CN107415721A - Method for operating battery system, battery management system and battery system - Google Patents

Abstract

A method for operating a battery system, a battery management system, and a battery system. The invention relates to a method for operating a battery system, wherein the power to be provided by the battery system is divided into power to be provided by a high-energy battery and a high-power battery according to a distribution factor, wherein the distribution factor is determined according to a nominal distribution factor, and wherein the nominal The distribution factor is calculated from the available energy of the high energy battery and the high power battery. The invention also relates to a battery management system for operating such a battery system, which is set up to split the power to be provided by the battery system into the power to be provided by the high energy battery and the high power battery according to a distribution factor, wherein the distribution factor It can be determined on the basis of the nominal distribution factor, and a nominal value generator is provided which determines the nominal distribution factor on the basis of the available energy of the high-energy battery and the high-performance battery. The invention also relates to a battery system comprising a battery management system according to the invention.

Description

Method for operating battery system, battery management system and battery system

technical field

The invention relates to a method for operating a battery system comprising a high energy battery and a high power battery, wherein the power supplied by the battery system is divided into power to be supplied by the high energy battery and power to be supplied by the high energy battery The power provided by the high power battery. The invention also relates to a battery management system for operating such a battery system and a battery system comprising such a battery management system.

Background technique

Battery systems, in particular battery systems in electrically driven vehicles, should be designed in such a way that they meet the requirements of the vehicle manufacturer with regard to the available energy and the available power. High-energy batteries are known which have a comparatively large storage capacity and can therefore store relatively large amounts of energy. Furthermore, high-performance batteries are known which can discharge relatively high power, for example in the form of high current. The high-power battery can be implemented as a capacitor, for example.

In order to meet the energy and power requirements with such disposable batteries, hybrid battery systems are known which have a combination of high-energy batteries and high-power batteries. Such a hybrid battery system requires an operating strategy for actuating the high-energy battery and the high-power battery depending on the current load situation, ie in motor operation and in generator operation.

The battery system also includes a battery management system for operating the high energy battery and the high power battery according to the current load situation. For this purpose, the battery management system has corresponding software with methods for operating the corresponding battery system.

From US 2014/0203633 a battery system is known which comprises a high energy battery and a high power battery for driving a vehicle. A method for operating the battery system is also described, according to which method a charging process or a discharging process of the high-power battery is prioritized, in particular as a function of the state of charge of the high-power battery.

Likewise, a battery system is known from US 2012/0025744 comprising a high energy battery and a high power battery. In particular, the battery system can be operated in a high-energy mode in which the high-energy battery is discharged and in a high-power mode in which the high-power battery is operated discharge. An operating mode for charging the high-energy battery and the high-power battery is also provided.

Contents of the invention

A method is proposed for operating a battery system, in particular a hybrid battery system, which includes a high-energy battery and a high-power battery. Here, the power to be supplied by the battery system is divided into power to be supplied by the high-energy battery and power to be supplied by the high-power battery according to a distribution factor. In this case, the distribution factor is determined on the basis of the calculated setpoint distribution factor.

Preferably, the allocation factor is a number between 0 and 1, wherein every value between 0 and 1 is possible for said allocation factor. If the distribution factor=1, then the power to be provided by the battery system is provided only by the high-energy battery. In this case, the power contribution of the high power battery is zero. If the distribution factor=0, then the power to be provided by the battery system is only provided by the high-power battery. In this case, the power contribution of the high energy battery is zero.

A high energy battery possesses an available energy that can be determined by measuring the state of charge of the high energy battery. Likewise, the high power battery possesses an available energy that can be determined by measuring the state of charge of the high power battery. A rated allocation factor is calculated from the available energy of the high energy battery and the available energy of the high power battery. In this case, the setpoint distribution factor is likewise a number between 0 and 1, wherein every value between 0 and 1 is possible for the setpoint distribution factor.

When determining the distribution factor, boundary conditions are often to be taken into account, which depend in particular on the properties of the high-energy battery and the high-power battery. In particular, under certain conditions it is not possible to achieve a distribution factor=1 and a distribution factor=0, where the power to be provided by the battery system is only provided by high-energy batteries, at which When the distribution factor=0, the power to be provided by the battery system is only provided by the high power battery.

Thus, according to an advantageous refinement of the method, the upper limit value of the allocation factor and the value of the allocation factor are determined taking into account such boundary conditions relating to the properties of the high-energy battery and the high-power battery. lower limit value.

In this case, if the setpoint distribution factor is greater than the determined upper limit value, the distribution factor is assigned the upper limit value. If the setpoint distribution factor is smaller than the determined lower limit value, the distribution factor is assigned the lower limit value. If the setpoint allocation factor is less than or equal to the upper limit value and greater than or equal to the lower limit value, the setpoint allocation factor is assigned to the allocation factor. Therefore, the distribution factor always lies between the upper limit value and the lower limit value.

In most cases, attention should be paid to several boundary conditions for determining the distribution factor that are not necessarily related to each other. Such boundary conditions concern, for example, the ratio of the output voltage to be provided by the battery system to the voltage of the high-energy battery and/or to the voltage of the high-power battery. For example, if the voltage of the high energy battery is less than the output voltage to be provided by the battery system, then the upper limit value must be less than 1. For example, the lower limit value must be greater than zero if the voltage of the high power battery is less than said output voltage to be provided by the battery system. Therefore, the upper limit value of the voltage and the lower limit value of the voltage are determined.

A further boundary condition concerns the ratio of the power to be provided by the battery system to the power that can be provided by the high-energy battery and/or to the power that can be provided by the high-power battery. For example, if the power that can be provided by the high energy battery is less than the power to be provided by the battery system, then the upper limit must be less than 1. For example, if the power that can be provided by the high power battery is less than the power to be provided by the battery system, then the lower limit value must be greater than zero. Thus, an upper power limit value and a lower power limit value are likewise determined.

According to an advantageous development of the method, the upper limit value of the distribution factor is determined as the minimum of the determined upper limit value for voltage and the determined upper limit value for power, and the lower limit value for the distribution factor is determined as The maximum value of the determined voltage lower limit value and the determined power lower limit value.

Here, preferably, the upper limit value of the voltage and the lower limit value of the voltage depend on the output voltage to be provided by the battery system and the voltage and/or high power battery voltage to calculate.

Preferably, said upper power limit value and said lower power limit value are also dependent on the power to be provided by the battery system and the power and/or energy that can be provided by the high-energy battery, taking into account the above-mentioned boundary conditions. Calculated by the power provided by the high-power battery.

A battery management system is also proposed for operating a battery system, in particular a hybrid battery system, which includes a high-energy battery and a high-power battery. The battery management system is set up to divide the power to be provided by the battery system into power to be provided by the high energy battery and power to be provided by the high power battery according to a division factor. In this case, the distribution factor can be determined on the basis of the calculated setpoint distribution factor.

Preferably, the allocation factor is a number between 0 and 1, wherein every value between 0 and 1 is possible for said allocation factor. If the distribution factor=1, only high energy batteries provide the power to be provided by the battery system. In this case, the power contribution of the high power battery is zero. If the allocation factor=0, then only the high power battery provides the power to be provided by the battery system. In this case, the power contribution of the high energy battery is zero.

A high energy battery possesses an available energy that can be determined by measuring the state of charge of the high energy battery. Likewise, the high power battery possesses an available energy that can be determined by measuring the state of charge of the high power battery. A setpoint value generator is provided which calculates a setpoint allocation factor as a function of the available energy of the high-energy battery and the available energy of the high-power battery. In this case, the setpoint distribution factor is likewise a number between 0 and 1, wherein every value between 0 and 1 is possible for the setpoint distribution factor.

According to an advantageous design solution of the present invention, the battery management system includes an evaluation unit, the evaluation unit determines the upper limit value of the distribution factor as the minimum value of the upper limit value of voltage and the upper limit value of power, and the evaluation unit The unit determines the lower limit value of the distribution factor as the maximum value among the lower limit value of voltage and the lower limit value of power.

If the setpoint distribution factor is greater than the upper limit value, the evaluation unit assigns the upper limit value to the distribution factor. If the setpoint distribution factor is smaller than the lower limit value, the evaluation unit assigns the lower limit value to the distribution factor. If the nominal allocation factor is less than or equal to the upper limit value and greater than or equal to the lower limit value, the assignment unit assigns the nominal allocation factor to the allocation factor.

For this purpose, the battery management system advantageously comprises a voltage calculation unit which calculates the upper voltage limit value from the output voltage to be provided by the battery system and the voltage of the high-energy battery and/or the voltage of the high-power battery and voltage lower limit.

Advantageously, the battery management system also comprises a power calculation unit which calculates an upper power limit as a function of the power to be provided by the battery system and the power which can be provided by the high-energy battery and/or the power which can be provided by the high-power battery value and power lower limit.

A battery system is also proposed which comprises the battery management system according to the invention and a high-energy battery and a high-performance battery. Preferably, the high energy battery and the high power battery are connected in series and connected to power electronics.

Advantageously, the method according to the invention, the battery management system according to the invention and the battery system according to the invention are used in an electric vehicle (EV), in a hybrid electric vehicle (HEV), in a plug-in hybrid electric vehicle (PHEV) It is used in light electric vehicles (LEV) or in electric bicycles (E-Bike).

Advantages of the invention

The method according to the invention permits the operation of a hybrid battery system, in particular a hybrid battery system in a vehicle, which ensures optimal handling of a high-energy battery and a high-power battery. In this way, in particular, the efficiency of the battery system and thus the range of the vehicle and the service life of the battery system can be increased. This means progress from an economic and ecological point of view.

In this case, the method is designed in particular for a battery system having a series connection of a high-energy battery and a high-power battery connected to the power electronics. Preferably, a multilevel inverter with an intermediate connection, for example an NPC inverter (Neutral Point Clamped Diode), is conceivable as power electronics.

Description of drawings

Embodiments of the invention are further explained with reference to the drawings and the following description.

Figure 1 shows a schematic diagram of the battery system, while

FIG. 2 shows a schematic diagram of the flow in the battery management system.

detailed description

In the following description of embodiments of the invention, identical or similar elements are identified with the same reference numerals, a repeated description of these elements being omitted in individual cases. The drawings only schematically represent the subject-matter of the invention.

FIG. 1 shows a schematic diagram of a battery system 10 which is connected to a power electronics system 23 . In the present case, the power electronics system 23 is designed as a multilevel inverter with intermediate connections. A three-phase electric motor 25 of the vehicle can be operated by means of power electronics 23 . The battery system 10 can be operated in motor mode, in which the battery system 10 releases energy to the electric motor 25 , and in generator mode, in which the battery system 10 extracts energy from the motor 25 . 25 absorb energy.

The battery system 10 comprises a high-energy battery 12 and a high-power battery 14 which are connected in series and are connected to a power electronics 23 . The high-energy battery 12 has relatively large storage capacity, while the high-power battery 14 can release relatively large power, especially in the form of high current.

In addition, the battery system 10 also includes a battery management system 20 for operating the battery system 10 . Here too, battery management system 20 is connected to power electronics 23 , for example via a CAN bus. The battery management system 20 controls and monitors the battery system 10 .

In motor operation, the electric motor 25 requires power PEM to be supplied by the battery system 10 . In this case, the power PEM to be supplied by the battery system 10 comes from the high-energy battery 12 and from the high-power battery 14 . Here, the power PEM to be provided by the battery system 10 is the sum of the power PHE to be provided by the high-energy battery 12 and the power PHP to be provided by the high-power battery 14:

PEM=PHE+PHP.

FIG. 2 shows a schematic diagram of the process in the battery management system 20 . Here, the power PEM to be provided by the battery system 10 is divided according to the distribution factor FP into the power PHE to be provided by the high-energy battery 12 and the power PHP to be provided by the high-power battery 14 as follows:

PHE=FE*PEM

PHP=(1-FP)*PEM.

Thus, the distribution factor FP is a number between 0 and 1, wherein every value between 0 and 1 is possible for the distribution factor FP.

If distribution factor FP=1, then apply: PHE=PEM and PHP=0;

If the distribution factor FP=1/2, then apply: PHE=PEM/2 and PHP=PEM/2;

If the distribution factor FP=0, then apply: PHE=0 and PHP=PEM.

The state of charge SOC-HE of the high-energy battery 12 and the state of charge SOC-HP of the high-power battery 14 are determined by means of sensors, not shown. The available energy EHE of the high energy battery 12 is determined from the state of charge SOC-HE of the high energy battery 12 . The available energy EHP of the high power battery 14 is determined from the state of charge SOC-HP of the high power battery 14 .

The battery management system 20 has a target value generator SG. In the nominal value generator SG, the nominal power factor FS is calculated as follows from the effective energy EHE of the high-energy battery 12 and the effective energy EHP of the high-power battery 14 :

FS=EHE/(EHE+EHP).

The setpoint distribution factor FS is thus likewise a number between 0 and 1, wherein every value between 0 and 1 is possible for the setpoint distribution factor FS. The calculated nominal distribution factor FS is used to determine the distribution factor FP.

The battery management system 20 also includes a voltage calculation unit URE, which calculates an upper voltage limit value UMax and a voltage lower limit value UMin. In this case, the voltage UHE of the high-energy battery 12 and the voltage UHP of the high-power battery 14 are measured by means of sensors, not shown. From the voltage UHE of the high-energy battery 12 and the voltage UHP of the high-power battery 14 and the output voltage UEM to be supplied by the battery system 10 to the electric motor 25, the voltage upper limit value UMax and the voltage lower limit value Umin are calculated as follows :

.

The battery management system 20 also includes a power calculation unit LRE, which calculates a power upper limit value LMax and a power lower limit value LMin. For this purpose, the power PLHE that can be supplied by the high-energy battery 12 and the power PLHP that can be supplied by the high-power battery 14 are known in the battery management system 20 . According to the power PEM to be provided by the battery system 10 and the power PLHE that can be provided by the high-energy battery 12 and the power PLHP that can be provided by the high-power battery 14, the power upper limit value LMax and the power lower limit are calculated as follows ValueLMin:

If PLHE>PEM>0 (under motor operation), then LMax=1;

If PEM>0 (under motor operation), then LMax=PLHE/PEM;

If PEM=0, then LMax=1;

If PEM<0 (under generator operation), then LMax=PLHE/PEM;

If PLHE<PEM<0 (under generator operation), then LMax=1;

If PLHP>PEM>0 (under motor operation), then LMin=0;

If PEM>0 (under motor operation), then LMin=1-(PLHP/PEM);

If PEM=0, then LMin=0;

If PEM<0 (under generator operation), then LMin=1-(PLHP/PEM);

If PLHP<PEM<0 (in generator mode), then LMin=0.

Thus, the upper power limit value LMax and the lower power limit value LMin are likewise each a number between 0 and 1, wherein each value between 0 and 1 is for the upper power limit value LMax and for the It is possible for the power lower limit value LMin.

In addition, the battery management system 20 also includes an evaluation unit ZE, which has a first maximum value calculator Max1 , a second maximum value calculator Max2 , a first minimum value calculator Min1 , and a second minimum value calculator Min2 .

The first maximum calculator Max1 determines the lower limit value Fmin of the distribution factor FP as the maximum value of the voltage lower limit value UMin and the power lower limit value LMin:

Fmin = maximum value (UMin, LMin).

The first minimum operator Min1 determines the upper limit value Fmax of the distribution factor FP as the minimum value of the voltage upper limit value UMax and the power upper limit value LMax:

Fmax = Minimum (UMax, LMax).

The second minimum value operator Min2 determines the intermediate value ZW as the minimum value of the upper limit value Fmax and the rated distribution factor FS:

ZW = min(Fmax, FS).

The second maximum calculator Max2 determines the distribution factor FP as the maximum value of the lower limit value Fmin and the middle value ZW:

FP = maximum value (Fmin, ZW).

Therefore, if the target distribution factor FS is greater than the upper limit value Fmax, the assignment unit ZE assigns the upper limit value Fmax to the distribution factor FP. If the target distribution factor FS is smaller than the lower limit value (Fmin), the assignment unit ZE assigns the lower limit value Fmin to the distribution factor FP. If the setpoint distribution factor FS is smaller than or equal to the upper limit value Fmax and greater than or equal to the lower limit value Fmin, the assignment unit ZE assigns the setpoint distribution factor FS to the distribution factor FP.

If FS>Fmax, then FP=Fmax;

If FS<Fmin, then FP=Fmin;

If Fmin≤FS≤Fmax, then FP=FS.

The invention is not limited to the embodiments described here and the aspects emphasized therein. Rather, within the scope of protection indicated by the claims, numerous variants are possible, which are within the purview of a person skilled in the art.

Claims (11)

1. Method for operating a battery system (10) comprising a high energy battery (12) and a high power battery (14), wherein, The power (PEM) to be provided by the battery system (10) is divided according to the distribution factor (FP) into the power (PHE) to be provided by the high energy battery (12) and the power to be provided by the high power battery (14) Power provided (PHP), where The distribution factor (FP) is determined according to the nominal distribution factor (FS), and where The rated allocation factor (FS) according to the effective energy (EHE) of the high energy battery (12) and The effective energy (EHP) of the high power battery (14) is calculated. 2. The method of claim 1, wherein, An upper limit value (Fmax) of the allocation factor (FP) and a lower limit value (Fmin) of the allocation factor (FP) are determined, wherein If the nominal distribution factor (FS) is greater than the upper limit value (Fmax), then the upper limit value (Fmax) is assigned to the distribution factor (FP), and If the nominal distribution factor (FS) is smaller than the lower limit value (Fmin), then the lower limit value (Fmin) is assigned to the distribution factor (FP), and If the rated distribution factor (FS) less than or equal to the upper limit value (Fmax) and greater than or equal to the lower limit value (Fmin), The setpoint distribution factor (FS) is then assigned to the distribution factor (FP). 3. The method of claim 2, wherein, The upper limit value (Fmax) of the distribution factor (FP) is determined as the minimum value among the upper limit value of voltage (UMax) and the upper limit value of power (LMax), and wherein, The lower limit value (Fmin) of the distribution factor (FP) is determined as the maximum value of a voltage lower limit value (UMin) and a power lower limit value (LMin). 4. The method of claim 3, wherein, The voltage upper limit value (UMax) and the voltage lower limit value (UMin) according to the output voltage (UEM) to be supplied by the battery system (10) and the voltage (UHE) of the high energy battery (12) and/or The voltage (UHP) of the high power battery (14) is calculated. 5. The method according to any one of claims 3 to 4, wherein, The power upper limit value (LMax) and the power lower limit value (LMin) according to the power (PEM) to be supplied by the battery system (10) and Power (PLHE) that can be provided by the high energy battery (12) and / or Can be calculated from the power (PLHP) provided by the high power battery (14). 6. A battery management system (20) for operating a battery system (10), said battery system (10) comprising a high-energy battery (12) and a high-power battery (14), and said battery management system (20) being set up to split the power (PEM) to be provided by said battery system (10) into power (PHE) to be provided by said high energy battery (12) and power to be provided by said high power battery (14) according to a distribution factor (FP) ) provides power (PHP), where, Said distribution factor (FP) can be determined from the nominal distribution factor (FS), and wherein, Set the setpoint generator (SG), the setpoint generator (SG) The nominal distribution factor (FS) is calculated from the available energy (EHE) of the high energy battery (12) and the available energy (EHP) of the high power battery (14). 7. The battery management system (20) according to claim 6, The battery management system (20) includes an evaluation unit (ZE), and the evaluation unit (ZE) determines the upper limit value (Fmax) of the allocation factor (FP) as a voltage upper limit value (UMax) and a power upper limit The minimum of values (LMax), And said evaluation unit (ZE) determines the lower limit value (Fmin) of said allocation factor (FP) as the maximum value of the lower limit value of voltage (UMin) and the lower limit value of power (LMin), And if said nominal distribution factor (FS) is greater than said upper limit value (Fmax), said assignment unit (ZE) assigns said upper limit value (Fmax) to said distribution factor (FP), And if said nominal distribution factor (FS) is smaller than said lower limit value (Fmin), said assignment unit (ZE) assigns said lower limit value (Fmin) to said distribution factor (FP), And if the rated allocation factor (FS) less than or equal to the upper limit value (Fmax) and greater than or equal to the lower limit value (Fmin), The assignment unit (ZE) then assigns the setpoint distribution factor (FS) to the distribution factor (FP). 8. The battery management system (20) according to claim 7, The battery management system (20) includes a voltage calculation unit (URE), and the voltage calculation unit (URE) is based on the output voltage (UEM) to be supplied by the battery system (10) and the voltage (UHE) of the high energy battery (12) and/or The voltage of the high power battery (14) (UHP) The voltage upper limit value (UMax) and the voltage lower limit value (UMin) are calculated. 9. The battery management system (20) according to one of claims 7 to 8, The battery management system (20) includes a power calculation unit (LRE), and the power calculation unit (LRE) is based on the power (PEM) to be supplied by the battery system (10) and Power (PLHE) that can be provided by the high energy battery (12) and / or Power (PLHP) that can be provided by said high power battery (14) The power upper limit value (LMax) and the power lower limit value (LMin) are calculated. 10. A battery system (10) comprising The battery management system (20) according to one of claims 6 to 9, and high energy battery (12) and high power battery (14), The high energy battery (12) and the high power battery (14) are connected in series. 11. The method according to one of claims 1 to 5 and/or the battery management system (20) according to one of claims 6 to 9 and/or the battery system (10) according to claim 10 ) in an electric vehicle (EV), in a hybrid electric vehicle (HEV), in a plug-in hybrid electric vehicle (PHEV), in a light electric vehicle (LEV) or in an electric bicycle .