WO2016074216A1

WO2016074216A1 - Energy storage system based on battery packs

Info

Publication number: WO2016074216A1
Application number: PCT/CN2014/091103
Authority: WO
Inventors: Mingliang Zhang
Original assignee: Robert Bosch Gmbh
Priority date: 2014-11-14
Filing date: 2014-11-14
Publication date: 2016-05-19
Also published as: DE112014007057T5; CN107005054A

Abstract

An energy storage system (1000) is provided. The energy storage system (1000) comprises a master BMS (100), one or more battery packs (200, 300, 400) each comprising a corresponding slave BMS (220, 320, 420), a DC bus (600) which is connected with terminals of each battery pack (200, 300, 400), and a communication bus (700) for connecting each battery pack (200, 300, 400) with a corresponding internal communication port of the master BMS (100), wherein the master BMS (100) receives battery variables of each battery pack (200, 300, 400) from the corresponding slave BMS (220, 320, 420) via the communication bus (700), calculates status of each battery pack (200, 300, 400) based on algorithms stored in a master controller of the master BMS (100), makes a decision on behavior of each battery pack (200, 300, 400), and switches on or off the battery pack (200, 300, 400) with a power electronics module of the master BMS (100) to charge or discharge the battery pack (200, 300, 400).

Description

Energy Storage System Based on Battery Packs

Technical Field

The invention relates to the field of energy storage, in particular to an energy storage system constituted by battery packs.

Background Art

Electric vehicles (EVs) are gaining popularity as one of the solutions for reducing green-house gas emissions of vehicles in view of its increased energy efficiency, and power supplies for the electric vehicles are rechargeable chemical power sources, including battery packs. As a result, more and more battery packs used in the electric vehicles will be introduced into electric vehicles market. The battery packs are replaced from the EV after used. A current solution typically is that EV dealers/service centers dispose of the used battery packs at a refurbishing facility where battery cells in the used battery packs will be screened, sorted, tested, and finally reconfigured for their second use in stationary applications. After this, the battery cells in the used battery packs are installed in a housing and managed by a battery management system (BMS) .

However, the processes of screening, sorting, testing, and reconfiguring the secondary battery packs are both costly and time-consuming. Also technically, only battery packs which are of almost identical characteristics (e.g. chemical characteristics, capacity, and even shapes) can be reused in a same system, which makes it difficult and costly to reconfigure and reuse different types of used battery packs.

There is a demand to solve the above problems.

Summary of the Invention

An object of the invention is to provide an open architecture to reuse different types of used battery packs. In this new architecture, the used battery packs can be utilized on a battery pack level, and therefore efforts for screening, sorting, testing, and reconfiguring can be eliminated. Batteries supplied from different manufacturers and having different characteristic parameters (for example, chemical characteristics, energy capacity etc. ) can be integrated together and reused.

According to a first aspect of the invention, an energy storage system is provided which comprises a master BMS, at least two battery packs each comprising a corresponding slave BMS, a DC bus which is connected with each battery pack for charging each battery pack, and a communication bus for connecting each battery pack with a corresponding internal communication port of the master BMS for transferring information of each battery pack to the master BMS, wherein the master BMS controls electric current and voltage outputs of each battery pack via the corresponding slave BMS of the battery pack.

According to a feasible embodiment, the power electronics module is configured as an array of DC-DC convertors which can control the electric currents of the corresponding battery packs and accommodate variation/difference of voltage of different battery packs.

According to a feasible embodiment, the power electronics module is configured as an array of relays which can connect or disconnect the corresponding battery packs with or from a charging station or a load.

According to a feasible embodiment, the master BMS switches on/off the relays to control charging/discharging of each battery pack individually.

According to a feasible embodiment, the charging/discharging operations of all battery packs are performed in sequence or simultaneously.

According to a feasible embodiment, the battery variables comprise one or more of: a voltage, an electric current, a charging/discharging time, a temperature, Status of Charge (SOC) , and Status of Health (SOH) .

According to a feasible embodiment, the at least two battery packs have different power connectors, and the energy storage system comprises adaptors for the power connectors, and the at least two battery packs have different communication protocols, and the energy storage system comprises a gateway for connecting communication buses of all battery packs.

According to a feasible embodiment, the adaptors are configured as sockets suitable for the different power connectors.

According to a feasible embodiment, the battery pack is a secondary battery pack used as a unit in an electric bicycle, in an electric motorcycle, in a HEV or in an EV.

According to a second aspect of the invention, an operating method of the energy storage system described above is provided, which comprises:

in a first step S1, each battery pack is connected with the master BMS via the DC bus and the communication bus to establish physical connections therewith；

in a second step S2, the energy storage system is powered on to establish communication between the battery packs and the master BMS while a power connection is disabled；

in a third step S3, the master BMS communicates with the slave BMS of each battery pack and obtains information about the status of each battery pack；

in a fourth step S4, the master BMS calculates the status of each battery pack and makes a decision on the behavior of each battery pack； and

in a fifth step S5, based on the decision it made, the master BMS switches on or off relays to control charging/discharging of each battery pack individually.

According to a fessible embodiment, the method further comprises the steps of: the master BMS generates control commands for selected battery packs and sends them to the slave BMSs corresponding to the selected battery packs, and the slave BMSs control their corresponding battery packs to charge or discharge them respectively.

With an energy storage system according to the invention, used battery packs can be utilized on a battery pack level, and therefore efforts for screening, sorting, testing, and reconfiguring the used battery packs can be eliminated. Batteries from different manufacturers having different characteristic parameters (for example, chemical characteristics, energy capacity etc. ) can be integrated together and reused.

Brief Description of the Drawings

Other features, aspects and advantages will be described in detail with reference to embodiments of the invention in combination with the drawings, in which:

Figure 1 shows a diagram of an energy storage system based on battery packs according to the invention；

Figures 2 and 3 show first and second embodiments of the energy storage system according to the invention； and

Figure 4 is a flow chart of an operation method of the energy storage system according to the invention.

Detailed Description of Preferred Embodiments

Special implementations of the invention will be described further in detail in combination with the drawings and embodiments. The embodiments herein are merely intended to illustrate the principle of the invention, not limiting the scope of the invention.

An energy storage system according to the invention is directed to reuse battery packs, and in particular secondary battery packs which are used in electric bicycles, in electric motorcycles, in hybrid electric vehicles or in electric vehicles before discarded, and said system is aimed at simplifying the process of and reducing the cost of reusing the secondary battery packs. The secondary battery packs may be produced by different manufacturers or comprise different chemical components or have different characteristic parameters including, but not limited to, a nominal voltage, an end-of-charge voltage, an energy capacity, a maximum allowed charging current, a maximum allowed discharging current, a maximum continuous charge current, a maximum continuous discharge current, and a maximum temperature etc.

For example, the battery pack in the invention can be a lithium iron phosphate battery pack, a cobalt-based li-ion battery pack, or any other type of battery pack.

The energy storage system according to the invention mainly comprises a master battery management system (also called master BMS hereinafter) and one or more battery packs which are controlled by the master BMS. Each battery pack comprises a battery and a slave battery management system (also called slave BMS hereinafter) corresponding to and controlling the battery pack. For each battery pack, its slave BMS functions as an independent master BMS of the individual battery pack before the battery pack is removed and integrated as a secondary battery pack into the energy storage system according to the invention.

Thus, when the energy storage system comprises different types of battery packs, these battery packs may include the secondary battery packs which are produced by different manufacturers or which comprise different chemical components or which have different characteristic parameters.

Figure 1 shows a diagram of an energy storage system 1000 based on battery packs according to the invention, which will be described in detail below.

It should be noted that three

battery packs

200, 300 and 400 are illustrated in the energy storage system 1000, but the number of the battery packs in the energy storage system 1000 is not limited to three. Instead, one, two, four or more battery packs can be provided in the energy storage system 1000. As can be seen from Figure 1, the three

battery packs

200, 300 and 400 comprise

batteries

210, 310 and 410 and

corresponding slave BMSs

220, 320 and 420, respectively.

In the energy storage system 1000 according to the present invention shown in Figure 1, a master BMS 100, a DC bus 600 (shown in a thick solid line) , and a communication bus 700 (shown in a thin solid line) are shown.

The master BMS 100 is configured for controlling all the

battery packs

200, 300 and 400. The DC bus 600 is connected with terminals of all the

battery packs

200, 300 and 400. The DC bus 600 is configured to be connected to a charging station in order to establish a power connection of the

battery packs

200, 300 and 400 with the charging station to charge the battery packs, or is configured to be connected to a target vehicle to establish a power connection of the

battery packs

200, 300 and 400 with the target vehicle on which the energy storage system 1000 is mounted to power the target vehicle.

The communication bus 700 is configured for connecting communication ports (in Figure 2) of the master BMS 100 with communication ports of the

battery packs

200, 300 and 400, so that the master BMS 100 can obtain battery variables of the

battery packs

200, 300 and 400 and can send control commands to the slave BMSs of the

battery packs

200, 300 and 400.

In general, different battery packs may be produced by different manufacturers and have different power connectors and different communication connectors of the communication ports.

In a case that the battery packs 200, 300 and 400 have the different power connectors, an adaptor 800 may be provided for connecting each power connector of the

battery packs

200, 300 and 400 with the DC bus 600. In an embodiment, the adaptor 800 can be configured as a socket suitable for the different power connectors of the

battery packs

200, 300 and 400. In a case that the battery packs 200, 300 and 400 have different communication protocols, they can not communicate with each other directly, and a communication gateway 900 may be provided in the communication bus 700 for converting the different communication protocols into a communication protocol that is acceptable for all battery packs. In this case, the master BMS 100 is connected with all

battery packs

200, 300 and 400 by means of the adapters 800 and the gateway 900.

However, it should be appreciated that the adaptors 800 and the communication gateway 900 are not always necessary, and thus they are optional. Ideally, if both power connectors and communication connectors are the same and the communication protocols are the same, the adapters and the gateway can be eliminated. For example, all the battery packs are produced by the same manufacturer.

Figures 2 and 3 show first and second embodiments of detail structure of the master BMS 100, respectively.

The master BMS 100 mainly comprises a master controller 110, a power electronics module (the adaptor 800 and the gateway 900) ,

internal communication ports

122, 123 and 124, and an external communication port 130.

The master controller 110 is configured for storing various algorithms and performing calculation operations upon receiving the battery variables of the battery packs.

The power electronics module is configured for controlling the behavior of all battery packs 200, 300 and 400, for example, for connecting/disconnecting each battery pack with/from the DC bus 600. In the first embodiment of the energy storing system 1000 shown in Figure 2, the power electronics module is mainly configured as an array of DC-

DC convertors

142, 143 and 144 for the battery packs 200, 300 and 400 which can control the electric currents of each battery pack and accommodate variation/difference of the voltages of different battery packs in order to meet the requirements of charging and discharging. In the second embodiment of the energy storing system 1000 shown in Figure 3, the power electronics module is mainly configured as an array of

relays

152, 153 and 154 for the battery packs 200, 300 and 400 which can connect each battery pack with the DC bus 600 or disconnect each battery pack from the DC bus 600, the relay being mainly suitable for accommodating variation/difference of the voltages of different battery packs. It can also be seen from Figures 2 and 3, the DC-DC convertors142, 143 and 144 or the

relays

152, 153 and 154 can control their own battery packs 200, 300 and 400 independently from each other, and therefore the

batteries

210, 310 and 410 of the battery packs 200, 300 and 400 can be charged or discharged independently from each other, in sequence or simultaneously depending on the DC-DC convertors142, 143 and 144 in the first embodiment or depending on the

relays

152, 153 and 154 in the second embodiment.

The

internal communication ports

122, 123 and 124 are configured for communicating with corresponding communication ports of the battery packs 200, 300 and 400 respectively, and the external communication port 130 is configured for communicating with a high level controller of the whole energy storage system 1000.

For the energy storage system, the battery packs act as a big battery pack. The master BMS reports status of individual battery packs to the energy storage system and receives commands from the energy storage system to control the behaviour of the individual battery packs.

As described above, each battery pack comprising its own slave BMS may optionally further comprise an interface module for connecting with an interface module of the master BMS 100, a switch, and a thermal management system, and each slave BMS may further comprise a monitoring module for monitoring and measuring battery variables of the corresponding battery pack, a charging/discharging module for charging/discharging the battery pack, a slave controller for receiving the control command from the master BMS 100 and charging or discharging the battery pack according to the control command while power connection is established, and a data storage for storing the measured battery variables.

Each slave BMS has a special control strategy for its own battery pack produced by different manufacturers and is developed to be adapted to different chemical characteristics and different energy levels, and each slave BMS itself may be developed by different manufacturers.

In the energy storage system 1000 according to the present invention, the master BMS 100 gathers information from the

slave BMS

220, 320 and 420 including the battery variables measured by the monitoring module of the slave BMS, such as SOC, SOH, a voltage, and an electrical current etc., calculates the status of the

batteries

210, 310 and 410 with the master controller 110 based on appropriate algorithms stored in the master controller 110, makes a decision on the behavior of the battery packs 200, 300 and 400, and switches on or off the battery packs 200, 300 and 400 with the DC-

DC convertors

142, 143 and 144 or with the

relays

152, 153 and 154 to charge or discharge the selected battery packs.

An operating method of the energy storage system 100 is described now with reference to Figure 4.

In a first step S1 of the operating method, the battery packs 200, 300 and 400 are connected with the DC bus 600 and the communication bus 700, and thus physical connections are established.

In particular, in the first step S1, terminals of each battery pack are connected with the DC bus 600, and communication ports of the battery packs 200, 300 and 400 are connected with the

corresponding communication port

122, 123 and 124 of the master BMS 100 respectively.

In a second step S2, the energy storage system is powered on, and then communication will be established while power connection is still disabled.

In a third step S3, the master BMS 100 communicates with the

slave BMSs

220, 320 and 420 of the battery packs 200, 300 and 400 and obtains information about the status of the battery packs from

slave BMSs

220, 320 and 420.

In particular, in the third step S3, the monitoring module of the slave BMS monitors the battery variables of the battery pack in a real-time manner, in a periodical manner, or according to a command from the controller, and the battery variables monitored include, but are not limited to, a voltage, an electrical current, a charging/discharging time, and a temperature.

The battery variables monitored can be stored in its own data storage and then transmitted to the master BMS under the command of the master BMS via the communication bus 700. Alternatively, the battery variables monitored can be transmitted to the master BMS actively.

In a fourth step S4, the master BMS 100 calculates the status of each battery pack based on the battery variables of the battery packs with the master controller 110, and makes a decision on the behavior of each battery pack.

In this step, the battery variables are used to calculate the status of the battery pack. For example, the voltage and the electrical current can be used to represent an output power of the battery pack at that time, and the charging/discharging time, the temperature and characteristic parameters of the battery pack can be used to calculate the SOC and SOH of the battery pack based on a specific algorithm. Preferably, different algorithms can be selected at different temperatures.

Based on the status generated and the battery variables monitored, the master BMS makes a decision on the behavior of each battery pack, for example, charging the battery pack or discharging that battery pack.

In a fifth step S5, based on the decision it made, the master BMS switches on or off relays to control charging/discharging of the battery packs individually.

Upon switching on the relay, power connection is established, and the slave controller of the slave BMS can receive the command from the master BMS and perform a charge/discharge operation on the battery pack.

The energy storing system described above is an open architecture, in which all the slave BMSs are connected with the master BMS through the DC bus and the communication bus, receive the commands from the master BMS and act accordingly. Additional slave BMS can be easily added or removed from the master BMS.

With an energy storage system according to the invention, used battery packs can be utilized on a battery pack level, and therefore efforts for screening, sorting, testing, and reconfiguring the used battery packs can be eliminated. Batteries supplied from different manufacturers and having different characteristic parameters (for example, chemical characteristics, energy capacity etc. ) can be integrated together and reused.

The system is used to control different battery packs in the same system to be charged and discharged, and the purpose of the invention is that the different battery packs can work well in said same system. The present invention is not limited to managing second battery packs, but could also be used in combination with new battery packs.

The disclosure described above is merely preferred embodiments of the invention. It should be noted that various developments and substitutions made by a skilled in the art without departing from the technical principle of the invention should be considered as falling within the protecting scope of the invention.

Reference Lists

1000 energy storage system

100 master BMS

110 master controller

122, 123, 124 internal communication port

130 external communication port

142, 143, 144 DC-DC convertor

152, 153, 154 relay

200, 300, 400 battery pack

210, 310, 410 battery

220, 320, 420 slave BMS

600 DC bus

700 communication bus

Claims

An energy storage system comprising a master BMS, at least two battery packs each comprising a corresponding slave BMS, a DC bus which is connected with each battery pack for charging each battery pack, and a communication bus for connecting each battery pack with a corresponding internal communication port of the master BMS for transferring information of each battery pack to the master BMS, wherein the master BMS controls electric current and voltage outputs of each battery pack via the corresponding slave BMS of the battery pack.
The energy storage system according to claim 1, wherein the power electronics module is configured as an array of DC-DC convertors which can control the electric currents of the corresponding battery packs and accommodate variation/difference of voltage of different battery packs.
The energy storage system according to claim 1, wherein the power electronics module is configured as an array of relays which can connect or disconnect the corresponding battery packs with or from a charging station or a load.
The energy storage system according to claims 3, wherein the master BMS switches on/off the relays to control charging/discharging of each battery pack individually.
The energy storage system according to any one of claims 1 to 4, wherein the charging/discharging operations of all battery packs are performed in sequence or simultaneously.
The energy storage system according to any one of claims 1 to 5, wherein the battery variables comprise one or more of: a voltage, an electric current, a charging/discharging time, a temperature, SOC, and SOH.
The energy storage system according to any one of claims 1 to 6, wherein the at least two battery packs have different power connectors, and the energy storage system comprises adaptors for the power connectors, and the at least two battery packs have different communication protocols, and the energy storage system comprises a gateway for connecting communication buses of all battery packs.
The energy storage system according to claim 7, wherein the adaptors are configured as sockets suitable for the different power connectors.
The energy storage system according to any one of claims 1 to 8, wherein the battery pack is a secondary battery pack used as a unit in an electric bicycle, in an electric motorcycle, in a HEV or in an EV.
An operating method of an energy storage system according to any one of claims 1 to 9 comprising:

in a first step S1, each battery pack is connected with the master BMS via the DC bus and the communication bus to establish physical connections therewith；

in a second step S2, the energy storage system is powered on to establish communication between the battery packs and the master BMS while a power connection is disabled；

in a third step S3, the master BMS communicates with the slave BMS of each battery pack and obtains information about the status of each battery pack；

in a fourth step S4, the master BMS calculates the status of each battery pack and makes a decision on the behavior of each battery pack； and

in a fifth step S5, based on the decision it made, the master BMS switches on or off relays to control charging/discharging of each battery pack individually.
The operating method according to claim 11, further comprising the steps of: the master BMS generates control commands for selected battery packs and sends them to the slave BMSs corresponding to the selected battery packs, and the slave BMSs control their corresponding battery packs to charge or discharge them respectively.