power system, including a battery and an online monitoring device for the battery as described above.

[0040] The present invention has the following advantages: when the battery cell group is abnormal and the main power supply of the DC bus fails, the bidirectional DC-DC converter module converts the DC bus voltage to the battery cell group voltage and together with the remaining battery cells in the battery to supply power to the DC bus. The bidirectional DC-DC converter module only needs to use relatively low-specification cables to connect the battery cell group and the DC bus, thereby reducing the overall cost of the backup power supply. Attached Figure Description

[0041] Figure 1 This is a schematic flowchart of the online battery monitoring method provided in an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of a backup power supply using the online battery monitoring method provided in this embodiment of the invention.

[0043] Figure 3 This is a schematic diagram of the process of grouping and detecting each battery cell group in the online monitoring method for storage batteries provided in this embodiment of the invention.

[0044] Figure 4 This is a schematic diagram of the process for detecting battery cell groups in the online monitoring method for storage batteries provided in this embodiment of the invention.

[0045] Figure 5 This is a schematic diagram of the process of discharging battery cell groups in the online monitoring method for storage batteries provided in this embodiment of the invention.

[0046] Figure 6 This is a flowchart illustrating the process of determining whether a battery cell group is abnormal in the online monitoring method for batteries provided in this embodiment of the invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] The battery online monitoring method of the present invention can be used to monitor the backup power supply used in substations, communication base stations, UPS rooms, data centers and other places online, and provide power supply guarantee for the main power supply line when the battery unit group in the backup power supply is abnormal, thereby improving the reliability of the backup power supply.

[0049] like Figure 1The diagram shown is a flowchart illustrating an online battery monitoring method provided in an embodiment of the present invention. This method is used to monitor batteries that serve as backup power for DC bus power supplies (used to power DC loads in substations, communication base stations, UPS rooms, data centers, etc.). Combined with... Figure 2 As shown, the aforementioned battery comprises N battery cells connected in series to a DC bus (i.e., N battery cells in the battery are connected in series between the positive and negative terminals of the DC bus). The DC bus is also connected to a main power supply (e.g., an AC / DC module that converts AC mains power to DC power) and multiple DC loads. N is an integer greater than 2. Those skilled in the art will understand that the output voltage of the N battery cells connected in series is adapted to the DC bus voltage (e.g., slightly less than the DC bus voltage). A bidirectional DC-DC converter module (i.e., a bidirectional DC / DC converter) is connected between the DC bus and the battery. This bidirectional DC-DC converter module is electrically connected to the DC bus via a first DC terminal group and electrically connected to a group of battery cells in the battery via a second DC terminal group. The group of battery cells electrically connected to the second DC terminal group comprises M battery cells connected in series, where M is an integer greater than or equal to 1 and less than N. Those skilled in the art will understand that the first DC terminal group and the second DC terminal group respectively include a positive terminal and a negative terminal, and the bidirectional DC-DC converter module can step down the voltage of the first DC terminal group and output it through the second DC terminal group, or step up the voltage of the second DC terminal group and output it through the first DC terminal group. The bidirectional DC-DC converter module can adopt common solutions in the art, including energy storage capacitors, etc., which will not be described in detail here.

[0050] The battery online monitoring method of the present invention can be integrated into a control module, that is, the method is executed by the control module. This control module is connected to a bidirectional DC-DC converter module and can control the operation of the bidirectional DC-DC converter module. Specifically, the method of this embodiment includes the following steps:

[0051] Step S11: Real-time detection of whether the main power supply to the DC bus has failed. This step is continuously performed during backup power supply operation. In this step, the main power supply to the DC bus can be confirmed by detecting the voltage of the first DC terminal group of the bidirectional DC-DC converter module. In practical applications, the main power supply to the DC bus can also be confirmed by detecting the DC bus voltage.

[0052] Specifically, in this step, the main power supply can be confirmed to be de-energized when the voltage of the DC bus drops below a preset voltage (which can be set in advance according to the application of the backup power supply, for example, the preset voltage can be 90% of the normal operating voltage of the DC bus).

[0053] Step S12: Check if the battery cell group electrically connected to the second DC terminal group is abnormal.

[0054] This step can be performed upon reaching a preset time or upon receiving a preset instruction from an external source (including a remote instruction). Specifically, abnormalities in the battery cell group connected to the second DC terminal group include damage to one or more battery cells within the group, or damage to the wiring between battery cells. Those skilled in the art will understand that this detection operation is performed when the voltage of the DC bus is within the normal range.

[0055] Step S13: When the battery cell group connected to the second DC terminal group is abnormal (i.e., the battery cell group is detected as abnormal in step S12 and has not been repaired) and the main power supply of the DC bus is lost, the bidirectional DC-DC converter module is controlled to reduce the voltage of the first DC terminal group to the voltage corresponding to the battery cell group connected to the second DC terminal group, and output through the second DC terminal group. Then, the second DC terminal group of the bidirectional DC-DC converter module is connected in series with the remaining battery cells in the battery to supply power to the DC bus.

[0056] Specifically, when controlling the bidirectional DC-DC converter module to perform voltage conversion, it can be placed in a constant voltage output mode, with its output voltage being the rated voltage of the battery cell group. Due to the energy storage capacitor within the bidirectional DC-DC converter module, the delay effect of the capacitor allows it to output voltage to the second DC terminal group at the instant the DC bus is completely disconnected. This voltage then replaces the faulty battery cell group and is connected in series with other battery cells in the battery to supply power to the DC bus, ensuring continuous power supply to the load on the DC bus. After the bidirectional DC-DC converter module and other battery cells supply power to the DC bus, the first DC terminal group of the bidirectional DC-DC converter module can obtain energy from the DC bus and continue voltage conversion, outputting through the second DC terminal group. This ensures that the bidirectional DC-DC converter module and other battery cells can continuously supply power to the DC bus, maintaining a stable DC bus voltage.

[0057] Of course, in practical applications, the control module can also control the bidirectional DC-DC converter to output the corresponding voltage to the battery cell group connected to the second DC terminal group when it detects an abnormality in the battery cell group electrically connected to the second DC terminal group (when the DC bus is de-energized, the bidirectional DC-DC converter maintains the voltage output of its second DC terminal group). Since the voltage of the entire battery (i.e., the sum of the voltage of the second DC terminal group and the voltage of other battery cells in the battery) is lower than the DC bus voltage, the battery will not output current, so the power loss is minimal.

[0058] The aforementioned online battery monitoring method, when the battery cell group malfunctions and the main power supply to the DC bus fails, uses a bidirectional DC-DC converter module to convert the DC bus voltage to the battery cell group voltage, which, together with the remaining battery cells in the battery bank, supplies power to the DC bus. In other words, when the battery cell group malfunctions, the bidirectional DC-DC converter module takes over, thus protecting the battery cell group.

[0059] Because the bidirectional DC-DC converter only needs to maintain voltage output when converting the DC bus voltage to the battery cell voltage, its power consumption is relatively low. Therefore, only lower-specification cables are needed to connect the battery cell group and the DC bus, thus reducing the overall cost of the backup power supply. Furthermore, when the main power supply to the DC bus fails, the bidirectional DC-DC converter module and other battery cells supply power to the DC bus in series, automatically achieving current sharing among the other battery cells. Compared to solutions that individually boost the voltage of each battery cell to the DC bus voltage and directly output it to the DC bus, this eliminates the need for complex current sharing control logic.

[0060] Combination Figure 2 As shown, in one embodiment of the present invention, the storage battery includes P battery cell groups, where P is an integer greater than or equal to 2 and less than N; a contactor array is connected between the second DC terminal group of the bidirectional DC-DC converter module and the storage battery. This contactor array includes a first terminal group, P second terminal groups, and contactor groups. The first terminal group is electrically connected to the second DC terminal group of the bidirectional DC-DC converter module, and the P second terminal groups are respectively electrically connected to the P battery cell groups of the storage battery. Figure 2 As shown. Those skilled in the art will understand that the first and second terminal groups described above each have a positive and a negative terminal, and the control module is connected to the control terminal of the contactor group. The contactor group is used to realize the electrical connection between the first terminal group and any of the second terminal groups, and it can specifically be composed of multiple contactors or multiple semiconductor switches.

[0061] Each of the aforementioned battery cell groups may include the same number of battery cells. For example, when the DC bus voltage is 220V, the battery may include six battery cell groups, each of which includes three battery cells connected in series (each battery cell has a voltage of 12V). In practical applications, each battery cell group in the battery may also include different numbers of battery cells, but this will lead to relatively complex subsequent control logic.

[0062] Of course, in practical applications, contactor arrays can be omitted, and P bidirectional DC-DC converter modules can be used to connect the P battery cells in the battery to the DC bus, but this will greatly increase the cost.

[0063] Accordingly, such as Figure 3As shown, in one embodiment of the present invention, the above-mentioned online battery monitoring method further includes:

[0064] Step S14: When the preset time is reached or a preset instruction is received (such as a capacity control instruction or a circuit validity detection instruction), the control contactor group causes P second terminal groups to be electrically connected to the first terminal group in sequence, and sequentially detects whether the battery cell group connected to the second DC terminal group is abnormal.

[0065] The discharge command can be input from a field operator or from a remote device. In this way, the bidirectional DC-DC converter module can be electrically connected to each battery cell group sequentially, thereby enabling the sequential detection of the P battery cell groups in the battery.

[0066] Step S15: After all the battery cell groups connected to the second terminal group have been tested, control the contactor group to electrically connect the first terminal group to the second terminal group connected to the abnormal battery cell group in the battery.

[0067] If step S15 confirms that all battery cell groups are normal, meaning there are no breaks between the battery cells in the battery cell group and the State of Health (SOH) of all battery cells is greater than or equal to a preset value (e.g., 70%), the battery cell group can be considered to be without abnormalities. In this case, the contactor group can be controlled to disconnect the first terminal group from any second terminal group. The aforementioned state of health is the ratio of full charge capacity to rated capacity. Those skilled in the art will understand that conventional methods in the art can be used to detect the state of health of the battery cell group. Furthermore, when there are breaks (i.e., disconnections) between the battery cells in the battery cell group, the battery cell group cannot discharge, and the state of health of the battery cell group can be considered zero. In practical applications, if step S15 confirms that all battery cell groups are without abnormalities, the contactor group can also be controlled to electrically connect the first terminal group to the second terminal group connected to the battery cell group with the lowest state of health in the battery.

[0068] Those skilled in the art will understand that when testing each battery cell group, it is necessary to discharge them and determine whether the battery cell group is abnormal based on the electrical parameters during or after the discharge process. In the above method, since each battery cell group is tested sequentially, the discharge capacity of the entire battery at any given time is relatively small. Even if the main power supply to the DC bus fails during the discharge process, the remaining battery cell groups can still meet the power demand of the DC bus, thus not affecting the system safety of the DC bus. Compared to existing methods that discharge the entire battery, there is no need to externally move the battery cell groups.

[0069] In one embodiment of the invention, the voltage of the battery (i.e., the sum of the voltages of the individual battery cells) is lower than the DC bus voltage; correspondingly, the battery is connected via a diode array (e.g., Figure 2The diode group consists of two diodes D1 and is electrically connected to the DC bus (the cathode of the diode is connected to the positive terminal of the battery pack, and the anode is connected to the positive terminal of the DC bus). A normally closed switch K13 is connected in parallel across the two ends of the diode group. Specifically, the normally closed switch K13 can be a contactor.

[0070] Accordingly, such as Figure 4 As shown, step S12 above, detecting whether the battery cell group connected to the second DC terminal is abnormal, includes:

[0071] Step S121: When the preset time is reached, control the normally closed switch K13 to open, so that the battery is electrically connected to the DC bus only through the diode group.

[0072] Step S122: Control the bidirectional DC-DC converter module to discharge the battery cell group connected to the second DC terminal group with a preset discharge current, and the preset discharge current is 0.1C (i.e., 0.1 of the capacity of the battery cell group connected to the second DC terminal group).

[0073] Of course, in practical applications, the preset discharge current can also be less than 0.1C. Because the preset discharge current is relatively small, the specifications of the cables connecting the bidirectional DC-DC converter module can be relatively low, saving costs.

[0074] Step S123: Detect the electrical parameters of the battery cell group connected to the second DC terminal group (i.e., detect the electrical parameters of the second DC terminal group), and determine whether the battery cell group connected to the second DC terminal group is abnormal based on the electrical parameters. If it is confirmed that the battery cell group connected to the second DC terminal group is abnormal, an alarm signal can be output to prompt the staff to carry out repair or replacement.

[0075] The preset time in step S121 can be set in advance according to the usage of the battery. In practical applications, steps S121-S123 can also be executed upon receiving a preset command (e.g., via a graphical user interface, operation buttons, remote platform, etc.). When the system has only one bidirectional DC-DC converter module, i.e., when a contactor array is connected between the bidirectional DC-DC converter module and the battery, the bidirectional DC-DC converter module can be controlled to discharge each battery cell group sequentially and detect each battery cell group sequentially.

[0076] By detecting the battery cell group connected to the second DC terminal group, it is possible to promptly understand whether there is any abnormality in the battery cell group, thereby facilitating the protection operation of the DC bus when the main power supply fails.

[0077] like Figure 5As shown, in one embodiment of the present invention, step S122 above, controlling the bidirectional DC-DC converter module to discharge the battery cell group connected to the second DC terminal group with a preset discharge current, includes:

[0078] Step S1221: Control the bidirectional DC-DC converter module to convert the voltage of the battery cell group connected to the second DC terminal group into a voltage corresponding to the DC bus voltage, and output it to the DC bus through the first DC terminal group.

[0079] Step S1222: When the preset discharge cutoff condition is reached, control the bidirectional DC-DC converter module to stop working.

[0080] By using the stored energy from the battery cells to power the DC bus during discharge (at which point the output current of the main power supply to the DC bus is relatively reduced), energy waste can be avoided. Of course, in practical applications, the bidirectional DC-DC converter module can also be connected to an external load for discharge operations.

[0081] In one embodiment of the invention, the abnormality of the battery cell group connected to the second DC terminal can be detected by nuclear discharge. Accordingly, the discharge cutoff condition in step S1222 is one of the following: the voltage of the battery cell group is lower than a first preset voltage (e.g., 90% of the rated voltage of the battery cell group), the voltage of each battery cell in the battery cell group reaches a second preset voltage (e.g., 90% of the rated voltage of the battery cell), and the discharge time reaches a first preset time, which is not less than the time for the battery cell group to be completely discharged (e.g., when the discharge current is 0.1C, the time is not less than 10 hours).

[0082] At this point, in step S123, the electrical parameters of the battery cell group connected to the second DC terminal group are detected, and the abnormality of the battery cell group connected to the second DC terminal group is determined based on the electrical parameters, including:

[0083] Step S1231: Obtain the discharge voltage and discharge current of the battery cell group connected to the second DC terminal group during the operation of the bidirectional DC-DC converter module. The detection of the discharge voltage and discharge current can adopt conventional methods in the art, and will not be described in detail here.

[0084] Step S1232: After the bidirectional DC-DC converter module stops working, calculate the total discharge amount based on the detected discharge voltage and discharge current integration, and confirm that the battery cell group connected to the second DC terminal group is abnormal when the total discharge amount is lower than 80% of the rated capacity of the battery cell group.

[0085] The frequency of the aforementioned core capacity discharge can be set to once a year or multiple times a year. When the system has only one bidirectional DC-DC converter module, i.e., the bidirectional DC-DC converter module is connected to the battery via a contactor array, after each battery cell group is detected and its status is confirmed (before the next battery cell group is detected), the bidirectional DC-DC converter module is controlled to charge the battery cell group to its rated capacity, and the charging current can also be controlled at 0.1C; and after all battery cell groups have been discharged and charged, the normally closed switch K13 is controlled to close. Normally, the ratio of the full-charge capacity to the rated capacity of the aforementioned battery cell group is greater than or equal to a preset value. Those skilled in the art will understand that when there is a breakpoint between battery cells in a battery cell group (at which point the battery cell group cannot discharge externally and can be considered as having a zero full-charge capacity), the ratio of the full-charge capacity to the rated capacity of that battery cell group is zero.

[0086] Since the capacity and voltage of the entire battery are fundamental to maintaining the stability of the DC bus voltage, compared to full capacity discharge of the entire battery (discharging all the charge or reducing the voltage to 90% of the total battery voltage), by discharging each battery cell separately, only one battery cell is completely discharged at a time, and the overall battery voltage is reduced to a minimum of (U-0.1U / P), where U is the rated voltage of the battery; the charge is also reduced to CC / P, where C is the rated capacity of the battery, which greatly improves the safety of online discharge.

[0087] For example, when P=6, U=216V, and the rated voltage of each battery cell is 36V, after a single battery cell discharges, the voltage of the battery pack is: U - 0.1U / 6 = 216 - 0.1 x 216 / 6 = 216 - 3.6 = 212.4V, which is much higher than the total capacity of the entire battery pack after discharge (0.9U = 0.9 x 216 = 194.4V). After a single battery cell discharges, the overall capacity of the battery pack still remains at C - C / 6 = 5 / 6C.

[0088] In one embodiment of the invention, the abnormality of the battery cell group connected to the second DC terminal can also be detected by loop validity detection. Accordingly, the discharge cutoff condition in step S1222 is that the discharge time reaches a second preset time, which is less than one-tenth of the time when the battery cell group is completely discharged. For example, when the discharge current is 0.1C, the second preset time can be about 10 minutes.

[0089] At this time, in step S123, the electrical parameters of the battery cell group connected to the second DC terminal group are detected, and the abnormality of the battery cell group connected to the second DC terminal group is determined based on the electrical parameters. This includes: during the operation of the bidirectional DC-DC converter module, detecting the output current of the battery cell group connected to the second DC terminal group, and confirming that the battery cell group connected to the second DC terminal group is abnormal when the output current is lower than a preset current threshold. For example, when controlling the discharge of 0.1C current, the preset current threshold can be 0.1C; or, after the bidirectional DC-DC converter module stops working, detecting the voltage of the battery cell group connected to the second DC terminal group, and confirming that the battery cell group connected to the second DC terminal group is abnormal when the voltage of the battery cell group is lower than a preset voltage threshold.

[0090] In practical applications, the effectiveness detection frequency of this circuit can be once or multiple times a month. When the system has only one bidirectional DC-DC converter module, i.e., the bidirectional DC-DC converter module is connected to the battery via a contactor array, after all battery cell groups have been detected, the normally closed switch K13 is closed, allowing the DC bus to charge the entire battery. At this time, the current in the battery circuit is detected, and an alarm signal is output when the current in the battery circuit is abnormal (e.g., zero). When the current in the battery circuit is normal, the normally closed switch K13 is opened, and the bidirectional DC-DC converter module sequentially charges P battery cell groups to their rated capacity. After all battery cell groups have been charged, the normally closed switch K13 is closed.

[0091] This invention also provides an online monitoring device for a storage battery used for online monitoring of a storage battery serving as a backup power source. The storage battery comprises N battery cells connected in series to a DC bus. A main power supply and a load are connected to the DC bus, where N is an integer greater than 2. The online monitoring device includes:

[0092] A bidirectional DC-DC converter module includes an energy storage capacitor, a first DC terminal group, and a second DC terminal group. The bidirectional DC-DC converter module is electrically connected to a DC bus through the first DC terminal group and electrically connected to a battery cell group in a battery through the second DC terminal group. The battery cell group includes M battery cells connected in series, where M is an integer greater than or equal to 1 and less than N.

[0093] The control module is electrically connected to the DC bus and the bidirectional DC-DC converter module, respectively. The control module includes a storage unit and a control chip. The storage unit is integrated into the control chip or connected to the control chip. The storage unit stores a computer program that can be executed on the control chip. When the control chip executes the computer program, it implements the steps of the battery online monitoring method as described above.

[0094] Those skilled in the art will understand that the above-mentioned online battery monitoring device can be installed on the monitoring panel or insulation monitoring panel in the DC power supply equipment room, or it can be installed in the battery room.

[0095] In one embodiment of the present invention, the storage battery includes P battery cell groups, where P is an integer greater than or equal to 2 and less than N; the online monitoring device includes a contactor array, the contactor array including a first terminal group, P second terminal groups, and a contactor group for electrically connecting the first terminal group and the P second terminal groups, and the control module is signal-connected to the contactor group.

[0096] The present invention also provides a backup power system, including a battery and an online monitoring device for the battery as described above.

[0097] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0098] Those skilled in the art will understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the functions can be assigned to different functional units and modules as needed. The functional units and modules in the embodiments can be integrated into a single processor, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units. Furthermore, the specific names of the functional units and modules are merely for easy differentiation and are not intended to limit the scope of protection of this application. The specific working processes of the units and modules in the above system can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0099] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0100] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0101] In the embodiments provided in this application, it should be understood that the disclosed battery online monitoring method, apparatus, and backup power system can be implemented in other ways. For example, the battery online monitoring apparatus and backup power system embodiments described above are merely illustrative.

[0102] Furthermore, the functional units in the various embodiments of this application can be integrated into a single processor, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The integrated units described above can be implemented in hardware or as software functional units.

[0103] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or interface switching device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0104] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for online monitoring of a storage battery, used to monitor a storage battery serving as a backup power source for a DC bus, wherein the storage battery comprises N battery cells connected in series between the positive and negative terminals of a DC bus, and a main power supply is connected to the DC bus, where N is an integer greater than 2, characterized in that... A bidirectional DC-DC converter module is connected between the DC bus and the battery. The bidirectional DC-DC converter module is electrically connected to the DC bus via a first DC terminal group and electrically connected to a battery cell group within the battery via a second DC terminal group. The battery cell group comprises M battery cells connected in series, where M is an integer greater than or equal to 1 and less than N. The method includes: Real-time detection of whether the main power supply to the DC bus is interrupted; Check for any abnormalities in the battery cell group electrically connected to the second DC terminal group: When the battery cell group connected to the second DC terminal group is abnormal and the main power supply of the DC bus is lost, the bidirectional DC-DC converter module is controlled to reduce the voltage of the first DC terminal group to the voltage corresponding to the battery cell group connected to the second DC terminal group, and output through the second DC terminal group. Then, the second DC terminal group of the bidirectional DC-DC converter module is connected in series with the remaining battery cells in the battery to supply power to the DC bus. The battery comprises P battery cell groups, where P is an integer greater than or equal to 2 and less than or equal to N; a contactor array is connected between the second DC terminal group of the bidirectional DC-DC converter module and the battery, the contactor array comprising a first terminal group, P second terminal groups, and a contactor group for electrically connecting the first terminal group to any of the second terminal groups, wherein the first terminal group is electrically connected to the second DC terminal group of the bidirectional DC-DC converter module, and the P second terminal groups are respectively electrically connected to the P battery cell groups of the battery; the method includes: When a preset time is reached or a preset command is received, the control contactor group causes P second terminal groups to be electrically connected to the first terminal group in sequence, and sequentially detects whether the battery cell group electrically connected to the second DC terminal group is abnormal. After all battery cell groups have been tested, the control contactor group electrically connects the first terminal group to the second terminal group that connects to the abnormal battery cell group in the battery. The battery is electrically connected to the DC bus via a diode group, and a normally closed switch is connected in parallel across the two ends of the diode group; The detection of whether the battery cell group electrically connected to the second DC terminal group is abnormal includes: When a preset time is reached or a preset command is received, the normally closed switch is controlled to open. The bidirectional DC-DC converter module is controlled to discharge the battery cell group connected to the second DC terminal group with a preset discharge current, and the preset discharge current is less than or equal to 0.1C. The electrical parameters of the battery cell group connected to the second DC terminal group are detected, and the abnormality of the battery cell group connected to the second DC terminal group is determined based on the electrical parameters.

2. The online monitoring method for a storage battery according to claim 1, characterized in that, The control bidirectional DC-DC converter module discharges the battery cell group connected to the second DC terminal group with a preset discharge current, including: The control bidirectional DC-DC converter module converts the voltage of the battery cell group connected to the second DC terminal group into a voltage corresponding to the DC bus voltage, and outputs it to the DC bus through the first DC terminal group; When the preset discharge cutoff condition is reached, the bidirectional DC-DC converter module is controlled to stop working.

3. The online monitoring method for a storage battery according to claim 2, characterized in that, The discharge cutoff condition is one of the following: the voltage of the battery cell group is lower than the first preset voltage, the voltage of each battery cell in the battery cell group is lower than the second preset voltage, and the discharge time reaches the first preset time, wherein the first preset time is not less than the time for the battery cell group to be completely discharged. The step of detecting the electrical parameters of the battery cell group connected to the second DC terminal group and determining whether the battery cell group connected to the second DC terminal group is abnormal based on the electrical parameters includes: The discharge voltage and discharge current of the battery cell group connected to the second DC terminal group during the operation of the bidirectional DC-DC converter module are obtained. After the bidirectional DC-DC converter module stops working, the total discharge is calculated by integrating the discharge voltage and discharge current, and the battery cell group connected to the second DC terminal group is confirmed to be abnormal when the total discharge is lower than 80% of the rated capacity of the battery cell group.

4. The online monitoring method for a storage battery according to claim 3, characterized in that, The method includes: When each battery cell group is detected and the battery cell group is normal, the bidirectional DC-DC converter module is controlled to charge the battery cell group to the rated capacity. The battery cell group is normal when the ratio of the full charge capacity of the battery cell group to the rated capacity is greater than or equal to a preset value. After all battery cells have been discharged and charged, the normally closed switch is closed.

5. The online monitoring method for a storage battery according to claim 2, characterized in that, The discharge cutoff condition is that the discharge duration reaches a second preset duration, and the second preset duration is less than one-tenth of the time when the battery cell group is completely discharged; The step of detecting the electrical parameters of the battery cell group connected to the second DC terminal group and determining whether the battery cell group connected to the second DC terminal group is abnormal based on the electrical parameters includes: During the operation of the bidirectional DC-DC converter module, the output current of the battery cell group connected to the second DC terminal group is detected, and if the output current is lower than a preset current threshold, it is confirmed that the battery cell group connected to the second DC terminal group is abnormal; or... After the bidirectional DC-DC converter module stops working, the voltage of the battery cell group connected to the second DC terminal group is detected, and if the voltage of the battery cell group is lower than a preset voltage threshold, it is confirmed that the battery cell group connected to the second DC terminal group is abnormal.

6. The online monitoring method for a storage battery according to claim 5, characterized in that, The method includes: After all battery cell groups have been tested, the normally closed switch is closed, and the current in the circuit containing the battery is detected. An alarm signal is output when the current in the circuit containing the battery is abnormal. When the current in the circuit where the battery is located is normal, the normally closed switch is opened, and the contactor group is controlled to make P second terminal groups electrically connected to the first terminal group in sequence, so that the bidirectional DC-DC converter module charges P battery cell groups to their rated capacity in sequence. After all battery cell groups have finished charging, the normally closed switch is closed.

7. A battery online monitoring device for online monitoring of a battery used as a backup power source, wherein the battery comprises N battery cells connected in series to a DC bus, and a main power supply and a load are connected to the DC bus, where N is an integer greater than 2, characterized in that... The online monitoring device includes: A bidirectional DC-DC converter module includes an energy storage capacitor, a first DC terminal group, and a second DC terminal group. The bidirectional DC-DC converter module is electrically connected to a DC bus through the first DC terminal group and electrically connected to a battery cell group in a battery through the second DC terminal group. The battery cell group includes M battery cells connected in series, where M is an integer greater than or equal to 1 and less than N. The control module is electrically connected to the DC bus and the bidirectional DC-DC converter module, respectively. The control module includes a storage unit and a control chip. The storage unit is integrated into the control chip or connected to the control chip. The storage unit stores a computer program that can be executed on the control chip. When the control chip executes the computer program, it implements the steps of the battery online monitoring method as described in any one of claims 1-6.

8. A backup power system, characterized in that, It includes a storage battery and the online monitoring device for the storage battery as described in claim 7.

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