DE102005044268A1 - Energy storage/energy flow`s charge state controlling or regulating method for use in vehicle, involves controlling or regulating charge state of energy storage/flow depending on cost function for energy consumption or emission output - Google Patents

Abstract

The method involves coupling or decoupling an internal combustion engine and an electrical engine with a drive transmission of a vehicle. A charge state of an energy storage or energy flow is controlled or regulated depending on a cost function for energy consumption or emission output. An actual rotation moment of the internal combustion engine and an actual rotational moment of the electrical engine are determined by an application of a band of energy cost vectors. An independent claim is also included for a device for controlling or regulating a state of charge of an energy storage or energy flow into a vehicle.

Description

The The invention relates to a method and a device for controlling or regulation of the state of charge of an energy store or the energy flow in a vehicle with a hybrid drive.

It are already known motor vehicles with hybrid drive. These wise an internal combustion engine and an electric machine, which during the Operation of the respective motor vehicle individually switched on and off can be. Vehicles with hybrid drive show in comparison to conventional ones Vehicles an additional Energy storage, in which recovered energy stored can be, for example in the sense of braking energy recuperation.

From the DE 103 46 213 A1 a method for controlling the state of charge of an energy storage device in a hybrid vehicle is known, which has an internal combustion engine and at least one electric machine, which can be coupled or coupled to a drive train of the vehicle. According to this known method, a state of charge of the energy store is regulated as a function of the travel speed of the vehicle.

Advantages of invention

One Method for controlling or regulating the state of charge of an energy store or the energy flow in a vehicle with a hybrid drive according to the present Invention achieves that the efficiency of the hybrid drive improved becomes. This is due to the increasing energy demand of future vehicles of great Importance. These benefits are essentially achieved by that the state of charge of the energy store or the energy flow dependent on from a cost function for the energy consumption or emission output is controlled or regulated.

through the features specified in claim 2 ensures that needed in the operation of the vehicle Types of energy, namely Output energy for driving the vehicle and electrical energy for the electrical system consumers, also correctly enter into the calculation of energy costs.

According to the claim 3 are using a bunch of energy cost vectors a target torque of the internal combustion engine and a target torque the electric machine determined. These values are determined in such a way that the state of charge of the energy store in each case necessary Way can be influenced.

These Influencing the state of charge of the energy storage in each desired Manner is further improved by the features of claim 4, according to which at least one of the other parameters existing state of charge of energy storage needed electric power and needed mechanical power in the determination of the specified target torques additionally considered become.

through in the claims 5 and 6 specified characteristics will continue to determine the energy costs improved.

The Advantages of in the claims 7 and 8 indicated interruptions of loading and unloading the Energy storage devices consist of not permanently extreme state of charge values be achieved.

According to the features of claim 9 is a weighting factor in the determination of energy costs considered, that of the deviation of the current state of charge of the energy storage is dependent on a desired value of the state of charge. In this procedure receives the necessity of charging the energy storage relative to the energy costs a higher Weight.

through the features specified in claim 10 is to simplify the Determination of costs for the electrical energy at reference from the energy storage medium Energy price determined on the basis of production costs.

Further advantageous features of the invention will become apparent from the exemplification thereof based on the drawing.

drawing

The 1 shows a block diagram in which the necessary for understanding the invention components of a vehicle provided with a hybrid drive vehicle are shown. The 2 shows a sketch to illustrate the determination of setpoints for the torque of the internal combustion engine and for the torque of the electric machine. The 3 shows a block diagram for explaining the determination of various energy costs. The 4 shows a diagram in which the total energy costs are shown over the torque of the internal combustion engine. The 5 shows a diagram illustrating the consideration of the state of charge of the battery.

description

object The present invention is a method and an apparatus for controlling or regulating the state of charge of an energy store or the energy flow in a vehicle with a hybrid drive. Here, a charging strategy is used, the energy costs considered. In particular, the energy costs for the electrical energy and determines the mechanical energy. In this determination of energy costs is preferably taken into account, how this energy is generated.

The Degree of freedom, which energy provided by which source is, you have only in the hybrid mode, there only as an alternative used as energy storage battery or the internal combustion engine can be. The energy taken from the battery must become one later Time fed again be or has to be in an already past period in the Battery has been charged.

at purely electrical driving, the internal combustion engine is switched off. The required Energy comes complete from the battery. In a Bremsenergierekuperation only the Battery charged.

The Loading strategy according to the present Invention is therefore used only in hybrid driving. This charging strategy is explained in more detail below with reference to FIGS.

The 1 shows a block diagram in which the necessary for understanding the invention components of a vehicle provided with a hybrid drive vehicle are shown. However, the invention can also be used in connection with any other hybrid configurations.

The device shown has a combustion engine as the main drive unit 1 on. This is about a clutch 3 with a gear 4 connected. This in turn drives over the output shaft 14 the drive wheels 5 of the vehicle. As a secondary drive unit of the hybrid drive is an electric machine 2 intended. This is also with the gearbox 4 connected and can on this in addition to the combustion engine or in place on the output shaft 14 act. The electric machine 2 refers the energy required from an energy store, which in the embodiment shown is a battery 6 is.

The electric machine 2 is also for the supply of consumers 7 provided, which are, for example, a heated rear window, a seat heating, air conditioning and a fan. These consumers send signals to a control unit 8th which contains information about the condition and energy needs of consumers. Furthermore, sensors or other information sources 9 provided, the other operating status signals to the control unit 8th to transfer. These other operating state signals include information about the speed n _{GE of} the transmission input shaft, the torque T _GE at the transmission input shaft, the engine temperature Temp _Engine and the battery temperature Temp _Batt .

The control unit 8th Forwards the information available to him, as far as they are in another control unit 10 be needed, continue to this. The further control unit 10 takes in the embodiment shown, the function of a charge controller, the charging and discharging of the battery 6 regulates and also the internal combustion engine 1 and the electric machine 2 Feeds setpoints. The control unit or the charge controller 10 has a realized in the form of a microcomputer arithmetic unit 11 as well as memory 12 and 13 on. The memory 12 is used to store required maps, the memory 13 for storing a loader price C _EBatt .

The 2 shows a sketch illustrating the determination of setpoints T _VBS for the torque of the internal combustion engine and setpoints T _EMS for the torque of the electric machine. These setpoints are determined in such a way that at all operating points a charge or discharge of the battery at optimum cost 6 is possible with correct output torque.

In the block 15 In a first step, a determination of the energy costs for the required electrical and the required mechanical energy. In particular, at the output of the block 15 Information about the calculated costs C _{VBmech of} the mechanical energy generated by the internal combustion engine, the calculated costs C _{VBel of} the electrical energy generated by the internal combustion engine, the calculated costs C _{Battmech of} the mechanical energy generated by the battery and the calculated costs C _Battel the electrical energy provided by generation with the help of the battery. To determine this information about the energy costs will be the block 15 Input side Information about the speed n _{GE of} the transmission input shaft, the engine temperature Temp _Engine , the torque T _GE at the transmission input shaft, the battery temperature Temp _Batt , the power requirement P _{ACC of} the electrical system consumers 7 , the current state of charge SOC of the battery 6 and the charging energy price C _EBatt supplied.

How this calculation of energy costs is made is described below on the basis of 3 explained in more detail.

The 3 shows a block diagram for explaining the determination of energy costs, the above in the 2 at the exit of the block 15 to provide. In this example, it is assumed that there is a hybrid drive with a parallel hybrid train, wherein there is no translation between the crankshaft of the internal combustion engine, the electric machine and the transmission input shaft.

The block 17 in which it is a limiter, the input side information about the speed n _{GE of} the transmission input shaft and the torque T _{GE are} supplied to the transmission input shaft. At the exit of the limiter 17 the information about the speed n _{GE of} the transmission _input shaft and a signal T _{VB range is} output, the latter being the meaningful torque range of the internal combustion engine 1 equivalent. These signals are used to address a memory 18 used, in which a map is included with a variety of price information, that of the internal combustion engine 1 assigned. At the output of the memory 18 Information provided is the cost C _VBmech the mechanical energy in production by means of the internal combustion engine 1 ,

Furthermore, from the information present at the input via the torque T _GE to the transmission input shaft in a subtractor 27 the information on the meaningful torque range T _VBBereich subtracted. From the at the output of the subtractor 27 present difference signal and the information about the rotational speed n _{GE of} the transmission input shaft is in a device 19 , which contains a map with stored efficiencies, the efficiency η _{ELM of} the electric machine 2 determined.

That at the output of the memory 18 provided signal C _Vbmech is in a divider 28 divided by the efficiency η _ELM the electrical machine. The output signal of the divider 28 corresponds to the cost C _{VBel of} the electrical energy when generated by means of the internal combustion engine.

The output signal of the subtractor 27 will continue in a multiplier 20 with the rotational speed n _GE multiplies the transmission input shaft. In a multiplier 20 subsequent divider 21 becomes the output signal of the multiplier 20 by the efficiency η _{ELM of} the electric machine 2 divided. The output signal of the divider 21 becomes an adder 22 fed and there with the power requirement P _{ACC of} the electrical consumers 7 merged.

The output of the adder 22 becomes a device 24 to determine the efficiency of the battery 6 fed. As further input signals of the device 24 the current state of charge SOC of the battery and the information about the battery temperature Temp _Batt supplied. In a next divider 26 the charging energy price C _{EBatt is divided} by the efficiency η _{Batt of} the battery. The charging energy price C _EBatt is from a store 23 made available. At the exit of the divider 26 The information about the cost C _{Battel of} the electrical energy when generating with the help of the battery 6 made available.

This value C _Battel will continue in a divider 25 by the efficiency η _{ELM of} the electroma divided. The result is the information C _Battmech about the cost of mechanical energy when generated by means of the battery.

The energy costs determined above are for a variety of operating points within the permissible Torque range of the internal combustion engine calculated. By a Interpolation can then for the entire operating range from charging the battery to discharging the battery Battery energy prices are calculated. Because of the possible power range the consumer or aggregates from operating point to operating point is different, this circumstance of the arithmetic unit must also communicated and taken into account by this become.

The limits of a maximum useful operating range are calculated as follows: T VBmin1 = max [T GE - min ((T. BattmaxEntladen - T ACC ), T. ELMmax ); T Vbmin2 ]

Where:
T _VBmin1 = minimum sensible torque of the internal combustion engine,
T _GE = required torque of the transmission input shaft,
min ((T _{Battmax unloading} - T _ACC ), T _ELMmax ) = maximum electrically generated torque of the transmission _input shaft and
T _VBmin2 = minimum allowable torque of the internal combustion engine.

According to the above relationship, the minimum useful torque of the internal combustion engine corresponds to the maximum of the minimum allowable torque of the internal combustion engine and the difference between the required torque of the transmission input shaft and the maximum electrically generated torque of the transmission input shaft. T VBmax1 = min [T GE - max ((T BattmaxLaden - T ACC ), T. ELMmin ); T VBmax2

Where:
T _VBmax1 = maximum useful torque of the internal combustion engine,
T = _GE demanded output torque,
max ((T _BattmaxLaden - T _ACC ), T _ELMmin ) = torque convertible into electrical power of the internal combustion engine and
T _VBmax2 = maximum permissible torque of the internal combustion engine.

According to this Relationship corresponds to the maximum meaningful torque of the internal combustion engine Minimum from the maximum allowable Torque of the internal combustion engine and the difference between the Required output torque and convertible into electrical power Moment of the combustion engine.

Between these limits further support points for the torque of the internal combustion engine are selected. For each of these nodes, a vector is formed, which is designated T _VB range.

From the individual energy prices determined, a summation of the energy prices weighted with the respective performance data of the consumers determines the total energy costs at the various operating points. This will be in the block 16 from 2 performed.

The 4 shows a diagram in which the total energy costs over the torque of the internal combustion engine 1 are shown. It was assumed that there is no translation between the transmission input shaft and the internal combustion engine. Furthermore, it was assumed that the overall cost function was optimized with regard to a minimum emission of carbon dioxide. Alternatively, it is also possible to optimize the overall cost function to a minimum emission of nitrogen oxides.

The Minimum of this total cost function gives the point with the lowest Energy costs or, alternatively, the lowest emissions output.

An advantageous development is to take into account the current state of charge of the battery in the strategy described above. This has the advantage that not permanently extreme state of charge values are brought about. An exemplary embodiment is to carry out a two-stage limitation of the state of charge. This embodiment is in the 5 illustrated. There at is applied to the right of the state of charge SOC of the battery. If, during normal operation of the vehicle, the state of charge of the battery is within the range indicated by B1, charging as well as discharging of the battery is permitted. This area B1 may only be exceeded if there is a boost operation or energy recuperation operation. The state of charge of the battery in boost mode and in energy recuperation mode is limited to the range denoted B2. Below the area B2 further discharge of the battery is prohibited. Above the range B2 further charging of the battery is not allowed.

Preferably, furthermore, a control circuit is used, by means of which the charge state of the battery is regulated to a fixed desired value, which lies within the range B1. This control circuit, the state of charge of the battery, for example, by influencing the consumer 7 or consumers 7 affect recorded performance.

alternative This can also be a one-step limitation of the state of charge of the battery be made. This is longitudinal the SOC axis defines only one area. Will this area be after below below, then further unloading is prohibited. Becomes this area has passed upwards, then another store is banned.

Another alternative of considering the state of charge of the battery is that in the 4 shown characteristic in response to the deviation of the state of charge of the battery from a target value to tilt. The greater the deviation from the setpoint, the more the characteristic is tilted in the respective direction. This corresponds to a weighting of the energy price with the need for charging or discharging the battery.

Yet another alternative of considering the state of charge of the battery is to use all the local minima in the 4 To consider the characteristic curve shown and to use the most appropriate in view of the deviation of the current state of charge of the battery of a setpoint minimum.

at The operating strategy described above has always been that a hybrid driving exists, d. H. a driving with switched combustion engine. The charge controller can after a exam of all different possibilities also come to the conclusion that it is more cost-effective, the hybrid Leave driving and go into a purely electric driving.

In order to determine the costs of the electric energy when generating with the aid of the battery, the following simplified approach can also be used, according to which a calculation of the average electric battery energy price is based on the generation costs. Each time the battery is charged, the newly generated energy is weighted with the corresponding price. This happens according to the following relationship:

Here are:
C _{EBatt, old} = average energy price of the energy stored in the battery before charging,
C _EBatt = average energy price of the energy stored in the battery after the charging process,
E _{EBatt, old} = amount of energy in the battery before charging,
E _{EBatt, L} = amount of energy during charging and
C _{EBatt, L} = average price of energy, which is stored in the charging process of the battery.

With each discharge process, the average energy price of the stored energy is retained, however, the stored amount of energy is reduced. The corresponding new amount of energy is then used in the new charging process as E _{EBatt, old} .

The Determination of the mechanical energy at the transmission input shaft, which is taken from the battery, is based on the price of the electric battery power and an efficiency map of the electric machine and the battery. The calculation of the mechanical Energy at the transmission input shaft, which is the fuel tank or which is taken from the internal combustion engine, is based on Characteristics over the speed of the internal combustion engine and the torque of the internal combustion engine. This also applies to the electrical energy taken from the internal combustion engine, at which still takes into account the efficiency of the electric machine becomes.

l

combustion engine

2

electric machine

3

clutch

4

transmission

5

drive wheel

6

Energy storage, battery

7

consumer

8th

control unit

9

sensors information store

10

Control unit, charge controller

11

computer unit

12

Storage

13

Storage

14

output shaft

15

block for the determination of energy costs

16

block for determining the target torque of the internal combustion engine and the electric machine

17

limiter

18

Storage for energy price map for the combustion engine

19

contraption for determining the efficiency of the electric machine

20

multipliers

21

divider

22

adder

23

Storage for charging energy price

24

contraption to determine the efficiency of the battery

25

divider

26

divider

27

subtractor

28

divider

Claims (11)

A method for controlling or regulating the state of charge of an energy store or the energy flow in a vehicle having a hybrid drive, comprising an internal combustion engine and at least one electric machine, which can be coupled or coupled to a drive train of the vehicle, characterized in that a state of charge of the energy store or the energy flow in Depending on a cost function for the energy consumption or the emission output is controlled or regulated. Method according to claim 1, characterized in that that in the control or regulation of the state of charge of the energy storage or energy flow, the cost of electrical energy Reference from the energy storage, the cost of electrical energy From the internal combustion engine, the cost of mechanical energy Reference from the energy storage and the cost of mechanical energy at Be considered from the internal combustion engine. Method according to claim 1 or 2, characterized that using a bunch of energy cost vectors Target torque of the internal combustion engine and a target torque of the Electric machine can be determined. Method according to claim 3, characterized that for determining the target torque of the internal combustion engine and the target torque of the electric machine continue at least the required mechanical Performance and one of the other parameters existing La dezustand of energy storage and needed electric power can be used. Method according to one of the preceding claims, characterized characterized in that the energy costs taking into account the speed of the Transmission input shaft and the torque of the transmission input shaft be determined. Method according to one of the preceding claims, characterized in that the energy costs taking into account the efficiency of the electric machine and / or the efficiency of the energy be determined memory. Method according to one of Claims 4-6, characterized that in the case that the state of charge of the energy storage a exceeds the upper threshold or below a lower threshold, a store or Discharging the energy storage is prevented. Method according to one of Claims 4-6, characterized that for the state of charge of the energy storage an inner and an outer boundary is specified and the inner limit in boost mode or exceeded during energy recuperation can be. Method according to one of the preceding claims, characterized characterized in that the state of charge of the energy storage in dependence from the weighted energy costs for the electrical and mechanical Energy is regulated, with the weighting of the deviation of the current state of charge of the energy storage of a setpoint the state of charge of the energy storage is dependent. Method according to one of claims 2-9, characterized in that when determining the cost of the electrical energy with reference from the energy storage, a mean electrical energy price is determined based on the production cost according to the following relationship:

where: C _{EBatt, alt} = average energy price of the stored energy in the battery before charging, C _EBatt = average energy price of the stored energy in the battery after charging, E _{EBatt, old} = amount of energy in the battery before charging, E _{EBatt , L} = amount of energy during charging C _{EBatt, L} = average price of the energy stored in the battery during the current charging process. Device for controlling or regulating the state of charge of an energy store or of the energy flow in a vehicle having a hybrid drive, comprising an internal combustion engine ( 1 ) and at least one electric machine ( 2 ), which are equipped with an output shaft ( 14 ) of the vehicle can be coupled or coupled, and an energy store ( 6 ) and a charge controller ( 10 ) for controlling or regulating the state of charge of the energy store ( 6 ), whereby the charge controller ( 10 ) controls or regulates the state of charge of the energy store or the energy flow by a method according to any one of claims 1-10.