US-12620636-B2 - Method for monitoring and controlling a battery pack, system for monitoring and controlling a battery pack, battery management system

US12620636B2US 12620636 B2US12620636 B2US 12620636B2US-12620636-B2

Abstract

A method for monitoring and controlling a vehicle battery pack that includes a plurality of battery cells. The battery cells each include a switching unit which serves to connect and disconnect the respective battery cells. Pack information of the battery pack is acquired, a pack voltage of the battery pack is calculated on the basis of the cell voltages and a current activation pattern for actuating the switching units. An electrical power requirement of the vehicle is predicted based on GPS information. A state of the battery pack is estimated based on the pack information and the current activation pattern and an optimized activation pattern for actuating the switching units on the basis of the predicted electrical power requirement and the estimated state of the battery pack is calculated. The switching units of the respective battery cells are actuated according to the optimized activation pattern.

Inventors

Abouzede Mondoha
Simon Tippmann

Assignees

ROBERT BOSCH GMBH

Dates

Publication Date: 20260505
Application Date: 20221101
Priority Date: 20211102

Claims (10)

1 . A method for monitoring and controlling a battery pack ( 24 ) of a vehicle ( 10 ), which battery pack comprises a plurality of battery cells ( 2 ) interconnected in parallel and/or in series, the battery cells ( 2 ) each comprising a switching unit ( 40 ) which serves to connect and disconnect the respective battery cells ( 2 ) separately, the method comprising the steps of: acquiring, via one or more sensors, pack information of the battery pack ( 24 ), the pack information comprising at least cell voltages (V mes ), cell temperature (T mes ) of the respective battery cells ( 2 ), and a pack current (I pack,mes ); calculating a pack voltage (V pack ) of the battery pack ( 24 ) on the basis of the cell voltages (V mes ) of the respective battery cells ( 2 ) and a current activation pattern (u) for actuating the switching units ( 40 ); predicting, via a power prediction module ( 14 ), an electrical power requirement (P elec ) of the vehicle ( 10 ) based on information GPS Info acquired by a GPS module ( 12 ), wherein the information GPS Info includes a speed and location of the vehicle ( 10 ); estimating, via a state estimation module ( 60 ), the state (x s ) of the battery pack ( 24 ) based on the pack information and the current activation pattern (u); calculating, via a control device, an optimized activation pattern (u*) for actuating the switching units ( 40 ) on the basis of the predicted electrical power requirement (P elec ) and the estimated state (x s ) of the battery pack ( 24 ); and actuating, via the control device, the switching units ( 40 ) of the respective battery cells ( 2 ) according to the optimized activation pattern (u*) for actuating the switching units ( 40 ) for connecting and disconnecting the respective battery cells ( 2 ).
2 . The method according to claim 1 , wherein the optimized activation pattern (u*) is calculated by means of model predictive control ( 76 ).
3 . The method according to claim 2 , wherein the model predictive control ( 76 ) is performed based on Pareto optimization.
4 . A system ( 100 ) for monitoring and controlling a battery pack ( 24 ) of a vehicle ( 10 ), which battery pack comprises a plurality of battery cells ( 2 ) interconnected in parallel and/or in series, the battery cells ( 2 ) each comprising a switching unit ( 40 ) which serves to connect and disconnect the respective battery cells ( 2 ) separately, the system ( 100 ) comprising: a GPS module ( 12 ) of the vehicle ( 10 ), a power prediction module ( 14 ) configured to predict an electrical power requirement (P elec ) of the vehicle ( 10 ) on the basis of information GPS Info acquired by the GPS module ( 12 ), wherein the information GPS Info includes a speed and location of the vehicle ( 10 ), a state estimation module ( 60 ) configured to estimate a state (x s ) of the battery pack ( 24 ) on the basis of pack information, and a control device ( 70 ) configured to calculate an optimized activation pattern (u*) for actuating the switching units ( 40 ) on the basis of the predicted electrical power requirement (P elec ) and the estimated state (x s ) of the battery pack ( 24 ), and to actuate the switching units ( 40 ) of the respective battery cells ( 2 ) according to the optimized activation pattern (u*) for actuating the switching units ( 40 ) for connecting and disconnecting the respective battery cells ( 2 ).
5 . A battery management system for monitoring and controlling a battery system ( 20 ) of a vehicle ( 10 ), which battery system comprises at least one battery pack ( 24 ) having a plurality of battery cells ( 2 ) interconnected in parallel and/or in series, each comprising a switching unit ( 40 ) which serves to connect and disconnect the respective battery cells ( 2 ) separately, the battery management system comprising: a power prediction module ( 14 ) configured to predict an electrical power requirement (P elec ) of the vehicle ( 10 ) based on information GPS Info acquired by the GPS module ( 12 ), wherein the information GPS Info includes a speed and location of the vehicle ( 10 ), a state estimation module ( 60 ) configured to estimate a state (x s ) of the at least one battery pack ( 24 ), and a control device ( 70 ) configured to calculate an optimized activation pattern (u*) for actuating the switching units ( 40 ) on the basis of the predicted electrical power requirement (P elec ) and the estimated state (x s ) of the at least one battery pack ( 24 ), and to actuate the switching units ( 40 ) of the respective battery cells ( 2 ) according to the optimized activation pattern (u*) for actuating the switching units ( 40 ) for connecting and disconnecting the respective battery cells ( 2 ).
6 . A battery system ( 20 ) of a vehicle ( 10 ), comprising at least one battery pack ( 24 ) having a plurality of battery cells ( 2 ) interconnected in parallel and/or in series, each comprising a switching unit ( 40 ) which serves to connect and disconnect the respective battery cells ( 2 ) separately, wherein the battery system ( 20 ) is configured to predict an electrical power requirement (P elec ) of the vehicle ( 10 ) on the basis of information GPS Info acquired via a GPS module ( 12 ), wherein the information GPS Info includes a speed and location of the vehicle ( 10 ), estimate a state (x s ) of the battery pack ( 24 ) on the basis of pack information, and calculate an optimized activation pattern (u*) for actuating the switching units ( 40 ) on the basis of the predicted electrical power requirement (P elec ) and the estimated state (x s ) of the battery pack ( 24 ), and to actuate switching units ( 40 ) of the respective battery cells ( 2 ) according to the optimized activation pattern (u*) for actuating the switching units ( 40 ) for connecting and disconnecting the respective battery cells ( 2 ).
7 . The battery system ( 20 ) according to claim 6 , wherein the at least one battery pack ( 24 ) comprises one or more strings ( 26 ) of battery cells ( 2 ) which are interconnected in series within the respective strings ( 26 ).
8 . The battery system ( 20 ) according to claim 6 , wherein the switching units ( 40 ) each comprise a first switching element ( 42 ) and a second switching element ( 44 ), the first switching element ( 42 ) and the corresponding battery cell ( 2 ) forming a series circuit ( 30 ), and the second switching element ( 44 ) being connected in parallel with the series circuit ( 30 ).
9 . The battery system ( 20 ) according to claim 8 , wherein the first and the second switching element ( 42 , 44 ) are each designed as semiconductor switches.
10 . A vehicle ( 10 ) comprising A battery pack having a plurality of battery cells ( 2 ) interconnected in parallel and/or in series, the battery cells ( 2 ) each comprising a switching unit ( 40 ) which serves to connect and disconnect the respective battery cells ( 2 ) separately, the vehicle configured to: acquire, via one or more sensors, pack information of the battery pack ( 24 ), the pack information comprising at least cell voltages (V mes ), cell temperature (T mes ) of the respective battery cells ( 2 ), and a pack current (I pack, mes ); calculate a pack voltage (V pack ) of the battery pack ( 24 ) on the basis of the cell voltages (V mes ) of the respective battery cells ( 2 ) and a current activation pattern (u) for actuating the switching units ( 40 ); predict, via a power prediction module ( 14 ), an electrical power requirement (P elec ) of the vehicle ( 10 ) based on information GPS Info acquired by a GPS module ( 12 ) of the vehicle ( 10 ), wherein the information GPS Info includes a speed and location of the vehicle ( 10 ); estimate, via a state estimation module ( 60 ), the state (x s ) of the battery pack ( 24 ) based on the pack information and the current activation pattern (u); calculate, via a control device, an optimized activation pattern (u*) for actuating the switching units ( 40 ) on the basis of the predicted electrical power requirement (P elec ) and the estimated state (x s ) of the battery pack ( 24 ); and actuate, via the control device, the switching units ( 40 ) of the respective battery cells ( 2 ) according to the optimized activation pattern (u*) for actuating the switching units ( 40 ) for connecting and disconnecting the respective battery cells ( 2 ).

Description

BACKGROUND OF THE INVENTION The invention relates to a method and a system for monitoring and controlling a battery pack of a vehicle which comprises a plurality of battery cells interconnected in parallel and/or in series, the battery cells each comprising a switching unit which serves to connect and disconnect the respective battery cells separately. The invention further relates to a battery management system and a battery system. The development of electrified vehicles aims to improve the energy efficiency of automotive systems and at the same time to reduce or even eliminate pollutant emissions. Currently, lithium ion batteries are the most frequently used energy storage system in electrified vehicles, because they provide a high energy density with respect to mass and volume, at a smaller size. A plurality of individual lithium ion cells are connected in series and/or in parallel in order to cover the energy and power requirement of the drive. Such a configuration leads to an unavoidable imbalance of the lithium ion cells, which in turn affects the power and service life of the battery pack. In this case, three linked types of imbalances occur within a battery pack. The imbalance of the state of charge (SoC) due to a non-uniform manufacturing process, is also known as a deviation of the remaining amount of energy stored in each lithium ion cell. This imbalance has a direct effect on the cell voltages and thus on the power. The thermal imbalance is caused by the internal resistance of the cells, the temperature gradients in the cooling system, and the position of the cells in the battery pack. The imbalance of the state of health (SoH) indicates the degree of degradation of the individual lithium ion cells within the battery pack. However, lithium ion batteries are complex electrochemical devices having a pronounced nonlinear behavior which depends on various internal and external conditions. Lithium reacts very sensitively to operating conditions and the environmental conditions imposed on it. The temperature is one of the most important factors that causes imbalances in the battery pack. Charging or discharging lithium ion batteries in an electrified vehicle generates strong electrical currents, which in turn leads to significant heating. The increase in temperature can be critical for the operational safety of the battery pack, and in any case leads to a faster aging of the lithium ion cells. Furthermore, the thermal imbalance leads to heterogeneity of the power delivered by each individual lithium ion cell and reduces the overall power of the battery pack. According to the prior art, the imbalance of the state of charge can be treated, for example, by the incorporation of passive or active electrical circuits into the battery configuration. Complex architectures are proposed for heat management, in order to cool the battery pack. These architectures focus primarily on the design of the cooling system, which can be passive or active. The cooling system aims to keep the temperature of the battery pack below a target value and to ensure uniform temperature distribution across all lithium ion cells within the battery pack. In the case of too high a temperature, the proposed solution consists in reducing the electrical power exchanged with the battery pack. With respect to the state of health, constraints are considered in order to reduce the degradation of the battery, such as limiting the charging current in order to avoid the lithium plating process. The document US 2019/0196427 A1 describes a system and a method for controlling a dispatch operation of one or more energy storage units in an energy storage system. The document US 2017/0361832 A1 describes a system and a method for controlling and operating a hybrid vehicle. In this case, a power requirement of the hybrid vehicle is predicted by a power flow control system on the basis of changing conditions during operation of the hybrid vehicle. SUMMARY OF THE INVENTION A method for monitoring and controlling a battery pack of a vehicle, in particular an electrically driven vehicle, such as hybrid and electric vehicles, is proposed. In this case, the battery pack has a plurality of battery cells which are interconnected in parallel and/or in series. In this case, the battery cells each comprise a switching unit which serves to connect and disconnect the respective battery cells separately. When the method according to the invention is carried out, pack information of the battery pack is acquired. In this case, the pack information comprises at least cell voltages and cell temperatures of the respective battery cells, and a pack current. In the event that a temperature sensor is not assigned to each of the battery cells, the cell temperature can be estimated by means of temperature measurement at different positions in the battery pack. In this case, the acquisition of the pack current can take place by measuring or calculating. For example, the batte