DE102014207395A1 - Method for battery management and battery management system - Google Patents

Abstract

The invention relates to a method for battery management of a battery having a plurality of battery modules each having a plurality of battery cells, sensors and at least one sensor control unit. It is provided that a failure of a sensor control device and / or sensor is at least temporarily compensated by non-existing measured values (46) of the relevant sensor control unit are calculated using measured values (46) of another sensor control unit and a correlation value of the relevant sensor control unit to the other sensor control unit , Furthermore, a computer program, a battery management system, a battery system and a motor vehicle are specified, which are set up to carry out the method.

Description

State of the art

The invention relates to a method for battery management of a battery, which comprises a plurality of battery cells. The invention also relates to a computer program, a battery management system, a battery system and a motor vehicle, which are set up to carry out the method.

Electronic control units are increasingly used in the automotive environment today, examples include engine control units and control units for ABS or the airbag. For electric powered vehicles, a current research focus is the development of powerful battery packs with associated battery management systems, i. Controllers equipped with software for monitoring battery functionality. Among other things, battery management systems ensure the safe and reliable functioning of the battery cells and battery packs used. They monitor and control currents, voltages, temperatures, insulation resistances and other sizes for individual cells and / or the entire battery pack. These sizes can be used to implement management functions that increase the life, reliability and safety of the battery system.

Battery management systems consist of a large number of control units on which individual software functionalities run. Depending on the number of battery cells, the number of sensors and the distribution of the battery modules to different installation spaces in the motor vehicle results in a ECU topology with a main control unit and a plurality of subordinate sensor control units for the acquisition of the measured values directly to the individual battery cells and battery modules. The collected data is exchanged between the controllers via a communication channel.

US 2008/0048619 shows a battery system with a plurality of accumulators, which are provided for driving a vehicle, wherein a fault detection unit is provided, which monitors the failure of current and voltage sensors.

US 2010/0136390 shows a plurality of battery modules, which are connected in parallel and in series, wherein first control units are provided which determine based on current and voltage values of sensors of the battery modules, how much power the battery modules can be removed and supplied, and wherein second control units are provided, which monitor the function of the first control units and if necessary actuate separation devices in the event of a sensor abnormality.

US 2012/0221172 shows a method for processing sensor data and for vehicle control, wherein in case of failure of sensor data via a communication unit alternatively data from sensors of other vehicles are used.

Disclosure of the invention

In a method according to the invention for battery management of a battery, which has a plurality of battery cells, sensors and sensor control devices, it is provided that a failure of a sensor control device and / or sensor is at least temporarily compensated by non-existing measured values of the relevant sensor control device being based on measured values of a further sensor control device and at least one correlation value of the relevant sensor control device to the further sensor control device can be calculated.

In order to increase the availability of the battery, limited operation is provided, at least temporarily, despite failed sensors or sensor control devices, by simulating the behavior of the failed measured values based on previously measured values and correlations with other control devices. By determining characteristic behavior of the measured values among each other, the failure of the affected sensor control device can be compensated.

As a result, the battery does not have to completely stop operation in the event of failure of sensors or control units, but can be brought into an emergency operation. Emergency operation restricts the operation of the battery, for example, by setting or narrowing limits on the power that can be called. It can also be provided that certain battery functions are not or only partially usable, such as the support of a start-stop system in a motor vehicle or the operation of electrical consumers.

By "at least temporarily" is meant that a failure may be permanent or only temporary, with "temporarily" meaning a certain amount of time. The failure and its duration is preferably also reported to a higher-level control device, for example a battery management system, so that corresponding reactions can take place.

The method may relate to any measured values by which battery management functions are implemented, such as the To determine the expected life of the battery system or state of health (SOH) of the battery. Such measured values include in particular cell voltages, cell temperatures, current strengths, module voltages, module temperatures. Further measured values, which are usually detected by sensor control devices and transmitted to the sensor control unit, are, for example, insulation resistances or states of charge of cells or modules. Likewise, measured values from variables of such sizes may include derived quantities, for example summed or integrated quantities, quantities multiplied together or otherwise aggregated. Also, difference values between minimum and maximum states may be included in the derived measurements.

For carrying out the battery functionalities, in particular the monitoring of the battery cells and the calculations for optimizing the battery use, a synchronous recording of the individual measured values, such as cell voltages, currents and temperatures, is advantageous. The measured values are therefore preferably recorded cyclically, for example every 50 ms.

The battery is preferably equipped with a battery management system for monitoring battery functionality. The battery management system includes the sensor controllers and a main controller, the sensor controllers communicating with the main controller via a communication channel. Preferably, the measured values of the sensors are received by the sensor control devices, optionally pre-processed and sent via the communication channel to the main control unit. The readings are processed by the main controller to complete the battery health monitoring function.

Preferably, the battery has a plurality of battery modules, each having a plurality of battery cells, sensors and at least one sensor control device. The terms "battery" and "battery unit" are used in the present description adapted to the usual language for accumulator or Akkumulatoreinheit. The battery includes one or more battery units, which may be a battery cell, a battery module, a module string or a battery pack may be designated. In the battery, the battery cells are preferably spatially combined and interconnected circuitry, for example, connected in series or parallel to modules. Several modules can form so-called Battery Direct Converters (BDCs), and several battery direct converters form a Battery Direct Inverter (BDI).

According to a preferred embodiment, a specific battery cell is defined as a correlation partner for each battery module. Calculating and storing correlation values from each individual measured value to all other measured values is considered to be costly. Advantageously, the failure of several sensor control devices is compensated, but the cost of this is kept low by a number of correlation partners is set, which corresponds to the number of existing battery modules in the battery. This can for example be the first cell on each connected battery module, but also any other cell. For each measurement cycle, the correlation values of all measured voltages to the correlation partners are calculated and stored. As a result, the memory requirement for the correlation values is kept low.

The correlation partners can be changed dynamically. For example, a re-selection of the correlation partner may be cyclic, and by determining a cell having a typical behavior in the battery module, which typical behavior may be determined by the average of the battery cell readings or by the value of most battery cells within the module. The correlation partners may also be different for different measurements.

According to one embodiment, the calculation of the correlation value comprises averaging or the formation of a median of a certain number of previously calculated correlation values. The mean value may be, for example, a geometric or an arithmetic mean. The determined number of correlation values used for the averaging is determined taking into account the memory requirement.

According to a preferred embodiment, the correlation values are determined in each measurement cycle. The continuous recording of the correlation values ensures that the age-related behavioral differences of the measured values can be faithfully reproduced. A frequent measurement and determination of the correlation values allows a precise reconstruction of measured values.

According to a preferred embodiment, a first correlation value for increasing measured values and a second correlation value for falling measured values are determined. As a result of aging, the cells show varying degrees of fluctuation in charging or discharging processes over the life of the batteries. The use of two correlation values for charging and discharging the battery therefore allows a more accurate reconstruction of the readings of failed sensor controllers.

According to a preferred embodiment, the correlation values are stored in a non-volatile memory at the end of a drive cycle. The non-volatile memory is, for example, a so-called EEPROM (Electrically Erasable Programmable Read-Only Memory), ie a non-volatile, electronic memory module whose stored information can be electrically erased. The nonvolatile memory is, for example, a memory of the main controller. When saving, values saved from previous driving cycles are compared with the current correlation values and updated, for example, by averaging.

According to the invention, a computer program is also proposed according to which one of the methods described herein is performed when the computer program is executed on a programmable computer device. The computer program may be, for example, a software module, a software routine or a software subroutine for implementing a battery management system on a control unit of a motor vehicle. The computer program can be stored on a machine-readable storage medium, such as on a permanent or rewritable storage medium or in association with a computer device, for example on a portable storage such as a CD-ROM, a DVD, a Blu-Ray Disc, a USB stick or a memory card. Additionally or alternatively, the computer program may be provided for download on a computing device, such as on a server or a cloud server, for example over a data network such as the Internet or over a communication link such as a telephone line or wireless connection.

According to the invention, a battery management system of a battery which has a plurality of battery cells, sensors and sensor control units is also proposed, wherein the battery management system has at least one unit for determining correlation values of the sensor control units and a failure compensation unit which is set up in the event of failure of a sensor control unit and / or sensor to calculate existing measured values of the relevant sensor control device based on measured values of a further sensor control device and at least one correlation value of the relevant sensor control device to the further control device.

The battery management system is preferably designed and / or set up to carry out the methods described herein. Accordingly, the features described in the context of the method apply correspondingly to the battery management system and, conversely, the features described within the scope of the battery management system apply correspondingly to the methods.

In particular, the battery management system preferably has a main control unit and a plurality of sensor control units which are connected to one another via a communication channel, wherein the sensor control units are set up to receive measured values of the sensors, optionally further process them and send them to the main control unit via the communication channel, these being sent from the main control unit be further processed.

The units of the battery management system are to be understood as functional units that are not necessarily physically separated from each other. Thus, several units of the battery management system can be implemented in a single physical unit, such as when multiple functions are implemented in software. Furthermore, the units of the battery management system can also be realized in hardware, for example by application-specific integrated circuits (ASIC) or in memory units. In particular, the failure compensation unit is preferably implemented as software or ASIC in the battery management system.

According to the invention, a battery system is also provided with a battery which comprises a plurality of battery cells and such a battery management system. The battery may in particular be a lithium-ion battery or a nickel-metal hydride battery and be connectable to a drive system of a motor vehicle.

According to the invention, a motor vehicle is also provided with such a battery system, wherein the battery is connected to a drive system of the motor vehicle. The motor vehicle may be configured as a pure electric vehicle and exclusively comprise an electric drive system. Alternatively, the motor vehicle may be configured as a hybrid vehicle comprising an electric drive system and an internal combustion engine. In some variants it can be provided that the battery of the hybrid vehicle can be charged internally via a generator with excess energy of the internal combustion engine. Externally rechargeable hybrid vehicles (PHEV) also provide the option of charging the battery via the external power grid. In motor vehicles designed in this way, the driving cycle includes a driving operation and / or a charging operation as operating phases in which operating parameters are detected as measured values.

In order to record the time course of the measured values, the sensors continuously monitor individual battery cells or individual battery modules and provide the corresponding data to the sensor control devices. For example, data may be exchanged between the sensors and the sensor controllers via a bus, such as via a Serial Peripheral Interface (SPI) bus or a Controller Area Network Bus (CAN) bus. In this case, continuous means that after defined time intervals or with a defined sampling rate, for example every minute, measured values are detected by the sensors and transmitted to the sensor control devices. To record the time course of the measured values, the acquired measured values are stored in a memory unit. The defined time interval or the defined sampling rate can be adapted to the frequency of the changes in the measured values, wherein an upper limit is also given by the data transmission rate of the bus between the sensors and the sensor control devices.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it:

1 a motor vehicle with a battery system,

2 a time course of various operating parameters of a battery,

3 a time profile of various operating parameters of a battery showing a failure of a sensor control unit,

4 exemplary voltage values of two consecutive measurement times of two sensors and

5 exemplary voltage values of three consecutive measurement times of two sensors.

In the following description of the embodiments of the invention, the same or similar components are denoted by the same or similar reference numerals, wherein in individual cases a repeated description of these components is dispensed with. The figures illustrate the subject matter of the invention only schematically.

Embodiments of the invention

1 shows an at least partially electrically powered motor vehicle 10 with a battery system 12 ,

The car 10 of the 1 can be designed as a purely electrically driven vehicle or as a hybrid vehicle, which additionally has an internal combustion engine. This is the motor vehicle 10 with an electric drive system 14 equipped, that the motor vehicle 10 via an electric motor (not shown) at least partially electrically drives.

The electrical energy is from a battery 16 provided. The battery 16 includes several battery cells 19 or accumulator cells, for example, lithium ion cells with a voltage range of 2.8 to 4.2 V. The battery cells 19 are in groups to battery modules 20 summarized, and in this case in series and sometimes additionally connected in parallel to the required performance and energy data with the battery 16 to achieve.

The battery 16 is part of a battery system 12 , which also includes a battery management system. The battery management system includes a main controller 18 and multiple sensor controllers 17 , which the battery modules 20 assigned.

To individual battery cells 19 or battery modules 20 These are with cell sensors to monitor 22 or module sensors 23 equipped with continuous sampling rates operating parameters such as voltages, currents or temperatures of individual battery cells 19 or individual battery modules 20 as measured values 46 capture and the recorded readings 46 the sensor control units 17 provide. The sensor control units 17 receive the readings 46 the cell sensors 22 and module sensors 23 , equip the readings 46 if necessary, with time stamps, process them and send them via a communication channel 24 such as a Serial Peripheral Interface (SPI) bus or a Controller Area Network Bus (CAN) bus to the main controller 18 so that the main control unit 18 Measured value series of the individual sensors 22 . 23 to be provided. The sampling rates of the sensors 22 . 23 are for example at 20 Hz, but may differ depending on the operating parameters.

The main control unit 18 implements functions to control and monitor the battery 16 , In particular, the main controller 18 an interface 26 for receiving the measured values 46 on the sensor bones 17 were shipped. The main control unit 18 has also a storage unit 30 on, for example, an EEPROM memory (Electrically Erasable Programmable Read-Only Memory) or a RAM memory (Random Access Memory), in which the measured values 46 temporary, ie volatile, or permanent, ie non-volatile.

The main control unit 18 still has a unit 28 for determining correlation values of the sensor control devices 17 whose operation in particular with reference to the 4 and 5 is described. The unit 28 to determine correlation values stores them in the memory unit 30 ,

The main control unit 18 also has a failure compensation unit 32 which depends on data from the storage unit 30 accesses. The failure compensation unit 32 is set up in case of failure of a sensor control unit 17 and / or sensors 22 . 23 non-existent measured values 46 the relevant sensor control unit 17 based on measured values 46 another sensor control unit 17 and a correlation value of the respective sensor control device 17 to calculate the further control unit, where the measured values 46 and the correlation values from the storage unit 30 determined and the failed readings are reconstructed. The failure compensation unit 32 sets the readings 46 and reconstructed readings 42 ready to implement the functions of the battery management system.

2 shows voltage curves 36 of six battery cells 19 , where three battery cells 19 each of a sensor control unit 17 be measured. The voltage curves 36 form the operating parameter cell voltage U as a continuous course over time t. The operating parameter cell voltage U is used here only as an example. The inventive method is applicable to any operating parameters, which continuously with a defined sampling rate of the sensors 22 . 23 be captured, what as readings 46 in the 2 at the different measuring times 38 is shown. The measured values 46 at the measuring times 38 are only for one sensor 22 . 23 actually shown, are in normal operation but for each sensor 22 . 23 in front.

Based on the illustrated voltage curves 36 it turns out that all the battery cells 19 behave similarly, both during the charging phases (increasing voltage) and discharging phases (decreasing voltage).

3 shows the voltage curves 36 the two sensor control units 17 with the measured values 46 each of the three battery cells 19 according to 2 , where at the measuring times t3 and t4 partly no measured values 46 available. This may be due to the failure of the second sensor control device 17 or the failure of the corresponding cell sensors 22 which are voltage sensors here.

4 shows by way of example the voltage values of two successive measurement times 38 wherein the to a first sensor control device 17 associated voltage values with the reference numeral S1 and to a second sensor control unit 17 associated measured values 46 are provided with the reference S2. In the example, the cell voltage of the first battery cell decreases 19 from 4.0V to 3.9V. The voltage of the second battery cell 19 drops from 3.9V to 3.75V. The values are merely illustrative of the method and are not meant to be limiting. In particular, they do not exactly match the real behavior of voltages in battery systems 12 , The stronger drop in the voltage of the second battery cell 19 is intentionally large in this example.

• – S1: fällt von 4,0 V auf 3,9 V → –0,1 V
• – S2: fällt von 3,9 V auf 3,75 V → –0,5 V
• – Verhältnis der Steigungen S2/S1: –0,15 V/–0,1 V = 1,5

The different slope is from the unit 28 correlated to determine correlation values as follows:

• S1: falls from 4.0 V to 3.9 V → -0.1 V.
• - S2: falls from 3.9 V to 3.75 V → -0.5 V.
• - Ratio of slopes S2 / S1: -0.15 V / -0.1 V = 1.5

The voltage S2 thus drops by 50% as that of the S1, which is a correlation value of the second sensor control device 17 to the first sensor control device 17 (S2: S1) equals 1.5.

In the case of "0 divided by 0" (that is, the differences of both voltages are 0), "1" is defined as the correlation value. No change in both voltages corresponds to an identical change of both voltages by definition. If the denominator or the counter = 0, no correlation value can be determined. In this case the correlation value "1" is also selected by definition.

5 shows by way of example the voltage values of three consecutive measurement times 38 wherein the first sensor control device 17 associated voltage values with the reference numeral S1 and the second sensor control unit 17 associated measured values 46 are provided with the reference S2. Based 5 becomes the reconstruction of non-existent measurements 46 shown. It will be a failure of the second sensor control unit 17 for the second voltage S2 at the times t2 and t3 and a correlation value of the second sensor control device 17 to the first sensor control device 17 from 1.5 accepted. By lowering the voltage S1 by 0.1 V. At time t2, the failed value for S2 is calculated as follows: S2 (t2) = S2 (t1) + (S1 (t2) - S1 (t1)) · correlation value S2 / S1.

The result is the voltage S2 (t2) = 3.9 V + (3.9 V - 4.0 V) · 1.5 = 3.75 V. Similarly, the voltage S2 (t3) = 3.75 V results + (3.95V - 3.9V) x 1.5 = 3.825V.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2008/0048619 [0004]
• US 2010/0136390 [0005]
• US 1012/0221172 [0006]

Claims (11)

Method for battery management of a battery ( 16 ), the several battery cells ( 19 ), Sensors ( 22 . 23 ) and sensor control devices ( 17 ), characterized in that a failure of a sensor control device ( 17 ) and / or sensors ( 22 . 23 ) is at least temporarily compensated for by non-existing measured values ( 46 ) of the relevant sensor control device ( 17 ) based on measured values ( 46 ) of another sensor control device ( 17 ) and at least one correlation value of the relevant sensor control device ( 17 ) to the further sensor control device ( 17 ) be calculated. Method according to claim 1, characterized in that the battery ( 16 ) is equipped with a battery management system for monitoring the battery functionality, which the sensor control devices ( 17 ) and a main control unit ( 18 ), wherein the sensor control devices ( 17 ) with the main control unit ( 18 ) via a communication channel ( 24 ) communicate with each other. Method according to one of the preceding claims, characterized in that for each battery module ( 20 ) a particular battery cell ( 19 ) is defined as a correlation partner. Method according to one of the preceding claims, characterized in that the calculation of the correlation value includes an averaging or median formation of a certain number of previously calculated correlation values. Method according to one of the preceding claims, characterized in that the correlation values are determined in each measurement cycle. Method according to one of the preceding claims, characterized in that a first correlation value for increasing measured values ( 46 ) and a second correlation value for falling measured values ( 46 ) be determined. Method according to one of the preceding claims, characterized in that the correlation values are stored in a non-volatile memory at the end of a drive cycle. A computer program for performing any of the methods of any one of claims 1 to 7 when the computer program is executed on a programmable computer device. Battery management system of a battery ( 16 ), the several battery cells ( 19 ), Sensors ( 22 . 23 ) and sensor control devices ( 17 ), characterized in that the battery management system comprises at least one unit ( 28 ) for determining correlation values of the sensor control devices ( 17 ) and a failure compensation unit ( 32 ), which is set up in the event of a failure of a sensor control device ( 17 ) and / or sensors ( 22 . 23 ) non-existent measured values ( 46 ) of the relevant sensor control device ( 17 ) based on measured values ( 46 ) of another sensor control device ( 17 ) and at least one correlation value of the relevant sensor control device ( 17 ) to the other control unit. Battery system ( 12 ) with a battery ( 16 ), which several battery cells ( 19 ), and a battery management system according to claim 9. Motor vehicle ( 10 ) with a battery system ( 12 ) according to claim 10.

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