TWI644467B - Control method for energy storage system - Google Patents

Abstract

A control method for an energy storage system. The energy storage system includes a plurality of battery modules. The control method includes: each of the battery modules reporting an individual communication state and an individual maximum charge / discharge current to a master control battery module of one of the battery modules; the master control battery module notifies an energy converter accordingly, To allow the energy converter to set a maximum charge / discharge current; when one of the battery modules in the online state determines that the first battery module is ready to go offline, the first battery module notifies the main control battery A module to allow the main control battery module to notify the energy converter to reduce the maximum charge / discharge current; and the first battery module to be taken offline for offline operation.

Description

Control method of energy storage system

The invention relates to a control method of an energy storage system.

Due to the rising awareness of environmental protection, the global electric vehicle and energy storage industry's demand has gradually exploded in recent years. In home / commercial / industrial energy storage systems, the amount of power consumption may need to be dynamically configured as the season (low season, peak season) affects. This dynamic configuration can be achieved by connecting the battery packs in parallel.

Existing battery pack parallel methods include, for example, isolated parallel and direct parallel. In isolated parallel, the output side of the battery pack is isolated by the DC / DC converter to adjust the input and output energy. The advantage of the isolated parallel architecture is that various battery packs with widely different characteristics can be applied without the generation of internal loop current. However, the main disadvantages of the isolated parallel architecture are large size, high weight and high cost.

The direct parallel architecture is limited to only battery packs with similar characteristics, but once the battery pack jumps off the wire, it needs to be processed manually to be able to return to the connected state.

Therefore, there is a need for a control method of an electric energy storage system, which can meet the elastic demand of the energy storage system for capacity expansion, and also realize the characteristics of hot plugging.

An embodiment of the present invention proposes a method for controlling an energy storage system. The energy storage system includes a plurality of battery modules. The control method includes: each of the battery modules reporting an individual communication state and an individual maximum charge / discharge current to the batteries. One of the modules is a main control battery module; the main control battery module notifies an energy converter according to which the energy converter sets a maximum charge / discharge current; when the battery modules are online, When one of the first battery modules determines that it is ready to go offline, the first battery module notifies the main control battery module so that the main control battery module notifies the energy converter to reduce the maximum charge / discharge current; And the first battery module ready to be taken offline is taken offline.

Another embodiment of the present invention provides a method for controlling an energy storage system. The energy storage system includes a plurality of battery modules. The control method includes: according to the individual battery voltage of the battery modules that are offline, the battery modules One of the main control battery modules notifies an energy converter to allow the energy converter to set a charging voltage or a charging current on the DC bus; and when a battery module of the battery modules detects itself When a voltage difference between a battery voltage and the charging voltage on the DC bus is less than a set value, the battery module is mounted on the DC bus.

Another embodiment of the present invention provides a method for controlling an energy storage system. The energy storage system includes a plurality of battery modules. The control method includes: according to the individual battery voltages of the battery modules that are offline. A main control battery module selects a target discharge battery module and a target rechargeable battery module from the battery modules; when a voltage difference between the target discharge battery module and the target rechargeable battery module is greater than one When the value is set, the target discharge battery module performs current-limit charging on the target rechargeable battery module; and when all When the individual voltage difference between any two of the battery modules is less than the set value, mount all battery modules to the DC bus.

In order to have a better understanding of the above and other aspects of the present invention, the following specific examples are described in detail below in conjunction with the accompanying drawings:

100‧‧‧ Energy Storage System

50‧‧‧ Energy Converter

10-30, 10B-30B‧‧‧ Battery Module

60‧‧‧DC bus

70‧‧‧ communication signal cable

11, 21, 31‧‧‧ battery pack

12, 22, 32‧‧‧ Battery Management System

13, 23, 33, 14, 24, 34‧‧‧ switches

T21-T23, T51-T54‧‧‧ timing

305-355, 805-870‧‧‧ steps

80‧‧‧DC / DC converter

90‧‧‧discharge bus

FIG. 1 is a functional block diagram of an energy storage system according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing that the discharge phase is offline according to the first embodiment of the present invention.

3A and 3B are flowcharts of offline control according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing the return of the energy storage system in charge balance according to the second embodiment of the present invention.

FIG. 5 shows a waveform diagram of the charge balance reset according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram showing the return of the energy storage system to a static current-limiting equilibrium according to the third embodiment of the present case.

FIG. 7 is a schematic diagram showing the return of the energy storage system to a static current-limiting equilibrium according to the fourth embodiment of the present invention.

8A to 8C show a connection control flowchart according to another embodiment of the present invention to restore (mount) an offline battery module.

The technical terms in this specification refer to the customary terms in the technical field. If some terms are described or defined in this specification, the interpretation of these terms is subject to the description or definition in this specification. Each embodiment of this disclosure has one or more technologies. feature. Under the premise of possible implementation, those with ordinary knowledge in the technical field may selectively implement part or all of the technical features in any embodiment, or selectively combine part or all of the technical features in these embodiments.

First embodiment-offline control

Please refer to FIG. 1 and FIG. 2. FIG. 1 shows a functional block diagram of the energy storage system according to the first embodiment of the present invention, and FIG. 2 shows waveform diagrams of the discharge phase offline according to the first embodiment of the present invention.

As shown in FIG. 1, the energy storage system 100 according to the first embodiment of the present application includes a plurality of battery modules. In the first figure, the energy storage system 100 includes three battery modules 10, 20, and 30 as an example, but it is understood that this case is not limited to this.

The energy converter 50 can convert AC mains power or DC renewable energy into direct current to charge the battery modules 10, 20, and 30 through the DC bus 60. Alternatively, the energy converter 50 may convert the DC power output from the battery modules 10, 20, and 30 of the storage system 100 into AC power to provide the AC power to the AC household power grid. The detailed structure and operation of the energy converter 50 are not particularly limited herein.

Through the communication signal line 70, the battery modules 10, 20, and 30 can communicate with each other, or one of the battery modules 10, 20, and 30 (the main control battery module) can communicate with the energy converter 50.

The battery module 10 includes a battery pack 11, a battery management system (BMS) 12, and a switch 13. Similarly, the battery module 20 includes a battery pack 21, a battery management system 22 and a switch 23. The battery module 30 includes a battery pack 31, a battery management system 32 and a switch 33.

In the first embodiment of the present invention, when the storage system 100 is in a discharged state, when any one of the battery packs (11, 21, or 31) runs out of power, or the voltage of any battery module and other battery modules When the voltage difference between them is too large, you can jump out of the battery module or the battery module with too low voltage from the online state to the offline state to avoid the battery module with exhausted power or the battery module with too low voltage Excessive discharge or absorption of a large amount of internal circuit recharge current at the end of discharge.

In the embodiment of the present case, the “online state” means that the switches (such as switches 13, 23, and 33) of the battery modules 10, 20, and 30 are turned on, so that the battery modules 10, 20, and 30 are connected to the DC bus 60, This status is called "online status". Conversely, if the switches (such as switches 13, 23, and 33) of the battery modules 10, 20, and 30 are in an open state, so that the battery modules 10, 20, and 30 are not connected to the DC bus 60, this state is called "Offline".

In the first embodiment of the present case, the battery module with the lowest number (taking the battery module 10 as an example) can be used as the preset main control battery module of the energy storage system 100 to take charge of the external or energy converter 50 Communication. Even if the main control battery module is offline, the main control battery module can still communicate.

It is assumed that the battery numbers of the battery modules 10, 20, and 30 are 1, 2, and 3, respectively. Number 1 (battery module 10, preset as master battery module) collects and compiles module information (such as battery voltage, battery temperature) and number 2 (battery module 20) and number 3 (battery module 30) , The maximum allowable charge / discharge current, etc.). The main control battery module 10 sends the module information of all battery modules to the energy converter 50 through the communication signal line 70, so that the energy converter 50 can be used to adjust the charging current or the discharging current.

In case the communication function of the battery module 10 of the number 1 fails, that is, when the remaining battery modules 20 and 30 cannot detect the existence of the number 1 (the battery module 10) through the communication signal line 70, the number is The next lowest battery module (battery module 20 with number 2) is taken as the new main control battery module, and the rest can be deduced by analogy.

The offline control of the first embodiment of the present case will now be described. Please refer to Figure 2. It is assumed that at the beginning, the battery modules 10, 20, and 30 are all discharged normally, and each of the battery modules 10, 20, and 30 normally outputs a current of 40 A to the energy converter 50.

At time T21, when the battery modules 10, 20, and 30 are discharged to a voltage of about 52 V at the DC bus 60, the battery module 10 is ready to switch to an offline state due to over-temperature protection. Before the battery module 10 goes offline, the battery management system 12 in the battery module 10 notifies the energy converter 50 via the communication signal line 70, so that the energy converter 50 reduces the upper limit of the discharge current of the storage system 100 from 120A to 80A. (That is, the energy converter 50 is changed to draw an output current of 80 A from the storage system 100). This is because if the battery module 10 to be taken offline does not report the energy converter 50, the remaining battery modules 20 and 30 will output a total of 120A (each output 60A), which may cause the battery module 20 and the The discharge current of 30 is overloaded and triggers the over-current power-off protection measures of the battery module 20/30.

When the voltage of the DC bus 60 is discharged to about 46V (timing T22), it is assumed that the battery module 20 has run out of power, the battery module 20 is ready to switch to an offline state, and the battery management system 22 of the battery module 20 communicates via communication. The signal line 70 notifies the main control battery module 10. Similarly, before the battery module 20 goes offline, the battery module 10 notifies the energy converter 50 via the communication signal line 70, so that the energy converter 50 reduces the upper limit of the discharge current of the storage system 100 from 80A to 40A.

After the timing T22, only the battery module 30 is left to continue to supply power. At the timing T23, the voltage drop of the DC bus 60 is 44V.

Of course, if the battery module 30 is ready to go offline and cut off the output (this situation is not shown in FIG. 2), the battery management system 32 of the battery module 30 notifies the main control battery module 10 via the communication signal line 70; Before the group 30 goes offline, the battery module 10 notifies the energy converter 50 via the communication signal line 70, so that the energy converter 50 reduces the upper limit of the discharge current of the storage system 100 from 40A to 0A.

That is, the two battery modules 10 and 20 originally mounted on the DC bus 60 are taken offline one by one during the discharging process.

In addition, if any battery module has abnormal protection such as overheating, the abnormal battery module can be switched from the online parallel state to the offline state at any time. Of course, before going offline, the abnormal battery module must notify the main control battery module to further allow the energy converter to adjust the upper limit of the charge / discharge current of the energy storage system.

It should be noted that although the above-mentioned embodiment is described with the offline control of the discharging process, it is not limited thereto. During the charging process, the battery module may also be abnormal or overheated and need to be disconnected. The offline control method is similar to the above description, and will not be repeated here.

Please refer to FIG. 3A and FIG. 3B, which show an offline control flowchart according to the first embodiment of the present invention. In step 305, each battery module periodically reports (such as, but not limited to, reporting per second) the individual communication status and its own maximum charge / discharge current to the main control battery module, where the communication status refers to the battery module Online or offline. In step 310, the main control battery module organizes the report information of all battery modules, and then informs the energy accordingly. The converter 50 allows the energy converter 50 to set a maximum charge / discharge current. In step 315, the main control battery module determines whether all the battery modules of the energy storage system 100 are in a resting state (that is, the resting state means that the battery module is not in a charging state or a discharging state). . If yes in step 315, the flow returns to step 305. If step 315 is no, each battery module in the online state determines whether protection is to be activated, that is, each battery module in the online state determines whether it is ready to go offline, as in step 320. If yes in step 320, the offline battery module is prepared to notify the main control battery module. In step 325, after receiving the notification of the battery module to be offline, the main control battery module notifies the energy converter to reduce the maximum charge / discharge current. In step 330, the offline battery module is prepared for offline, that is, the switches 13, 23, and 33 are disconnected from the DC bus 60 to complete offline. In step 335, the offline battery module notifies the main control battery module of its own number so that the main control battery module can know which battery modules are still online at present, and the flow returns to step 305.

In addition, if it is not in step 320, then in step 340, the main control battery module determines whether the number of battery modules that are still online is 0, or if the main control battery module judges that the battery modules are still online. Are all battery modules empty? If YES in step 340 (that is, the two match one of the two), the main control battery module notifies the energy converter so that the energy converter stops drawing power to the battery modules, such as step 345.

If the answer in step 340 is no, the main control battery module determines whether all the battery modules in the online state have reached the full state, as in step 350. If step 350 is If yes, the main control battery module notifies the energy converter so that the energy converter stops charging the battery modules, as shown in step 355. If NO in step 350, the flow returns to step 315.

From the above, in the first embodiment of the present case, when the energy storage system 100 is powered, before the battery module goes offline, the main control battery module is notified by the off-line battery module, and the main control battery module reports energy The converter 50 to prevent the remaining online battery modules from burdening the charging / discharging current too much.

Second embodiment-charge balance reset

Please refer to Figure 4 and Figure 5. FIG. 4 shows a schematic diagram of the charging balance restoration of the energy storage system according to the second embodiment of the present case, and FIG. 5 shows a waveform diagram of the charging balance restoration according to the second embodiment of the present case.

In the second embodiment of the present case, the battery management systems 12, 22, and 32 communicate with each other through the communication signal line 70, so the battery management systems 12, 22, and 32 can know each other's battery voltage. Here, it is assumed that the battery voltage from low to high is the battery module 30, the battery module 20, and the battery module 10, wherein the voltage of the battery pack 31 of the battery module 30 is 44V, and the battery pack 21 of the battery module 20 And the voltage of the battery pack 11 of the battery module 10 is 52V. The battery modules 10, 20, and 30 are all offline. The following will explain how to reset these battery modules 10, 20, and 30 after the offline battery modules 10, 20, and 30 have returned to normal (for example, the temperature has returned to normal).

Before the reset, the main control battery module knows the voltage of all battery modules 10, 20, and 30. Therefore, the main control battery module can report energy according to the voltage of all battery packs in those battery modules. The converter 50 allows the energy converter 50 to set a curve of its charging voltage, as shown in FIG. 5. The voltage on the DC bus 60 is the charging voltage or charging current of the energy converter 50, and in the second embodiment of the present case, the DC bus 60 The voltage (ie, the charging voltage of the energy converter 50) is increasing. During the reset process, when one of all battery modules detects that the voltage difference between the battery voltage and the charging voltage on the DC bus is less than the set value, the battery module is mounted on the DC bus to Charge it. Because the charging voltage on the DC bus is increasing, the battery module will be mounted on the DC bus in order from the lowest battery voltage to the highest battery voltage.

In detail, at time T51, the battery management system 32 of the battery module 30 with the lowest battery voltage detects that the current voltage of the DC bus 60 is about 44V. Therefore, the battery management system 32 of the battery module 30 judges itself The voltage difference between the battery voltage of 44V and the current voltage of the DC bus 60 is about 44V is less than a set value, and the set value may be, for example, but not limited to 3V. Therefore, the battery management system of the battery module 30 having the lowest battery voltage 32 judges that it can be mounted to the DC bus 60. Or, at timing T51, the battery management system 32 of the battery module 30 with the lowest battery voltage detects that the voltage value of the DC bus 60 is 0, which means that the DC bus 60 is currently in a clear state, that is, there is no one The battery module is connected to the DC bus 60. Therefore, the battery management system 32 of the battery module 30 having the lowest battery voltage determines that the battery module 30 can be mounted on the DC bus 60.

In order to complete the mounting, the battery management system 32 of the battery module 30 with the lowest battery voltage controls the switch 33 to be turned on to mount to the DC bus 60. After the battery module 30 is mounted on the DC bus 60, the battery module 30 is reset at time T51. After that, the energy converter 50 charges the battery module 30 through the DC bus 60. Similarly, the battery management system of the main control battery module notifies the energy converter 50 to regulate the charging current value, for example, it is adjusted to 20A.

Similarly, at timing T52, the battery management system 22 of the battery module 20 with the next lowest battery voltage detects the voltage between the current voltage of the DC bus 60 (that is, the voltage of the battery module 30) and its own battery voltage Both are about 48V, and the voltage difference between the two is less than Set value. Therefore, the battery management system 22 of the battery module 20 with the second lowest battery voltage determines that it can be mounted on the DC bus 60 itself.

In order to complete the mounting, the battery management system 22 of the battery module 20 with the second lowest battery voltage controls the switch 23 to be turned on to mount to the DC bus 60. At the timing T52, the battery module 20 is reset. After the battery module 20 is mounted on the DC bus 60, the energy converter 50 charges the battery modules 20 and 30 through the DC bus 60. At this time, the battery modules 20 and 30 are connected in parallel. Similarly, the battery management system of the main control battery module notifies the energy converter 50 to regulate the charging current value, for example, it is adjusted to increase to 40A.

Similarly, at timing T53, the battery management system 12 of the battery module 10 with the highest battery voltage detects that the current voltage of the DC bus 60 and its own battery voltage are about 52V, and the voltage difference between the two is less than the set value. . Therefore, the battery management system 12 of the battery module 10 with the highest battery voltage determines that it can be mounted on the DC bus 60 itself.

In order to complete the mounting, the battery management system 12 of the battery module 10 with the highest battery voltage controls the switch 13 to be turned on to mount to the DC bus 60. At the timing T53, the battery module 10 is reset. After the battery module 10 is mounted on the DC bus 60, the energy converter 50 charges the battery modules 10, 20, and 30 through the DC bus 60. At this time, the battery modules 10, 20, and 30 are connected in parallel. Similarly, the battery management system of the main control battery module notifies the energy converter 50 to regulate the charging current value, for example, it is adjusted to increase to 60A.

At time T54, since all battery voltages are close to a full charge state, the energy converter 50 is switched from a constant current (CC) mode to a constant voltage (CV) mode for charging.

That is, in the second embodiment of the present case, after the offline battery module returns to normal, if the offline battery module determines that the voltage difference between its own battery voltage and the current voltage of the DC bus 60 is less than a set value, then The battery module can be mounted to a DC bus The flow row 60 completes the return of the battery module. Therefore, these battery modules are reset in accordance with their own voltage levels. The lowest voltage battery module is reset first, so that the energy converter continues to charge the lowest voltage battery module, followed by the next lower voltage battery module. The second reset is to enable the energy converter to continuously charge the lowest and second lowest voltage battery modules, and the highest voltage battery module is finally reset. And so on, until all normal battery modules are mounted online.

Third Embodiment-Resting Current Limiting Balance

FIG. 6 is a schematic diagram showing the return of the energy storage system to a static current-limiting equilibrium according to the third embodiment of the present case. The battery management systems 12, 22, 32 communicate with each other, so all battery management systems 12, 22, 32 can know each other's battery voltage. Here, it is assumed that the battery voltage from low to high is the battery module 30, the battery module 20, and the battery module 10, wherein the voltage of the battery pack 31 of the battery module 30 is 44V and the battery pack 21 of the battery module 20 And the voltage of the battery pack 11 of the battery module 10 is 52V. The battery modules 10, 20, and 30 are all offline. The following will explain how to reset these battery modules 10, 20, and 30 after the offline battery modules 10, 20, and 30 have returned to normal (for example, the temperature has returned to normal). It should be noted that, in the present embodiment, during the reset, the current is not provided by the energy converter 50 to charge the offline battery modules 10, 20, 30, but the battery modules 10, 20, 30 30 charge / discharge each other to achieve the voltage balance between the battery modules 10, 20, and 30. In addition, the main control battery module can select a target discharge battery module and a target rechargeable battery module for static current-limiting balance according to the individual battery voltage of the multiple battery modules that have been offline. In the energy system, the battery module with the highest battery voltage is used as the target discharge battery module, and the battery module with the lowest battery voltage is used as the target rechargeable battery module, but it is not limited to this.

In the third embodiment of the present case, the operating state is determined based on whether the voltage difference between each battery voltage and the highest battery voltage is less than a set value.

Scenario 1: The current voltage difference between the lowest battery voltage and the highest battery voltage is less than the set value: In this case, turn on the switch 13 or 23 or 33 to allow the two battery modules to quickly balance.

Scenario 2: The current voltage difference between the lowest battery voltage and the highest battery voltage is greater than the set value. The battery module with the highest battery voltage performs current-limit charging on the battery module with the lowest battery voltage. At this time, the battery module with the highest battery voltage Turn on the switch. In one embodiment, the switch is implemented by a metal-oxide-semiconductor field-effect transistor (MOSFET), and the battery module with the highest battery voltage operates the switch in a fully open saturation region state to prepare to charge the selected battery module. The battery module with the lowest battery voltage turns on the switch and operates the switch in the linear region to have the current limiting function to accept the charging of the battery module with the highest voltage.

In the above example, the battery voltages from low to high are the battery module 30, the battery module 20, and the battery module 10, respectively. The battery module 30 having the lowest battery voltage is charged by the battery module 10 having the highest battery voltage. Therefore, the switch 33 of the battery module 30 is operated in the linear region, and the switch 13 of the battery module 10 is operated in the saturation region. As a result, the battery module 10 can charge the battery module 30 through the DC bus 60 in a current-limiting manner. In this embodiment, the battery module 10 having the highest battery voltage charges the battery module 30 having the lowest battery voltage with a small current, and the charging current may be, but is not limited to, 2A. In other embodiments, the battery module with the highest battery voltage can also charge the battery module with the lowest battery voltage with a large current to save charging time. As the charging operation proceeds, the voltage of the battery module 10 gradually decreases, and the voltage of the battery module 30 gradually increases.

When the voltage difference between the voltage of the battery module 30 and the voltage of the battery module 10 is less than the set value, the switch 33 of the battery module 30 can be operated in a fully-opened saturation region state, so that the battery module 30 and the battery module 10 can reach voltage balance quickly.

After the balance between the battery module 10 with the highest battery voltage and the battery module 30 with the lowest battery voltage is completed, the battery module with the highest current battery voltage and the current lowest battery voltage in the energy storage system 100 can be re-revised in the manner described above. The battery module is balanced, and its details are not repeated here.

Therefore, when all the battery modules 10, 20, and 30 are in balance or the voltage difference between any of the battery modules 10, 20, and 30 is less than the set value, all battery modules 10, 20, and The switches 13, 23, and 33 in 30 are turned on to mount all the battery modules 10, 20, and 30 on the DC bus 60 to complete the online return.

Please note that in the third embodiment of the present case, after all the battery modules 10, 20, and 30 are mounted (returned), the energy converter 50 can be used to connect all the battery modules 10, 20, and 30 to the energy storage system 100 online. Charge it.

That is to say, in the third embodiment of the present case, when the energy storage system 100 is in a charging state, if the energy converter 50 is not immediately charged, in a static state, the battery module with the highest voltage can be limited. The current mode charges the battery module with the lowest voltage so that the two battery modules can reach equilibrium.

Fourth Embodiment-Resting Current Limiting Balance

Please refer to FIG. 7, which shows a schematic diagram of the energy storage system according to the fourth embodiment of the present invention at the standstill current-limiting equilibrium. As shown in FIG. 7, the energy storage system 100A according to the fourth embodiment of the present case includes: battery modules 10B, 20B, and 30B.

It should be noted that, in the energy storage system 100A, the battery modules 10B, 20B, and 30B are coupled to the DC / DC converter 80 through the discharge bus 90. In one embodiment, the DC / DC converter 80 is, for example, However, the DC / DC converter is not limited to 48V / 2A, and the DC / DC converter 80 is coupled to the DC bus 60.

The battery module 10B includes a battery pack 11, a battery management system 12, and switches 13 and 14. Similarly, the battery module 20B includes a battery pack 21, a battery management system 22, and switches 23 and 24. The battery module 30B includes a battery pack 31, a battery management system 32, and switches 33 and 34. The switches 14, 24, and 34 are coupled to the discharge bus 90. An input terminal of the DC / DC converter 80 is coupled to the discharge bus 90, and an output terminal of the DC / DC converter 80 is coupled to the DC bus 60. Among them, switches 13, 23, and 33 are low-current switches for controlling whether the battery modules 10B, 20B, and 30B are connected to the DC bus 60; and switches 14, 24, and 34 are high-current switches for controlling the battery mode. Whether the groups 10B, 20B, 30B are connected to the discharge bus 90.

The battery management systems 12, 22, 32 communicate with each other, so all battery management systems 12, 22, 32 can know each other's battery voltage. Here, it is assumed that the battery voltage from low to high is the battery module 30B, the battery module 20B, and the battery module 10B. It is assumed that the voltage of the battery pack 31 of the battery module 30B is 44V, and the battery of the battery module 20B is a battery. The voltage of the group 21 is 48V and the voltage of the battery group 11 of the battery module 10B is 52V. The battery modules 10B, 20B, and 30B are currently offline. The following will explain how to restore these battery modules 10B, 20B, 30B after the offline battery modules 10B, 20B, 30B have returned to normal (for example, the temperature has returned to normal). It should be noted that, in the present embodiment, during the reset, the current is not provided by the energy converter 50 to charge the offline battery modules 10, 20, and 30, but the battery modules 10, 20, and 30 are used for charging. 30 Charge / discharge each other to achieve the voltage balance between the battery modules 10, 20, and 30. In addition, the main control battery module can select a target discharge battery module and a target rechargeable battery module for static current-limiting balance according to the individual battery voltage of the multiple battery modules that have been offline. In the energy system, the battery module with the highest battery voltage is used as the target discharge battery module, and the battery module with the lowest battery voltage is used as the target rechargeable battery module, but it is not limited to this.

In the fourth embodiment of the present case, the operating state is determined based on whether the voltage difference between each battery voltage and the highest battery voltage is less than a set value.

Scenario 1: The current voltage difference between the lowest battery voltage and the highest battery voltage is less than the set value: In this case, turn on the switch 13 or 23 or 33 to allow the two battery modules to quickly balance through the DC bus 60.

Scenario 2: The current voltage difference between the lowest battery voltage and the highest battery voltage is greater than the set value. Then the battery module with the highest battery voltage performs current-limit charging on the battery module with the lowest battery voltage. At this time, the battery module with the highest battery voltage The group 10B turns on the switch 14 to output electric energy to the DC / DC converter 80 through the discharge bus 90. After the voltage conversion by the DC / DC converter 80, the DC / DC converter 80 charges the battery module 30B having the lowest battery voltage through the DC bus 60. At this time, the switch 33 of the battery module 30B with the lowest battery voltage is on, while the switch 13 of the battery module 10B with the highest battery voltage and the switches 23 and 24 of the battery module 20B are not turned on.

That is, in the fourth embodiment of the present case, the current limiting effect is realized by the DC / DC converter 80, because the output current of the DC / DC converter 80 can have an upper limit (such as 2A) to prevent the battery module from being suddenly large. Damaged by current charging.

In the above example, the battery voltage from low to high is the battery module 30B, the battery module 20B, and the battery module 10B. First selected by the highest voltage battery module 10B (selected The battery module to be discharged may also be referred to as a target discharge battery module) to charge the lowest voltage battery module 30B (the battery module selected to be charged may also be referred to as a target rechargeable battery module). The switch 33 of the battery module 30B is turned on, and the switch 14 of the battery module 10B is also turned on. Thereby, the battery module 10B can be discharged to the DC / DC converter 80 through the discharge bus 90, and then coupled to the DC bus 60 to charge the battery module 30B. In other words, the electric energy of the battery module 10B is transmitted to the DC / DC converter 80 through the discharge bus 90 through the switch 14. Then, the DC / DC converter 80 performs DC / DC conversion and then transmits the electric energy to the DC bus. 60, and the battery module 30B is charged through the switch 33 in a conducting state of the battery module 30B. It should be noted that although in this embodiment, the target discharge battery module charges a single target rechargeable battery module, in other embodiments, there may be multiple target rechargeable battery modules, as long as each target rechargeable battery The battery characteristics and voltages among the modules are similar. The target discharge battery module can charge multiple target rechargeable battery modules at the same time, and it is not limited to the list.

As the charging operation progresses, the voltage of the battery module 10B gradually decreases, and the voltage of the battery module 30B gradually increases.

When the voltage difference between the voltage of the battery module 30B and the voltage of the battery module 10B is less than a set value, the switch 33 of the battery module 30B can continue to be turned on. At the same time, turn off the switch 14 of the battery module 10B, disconnect the conduction between the battery module 10B and the DC / DC converter 80, so that the power no longer flows to the DC / DC converter 80 (that is, the current limiting function is turned off), and then let the battery The switch 13 of the module 10B is turned on to be coupled to the DC bus 60 and directly and quickly charge the battery module 30B, so that the battery module 10B and the battery module 30B can be quickly balanced.

Similarly, after the balance between the battery module 10B with the highest battery voltage and the battery module 30B with the lowest battery voltage is completed, the energy storage system can be re-adjusted in the above manner. The battery module with the highest battery voltage in 100A is currently balanced with the battery module with the lowest battery voltage at present. The details are not repeated here.

Through the fourth embodiment of the present case, when all the battery modules 10B, 20B, and 30B are balanced or the voltage difference between any of the battery modules 10B, 20B, and 30B is less than the set value, all battery modules can be changed. The switches 13, 23, and 33 in 10B, 20B, and 30B are turned on to mount all the battery modules 10B, 20B, and 30B to the DC bus 60 to complete the return to online.

Please note that in the fourth embodiment of the present case, after all the battery modules 10B, 20, and 30B are mounted (returned), the energy converter 50 can connect all the online battery modules 10B, 20B, and 30B of the energy storage system 100. Charge it.

That is to say, in the fourth embodiment of the present case, when the energy storage system 100A is in the charging state, if the energy converter 50 is not immediately charged, in the static state, the battery module with the highest voltage can be limited. The current mode charges the battery module with the lowest voltage so that the two battery modules can reach equilibrium.

Please refer to FIG. 8A to FIG. 8C, which show a connection control flowchart according to another embodiment of the present invention to restore (mount) the offline battery module. In principle, the flowcharts of FIGS. 8A to 8C may include the above-mentioned charge balance method (second embodiment) and the stationary current-limiting balance method (third and fourth embodiments).

In step 805, each battery module periodically reports (such as, but not limited to, reporting per second) the individual communication status and its own maximum charge / discharge current to the main control battery module, where the communication status refers to the battery module Online or offline. In step 810, after the main control battery module sorts the report information of all battery modules, the main control battery module determines the maximum voltage difference of all battery modules in the communication state, that is, one of the battery modules. most Whether the high battery voltage value minus a minimum battery voltage value of the battery modules exceeds a set value. Here, "in communication state" means that the battery module can still communicate with the main control battery module. That is, if the communication between the battery module and the main control battery module is interrupted, the battery module is said to be in an interrupted state.

If the maximum voltage difference of all battery modules in the communication connection state exceeds the set value, the flow continues to step 815; otherwise, the flow continues to step 820.

In step 815, if the battery module currently connected to the DC bus does not have the lowest battery voltage, that is, if the battery module currently online to the DC bus does not include the lowest battery in the communication state Voltage battery modules. At this time, all battery modules are taken offline first, and then the battery module with the lowest battery voltage is mounted on the DC bus 60. In step 820, the main control battery module controls all battery modules to be connected in parallel and mounted on the DC bus 60.

Step 817 is related to the charge balancing method of the second embodiment, and step 847 is related to the static current limiting balance method of the third and fourth embodiments. Step 817 includes steps 825-845, and step 847 includes steps 850-867.

In step 825, after the report information of all battery modules is arranged by the main control battery module, the energy converter 50 is notified, so that the energy converter 50 can set the charging current or the charging voltage accordingly.

In step 830, the main control battery module determines whether to use the energy converter to charge the energy storage system, which is the charging balance method. If step 830 is YES, the flow continues to step 835; if step 830 is No, the flow continues to step 850 in step 847.

In step 835, the main control battery module determines whether all offline battery modules have been mounted. If step 835 is YES, end step 817 and proceed to subsequent step 870; if step 835 is no, flow continues to step 840.

In step 840, the offline battery modules determine whether the voltage difference between the battery voltage of the battery module and the voltage of the DC bus is less than a set value. If YES in step 840, the flow proceeds to step 845, and the battery module whose voltage difference between the battery voltage and the DC bus voltage is less than a set value is mounted on the DC bus. If no in step 840, the flow proceeds to step 842, and the energy converter charges the battery module mounted on the DC bus. After performing step 842, the flow returns to step 830, and the main control battery module determines whether to use the energy converter to charge the energy storage system.

On the other hand, if step 830 is no, that is, during mounting, instead of using the energy converter to charge the energy storage system, but using the static current-limiting balancing method, the process continues to step 850 to limit In the current mode, the battery module with the highest battery voltage charges the battery module with the lowest battery voltage. Step 850 includes in the third embodiment, the battery module with the highest battery voltage directly charges the battery module with the lowest battery voltage. In addition, step 850 may also include charging the battery module with the lowest battery voltage by the battery module with the highest battery voltage through the DC / DC converter in the fourth embodiment.

In step 855, it is determined whether the voltage difference between the highest battery voltage and the lowest battery voltage is less than a set value. If the answer of step 855 is no, then proceed to step 850, and the battery module with the lowest battery voltage is charged by the battery module with the highest battery voltage until the voltage difference between the two is less than the set value.

If YES in step 855, then in step 860, the current limiting function is turned off, and the two battery modules are coupled to the DC bus (for example, the on-switches 13, 23, and 33, etc.) to achieve rapid balance.

Next, in step 865, the main control battery module determines whether all offline battery modules have completed offline balancing, that is, the voltage difference between any two of the offline battery modules is less than a set value. If YES in step 865, it means that all the battery modules have completed off-line balancing. At this time, it proceeds to step 867, and mounts all the battery modules on which off-line balancing is completed, so that the flow returns to step 835 in step 817. After all battery modules have been offline-balanced and all battery modules are mounted on the DC bus, all battery modules mounted on the DC bus are charged. In one embodiment, it is organized by the main control battery module After reporting the information of all battery modules, the energy converter 50 is notified, so that the energy converter 50 can set the charging current or the charging voltage accordingly, as shown in step 870. If NO in step 865, the flow returns to step 850.

It can be known from the above embodiments that if the energy storage system needs to expand the capacity to mount more battery modules, the second to fourth embodiments can be used to automatically mount the battery modules to be expanded, which can reduce manual hanging. Contained trouble.

Of course, if a battery module is found to be faulty and needs to be replaced, hot swapping of the faulty battery module can also be achieved through the first embodiment described above.

In addition, in other possible embodiments of the present case, the battery module may further be provided with a "switch button". In response to a user operation, the power on / off button allows the battery module to be turned on. Or, in response to a user operation, the on / off button can force the The battery module in the online state is switched to the offline state to facilitate routine inspection and maintenance work.

In the above-mentioned embodiment of the present case, through the software control technology of the battery management system and the design of the hardware circuit, the direct-connected low-cost architecture can meet the elastic demand of the energy storage system for capacity expansion.

What's more, the above-mentioned embodiments in this case can realize offline / online automatic detection and control. Moreover, the above-mentioned embodiments of the present case can avoid abnormal use of the battery module (overdischarge, overcharge, overheat, etc.) by using automatic offline / connection. Moreover, after the abnormal battery module status returns to normal, the above-mentioned embodiments in this case may automatically return to the online mode.

In addition, in the embodiments described above, battery modules with different characteristics can also be used in the same energy storage system. This will help reduce the potential cost of energy storage systems.

In summary, although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims (9)

An energy storage system control method. The energy storage system includes a plurality of battery modules. The control method includes: each of the battery modules reports an individual communication state and an individual maximum charge / discharge current to one of the battery modules. Control battery module; the main control battery module notifies an energy converter according to which the energy converter sets a maximum charge / discharge current; when the battery is online, one of the battery modules is the first battery When the module determines that it is ready to go offline, the first battery module notifies the main control battery module so that the main control battery module notifies the energy converter to reduce the maximum charge / discharge current; and the The first battery module is offline. The method for controlling an energy storage system according to item 1 of the scope of patent application, further comprising: after the first battery module is offline, the first battery module that is offline will notify the main controller of a number of itself Battery module. The method for controlling an energy storage system according to item 1 of the scope of the patent application, wherein the step of preparing the first battery module to be offline for offline includes: preparing the first battery module to be offline to disconnect a switch from A DC bus to complete offline. According to the method for controlling the energy storage system described in item 1 of the scope of the patent application, the method further includes: determining, by the main control battery module, whether the number of the battery modules that are still online is zero, or by the main battery module. The control battery module judges whether all the battery modules that are still online have no power; and if it is determined as yes, the main control battery module notifies the energy converter so that the energy converter stops the energy converter. Power extraction from battery modules. According to the control method of the energy storage system described in item 1 of the scope of the patent application, the method further includes: in response to a user operation, a switch button of the battery module turns on the battery module; , The on / off button forcibly switches the battery module in an online state to an offline state. An energy storage system control method. The energy storage system includes a plurality of battery modules. The control method includes: according to the individual battery voltage of the battery modules that are offline, one of the battery modules controls the battery mode. The group notifies an energy converter to enable the energy converter to set a charging voltage or a charging current on the DC bus; and when a battery module of the battery modules detects its own battery voltage and the DC bus When a voltage difference between the charging voltages on the bank is less than a set value, the battery module is mounted on the DC bus. The method for controlling an energy storage system according to item 6 of the scope of patent application, wherein the charging voltage on the DC bus is increasing. The control method of the energy storage system according to item 7 of the scope of patent application, wherein, according to the individual battery voltage of the battery modules, from a minimum battery voltage to a maximum battery voltage, the battery modules are mounted in order. To the DC bus. According to the control method of the energy storage system described in item 6 of the scope of the patent application, the method further includes: in response to a user operation, a switch button of the battery module turns on the battery module; or, in response to a user operation , The on / off button forcibly switches the battery module in an online state to an offline state.