DE102023200642A1 - Method and device for preconditioning an energy storage device - Google Patents

Abstract

In a method for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device, wherein the motor vehicle has a plurality of actuators for influencing the temperature of the energy storage device, an expected temperature of the energy storage device and an expected state of charge of the energy storage device at a start time of the charging process are calculated. A power loss of the energy storage device is calculated. A possible cooling and/or heating output of at least one actuator is calculated. A target temperature of the energy storage device to be achieved at the start time of the charging process is calculated by means of model-based simulation for at least one possible target temperature of the energy storage device, taking into account an energy consumption for the preconditioning with the at least one actuator, taking into account the possible cooling and/or heating output of the at least one actuator. The at least one actuator is controlled to precondition the energy storage device, depending on the determined target temperature.

Description

The present invention relates to a method and a device for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device.

State of the art

When charging batteries of high-performance electric vehicles, the charging time depends largely on the temperature of the battery. If the battery is too cold or too warm, the charging process takes longer. It can therefore be advantageous to bring the battery to a suitable temperature range before charging, i.e. to carry out preconditioning.

Cooling a motor vehicle battery is a matter of EP 2 565 560 B1 known.

Due to the high mass of lithium-ion batteries, it takes a significant amount of time to change the battery temperature, which is why the preconditioning process must be planned in advance.

Simple rule-based algorithms can be used to bring the high-voltage battery into a more favorable temperature range before an upcoming quick-charge process. Heating or cooling can begin at a fixed time before charging begins. The battery can also be heated or cooled to a fixed target temperature. The battery can also be preconditioned with a predefined, maximum heating or cooling output.

With such measures, it can happen that the battery reaches the target temperature either too early or too late. It can also happen that the predefined target temperature for the subsequent charging process is not optimally selected, i.e. it is too high or too low.

Furthermore, the method of preconditioning, i.e. the selection of actuators, may not represent the most efficient type of cooling or heating. This is relevant, for example, in thermal system topologies that offer different options for heating or cooling, such as cooling the battery using a coolant radiator or a refrigerant heat exchanger.

Disclosure of the invention

The invention provides a method and a device for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device with the features of the independent patent claims.

Preferred embodiments are the subject of the respective subclaims.

According to a first aspect, the invention relates to a method for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device, wherein the motor vehicle has a plurality of actuators for influencing the temperature of the energy storage device. An expected temperature of the energy storage device and an expected state of charge of the energy storage device at a start time of the charging process are calculated. A power loss of the energy storage device is calculated. A possible cooling and/or heating output of at least one actuator is calculated. A target temperature of the energy storage device to be achieved at the start time of the charging process is calculated by means of model-based simulation for at least one possible target temperature of the energy storage device, taking into account an energy consumption for the preconditioning with the at least one actuator, taking into account the possible cooling and/or heating output of the at least one actuator. The at least one actuator is controlled to precondition the energy storage device, depending on the determined target temperature.

According to a second aspect, the invention relates to a device for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device, wherein the motor vehicle has a plurality of actuators for influencing the temperature of the energy storage device. The device comprises a computing device which is designed to calculate an expected temperature of the energy storage device and an expected state of charge of the Energy storage device at a start time of the charging process and to calculate a power loss of the energy storage device. The computing device is further designed to calculate a possible cooling and/or heating output of the at least one actuator and to calculate a target temperature of the energy storage device to be achieved at the start time of the charging process, by means of model-based simulation for at least one possible target temperature of the energy storage device, taking into account an energy consumption for the preconditioning with the at least one actuator, taking into account the possible cooling and/or heating output of the at least one actuator. The device also comprises a control device which is designed to control the at least one actuator for preconditioning the energy storage device, depending on the determined target temperature.

Advantages of the invention

In the method according to the invention, the optimal starting time for a preconditioning process of the energy storage device can be determined, which reaches the best possible target temperature necessary for a fast charging process with the most efficient heating or cooling option.

By optimally selecting the start time for preconditioning and the target temperature, the energy required for preconditioning is minimized, thereby increasing the vehicle's range.

By selecting a suitable actuator for the preconditioning process depending on the situation, energy consumption is also reduced and the range is improved.

By selecting the optimal target temperature, the subsequent charging process is shortened as much as possible.

By using special algorithms and model-based methods, the improvements mentioned can be achieved without the need for additional sensors, actuators or other additional hardware.

The method can easily be combined with existing thermal management software.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation determines a temporal progression of a state of charge of the energy storage device during charging.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation determines a temporal progression of a temperature of the energy storage device during charging.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation determines a temporal progression of a possible charging power during the charging process.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation is used to determine an expected charging time for the charging process.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation determines a cooling or heating output required for preconditioning.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation is carried out depending on a current charge state of the energy storage device and a current temperature of the energy storage device. This allows the current state of the energy storage device to be taken into account.

According to a further development of the method for preconditioning the energy storage device, the model-based simulation is carried out depending on map data and route information. For example, a wheel power can be estimated based on the route profile ahead, ie in particular permissible speeds and gradients of the route. From this, a power output on the electric drive and in the energy storage device. From this, the power loss, ie waste heat of the respective components, can then be determined. This improves the accuracy of the calculations.

According to a further development of the method for preconditioning the energy storage device, the selection of at least one of the actuators for preconditioning the energy storage device takes place taking into account the energy required to operate the actuators. The energy required for preconditioning can thus be taken into account. Furthermore, a potential shortening of the charging process can be weighted with the necessary energy requirement for preconditioning.

According to a further development of the method for preconditioning the energy storage device, at least one of the actuators for preconditioning the energy storage device is selected taking into account the expected charging time. In this way, the charging time can be minimized or specified as one of several optimization goals. The charging time can, for example, be included in a cost function that is minimized.

According to a further development of the method for preconditioning the energy storage device, the at least one actuator comprises a coolant heating device, such as a PTC coolant heater (positive temperature coefficient, PTC). The electrical and thermal output of the installed PTC coolant heater are known and stored as parameters.

According to a further development of the method for preconditioning the energy storage device, the at least one actuator comprises a waste heat heating device. For this purpose, the power loss of the drive train can be filtered over the long term and used as a prediction value. No electrical energy is required for this. Route data is optionally used to improve the accuracy of the waste heat estimation.

According to a further development of the method for preconditioning the energy storage device, the at least one actuator comprises a radiator cooling device. The radiator can optionally be used jointly for the electric drive train and the energy storage device. The coolant temperature level in combined cooling circuits of the drive train and energy storage device can be modeled and used to calculate the maximum amount of heat that can be dissipated from the energy storage device by a radiator. The electrical power required for this results from the necessary use of a cooling fan.

According to a further development of the method for preconditioning the energy storage device, the at least one actuator comprises a refrigerant circuit cooling device (chiller). It can be estimated how much cooling power the refrigerant circuit can provide for the battery at the current ambient temperature. The cooling power requirement of the passenger compartment is taken into account. The required electrical power of the refrigerant compressor can be approximated based on the total thermal power and the ambient temperature.

According to a further development of the method for preconditioning the energy storage device, the at least one actuator is controlled in such a way that the temperature of the energy storage device is guided linearly from a temperature at the start of the preconditioning to the target temperature. According to other embodiments, the course can also be non-linear.

Further advantages, features and details of the invention emerge from the following description, in which various embodiments are described in detail with reference to the drawing.

Short description of the drawings

• 1 ein schematisches Blockdiagramm einer Vorrichtung zum Vorkonditionieren eines Energiespeichers eines zumindest teilweise elektrisch betriebenen Kraftfahrzeugs für einen Ladevorgang des Energiespeichers gemäß einer Ausführungsform der Erfindung;
• 2 ein Flussdiagramm eines Verfahrens zum Vorkonditionieren eines Energiespeichers eines zumindest teilweise elektrisch betriebenen Kraftfahrzeugs für einen Ladevorgang des Energiespeichers gemäß einer Ausführungsform der Erfindung;
• 3 verschiedene simulierte zeitliche Verläufe des Ladezustandes des Energiespeichers während des Ladens;
• 4 verschiedene simulierte zeitliche Verläufe der Temperatur des Energiespeichers während des Ladens;
• 5 verschiedene simulierte zeitliche Verläufe der Ladeleistung während des Ladens;
• 6 verschiedene simulierte zeitliche Verläufe der zum Vorkonditionieren benötigten Kühlleistung während des Ladens;
• 7 eine schematische Abhängigkeit der Ladezeit von der Starttem peratu r;
• 8 verschiedene zeitliche Verläufe des Ladezustands des Energiespeichers während des Vorkonditionierens;
• 9 verschiedene simulierte zeitliche Verläufe des Ladezustandes des Energiespeichers während eines Zeitraums zu Beginn des Ladens; und
• 10 einen zeitlicher Verlauf einer Temperatur des Energiespeichers während der Fahrt und des Vorkonditionierens am Ende der Fahrt.

Show it:

• 1 a schematic block diagram of a device for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device according to an embodiment of the invention;
• 2 a flow chart of a method for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device according to an embodiment of the invention;
• 3 various simulated temporal courses of the charge state of the energy storage device during charging;
• 4 various simulated temporal profiles of the temperature of the energy storage device during charging;
• 5 various simulated time courses of the charging power during charging;
• 6 various simulated time courses of the cooling capacity required for preconditioning during charging;
• 7 a schematic dependence of the charging time on the starting temperature;
• 8th different temporal courses of the state of charge of the energy storage during preconditioning;
• 9 various simulated time courses of the state of charge of the energy storage device during a period at the beginning of charging; and
• 10 a temporal progression of the temperature of the energy storage during the journey and the preconditioning at the end of the journey.

In all figures, identical or functionally identical elements and devices are provided with the same reference symbols. The numbering of process steps serves the purpose of clarity and is generally not intended to imply a specific chronological order. In particular, several process steps can also be carried out simultaneously.

Description of the embodiments

1 shows a schematic block diagram of a device 1 for preconditioning an energy storage device for a charging process. The energy storage device is part of an at least partially electrically operated motor vehicle. The energy storage device is, for example, a battery, in particular a lithium-ion battery.

The motor vehicle has a plurality of actuators 4 which can increase and/or decrease the temperature of the energy storage device, i.e. are designed to heat and/or cool the energy storage device. The actuators can comprise, for example, a coolant heating device, a waste heat heating device, a radiator cooling device and/or a coolant circuit cooling device.

A computing device 2 comprises, for example, a microprocessor, an integrated circuit or the like and is designed to carry out a model-based simulation for each actuator 4 for at least one possible target temperature. Each combination of actuator and possible target temperature corresponds to a preconditioning option.

The possible target temperature corresponds to a possible temperature of the energy storage device at the start of the charging process. The model includes in particular the effect of the actuator on the temperature of the energy storage device. The model can include a temporal progression of the charging and optionally the preconditioning.

When simulating, possible cooling and heating performance of the various actuators can be taken into account, such as PTC heaters, waste heat from the electric drive, cooling through a common cooler, cooling using a coolant circuit (chiller) or the like. The respective power losses can be taken into account. The respective consumption of electrical energy can also be taken into account. The thermal properties of the energy storage device can be taken into account, such as thermal mass, thermal resistance to the cooling medium, and/or thermal resistance to the environment.

Furthermore, predictive route data, i.e. in particular map information, can be taken into account. Power losses can be calculated from the route data.

The estimated charge level of the energy storage device when the charging point is reached and the desired charge level of the energy storage device at the end of the charging process can be taken into account. The available power of the charging station can also be taken into account. In addition, the charging characteristics of the energy storage device can be taken into account depending on its temperature and charge level.

The computing device 2 determines a target temperature of the energy storage device at the beginning of the charging process and a starting time for the preconditioning of the energy storage device, wherein the computing device 2 takes into account the result of the model-based simulation.

The computing device 2 is further designed to select at least one of the actuators 4 for preconditioning the energy storage device depending on the result of the model-based simulation.

Furthermore, the device comprises a control device 3, which controls the at least one selected actuator 4 for preconditioning the energy storage device, depending on the determined target temperature and the determined start time for the preconditioning.

If the possible thermal outputs (heating or cooling outputs) for the different preconditioning options are known, the required preconditioning time can be estimated as follows: $$\begin{array}{c}\text{Ben}\ddot{\text{O}}\text{ted time}=(\text{current}\text{temperature}-\text{Target temperature})*\text{W}\ddot{\text{a}}\text{rmecapacit}\ddot{\text{a}}\text{t of}\\ \text{Energy storage}/(\text{thermal performance of the preconditioners}-\text{option}+\\ \text{Loss of energy storage}+\text{Abw}\ddot{\text{a}}\text{rme of the energy storage in the}\\ \text{Vicinity})\end{array}$$

The time required for the preconditioning process is used to determine the time at which preconditioning should be started: $$\text{Start time}=\text{Time to fast charge}-\text{ben}\ddot{\text{O}}\text{ted time}$$

As soon as the start time is reached, a trigger flag is set so that the actual actuator control can begin heating or cooling.

2 shows a flow chart of a method for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device.

In a step S1, external inputs are received, such as a time to the charging station, a desired end of charging, a desired state of charge of the energy storage device, a current state of charge of the energy storage device, a power of the charging station and/or a current temperature of the energy storage device.

In an optional step S2, route information is processed, i.e. speeds along the route and gradients along the route, from which a wheel power and, from this, power losses and the temperature and state of charge of the energy storage device are predicted in a step S3.

In a step S4, the battery temperature and the state of charge at the beginning of the charging process are predicted.

In step S5, the desired target temperature of the energy storage device is determined using a model-based simulation.

In a step S6, the cooling or heating output is calculated for the various preconditioning options, i.e. for various actuators, such as heaters, waste heat recovery or cooling devices. The time required for preconditioning is calculated.

In a step S7, a preconditioning option is selected based on the energy requirement and the attainability of the target temperature. Setpoints for the preconditioning are calculated, such as a temperature trajectory.

In a step S8, the actuators are controlled according to the selected preconditioning option.

3 shows various simulated curves of the state of charge SOC of the energy storage device during charging as a function of time t. To determine the target temperature, simulations of the upcoming charging process for different target temperature candidates for different actuators.

4 shows various simulated temporal profiles of the temperature temp of the energy storage during charging, according to the 3 shown courses.

5 shows various simulated time profiles of the charging power P1 during charging, according to the 3 and 4 shown courses.

6 shows various simulated time profiles of the cooling power P2 required to cool the energy storage system during charging, according to the 3 to 5 shown courses.

In the 5 charging power shown and the 6 The cooling performance shown is calculated from the charge state and the temperature curve.

7 shows a schematic dependence of the charging time tc on the starting temperature T for a specific simulation. T1 corresponds to the estimated temperature at the start of preconditioning. A temperature T2 corresponds to the selected target temperature of 8 °C. The charging time advantage is less pronounced above 8 °C, so further preheating only improves the charging time slightly, but still requires energy proportional to the temperature delta. Therefore, in this case, 8 °C would be selected as the target temperature.

8th shows various temporal progressions of the energy storage unit's state of charge (SOC) during preconditioning. Preconditioning the energy storage unit using an actuator 4, such as a PTC heater or a coolant circuit including a compressor, requires energy from the energy storage unit. The more preconditioning is carried out, the more the energy storage unit's state of charge drops by the end of the journey and the more must be charged during the charging process.

The influence of preconditioning on the state of charge of the energy storage device at the beginning of the charging process can be taken into account. For this purpose, the 8th The energy requirement shown for the preconditioning process itself is calculated and subtracted as the difference △ from the estimated state of charge of the energy storage device at the end of the journey.

9 shows various simulated temporal progressions of the state of charge of the energy storage device during a period at the beginning of the preconditioning. The simulations of the charging process for the various target temperature candidates are each started with the adjusted initial state of charge (see area A).

10 shows a curve of the temperature T of the energy storage as a function of time t. The different preconditioning options require different energy consumption and a different time duration for the process. The option that is sufficient to reach the target temperature within the available time is selected. If several options are sufficient, the one with the lowest energy consumption is selected. If no option is sufficient, the option that comes closest to the actual target temperature is selected.

If the preconditioning option has been selected and the required time is known, a target temperature trajectory for the energy storage can be calculated. This is linearly guided from the actual temperature at the start of the preconditioning process to the target temperature at the end of the journey, as in 10 shown for two options I and II. This target temperature trajectory can be used as an input variable by an actuator control of the thermal system.

Furthermore, other output variables can be provided, physically consistent with the target temperature trajectory, namely the selected actuator and its thermal performance as well as the battery inlet coolant temperature.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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 accepts no liability for any errors or omissions.

Cited patent literature

• EP 2565560 B1 [0003]

Claims (10)

Method for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device, wherein the motor vehicle has at least one actuator (4) for influencing the temperature of the energy storage device, with the steps: Calculating (S4) an expected temperature of the energy storage device and an expected state of charge of the energy storage device at a start time of the charging process and calculating (S3) a power loss of the energy storage device; Determining (S6) a possible cooling and/or heating power of the at least one actuator (4) and calculating (S5) a target temperature of the energy storage device to be achieved at the start time of the charging process by means of model-based simulation for at least one possible target temperature of the energy storage device, taking into account an energy consumption for the preconditioning (S5) with the at least one actuator (4) taking into account the possible cooling and/or heating power of the at least one actuator (4); Controlling (S8) the at least one actuator (4) for preconditioning the energy storage device, depending on the calculated target temperature. Procedure according to Claim 1 , wherein in the model-based simulation at least one of a temporal course of a state of charge of the energy storage device during charging, a temporal course of a temperature of the energy storage device during charging, an expected charging duration of the charging process, a temporal course of a possible charging power during the charging process, and a cooling or heating power required for charging is determined. Procedure according to Claim 1 or 2 , whereby the model-based simulation is carried out depending on a current state of charge of the energy storage device and a current temperature of the energy storage device. Method according to one of the preceding claims, wherein the model-based simulation and a selection of the actuator (4) for the preconditioning takes place depending on map data and route information. Method according to one of the preceding claims, wherein an actuator (4) for preconditioning the energy storage device is selected taking into account an energy required to operate the actuators (4). Method according to one of the preceding claims, wherein an actuator (4) for preconditioning the energy storage device is selected taking into account the expected charging time. Method according to one of the preceding claims, wherein the at least one actuator (4) comprises at least one of a coolant heating device, a waste heat heating device, a radiator cooling device and a refrigerant circuit cooling device. Method according to one of the preceding claims, wherein the at least one actuator (4) is controlled such that the temperature of the energy storage device is guided linearly from a temperature at the beginning of the preconditioning to the target temperature. Method according to one of the preceding claims, wherein for calculating (S5) the target temperature to be achieved, at least one of a predicted state of charge at the start time of the charging process, a desired state of charge at an end time of the charging process, a maximum charging current depending on the temperature and the state of charge of the energy storage device, and a power of a charging station is taken into account. Device (1) for preconditioning an energy storage device of an at least partially electrically operated motor vehicle for a charging process of the energy storage device, wherein the motor vehicle has a plurality of actuators (4) for influencing the temperature of the energy storage device, comprising: a computing device (2) which is designed to: - calculate an anticipated temperature of the energy storage device and an anticipated state of charge of the energy storage device at a start time of the charging process and to calculate a power loss of the energy storage device, and - calculate a possible cooling and/or heating power of the at least one actuator (4) and to to calculate the target temperature of the energy storage device to be achieved at the start of the charging process, by means of model-based simulation for at least one possible target temperature of the energy storage device, taking into account an energy consumption for the preconditioning (S5) with the at least one actuator (4), taking into account the possible cooling and/or heating output of the at least one actuator (4); and a control device (3) which is designed to control the at least one actuator (4) for preconditioning the energy storage device, depending on the determined target temperature.

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