DE102019003571A1 - Method for regulating a fuel cell for an increased range of a vehicle and vehicle with a fuel cell and a control unit - Google Patents

Abstract

The invention relates to a method for regulating a fuel cell (REX) for an increased range of a vehicle with a high-voltage battery (HVB). A difference (e) in the current state of charge (SoC) with a predetermined state of charge (SoC) is used as the input signal (e) for a PI controller (10). A power value (P) is determined for the fuel cell (REX) by means of the PI controller (10) to reduce the difference (e). A thermal parameter (TS) is taken into account. It is checked whether, during a predefined first time period (sp1), each demand value (LB) for an air conditioning unit (CCU) of the vehicle lies within a predefined first interval, which contains the determined performance value (P). If the test is answered in the affirmative, the respective demand value (LB) for the air conditioning unit (CCU) is defined as the respective thermal parameter (TS) for the determination of a further power value (P) a further time step (t). The definition is carried out continuously for the duration of a second period (sp2) in order to regulate the fuel cell (REX).

Description

The invention relates to a method for regulating a fuel cell for an increased range of a vehicle with a high-voltage battery. Furthermore, the invention relates to a vehicle which has a high-voltage battery, a fuel cell and a control unit.

Fuel cell technology in the transportation industry generates electrical energy to power vehicles or large vehicles. This conversion of chemical energy into electrical energy has an efficiency of around 40 - 50%. Fuel cells can run on hydrogen. The formation of water through the combination of hydrogen with oxygen molecules releases not only electrical energy, but also thermal energy (heat). This can be used by the vehicle to heat a vehicle interior or to defrost a high-voltage battery, which leads to less use of a braking resistor for heating purposes and thus to a reduction in energy and thus hydrogen consumption.

The publication US 2015/0053491 A1 describes a thermal management system for a fuel cell, a fuel cell system and a vehicle equipped therewith. The thermal management system for a fuel cell includes a cooling system for recovering waste heat generated by the fuel cell system, a heat supply system connected to the cooling system to supply heat using the waste heat recovered from the cooling system. The thermal management system reduces the temperature of each component of the fuel cell system by cooling the components that the cooling system uses.

The waste heat generated by the fuel cell system is used as a heat source by the heat supply system.

The publication WO 2013/084038 A1 relates to a device with a fuel cell and a vehicle air conditioning system. The device includes a cooling system that sets a temperature of a fuel cell, a waste heat collection unit that collects at least a portion of the waste heat from the fuel cell and uses the collected waste heat to heat a cabin interior of the fuel cell vehicle, and a heat generation unit that generates heat to heat the fuel cell vehicle. The device calculates a fuel consumption amount required for the fuel cell to generate a total power amount. An optimal temperature is calculated, which is a temperature of the fuel cell at which the amount of fuel consumption reaches a minimum, and the device controls the cooling system so that the temperature of the fuel cell reaches the optimal temperature.

It is an object of the invention to offer a better method for regulating a fuel cell, which takes into account at least a state of charge of a high-voltage battery and a need for thermal power.

This object is sensibly achieved in accordance with the independent claims of this application. Advantageous further developments and alternative embodiments result from the subclaims, the description and the figures.

• In einem ersten Schritt a) wird ein Pl-Kontroller zum Regeln eines Ladezustands der Hochvoltbatterie aktiviert. Dabei wird eine Differenz des aktuellen Ladezustands mit einem vorgegebenen Ladezustand als Eingangssignal für den Pl-Kontroller verwendet. Die Hochvoltbatterie ist insbesondere eine Traktionsbatterie oder Fahrzeugbatterie.

The invention provides a method for regulating a fuel cell for an increased range of a vehicle with a high-voltage battery. The following process steps are carried out:

• In a first step a), a PI controller for regulating a state of charge of the high-voltage battery is activated. A difference in the current state of charge with a predetermined state of charge is used as the input signal for the PI controller. The high-voltage battery is in particular a traction battery or vehicle battery.

In a further step b), a power value for the fuel cell is determined for a time step by means of the PI controller to reduce the difference. A thermal parameter is taken into account. When the method is initiated, this thermal parameter can be taken into account using a starting value. This start value can be specified and constant.

In a further step c) it is checked whether, during a predefined first time period, each demand value for an air conditioning unit of the vehicle lies within a predefined first interval. The specified first interval contains the determined power value.

If step c) is answered in the affirmative, the respective demand value for the air conditioning unit is defined as the respective thermal parameter for determining a further power value for a further time step. The definition is carried out continuously for a second period of time in order to regulate the fuel cell. The predefined state of charge can be determined on the basis of a function which assigns a distance to a state of charge. Thus, the state of charge can be a function of the state of charge depending on the route s or a distance traveled. The PI controller can have a proportional term as well as an integral term. Prefers the PI controller takes the thermal parameter into account. The PI controller can in particular be a PI controller. This thermal parameter can be approximated for an initiation of the method using a predefined starting value.

Previous control or regulation methods only take control into account based on the state of charge of the battery, or they only take into account maximum performance, service life or maximum efficiency of the fuel cell. Other control methods only consider hydrogen consumption by the fuel cell. In addition to the state of charge, the proposed method also takes into account an energy requirement for the air conditioning unit of the vehicle. An important influencing factor for regulating the fuel cell can thus be taken into account. The term "regulate" can also mean "regulate".

The invention also provides a vehicle with a fuel cell and a control unit, which together are configured to carry out a method according to one of the described implementation options. In addition to the fuel cell and the control unit, the vehicle can also have a high-voltage battery. The vehicle can in particular be designed as a large-capacity vehicle. The open-top vehicle can be designed as a bus or a transport vehicle larger than conventional cars. All the process features that are described in the application can be regarded as corresponding device features. In this respect, the advantages and examples described for the method steps apply analogously and analogously to the device features and vice versa.

The invention will now be explained in more detail with reference to the accompanying drawings. In the figures, the described embodiments of the invention represent preferred examples, which, however, do not restrict the invention.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawings. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the combination indicated in each case, but also in other combinations or on their own, without the scope of Leaving invention.

• 1 ein schematisches Ablaufdiagramm für ein mögliches Verfahren zum Regeln der Brennstoffzelle;
• 2 eine Darstellung für eine Funktion des Ladezustands in Abhängigkeit von einem zurückgelegten Weg des Fahrzeugs;
• 3 eine schematische Darstellung betreffend verschiedene Bedingungen für das Verfahren;
• 4 eine Übersicht möglicher Komponenten, welche eine Energiemanagementeinheit beeinflussen.

It shows:

• 1 a schematic flow diagram for a possible method for regulating the fuel cell;
• 2 a representation of a function of the state of charge depending on a distance traveled by the vehicle;
• 3 a schematic representation of various conditions for the method;
• 4 an overview of possible components that influence an energy management unit.

1 shows an example of a method for regulating a fuel cell REX , It should be noted that the index i represents a time step and the index i + 1 represents another time step. First, a state of charge SoC , with a current state of charge SoC _{i + 1} compared. A function is preferred f (s) for the state of charge SoC used which as a parameter a way s considered. So the state of charge SoC depending on the way s through the function f (s) to be discribed. The difference in state of charge SoC _i with the current state of charge SoC _{l + 1} makes a difference e or an input signal e for a PI controller 10 , The Pl controller 10 is often referred to as a PI controller. The PI controller 10 has different terms. The PI controller 10 has a constant term K _p as well as an integral term K , on. In contrast to the prior art, a thermal parameter TS in the PI controller 10 considered.

This thermal parameter can be used to initiate or initiate the process TS are first approximated using a predetermined starting value. The PI controller 10 delivers a performance value in particular P _{i + 1} at a time step t _{l + 1} ,

This performance value P _{l + 1} becomes an energy management unit ENM fed. 3 shows an example of a interaction of the performance value P _{l + 1} with the energy management unit ENM , In 3 two rectangles are indicated on the right. An energy scale is plotted in the smaller rectangle. This energy scale ranges from 10 kW to 30 kW. A need value LB is together with the performance value P _{l + 1} indicated. The energy management unit ENM can be a switch SW exhibit. That switch SW can take into account the thermal parameter TS activate or deactivate. Thus the control unit ECU by means of the switch SW turn on or neglect the thermal parameter. It can be used to regulate or regulate the fuel cell REX be activated or deactivated.

The method preferably provides that for the duration of a first period of time sp1 is checked whether every need value LB for an air conditioning unit CCU of the vehicle is within a predetermined first interval, which is the determined power value P _{i + 1} includes. This test can be continued for the duration of the first period sp1 respectively. The determined performance value P _{i + 1} assumed to be constant. In the 3 Conditions shown for the smaller rectangle mean that during this first period sp1 every single need value LB must be within the specified first interval. The default first interval is in 3 shown in the smaller rectangle as a small box. The predetermined first interval can change or shift dynamically over time. In the example of 3 this interval ranges from 13 kW to 19 kW.

Is the need value LB or those during the first period sp1 determined demand value of the LP during this first period sp1 continuously within this predetermined first interval, the process is continued. In this case, the performance value P _{i + 1} the energy management unit ENM fed which the thermal parameter TS determined. The energy management unit ENM defines the thermal parameter TS than the respective demand value LB and derives this value as the thermal parameter TS , as in 1 shown to the PI controller 10 further. This thermal parameter TS influenced the determination of a further performance value in this case P _{i + 2} , Is that in 3 shown condition for the smaller right rectangle, it is provided that the feedback with the energy management unit ENM for at least the duration of a second period sp2 is carried out. This can ensure that the fuel cell REX of the vehicle is regulated for a certain minimum time. For example, would be the need value LB significantly smaller than the waste heat generated by the fuel cell REX , this discrepancy could be determined using the thermal parameter TS be at least partially reduced. In this case, the further performance value P _{l + 2} for another time step t _{i + 2} be reduced. The time steps t _{l + 1} or t _{l + 2} can each be designed as points in time. There is therefore a time difference between these times, which can be regarded as a time span.

The lower area of 1 has an anti-windup unit AW on. This can limit the integration by the PI controller 10 be effected. For example, the integral part K , be frozen when a predetermined limit to the last value is reached. By supplying the power value accordingly P _{l + 1} to the anti-windup unit AW and by means of a deliberate slight deviation from its operating point, it is possible to meet the thermal requirements and thus save more energy. This can help reach a fuel cell range REX or increase the vehicle.

A further advantageous embodiment of the method provides that after the uninterrupted definition of the respective demand value LB during the second period sp2 at least process steps c) and d) during a third period sp3 cannot be executed. The first condition regarding the smaller right rectangle is in 3 the method is fulfilled for the duration of the second period sp2 initiated and during this second period sp2 performed continuously. After the second period sp2 the control procedure is ended or interrupted. This embodiment now provides that at least for the duration of the third period sp3 the procedure will not be resumed or for the duration of the third period sp3 remains interrupted. This can ensure that the fuel cell REX is not overregulated and can stabilize accordingly. The first period sp1 can be about 1 minute, the second period sp2 can be about 2 minutes and the third period sp3 can be about 5 minutes. The predetermined first interval can be symmetrical about the determined power value P _{l + 1} be trained. This predetermined first interval takes into account tolerance deviations with regard to measured values and / or calculations relating to the determined power value P _{i + 1} ,

The method advantageously provides that only then the further performance value P _{l + 2} for the further time step t _{l + 2} is used for regulation if a power gradient UR or DR lies within a predetermined second interval. After the Pl controller 10 the output value is fed to a test with regard to the power gradient UR, DR. In particular, it is checked whether the required power gradient, that is to say the change in power per unit of time, lies within the predetermined second interval. The method is preferably only carried out if this condition is met.

Additionally or alternatively, the method can provide a further condition. In this case only the further performance value P _{l + 2} for the further time step t _{l + 2} used for control if the determined performance value P _{l + 1} is within a predetermined third interval. This condition is in 1 before the performance value P _{i + 1} shown as a starting value. The procedure for regulating the fuel cell REX which the thermal parameter TS is taken into account, in this case it will only be executed or continued if the determined performance value P _{i + 1} is within the predetermined third interval. The predetermined third interval is determined by a minimum performance value FC-min and a maximum performance value FC-max represents. Regarding the in 3 conditions shown is in particular the third period sp3 larger than the first period sp1 and the second period sp2 , The third time span sp3 be greater than a sum from the first period sp1 and the second period sp2 , In particular, the third period sp3 each be greater than the first period sp1 or the second period sp2 ,

In 2 is an example of a function f (s) for the state of charge SoC depending on the distance covered s shown. The state of charge is along a y-axis SoC plotted along an x-axis is the distance covered s applied. The method can be carried out, for example, using a control unit. The control unit ECU can the energy management unit ENM as well as the fuel cell REX drive. Several dashed lines are shown along the x-axis. The first dashed line indicates when the control unit ECU is activated. The method is preferably not activated immediately when the vehicle is traveling, but rather after a predetermined path section has been covered. The inventive method is in the example of 2 activated at the point designated FC. The control unit ECU can charge SoC the high-voltage battery HVB monitor.

At the time or the "REX" route, the vehicle has covered approximately 80% of a planned route. From the "ECU" time, the control unit is preferred ECU activated. The control unit ECU later activates the process for regulating the fuel cell at the time “REX” REX , The state of charge SoC is in this example when the method is activated to about 40% of the maximum charging capacity of the high-voltage battery HVB dropped. An additional buffer with regard to the state of charge can be provided SoC provided. This buffer can be 10% of the state of charge SoC be. In this case, the control unit initiates ECU the process earlier than without using the additional buffer. The buffer or an associated buffer value can be designed dynamically. The buffer can be from a state of the high-voltage battery HVB be dependent. In the example of the 2 falls due to the process of regulating the fuel cell REX the state of charge SoC much slower than before without the procedure. In the example of 2 the drop in state of charge SoC limited to about 35% while the process is active.

From the point "REX" on the s axis, the thermal parameter TS for determining the performance value P _{i + 1} considered. As in 2 the drop in the state of charge changes clearly SoC clear. By considering the thermal parameter TS can discharge the high-voltage battery HVB be clearly delayed. Thus, the energy capacity of the high-voltage battery HVB be used much better. According to the example of 2 the procedure is carried out from the point "FC on".

The control unit ECU can contain several components. 4 shows possible components that the control unit ECU can have or which components with the control unit ECU can work together. The control unit ECU the energy management unit is designed in particular ENM to control and / or regulate. The air conditioning unit ECU transmits the required value LB to the energy management unit ENM , An electrical vehicle control unit can also be used EDCU Information to the energy management unit ENM to transfer. The electrical vehicle control unit EDCU can in particular refer to information regarding a drive inverter AWR and a braking resistor BRC To fall back on. The energy management unit ENM can also use a backup power source API be supplied with energy. The high-voltage battery HVB can send information to a battery management system BMS to transfer. The battery management system BMS can in turn send the information received to the energy management unit ENM transfer. The energy management unit ENM can analyze and evaluate the information received from the various components. In particular, the information thus obtained becomes the method for regulating the fuel cell REX used. From this, the energy management unit in the performance value P _{l + 1} as well as the further performance value P _{l + 2} determine.

In connection with the determined performance value P _{l + 1} for the time step t _{l + 1} The examples and process steps mentioned apply analogously and analogously to the other performance values P _{l + 2} for the further time steps t _{l + 2} , The further time steps t _{l + 2} are preferred the time steps t _{i + 1} downstream. The further time steps t _l-2 thus preferably occur later than the time steps t _{i + 1} , When determining the further performance values P _{l + 2} the respective thermal parameters are preferred TS considered. The performance values determined in this way P _{i + 1} or other performance values P _{l + 2} are at an interface FCG the fuel cell REX transfer. This interface FCG is often referred to as the "Fuel Cell Gateway". Using the interface FCG the power values determined in this way are sent to the fuel cell REX transfer.

The invention shows in particular that the time step in which the demand value can be identified LB the air conditioning unit CCU the current operating point of the electrical Energy management system ENM approaches. This allows both the energy requirement for the air conditioning unit CCU and the energy requirements for the vehicle can be regulated more efficiently. These different energy needs can thus be effectively combined to form a focus.

LIST OF REFERENCE NUMBERS

10

PI controller, PI controller

CCU

air conditioning unit

ti

time step

ti + 1

another time step

SoC

SOC

SoC _{l + 1}

specified state of charge

SoC _{l + 2}

current state of charge

P _{i + 1}

power value

P _{l + 2}

further performance value

s

Path, path section

REX

fuel cell

e

Difference, input signal

K _p

constant term

K

integral term

TS

thermal parameter

ENM

Energy management unit

LB

demand value

sp1

first period

sp2

second period

sp3

third period

AW

Anti-windup unit

FC-max

maximum power value

FC-min

minimal performance value

ECU

control unit

EDCU

electric vehicle control unit

AWR

Drive inverter

BRC

braking resistor

API

Backup power source

HVB

High-voltage battery

BMS

Battery Management System

FCG

Interface of the fuel cell

f (s)

Function of the state of charge

SW

switch

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• US 2015/0053491 A1 [0003]
• WO 2013/084038 A1 [0005]

Claims (6)

Method for regulating a fuel cell (REX) for an increased range of a vehicle with a high-voltage battery (HVB) characterized by the method steps: a) activating a PI controller (PI) for regulating a state of charge (SoC) of the high-voltage battery (HVB), one of which Difference (e) of the current state of charge (SoC _{l + 1} ) with a predetermined state of charge (SoC _i ) is used as the input signal (e) for the PI controller (PI), b) determining a power value (P _{i + 1} ) for the Fuel cell (REX) for a time step (t _{i + 1} ) using the PI controller (PI) to reduce the difference (e), taking into account a thermal parameter (TS), c) Checking whether during a predetermined first time period ( sp1) each demand value (LB) for an air conditioning unit (CCU) of the vehicle lies within a predetermined first interval, which includes the determined power value (P _{l + 1} ), d) if step c) is answered in the affirmative, define the respective demand value (LB) for the air conditioning unit (CCU) as the respective thermal parameter (TS) for determining a further power value (P _{l + 2} ) for a further time step (t _{i + 2} ), the definition being continuous for the duration of a second period (sp2) is executed to regulate the fuel cell. Procedure according to Claim 1 , wherein after the uninterrupted definition of the respective demand value (LB) during the second period (sp2), at least process steps c) and d) are not carried out for a third period (sp3). Method according to one of the preceding claims, wherein only then the further power value (P _{l + 2} ) for the further time step (t _{i + 2} ) is used for regulation, if a power gradient (UR, DR) which is based on immediately successive time steps (t _{l + 1} , t _{l + 2} ) with the associated power values (LB) is determined, lies within a predetermined second interval. Procedure according to one of the Claims 1 to 2 , the further power value (P _{i + 2} ) for the further time step (t _{l + 2} ) being used for regulation only if the determined power value (P _{l + 1} ) lies within a predetermined third interval. Procedure according to Claim 2 , wherein the third period (sp3) is defined larger than the first period (sp1) and the second period (sp2) in order to stabilize the fuel cell (REX). Vehicle with a fuel cell (REX) and a control unit (ECU), which are configured together to carry out a method according to one of the preceding claims.

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