ES2875953A1 - INTEGRATED BATTERY MANAGEMENT SYSTEM FOR AN ELECTRIC VEHICLE (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Integrated battery management system for an electric vehicle comprising several interface substrates (20), each supporting and electrical connection to a cell management device (30); measurement units (41) each associated with a cell (10); cell communication units (43) based on visible light; cell management devices (30) for receiving and processing the measured parameters and monitoring whether the cell (10) is functioning correctly; a battery management unit (2) with a processor and a communication unit by means of visible light, which, based on the operating information of each cell (10), generates management information of the cells (10), where the Management information comprises information to modify the operation and connection of at least one cell (10) through an integrated power circuit (50). (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

INTEGRATED BATTERY MANAGEMENT SYSTEM FOR AN ELECTRIC VEHICLE

FIELD OF THE INVENTION

The present invention refers to an integrated battery management system in electric vehicles, in particular, to an energy management system of the individual cells that make up a battery of an electric vehicle, understanding electric vehicle as any means of transport whose plant of power contains a battery.

BACKGROUND OF THE INVENTION

There are numerous proposals that seek to extend the useful life of the battery and improve the reliability of the electric vehicle. To do this, some focus on monitoring the correct electrical operation of the battery in the vehicle, which implies analyzing multiple parameters to act appropriately, such as passively balancing the power supply between the different cells.

At the same time, there is a growing interest in the design of batteries, including the management system and its integration in electric vehicles with the aim of facilitating assembly.

In the state of the art there are various types of solutions for managing batteries in electric vehicles. A first majority type performs the management using cabling, which implies giving up a greater integration of the components and / or individual control per cell of certain parameters. A second, less common type of solution uses wireless communications, usually radio frequency (RF), to eliminate wiring between certain battery components. However, the use of wireless communications sometimes implies additional less integrable components or cybersecurity problems.

It should be noted that there are inherent problems with RF communications. Inside a drum set is a very noisy environment. In addition, a cybersecurity problem appears, since this type of communication is not confined to the battery and is easily accessible from outside it through an external radio frequency antenna.

Therefore, the existing proposals, although they go in the direction of improving the atomization present in an electric car battery, do not achieve a solution optimal taking into account the problem of atomization, cybersecurity and integration or assembly of the complete battery management system.

DESCRIPTION OF THE INVENTION

The present invention has been developed in light of the limitations existing in the state of the art.

The invention has main application in the electrical management of the cells of a battery, in particular, in a battery of an electric vehicle.

An advantageous aspect of the invention relates to improving the degree of atomization present in a battery, simplifying its integration and assembly. By atomization it is understood the reduction of components and the improvement of their distribution and integration. Also an advantageous aspect of the invention is to promote physical robustness and cybersecurity by shielding communications between devices. Finally, another advantageous aspect of the invention refers to a distributed architecture of integrated devices with wireless communication, for the monitoring of different parameters of interest of each individual cell within the battery, in such a way that an optimal operation of the battery is guaranteed. thus increasing, on the one hand, its energy efficiency, and on the other hand, also increasing its useful life, guaranteeing that it operates within a safe electrical range.

In the invention, as indicated, the use of wireless communications is proposed, preferably based on visible light (in English: Visible Light Communications - VLC) and integrated into an application-specific semiconductor (in English: Application-Specific Integrated Circuit - ASIC) which, by being able to be integrated in contact with the cell, at the same time, enables local and individual monitoring of each cell completely inaccessible from the outside, allowing full traceability of them and, therefore, greatly facilitating their reusability.

Visible light is understood to be light in the wavelength range 380 to 750 nm, that is, frequencies between 400 and 790 THz. This implies, on the one hand, being able to easily confine communications within the battery using opaque materials for its construction, and, on the other, achieving high data transmission speeds, high bandwidth and avoiding electrical noise problems.

Lithium ion batteries are commonly used to power electric vehicles due to their high energy and power density and long service life. Nevertheless, This type of battery must operate within a safe and reliable range. This implies the need for a Battery Management System (BMS) to monitor and manage the battery, ensuring that its operation is within the safety window under any operating condition. This leads to monitoring each of the hundreds or thousands of cells that can make up an electric vehicle battery.

The basic variables to monitor are voltage, current and temperature. From these variables, an important parameter to control in the batteries can be calculated, the state of charge (in English: State Of Charge - SOC). The state of charge should be approximately the same in all cells for maximum battery performance. This implies a load balancing of the cells, which can be active or passive, the asset being the most complex to perform, but also the most efficient.

Active balancing means the redistribution of charge between the different cells to achieve an equal state of charge in all the cells of the battery.

By passive balancing is understood the dissipation of energy in the form of heat from the cells with a higher state of charge to reach an equal state of charge in all the cells present in the battery, for example, discharging a cell through an ohmic resistance.

However, it should be noted that the monitoring, if desired, can be more complete by including more electrochemical parameters than usual to achieve greater accuracy in the calculation of the state of charge and thus achieve even more efficient battery management. In any type of battery with an electrochemical charge exchange process, the impedance measurement (Electrochemical Impedance Spectroscopy - EIS) of cells is applicable as a precision measurement technique. Furthermore, the cell's internal temperature can also be estimated more precisely from the impedance of the cell.

As can be concluded from the previous paragraphs, the individual management of each cell of a battery involves a high degree of atomization, given the deployment of elements necessary to carry out this task. In addition, these elements, which include sensors, control electronics, communication elements, etc., increase, in addition to cost, the weight and volume of the battery, which reduces its energy and power density. On the other hand, these elements also make the assembly or integration of the batteries difficult. That is why current battery pack solutions designed for transportation typically sacrifice access to individual cell and manage (monitoring and control) at module level (connected set of cells).

Using wireless communications between the monitoring and control elements present in a battery, the elements dedicated to communication are reduced by eliminating the cables used for this purpose. However, a reliability problem appears in RF communications due to the electrical noise present in a battery, aggravated if it is of high voltage and high power. Together, a cybersecurity problem also appears, since this type of communication is difficult to confine and is easily accessible from outside the battery.

The present invention relates to a battery management system (BMS) for an electric vehicle with visible light-based wireless communication (VLC) and an arrangement that can be easily integrated into the battery assembly line. Furthermore, the type of communications used can easily be confined within the battery and is not affected by electrical noise.

The integrated battery management system with cells connected in series includes various interface substrates to support and electrical connection to multiple cell management devices (System on Cell - SoCell) each installed on each interface substrate for monitoring , control and balance the cells, as well as for communications and identification of each cell. Units of measurement are included in the device, each one associated with a cell. Visible light based cell communication units are included. Cell control units are included to receive and process the measured parameters and monitor if the cell is operating correctly. The cell management devices can send and receive operating information using the cell communication units.

Included in the system is a Battery Management Unit (BMU) with a processor and a visible light communication unit. The battery management unit, based on the operating information of each cell, provides management information of the cells to eventually modify their operation for safety or efficiency reasons. It analyzes the battery globally and allows communication with the outside in a wired and secure way.

The battery management system that is the object of the present invention is based on the inclusion of the monitoring and control electronics of the cells instead of the traditional connection or junction plates of the cells. These connecting plates are replaced by an interface substrate, which serves to install the cell management device, connected to the cell electrodes. A bus bar connects adjacent interface substrates. This integration facilitates the battery mounting process by not modifying the arrangement of cells in the battery.

The cell management device can encompass the measurement, control and communication electronics, including the optoelectronic elements necessary for the transmission / reception of light. The cell management device in turn includes a cell integrated circuit to monitor, control and communicate the cells and an energy integrated circuit for the connection between cells and consequently, active balancing or "bypass" in the event of a cell failure. as well as additional electronic components necessary for its operation.The cell anode provides the positive supply voltage of the cell management device to which it is connected and the busbar from the adjacent lower voltage cell management device provides the voltage negative reference.

The cell integrated circuit includes a measurement unit with sensing circuits for the variables to be monitored, as well as a communication unit for the implementation of wireless communications based on visible light.

The integrated power circuit includes switches to manage the connections between the different cells, allowing, among other cell control functionalities, the disconnection of all cells for safety reasons or for mounting the cell management devices in the battery, active balancing, or "bypass" in the event of a cell failure.

The battery management unit globally manages the battery and communicates wirelessly via visible light with all cell management devices. The battery management unit can perform the calculations of the different parameters of interest of the battery locally or send the measured data via cables to another electronic control unit (ECU) of the vehicle for transmission and processing in the cloud.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a global diagram of the integration of the proposed integrated battery management system.

Figure 2 shows a particular embodiment of the interface substrate.

Figure 3 shows a particular embodiment of the cell management device.

Figure 4 shows a particular embodiment of the cell integrated circuit.

Figure 5 shows a particular embodiment of the energy integrated circuit.

Figure 6 shows the connection of the integrated power circuits with the battery cells and the different operating modes.

Figure 7 shows visible light optical communications between cell management devices and the battery management unit.

Numerical references:

1 Battery

2 Battery management unit (BMU)

3 Busbar

10 Cell

11 Cathode

12 Anode

20 Interface Substrate

24 Temperature sensor

30 Cell management device

21,23,22,31-35,37 Connections

36 Additional components

40 Cell Integrated Circuit

41 Unit of measurement

42 Power management unit

43 Visible light based communication unit

431 Visible light beam

44 Cell Identification Unit

441 RFID tag

45 Control unit

50 Integrated Power Circuit

51 Stopcock

DETAILED DESCRIPTION OF THE INVENTION

Next, a particular embodiment of the invention is described. In the present invention, the cell junction plates of a conventional battery are replaced by an interface substrate (20) that serves as a support for the cell management electronics (10), that is, a cell management device ( 30), see Figure 1 and Figure 2 .

In a particular embodiment of the invention, the interface substrate (20) must include connections (21) that join the poles and available connections of the cells with the cell management device (30) and other connections (22) that join the cells. two terminations of the bus bar (3) also to the cell management device (30), as shown in Figure 2 . These connections are isolated and are included in the substrate itself, avoiding moving parts (cables). Both the design of the interface substrate (20) and the connections will be adapted to the specific morphology of the cells (10) on which they act, whether prismatic, cylindrical, etc. On the other hand, the interface substrate (20) can also optionally include temperature sensors (24) in direct contact with the surface of the cells (10) with connections (23) on the substrate (20) itself (without moving parts) to the cell management device (30).

In a particular embodiment of the invention, the cell management device (30) includes the measurement, control and communication electronics. Among this electronics we can identify a cell integrated circuit (40), an energy integrated circuit (50) and additional electronic components (36) necessary for its operation, see Figure 3 . The cell management device (30) is fed from the anode (12) to which it is connected. The reference voltage reaches this cell management device (30) through a busbar (3) coming from the adjacent lower voltage cell management device (30), see Figure 1. The cell management device ( 30), as a minimum, must include the following connections (no moving parts, i.e. not wired), as shown in Figure 3 :

to. Power connections (31) from the anode of the cell to which it is connected to power both the cell integrated circuit (40) and the energy integrated circuit (50).

b. Connections (32) of the bus from the adjacent lower voltage cell management device (30) with the cell integrated circuit (40) and the power integrated circuit (50).

c. Connection (33) of the integrated energy circuit (50) with the cathode (11) of the cell to which it is connected.

d. Connection (34) of the integrated power circuit (50) with the bus bar that connects with the adjacent higher voltage cell management device (30).

and. Connections (35) for communication between the cell integrated circuit (40) and the energy integrated circuit (50) (the cell integrated circuit controls the energy integrated circuit).

F. Connections (37) to connect the optional temperature sensors (24) installed on the interface substrate (20).

Additional electronic components may include, but are not limited to, filter or energy storage capacitors, resistors, inductions, antenna for NFC, etc.

In another aspect of the invention, the cell integrated circuit is in charge of measuring the different parameters of the cells, of the control and of the communications. Therefore, as shown in Figure 4 , the cell integrated circuit may include, but is not limited to, the following blocks:

to. A unit of measurement (in English: Analog Front End - AFE) (41), including sensors of voltage, current, temperature and impedance (EIS). In addition, this measuring unit must perform filtering and analog-digital conversion of the measured signals.

b. A Power Management Unit (PMU) (42) that controls the power supply of the cell IC. This unit must filter and regulate the voltage supplied by the cells, in addition to being able to manage a possible failure of the cell that feeds it.

c. Visible light based communication unit (43). This unit must include an emitting element and a receiving element for visible light, if possible, integrated into the substrate of the cell integrated circuit itself.

d. Cell identification unit (optional) (44). This unit, not necessary in all implementations, must be able to identify the cell to which the cell management device (30) is connected. A particular implementation of this unit is by means of NFC communication with an RFID tag (in English: Radio Frequency Identification tag) (441) installed in the cell (10) to which the cell management device (30) is connected.

and. Control unit (45). This unit must manage the other blocks of the cell integrated circuit (40), as well as the energy integrated circuit (50). The control unit manages the performance of voltage, current and temperature measurements. It also manages and performs a pre-processing of the data obtained through the impedance sensor (EIS). Furthermore, this unit must implement the communication protocol, which must be compatible with a mesh network that communicates all cell management devices (30). The battery management unit (2) must also be in the communication network of the cell management devices (30). The control unit must also implement primary safety measures, for example by applying an elementary safety protocol that includes disconnection and / or bypass orders.

In another aspect, the invention comprises an integrated power circuit as an element in charge of managing the electrical connections between cells. It includes stopcocks (51) to allow these connections, see Figure 5 . These stopcocks (51) can be physically implemented with discrete power transistors or they can be designed as a single integrated circuit (ASIC) in an appropriate technology, such as GaN-on-SOI. These stopcocks (51) are controlled by the cell integrated circuit.

In a particular embodiment of the invention, the connections between cells are defined through the integrated power circuit (50) and the bus bar (3), as shown in Figure 6A .

In another aspect, the invention comprises the following operating modes with their respective connection between cells, see Figure 6B-6D :

to. Total disconnection. In this operating mode all the stopcocks (51) of the power integrated circuits (50) are disconnected. This mode allows the secure installation of the interface substrate (20) including the cell management device (30) in the battery. This mode is also a security mode. In the event of a global failure of the battery (1), as can happen in a serious vehicle accident, all cells (10) would be disconnected to avoid greater damage to the vehicle and, above all, to its occupants.

b. Normal operation. In this operating mode all cells (10) are connected in series, as shown in Figure 6B .

c. Active balancing. In this operating mode, two cells are connected in parallel to balance their load, as shown in Figure 6C (shaded cells).

d. Bypass. In this operating mode, a minimum of two cells are disconnected to allow the use of the rest of the cells of the module, as shown in Figure 6D (shaded cells). This operating mode makes it possible to electrically isolate damaged cells. The voltage generated by a damaged module will be less than nominal, but a DC-DC converter can be used to obtain the desired voltage at the output of the module. The cell management devices of the cells with "bypass" are fed with energy coming in a specific way from other cells as shown in Figure 6E (see shaded areas). This energy can be stored in a storage capacitor reserve installed as an additional electronic component of the cell management device for cells with "bypass".

There could be other modes of operation, such as impedance measurement mode (EIS), in which the cell under measurement would be isolated in a given period of time and which would have specific switching topologies based on the same principle.

In a particular embodiment of the invention, a battery management unit (2) is included to globally manage the battery (1) acting as a Master. The battery management unit communicates wirelessly by visible light with all cell management devices (30) as shown in Figure 7 . Since the information to be transmitted is included in visible light beams (431), this type of communication is very secure as it is easily confined within the battery itself (1) (the materials commonly used for battery construction are opaque). The battery management unit (2) can perform the calculation of different parameters of interest of the battery locally, such as SOC, State Of Health (SOH), etc. In another implementation of the present invention, the battery management unit (2) can send by wired communication the data measured by the individual cell management devices (30) to the vehicle's ECU for transmission and processing in the cloud. .

Claims (18)

1. Integrated battery management system for an electric vehicle comprising: - a plurality of interface substrates (20), each interface substrate (20) configured to support and electrical connection to a cell management device (30); - a plurality of measurement units (41), where each measurement unit (41) is configured to perform measurements associated with a cell (10); - a plurality of communication units for cells (43), said units based on visible light, with each unit (43) comprising a pair of emitter and receiver associated with a cell (10); - a plurality of cell management devices (30) configured to receive and process the measured parameters and monitor if the operation of the cell (10) is correct, where the cell management devices (30) are further configured to emit and receiving operating information through the cell communication units (43), where the operating information comprises information on electrical operation and on energy efficiency; - a battery management unit (2) comprises a processor and a communication unit by means of visible light, where the battery management unit (2), based on the operating information received from each cell management device (30 ) associated with each cell (10), processes and transmits management information of the cells (10), where the management information comprises information on modifying the operation of at least one cell (10). 2. Integrated battery management system for an electric vehicle according to claim 1, wherein the interface substrate (20) comprises the cell management device (30). Integrated battery management system for an electric vehicle according to claim 2, wherein the cell management device (30) comprises a cell integrated circuit (40) for managing the cell (10) and an energy integrated circuit ( 50) to manage the electrical connections between cells. 4. Integrated battery management system for an electric vehicle according to claim 3, wherein the integrated cell circuit (40) comprises, to measure operating information, a measurement unit (41) comprising at least one sensor of the following : a voltage sensor, a current sensor, a temperature sensor and an impedance sensor, with a first group of connections (21,22,23) fixed to the interface substrate itself (20) and a second group of connections ( 31,32,35,37) fixed to the cell management device itself (30). An integrated battery management system for an electric vehicle according to claim 3 or 4, wherein the cell integrated circuit (40) comprises a cell power management unit (42). 6. Integrated battery management system for an electric vehicle according to claim 5, wherein the cell power management unit (42) performs the following functions: filtering and regulating the voltage supplied by the cell (10) that powers the cell integrated circuit (40); Management to keep the cell integrated circuit (40) powered and operational despite possible failures of the cell (10) that supplies the circuit or disconnection thereof. 7. Integrated battery management system for an electric vehicle according to any one of claims 3 to 6, wherein the integrated cell circuit (40) comprises a communication unit based on visible light (43). 8. Integrated battery management system for an electric vehicle according to any one of claims 3 to 7, wherein the cell integrated circuit (40) comprises a cell identification unit (44). 9. Integrated battery management system for an electric vehicle according to claim 8, wherein the cell identification unit (44) identifies the cell (10) to which the cell management device (30) is connected through an RFID tag (441) associated with the cell (10). 10. Integrated battery management system for an electric vehicle according to any one of claims 3 to 9, wherein the cell integrated circuit (40) comprises a control unit (45) configured to implement an elementary security protocol through the application of disconnection and / or bypass orders to preserve the integrity of the cell (10). 11. Integrated battery management system for an electric vehicle according to claim 10, wherein the control unit (45) is further configured to control the visible light-based communication unit (43), the measurement unit (41) and the cell identification unit (44). 12. Integrated battery management system for an electric vehicle according to any one of claims 9 to 11, wherein the management information issued by the battery management unit (2) comprises management information associated with identification information of at least a cell (10) to selectively modify the switching topology. Integrated battery management system for an electric vehicle according to any one of the preceding claims, wherein the battery management unit (2) is configured to send information about the operation of the battery (1) to an electronic processing unit of the electric vehicle. 14. Integrated battery management system for an electric vehicle according to claim 13, wherein the information on the operation of the battery (1) is sent in a wired way. 15. Integrated battery management system for an electric vehicle according to any one of the preceding claims, wherein the battery management units (2) are configured to selectively act on one or more energy integrated circuits (50) and establish a modification operating according to one of the following operating modes: a disconnection of a cell (10); a series connection between at least two cells (10); a parallel connection of at least two cells (10) to balance load; a bypass where at least two consecutive cells (10) are disconnected. 16. Integrated battery management system for an electric vehicle according to claim 15, wherein the battery management units (2) act on the integrated energy circuit (50) through the control unit (45) of the integrated circuit of cell (40). 17. Integrated battery management system for an electric vehicle according to any one of the preceding claims, wherein each cell management device (30) is arranged on an interface substrate (20), where each interface substrate (20) is connected to the electrodes of a cell (10) and where a bus bar (3) connects interface substrates (20) that are contiguous. 18. Integrated battery management system for an electric vehicle according to any one of the preceding claims, wherein the visible light communications are based on a mesh network.