WO2016119986A1

WO2016119986A1 - Monitoring of a battery systems during debouncing times resulting from control

Info

Publication number: WO2016119986A1
Application number: PCT/EP2015/081319
Authority: WO
Inventors: Frank Stimm
Original assignee: Robert Bosch Gmbh
Priority date: 2015-01-30
Filing date: 2015-12-29
Publication date: 2016-08-04
Also published as: DE102015201628A1

Abstract

The invention relates to a method for monitoring operating parameters (x) of a rechargeable high-voltage battery system (11) of an electric or hybrid vehicle during debouncing times resulting from control, wherein the high-voltage battery system (11) comprises a plurality of battery cells (15) interconnected to each other. The operating parameters (x) of the high-voltage battery system (11) or of the individual battery cells (15) are sensed during the debouncing times and evaluated by comparison with permissible limit values (x₀). Limit-value exceedances are counted and stored as a number of error entries (N) for further evaluation. The invention further relates to an electric drive train (10) of an electric or hybrid vehicle, comprising a high-voltage battery system (11) and an electric machine (14), which are electrically connected to each other by means of an open-loop and/or closed-loop control unit (13). Operating parameters (x) of the high-voltage battery system (11) sensed during debouncing times resulting from control can be mathematically evaluated by the open-loop and/or closed-loop control unit (13).

Description

description

title

Monitoring a battery system during control-related

debounce

The present invention relates to electric and hybrid vehicles with

rechargeable high-voltage battery systems, and in particular a method for monitoring operating parameters of the high-voltage battery system during derailleur-related Entprellzeiten and an electric drive train of such a vehicle.

State of the art

Among other things, the automotive industry is reducing the consumption of fossil fuels through a gradual electrification of vehicle drives, so-called hybrid-electric (HEV) or battery-electric (BEV) vehicles. In addition, auxiliary and auxiliary units of such vehicles are increasingly electrified, such as the electric power steering. In order to provide the required performance in hybrid and electric vehicles, high-voltage battery systems are used as rechargeable or rechargeable energy storage. Such battery systems typically have a plurality of

Battery modules, which are composed of several interconnected battery cells. High voltage battery systems include, for example, nickel metal hybrid, lithium ion and sodium nickel chloride battery systems.

Lithium-ion batteries are increasingly being used, as they are characterized by their relatively high energy densities and cell voltages. However, lithium-ion batteries are relatively sensitive to both overcharging and over-discharging. The aging of lithium-ion batteries is general strongly from the ambient temperature, the cell voltages and the

Charging currents dependent. Therefore, it should be ensured for all lithium-ion battery cells to comply with upper and lower cell voltage limits. On the other hand, at low temperatures by the specific

Electrochemical cell kinetics significantly reduced the discharge performance, which manifests itself above all in an increased internal resistance of a battery cell, but also in a reduced discharge capacity, especially at high currents. The height of the charging currents should therefore be limited, especially at low temperatures. To avoid critical conditions, various operating parameters of battery cells, such as current, voltage and temperature, are continuously or periodically measured and evaluated.

Due to control processes in a vehicle and for reasons of robustness, cut-off limits for operating parameters of battery cells, such as, for example, current, voltage and temperature, are typically debounced in time. During such debouncing, ie in the debounce time, there may be an operation of battery cells outside of a predetermined

Operating range, which is not registered by standard control and / or regulating units. If operation of battery cells outside of the predetermined operating range frequently occurs, this can lead to an accelerated and unexpected aging of the affected battery cells, which in extreme cases can pose a safety risk.

The use of debouncing for reasons of robustness is known, for example, from the document DE 10 201 1 086 043 A1 in the context of the classification of the functional capability of an energy storage cell. Here will be one

Calculated a plurality of debouncing factors, one each

Debouncing factor associated with a determination of an internal resistance of at least one energy storage cell is assigned. The classification of the functionality of the at least one energy storage cell is carried out based on a calculated integral.

The document DE 10 2009 054 959 A1 discloses a method for

Error detection in a control unit for controlling and / or regulating a Drive machine in a vehicle known to be monitored with the operating variables to the presence of fault conditions. In particular, the method also makes it possible to specify a debounce time, wherein the erroneous state is evaluated as an error after the debounce time has expired.

From the document DE 10 2005 062 873 A1 a method for operating a control and / or regulating device is known, in which debouncing is provided in order to prevent fault reactions from being triggered unnecessarily for only very short-term fault states.

Against this background, it is an object of the present invention to enable monitoring of battery cells of a battery system, which serves to drive a motor vehicle, during operational debounce times. Disclosure of the invention

To solve the problem, a method for monitoring

Operating parameters of a rechargeable high-voltage battery system of an electric or hybrid vehicle during regulatory technical conditional

Entprellzeiten and an electric drive train of an electric or

Hybrid vehicle having a control and / or regulating unit for

Processing and evaluation of the operating parameters proposed.

Accordingly, the invention provides a method for monitoring operating parameters of a rechargeable high-voltage battery system of an electric or hybrid vehicle during regulatory technical conditional

Entprellzeiten, wherein the high-voltage battery system a plurality of

includes interconnected battery cells. The operating parameters of the high-voltage battery system or of the individual battery cells are recorded during the debounce times and evaluated by comparison with permissible limit values. Limit overruns are counted and stored as a number of error entries for further evaluation. By detecting and evaluating fault entries when limit values are exceeded for the various operating parameters, early aging of the battery cells of the battery system as well as problems in the electric powertrain of an electric or hybrid vehicle can be detected and safety risks avoided.

Compared with the prior art, the method according to the invention has the advantage that premature aging of the high-voltage battery system or of the individual battery cells can be diagnosed by an insufficient regulation of the electric drive.

In an advantageous embodiment of the invention, it is provided that the number of fault entries are compared with a predetermined reference value in order to detect premature aging of the high-voltage battery system. If the reference value is reached or exceeded, the battery system or the entire electric drive train of the electric or

Hybrid vehicle shut down or a maintenance arranged.

In a further advantageous embodiment of the invention, it is provided that a temporal analysis of the number of error entries is performed, being drawn from the temporal analysis conclusions regarding the beginning and the frequency of the error entries.

This time analysis can be used to detect problems in the powertrain of a vehicle. In particular, with this temporal

Analysis conclusions are drawn since when the error entries occur and whether the frequency over time, ie the frequency of error entries, has increased and thus, whether an accelerated aging of the battery system or individual battery cells has occurred or occurs and whether the regulation of Driveline has worsened or increasingly deteriorated.

According to a preferred embodiment of the invention, it is provided that for the temporal analysis, the number of error entries over a certain period of time is recorded, the number of error entries is stored, and thus provided for later evaluation and a division of the recorded error entries is made in different periods.

According to a further preferred embodiment of the invention, it is provided that the number of defect entries over time is displayed graphically and the slope of the graph is used to analyze the defect entries.

It is further provided that an exponentially increasing number of fault entries early diagnosis of battery cells is diagnosed.

A further advantageous embodiment of the invention provides that the high-voltage battery system is used as part of an electric drive train of the electric or hybrid vehicle, wherein at a

exponentially increasing number of fault entries a problem of the electric drive train is diagnosed.

A further advantageous embodiment of the invention provides that as

Operating parameters of the current, the voltage, the average current and the

Temperature can be detected during the Entprellzeiten.

A further advantageous embodiment of the invention provides that the

Evaluation of the fault entries of a control or regulating unit, which is carried out with the high-voltage battery system and an electric motor of the electric or hybrid vehicle.

To achieve the object mentioned above, an electric drive train of an electric or hybrid vehicle comprising a high-voltage battery system and an electric machine, which are electrically connected to each other via a control and / or regulating unit, also proposed. During regulatory-related Entprellzeiten detected operating parameters of the high-voltage battery system are mathematically evaluated by the control and / or regulating unit. Limit overruns of the operating parameters can be determined by the control and / or regulating unit and counted as a number of fault entries. By comparing the number of fault entries with a reference value and / or a time analysis of the number of fault entries, problems in the electric drive train can be diagnosed by the control and / or regulating unit. Brief description of the drawings

Further advantageous details, features and design details of the invention are explained in more detail in connection with the exemplary embodiments illustrated in the figures. Showing:

Fig. 1 is a schematic representation of a block diagram of a

electric drive train of an electric or hybrid vehicle; and FIG. 2 is a schematic representation of the detection of

Error events over time.

In the figures, identical or functionally identical components are provided with the same reference numerals.

Embodiment (s) of the invention

In Fig. 1 is a block diagram of an electric drive train 10 of an electric or hybrid vehicle according to a possible

Embodiment shown. The electric drive train 10 has inter alia a rechargeable high-voltage battery system 1 1, a

Battery Management System (BMS) 12, a control and / or regulating unit 13 and an electric machine 14, which are electrically connected to each other are. The high-voltage battery system 1 1 has a plurality of interconnected battery cells 15. High-voltage battery systems 11 include, for example, nickel-metal hybrid, lithium-ion and sodium-nickel chloride battery systems. The high-voltage battery system 1 1 is according to a possible embodiment, preferably a lithium-ion battery system.

The battery management system (BMS) 12 is an electronic circuit which serves for monitoring and regulating the rechargeable battery system 1 1, that is to say an accumulator system. The battery management system (BMS) 12 is often referred to as a battery control unit (BCU) .The necessity of a BMS 12 results in the interconnection of multiple battery cells to the

Battery system 1 1. The BMS 12 should be the inevitable

production-related variations of various parameters of the battery cells 15, such as capacitance and leakage currents, detect, monitor and compensate. In some cases, operating data is displayed or stored for service purposes.

For example, if the vehicle is started, a command from the

Control unit 13 of the vehicle sent to the BMS 12, which then controls the condition of a drive battery and the electric machine 14 in the programmed cases for power. Occurs during operation an error in the battery system 1 1, it will be processed by the BMS 12 and passed to the control unit 13. The error can now be assigned to an error category from which the driver of the vehicle is informed and / or the battery system 11 is brought into a safe state.

Shutdown limits for operating parameters of the battery system 1 1, as

For example, current, voltage and temperature are due to

Regulation processes in the vehicle and for the sake of robustness usually entprellt time. As a result of this debouncing, the battery system 11 or the individual battery cells 15 can be operated during the debounce time outside of a prescribed operating range. To such

to be able to record impermissible operating times will be calculated according to one possible embodiment, the operating parameters of the individual battery cells 15 and the battery system 1 1, such as the current I, the voltage U, the average current l _rms and the temperature detected during the _{Entprellzeiten} and by comparing with allowable limits, ie minimum and maximum allowable Values, the current I, the voltage U, the average current l _rm s and the temperature evaluated. There are several

Functions applicable.

On the one hand, according to equation (1), a linear integral can be formed:

with N - number of error entries

x - voltage U, current I, average current I _rms , or temperature T xo - limit value (maximum or minimum voltage U, maximum or minimum current I, maximum or minimum average current I _rms and maximum or minimum temperature T)

t - time

Tend - total duration of the state outside of x ₀

1/60 - normalization to minutes

On the other hand, according to equation (2) a quadratic integral as

Energy equivalent are formed:

N - number of error entries

t - time - Total duration of the state outside of x ₀

1/60 - normalization to minutes

For both equations, normalization to minutes rather than seconds is an optional normalization. Other standards or no standardization can be used.

During each operation of the battery system 1 1 or individual battery cells 15 outside the predetermined limits, the integral is now counted up. The implementation of the integral takes place according to a possible

Embodiment in the control and / or regulating unit 13 time-discrete and thus as a sum, for example via the known from the prior art trapezoidal formula, instead. Thus, counters are realized which reproduce the number of error entries (N) occurring during control-related debounce times.

For each monitored operating parameter, a comparison with a reference value (R) or threshold value may be performed according to a possible embodiment. For example, 500 V ² s may be permitted by the manufacturer of the battery cells 15. This results in the following check:

with N number of error entries

U voltage

Uo maximum or minimum voltage U (limit)

Time

Total duration of the state outside of x ₀

1/60 - normalization to minutes

R reference value, for example R = 500 V ² s If the reference value (R) is reached or exceeded, the battery system 11 or the entire electric drive train 10 can be shut down or maintenance arranged. By coupling the monitoring of operating parameters of the

Battery system 1 1 and the individual battery cells 15 during

Regulatory-related Entprellzeiten with a limit value monitoring and a reference value comparison critical states of the battery system 1 1 and the electric drive train 10 can be detected early and provided in warranty cases, evidence that the vehicle over the life of the battery system 1 1, or individual battery cells 15, not has sufficiently regulated and thus the battery cells 15 are aged faster than intended. Should the occurrence of the error entries (N) and thus the operation of the

Battery system 1 1 or the individual battery cells 15 outside the predetermined limits (xo) increase over time, is expected from a major problem. Therefore, according to a possible embodiment, furthermore, a diagnosis function is proposed which specifically evaluates a time-changed behavior of the number of error entries (N). This diagnostic function can be performed by the control and / or regulating unit 13.

In addition to the already described comparison with one

Reference value (R), a temporal analysis of the determined as described above integral values (N) can be performed. This temporal analysis of the integral values (N) can reveal problems in the drive train 10 of a vehicle. In particular, conclusions can be drawn with this temporal analysis of the integral values (N) since when the error entries occur and whether the frequency over time, that is the

Frequency of error entries (N) has increased and thus, whether an accelerated aging of the battery system 1 1 or individual battery cells 15 has occurred or occurs and whether the control of the drive train 10 has deteriorated or increasingly deteriorated. FIG. 2 schematically shows the detection of the number of defect entries (N) over time (t). To carry out the temporal analysis of the calculated integral value or the error entries (N) and thus the limit value excesses of... Occurring during the debounce times

Operating parameters of the battery system 1 1 or individual battery cells 15, the following steps are proposed. First, the error entries (N), ie the limit value exceedances or integral values, over a certain period of time (T), z. From 15 days. The number of defect entries (N) is preferably stored so that it is available for later comparison. According to one possible embodiment, it is possible to divide the recorded error entries (N) into different periods (T). As shown in FIG. 2, this can be, for example, a division into periods (T) of 5 days each, ie from day 1 to 5 days, from 5 days to 10 days ago and from 10 days to 15 days ago, etc ,

The evaluation of the recorded error entries (N) can be carried out, for example, in three different categories, which are shown by way of example in the characteristics a, b and c of FIG. Decisive for the temporal analysis of the recorded error entries (N) is the slope of the characteristic curves. The

Characteristic a shows a constant integral value. This means that the error occurs only sporadically and the number of error events (N) does not increase with time (t).

The characteristic curve b shows a linearly increasing integral value. Thus, a constant rate of change for the integral value is defined, e.g. 2V ^2s / 24h. Exceeding indicates an increased frequency of error entries (N). With an exemplary integral value of 2V ² s, the following test can be used to check whether the occurrence of the error entries (N) increases.

N (t = 0) - N (t = 0 - 5 days) / 5 days> 2V ² s (4) The characteristic curve c shows an exponentially increasing integral value. An exponential rate of change for the integral value is defined. Exceeding can indicate a serious problem in the powertrain 10.

The exponential rate of change can be determined, for example, as follows:

N (T) (S)

or

N (T) e (6)

with N - number of error entries

T - period

t - time

R reference value

The exponential functions are relatively flat for negative values and have a steep slope in the range 0 to 1. Accordingly, a section of the exponential function according to equation (5) or (6) in which a relatively steep slope occurs is preferably used for the diagnosis. In the embodiment shown in FIG. 2, therefore, the time range T of -15 to 0 days is taken into account, as well as a shift by 1 and possibly a normalization to a time range. The reference value (R), z. B. 2V ² s, then controls the

Limit. Several values, for example for t = -15 days, -10 days, -5 days, can then be stored in a table in the battery management system (BMS) 12 and then compared with values already stored. If exceeded, the driver may be notified of a problem in the powertrain 10, e.g. B. by activating a warning lamp.

Thus, operating parameters of a battery system 11 or of the individual battery cells 15 can be determined by means of the described methods

control-related debounce times are monitored. By recording and evaluating fault entries (N) in the event of limit violations of the various operating parameters, premature aging of the engine can be prevented Battery cells 15 of the battery system 1 1 and problems detected in the electric drive train 10 of an electric or hybrid vehicle and

Safety risks are avoided. The illustrated in the figures and explained in connection with these embodiments are illustrative of the invention and are not limiting for this.

Claims

claims

Method for monitoring operating parameters (x) of a

Rechargeable high-voltage battery esystems (1 1) of an electric or

Hybrid vehicle during control-related Entprellzeiten, wherein the high-voltage battery system (1 1) comprises a plurality of interconnected battery cells (15), characterized in that the operating parameters (x) of the high-voltage battery system (1 1) or the individual battery cells (15 ) are detected during the debounce times and evaluated by comparison with permissible limit values (x ₀ ), wherein limit value overflows are counted and counted as the number of

Error entries (N) are stored for further evaluation.

A method according to claim 1, characterized in that the number of defect entries (N) with a predetermined reference value (R) is compared, which is adapted to detect an early aging of the high-voltage battery system (1 1).

Method according to one of claims 1 or 2, characterized

characterized in that a temporal analysis of the number of

Error entries (N) is performed, which is suitable to draw conclusions regarding the beginning and the frequency of the error entries (N).

A method according to claim 3, characterized in that for the temporal analysis, the number of error entries (N) over a certain period (T) is recorded, the number of error entries (N) is stored and thus provided for later evaluation and a division of the recorded error entries in different periods (T) is made. Method according to one of claims 3 or 4, characterized

characterized in that the number of defect entries (N) is graphed over time and the slope of the graph is used to analyze the defect entries (N).

A method according to claim 5, characterized in that at an exponentially increasing number of defect entries (N) early aging of the battery cells (15) is diagnosed.

A method according to claim 6, characterized in that the

High-voltage battery system (1 1) is used as part of an electric drive train (10) of the electric or hybrid vehicle, wherein at an exponentially increasing number of fault entries (N) a problem of the electric drive train (10) is diagnosed.

Method according to one of the preceding claims, characterized in that as operating parameter (x) of the current (I), the

Voltage (U), the average current (Irms) and the temperature (T) are detected during the Entprellzeiten.

Method according to one of the preceding claims, characterized in that the evaluation of the fault entries (N) by a control and / or regulating unit (13) connected to the high-voltage battery system (1 1) and an electric machine (14) of the electric or Hybrid vehicle is electrically connected, is performed.

Electric drive train (10) of an electric or hybrid vehicle comprising a high-voltage battery system (1 1) and an electric machine (14) via a control and / or regulating unit (13) electrically

connected to each other, characterized in that detected during control-related Entprellzeiten operating parameters (x) of the high-voltage battery system (1 1) of the control and / or regulating unit (13) are mathematically evaluated, wherein limit value exceed the Operating parameters (x) by the control and / or regulating unit (13) detectable and counted as a number of error entries (N), and wherein by comparing the number of error entries (N) with a reference value (R) and / or a temporal Analysis of the number of fault entries (N) Problems in the electric drive train (10) can be diagnosed by the control and / or regulating unit (13).