DE102009008474A1 - Hybrid system operating method involves determining current charging condition of energy storage associated with electric motor, where cost threshold value and saving threshold value are determined based on current charging condition - Google Patents

Abstract

The hybrid system operating method involves determining a current charging condition of an energy storage (6) associated with an electric motor (5). A cost threshold value and a saving threshold value are determined based on the current charging condition. A current speed and torque-dependent operating point of the hybrid system (1) is determined.

Description

Technical area

The The invention relates to a method for selecting or creating a Operating strategy of a hybrid system, which at least one combustion engine mesh and at least one electric machine, which is motor and regenerative can be operated, with at least one associated Energy storage includes.

State of the art

From the DE 199 38 623 C2 a system is known for minimizing the power dissipation equivalents of a multi-component drive system.

The Drive system has at least one degree of freedom to a variation an operating point of at least one of the components of the drive system on, wherein the variation by a control and regulating device of the drive system takes place. Different state variables the components of the drive system are taken into account governed by predetermined control parameters, this regulation by a control and regulating device of the drive system based on the actuating parameters as manipulated variables of the control he follows.

Of the Degree of freedom is used in the way that through the variation at least one of the operating points a sum of the power loss equivalents the components of the drive system for a given request has at least one local minimum.

The Components of the drive system become the state variables monitored, with the influence on the with the by the respective state variable corresponding setting parameters the variation of at least one of the operating points occurs when the respective state variable is a critical value accepts.

A Sensitivity is determined, which is a value for it is how strong the variation is at least one of the operating points to the adjustment parameters of the respective state variable and affects the sum of the power loss equivalents.

Out a set of the determined operating points with a corresponding one Sensitivity smaller than a given allowable Sensitivity, the operating point is selected, the biggest change of each State variable, which with the respective control parameters corresponds, causes and at the same time a local minimum with respect represents the sum of the power loss equivalents.

The Components are operated at the selected operating point and the adjusting parameter (s) thereby changed used for the scheme.

Object of the invention

Of the Invention has the object of providing a more efficient Method for operating a hybrid system based.

Solution of the task

The Task is achieved by a method according to claim 1 solved.

Advantages of the invention

• – alleiniger Betrieb der Verbrennungskraftmaschine;
• – alleiniger Betrieb der elektrischen Maschine als Motor;
• – alleiniger Betrieb der elektrischen Maschine als Generator (Rekuperation);
• – gemeinsamer Betrieb der Verbrennungskraftmaschine und der elektrischen Maschine als Motor;
• – gemeinsamer Betrieb der Verbrennungskraftmaschine und der elektrischen Maschine als Generator.

The hybrid system can be operated in the following operating modes:

• - sole operation of the internal combustion engine;
• - sole operation of the electric machine as a motor;
• - sole operation of the electric machine as a generator (recuperation);
• - Common operation of the internal combustion engine and the electric machine as a motor;
• - Combined operation of the internal combustion engine and the electric machine as a generator.

For the inventive method is in all operating points the hybrid system is a sole operation of the internal combustion engine with the other operating modes (excluding sole operation) the electric machine as a generator) of the hybrid system.

in the The following are - unless otherwise explicitly described - as Speed and torque of the hybrid system those understood which abut the output of a transmission or on the output shaft.

For the inventive method is a certain Driving cycle with the hybrid system in different operating modes hazards. Here are for each time in addition to the speed of the hybrid system (preferably measured at the output of the transmission) the current fuel consumption, pollutant emissions (for example determined on a test bench by means of maps) or Composition of the emissions, the instantaneous charge quantity (charging current) the energy storage and possibly the selected gear detected.

For the two modes of operation of a common operation of the internal combustion engine and the electric machine as a generator and a common Operation of the internal combustion engine and the electric machine as engine different proportions can be realized. Therefore, in addition to these two operating modes further information recorded. For the operating mode of the common operation of the internal combustion engine and the electric Machine form the amount of increase in the torque of the combustion engine and the additional amount of charge (increasing the Charging current) of the energy storage additional information. For the operation mode of the common operation of the internal combustion engine and the electric machine as the motor constitute the amount of reduction the torque of the internal combustion engine and the reduced Amount of charge (reduction of the charging current) of the energy storage the additional information.

One potential specific cost value represents a relation between an additional fuel consumption (for example, in [liters]) of the internal combustion engine to an additional amount of charge (for example in [Ah]) of the energy storage. Instead of the additional fuel consumption the pollutant emissions can be taken into account become. The potential specific cost value is determined by the operating mode a joint operation of the internal combustion engine and the gained electrical machine as a generator. In this operating mode is the torque of the hybrid system by a certain amount increased and the speed kept constant (not changed). For each amount increase of torque (at constant speed) can be a potential specific cost value. Of these potential specific cost values may have an optimum, for example a minimum at a quotient of additional fuel consumption to additional charge amount (Charging the energy storage) to be determined. Any potential specific cost value, the particular Optima or the order of the Optima located in a certain area potential specific Cost values are read into a cost map. Any potential specific cost value is in the cost map via the torque and the speed of the hybrid system is referenced. Furthermore, can the potential specific cost value as additional Information the corresponding magnitude torque increase of Internal combustion engine included.

One potential specific savings value represents a relation between a fuel consumption (for example, in [liter]) of the Internal combustion engine to a lower charge amount (for example in [Ah]) of the energy storage. Instead of fuel consumption the pollutant emissions can be considered become. The potential specific savings value becomes greater, the greater the saving (under-consumption) Fuel or reducing the emission of pollutants. The potential specific savings value is determined either by the Operating mode of a common operation of the internal combustion engine and the electric machine as a motor or a sole operation of the electrical machine won as a motor. In this operating mode is the torque of the hybrid system by a certain amount lowered and the speed kept constant (not changed). For any reduction in torque (at constant speed) can be a potential specific savings value be determined. Of these potential specific savings can be an optimum, for example a maximum at a quotient from fuel consumption to less charge (unloading of the energy store). Any potential specific savings value, the respective Optima or the Optima in a certain Range of potential specific savings read into a savings map. Any potential specific Savings value is in the savings map over the Torque and the speed of the hybrid system referenced. Farther the potential specific savings value may be additional Information the corresponding amount torque reduction the internal combustion engine included.

In an embodiment of the invention contains the current operating point as additional information the currently selected gear.

in the The scope of the method according to the invention is a current charge state of the energy storage determined.

through This state of charge will be at least a corresponding cost threshold and at least one corresponding savings threshold determined. The cost threshold and the savings threshold, for example determined from a defined driving cycle.

One current speed and torque-dependent operating point of the hybrid system is determined. Because the hybrid system in different Operating modes is operable and thus either or together internal combustion engine and electric machine can operate the torque and determines the speed at the input shaft of a transmission become.

Based on the current operating point, a potential specific cost value is determined by means of a Costs map determined.

Of the potential specific cost will be with the cost threshold compared. If the potential specific cost value is the cost threshold below or the potential specific cost value falls below the cost threshold corresponds, the potential specific cost value becomes more specific Cost value taken into account in the further procedure.

Based the current operating point becomes a potential more specific Savings value determined by means of a savings map.

Of the Potential specific savings will be with the savings threshold compared. If the potential specific savings value is the Saving threshold exceeds or the potential specific saving value corresponds to the savings threshold the potential specific savings value becomes more specific Savings value considered in the further procedure.

Provided no specific cost value and no specific savings value present is the future mode of operation of the hybrid system a sole operation of the internal combustion engine.

Provided a specific cost value and / or a specific saving value are present, based on this and the current operating point a future operating point and a future one Operating mode of the hybrid system selected.

Provided only a specific cost value for the current operating point is the future operating mode of the hybrid system an operation of the internal combustion engine and a generator operation the electric machine by the internal combustion engine. Farther there is a possibility that if there is a specific Economy value of the operating mode of a sole operation of the electric machine as an engine operating mode of a common Operation of the internal combustion engine and the electric machine is preferred as a motor.

Provided only a specific saving value for the current one Operating point is present, the future operating mode the hybrid system is a sole motor operation of the electric Engine or operation of the internal combustion engine and a Motorized operation of the electric machine.

Provided both a specific cost value and a specific saving value either only the specific saving value is taken into account, so that the future mode of operation of the hybrid system a sole motorized operation of the electric machine or an operation of the internal combustion engine and a motor operation the electric machine is or it becomes the one specific Cost or saving value taken into account, which the largest absolute distance to its threshold (Cost threshold or savings threshold) and has the future operating mode selected accordingly becomes.

In an advantageous embodiment is for the Determination of the cost threshold and the savings threshold used a hysteresis value of the internal combustion engine in addition to the state of charge, to the uneconomical operation of the internal combustion engine to be considered in a fast / frequent start-stop change. For example, it may be specified that the internal combustion engine has a minimum term or, if possible, a sole one Operation of the electric machine as a motor over a pure one Saving threshold criterion, a minimum runtime operated becomes.

In a further advantageous embodiment is for the determination of the cost threshold and the savings threshold an electrical system power in addition to the state of charge and possibly used in addition to the hysteresis value, in the sense that, for example the cost threshold of the load point increase of the internal combustion engine (Torque increase at constant speed) compared favored the sole operation of the electric machine as a motor becomes.

In Another embodiment of the invention comprises future operating point additionally one in the future gear to be selected.

drawings

It demonstrate:

1 a schematic representation of a hybrid system;

2 : a block diagram of a method according to the invention.

In 1 is a hybrid system 1 shown schematically. The hybrid system 1 includes an internal combustion engine 2 coming from a fuel tank 3 is supplied with fuel. By means of a clutch 4 is the internal combustion engine 2 with an electric machine 5 connectable. The electric machine 5 is an energy storage 6 assigned. By means of a clutch 7 is the electric machine 5 with a gear 8th connectable. By means of a clutch 9 is the internal combustion engine 2 with the gearbox 8th connectable. The couplings 4 . 7 . 9 are in a fixed or variable speed ratio nis operable.

Below are the different operating modes of the hybrid system 1 listed.

Will the hybrid system 1 only with the internal combustion engine 2 driven, so is the clutch 9 closed and the clutches 4 and 7 are opened. Furthermore, there is the possibility that the couplings 4 and 7 are also closed, so that the generator of the electric machine 5 Resistance-free, ie without motor or generator effect, is operated as a shaft.

Will the hybrid system 1 only from the electric machine 5 driven, so is the clutch 7 closed and the clutches 4 and 9 are opened.

Will the hybrid system 1 both from the internal combustion engine 2 as well as from the electric machine 5 driven, so are the clutches 4 and 7 closed and the clutch 9 it is open.

Will the generator of the electric machine 5 from the transmission 8th driven, for example, braking energy in the energy storage 6 to feed is the clutch 7 closed and the clutches 4 and 9 are opened. Furthermore, the clutch 4 also be closed, so that the internal combustion engine 2 is in tow mode.

Will the electric machine 5 from the internal combustion engine 2 driven by a generator, that is the clutch 4 closed. The coupling 9 is closed to the gearbox 8th of the hybrid system 1 from the internal combustion engine 2 drive. The coupling 7 it is open.

The speed 10 and the torque 11 of the hybrid system 1 are at the output of the gearbox 8th at.

Furthermore, there is the possibility at the output of the transmission 8th the electric machine 5 to arrange (this variant is in 1 not shown).

Also are in 1 Variants not shown, in which the clutch 9 is omitted and in which the clutch 4 to realize a so-called "mild hybrid" is omitted. In the last variant, the operating mode is a sole operation of the electric machine 5 as engine not possible.

The 2 shows a block diagram of a method according to the invention. A current speed 10 and a current torque 11 (Traction Desired Moment) of the hybrid system 1 operated in a current operating mode are supplied to a map K1. By means of the map K1 becomes a current operating point 12 of the hybrid system 1 read. For the inventive method, the speed 10 and the torque 11 at the output of the transmission 8th be used. It is also possible, depending on the current operating mode of the hybrid system 1 , the speed 10 and the torque 11 at the entrance of the internal combustion engine 2 or at the entrance of the electric machine 5 consulted.

The current operating point 12 is supplied to a cost map K2 and a savings map K3.

The cost map K2 includes for each operating point 12 of the hybrid system 1 at least one specific cost value. The specific cost value is determined by means of the operating mode of a common operation of the internal combustion engine 2 and the electric machine 5 won as a generator. The basis for the specific cost value is a cost value obtained by means of the operating mode of a sole operation of the internal combustion engine 2 is won. The cost value may relate to fuel costs, emissions, composition of emission components or a combination of these.

At constant speed 10 or transmission output power (product of speed 10 and torque 11 ) of the hybrid system 1 becomes the torque of the internal combustion engine 2 increased by a certain amount. On the one hand, this increase results in an increase in the cost value and, on the other hand, an increase in the charge quantity (increase in the charging current, charging) of the energy store 6 , The specific cost value is the quotient of the increase of the cost value to the increase of the charge amount. Furthermore, it is possible to form the quotient of an increased temporal cost value to an increase of the charging current.

Because the torque of the internal combustion engine 2 at constant speed 10 different amounts can be increased resulting in several cost values and specific cost values. From these specific cost values a minimum can be determined.

• 1) spezifischer Kostenwert ≤ a·minimaler spezifischer Kostenwert
• 2) Ladungsmenge des spezifischen Kostenwerts ≥ b·Ladungsmenge des minimalen spezifischen Kostenwerts

The minimum specific cost value does not automatically include the maximum amount of charge (compared to the charge amounts of the other specific cost values). Unless the goal is the minimum specific cost value, but a specific cost value with a favorable one If the ratio between the costs used and the quantities of charge obtained is higher than the minimum specific cost value, then the one selected from the determined specific cost values satisfies the following two conditions (only one example of deviation from the specific cost optimum):

• 1) specific cost value ≤ a · minimum specific cost value
• 2) Charge amount of the specific cost value ≥ b · Charge amount of the minimum specific cost value

The Factors "a" and "b" are respectively greater than "1". They are in advance suitable to determine. If several specific cost values this meet both conditions, the one to select which has the largest charge amount (charge current).

Furthermore, the cost map K2 for each gear of the transmission 8th contain an optimal cost function. The specific cost value thus receives as additional information, whether the currently selected gear is to be maintained or whether a gear change in increasing the torque of the internal combustion engine 2 and increasing the charge amount of the energy storage 6 to an operating point in the map of the internal combustion engine 2 and to an operating point in the map of the electric machine 5 as a generator leads, which have a lower or better efficiency.

The economy map K3 includes for each operating point 12 of the hybrid system 1 at least one specific saving value. The specific economy value is determined either by the operation mode of common operation of the internal combustion engine 2 and the electric machine 5 as a motor or by means of the operating mode of a sole operation of the electric machine 5 won as an engine.

The basis for the specific economy value is an economy value generated by the operation mode of sole operation of the internal combustion engine 2 is won. The savings value may relate to fuel costs, pollutant emissions, or a combination of both. The lower the fuel cost or the pollutant emissions, the higher the savings value becomes.

At constant speed 10 and transmission output power (product of speed 10 and torque 11 ) of the hybrid system 1 becomes the torque of the internal combustion engine 2 by a certain amount or completely (in case of sole operation of the electric machine 5 as engine) lowered. On the one hand, this reduction results in a saving value and, on the other hand, a reduction in the amount of charge (increase in the discharge current, discharge) of the energy store 6 ,

The the specific saving value is the quotient of the saving value to reduce the amount of charge. An increase in the discharge current leads to an increase in the savings value. The specific one Savings value is the quotient of savings value to the reduction the amount of charge. Furthermore, there is the possibility of the Quotient of a saved time fuel quantity too to form an increase in the discharge current.

• 1) spezifischer Einsparungswert ≥ maximaler spezifischer Einsparungswert/c
• 2) Ladungsmenge des spezifischen Einsparungswerts ≤ Ladungsmenge des maximalen spezifischen Einsparungswerts/d

Because the torque of the internal combustion engine 2 at constant speed 10 This results in several savings and specific savings values. From these specific savings values a maximum can be determined. The maximum specific savings value does not automatically include the minimum charge amount (compared to the charge amounts of the other specific savings values). If the target is not the maximum specific saving value but a specific saving value with a more favorable ratio of saved costs to smaller discharge amounts compared to the maximum specific saving value, one of the determined specific savings values is selected which satisfies the following two conditions (only one example) for deviation from the specific savings optimum):

• 1) specific saving value ≥ maximum specific saving value / c
• 2) amount of charge of the specific economy value ≤ charge amount of the maximum specific economy value / d

The Factors "c" and "d" are respectively greater than "1". They are in advance suitable to determine. Provided several specific savings satisfy these two conditions, the one to choose which has the least amount of charge (discharge current).

Furthermore, the economy map K3 for each gear of the transmission 8th contain an optimal saving function. The specific savings value thus receives as additional information, whether the currently selected gear is to be maintained or whether a gear change in reducing the torque of the internal combustion engine 2 and reducing the amount of charge of the energy storage 6 to an operating point in the map of the internal combustion engine 2 and to an operating point in the map of the electric machine 5 As an engine leads, which have lower costs.

A current state of charge 15 of the energy store 6 is detected and fed to a map K4. There is also the possibility that in addition a hysteresis value 16 the internal combustion engine 2 the map K4 is supplied to a frequent and short-term switching on and off of the internal combustion engine 2 to avoid. It is also possible, depending on the current state of charge 15 of the energy store 6 , the hybrid system 1 in the operating mode of the sole operation of the electric machine 5 to operate as a generator (recuperation).

Furthermore, there is the possibility that the map K4 a current vehicle electrical system load is supplied. By means of the map K4 become a current cost threshold 17 and a current savings threshold 18 receive.

The current cost threshold 17 and the potential specific cost value 13 are supplied to a comparator V1. Unless the potential specific cost value 13 less than or equal to the current cost threshold 17 is, becomes out of the potential specific cost value 13 a specific cost value 19 , Otherwise, the potential specific cost value becomes 13 an AND link U supplied.

A comparator V2 becomes the current savings threshold 18 and the potential specific savings value 14 fed. Is the potential specific savings value 14 greater than or equal to the current savings threshold 18 , so will the potential specific savings 14 a specific saving value 20 , Otherwise, the potential specific saving value becomes 14 an AND link U supplied. Unless a specific cost value 19 another specific saving value 20 present, the hybrid system 1 at the current operating point 12 and in the operating mode 21 a sole operation of the internal combustion engine 2 operated, or possibly in the operating mode mode of recuperation.

Unless a specific cost value 19 and / or a specific savings value 20 are / will be / this together with the current operating point 12 fed to a map K5. By means of the map K5 becomes a future operating point 22 for a future mode of operation of the hybrid system 1 determined.

If only a specific cost value 19 is present, the hybrid system 1 in the future in the operating mode of a common operation of the internal combustion engine 2 and an operation of the electric machine 5 operated as a generator.

If only a specific saving value 20 is present, the hybrid system 1 in the future either in the operating mode of a sole operation of the electric machine 5 as an engine or in the operating mode of a common operation of the internal combustion engine 2 and the electric machine 5 operated as a motor. Furthermore, there is the possibility that if there is a specific saving value 20 the operation mode of a sole operation of the electric machine 5 as an engine, the operating mode of a common operation of the internal combustion engine 2 and the electric machine 5 is preferred as a motor.

If both a specific cost value 19 as well as a specific saving value 20 is either only the specific savings value 20 takes into account or it becomes the absolute distances of the specific cost value 19 to the cost threshold 17 or the specific savings value 20 to the savings threshold 18 determined and takes into account that specific value which has the smallest distance to the threshold. Will the specific saving value 20 considered, the hybrid system becomes 1 in the future either in the operating mode of a sole operation of the electric machine 5 as an engine or in the operating mode of a common operation of the internal combustion engine 2 and the electric machine 5 operated as a motor. Will the specific cost value 19 considered, the hybrid system becomes 1 in the future in the operating mode of a common operation of the internal combustion engine 2 and an operation of the electric machine 5 operated as a generator.

1

hybrid system

2

Internal combustion engine

3

Fuel tank

4

clutch

5

electrical machine

6

energy storage

7

clutch

8th

transmission

9

clutch

10

current rotation speed

11

Current torque

12

current operating point

13

potential specific cost value

14

potential specific saving value

15

current SOC

16

hysteresis

17

current Kostenschwellwert

18

current Einsparungsschwellwert

19

specific cost value

20

specific saving value

21

operation mode with sole operation of the internal combustion engine

22

future operating point

K1

map

K2

Cost map

K3

Saving map

K4

map

K5

map

U

AND operation

V1

comparator

V2

comparator

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19938623 C2 [0002]

Claims (7)

Method for operating a hybrid system ( 1 ), which at least one internal combustion engine ( 2 ) and at least one motor and generator operable electric machine ( 5 ) with at least one associated energy store ( 6 ), wherein - a current state of charge ( 15 ) of the energy store ( 6 ), and - based on the current state of charge ( 15 ) at least one cost threshold ( 17 ) and at least one savings threshold ( 18 ), and - a current speed and torque dependent operating point ( 12 ) of the hybrid system ( 1 ), and - based on the current operating point ( 12 ) from a cost map (K2) at least one potential specific cost value ( 13 ), and - the potential specific cost value ( 13 ) with the cost threshold ( 17 ), whereby if the cost threshold falls below or equals ( 17 ) the potential specific cost value ( 13 ) as a specific cost ( 19 ) is taken into account in the further procedure, and - based on the current operating point ( 12 ) from a savings map (K3) at least one potential specific savings value ( 14 ), and - the potential specific savings value ( 14 ) with the savings threshold ( 18 ), in the event of exceeding or equality of the savings threshold ( 18 ) the potential specific savings value ( 14 ) as a specific saving value ( 20 ) is taken into account in the remainder of the procedure and, in the absence of a specific cost value ( 19 ) and a specific saving value ( 20 ) the hybrid system ( 1 ) in the future in addition to a possible Rekuperationsbetrieb only with the internal combustion engine ( 2 ) and, in the case of a specific cost value ( 19 ) and / or a specific saving value ( 20 ) based on this and the current operating point ( 12 ) a future operating point ( 22 ) and a future operating mode of the hybrid system ( 1 ) is selected. A method according to claim 1, characterized in that for the determination of the cost threshold ( 17 ) and the savings threshold ( 18 ) a hysteresis value ( 16 ) of the internal combustion engine ( 2 ) in addition to the state of charge ( 15 ) of the energy store ( 6 ) is used. Method according to claim 1 or 2, characterized in that for the determination of the cost threshold ( 17 ) and the savings threshold ( 18 ) an onboard power of the internal combustion engine ( 2 ) in addition to the state of charge ( 15 ) of the energy store ( 6 ) is used. Method according to claim 1, characterized in that the potential specific cost value ( 13 ) a relation between an additional fuel demand for the internal combustion engine ( 2 ) to an additional charge amount of the energy store ( 6 ). Method according to claim 1, characterized in that the potential specific saving value ( 14 ) a relation between a lower fuel demand for the internal combustion engine ( 2 ) to a lower charge amount of the energy store ( 6 ). Method according to claim 1, characterized in that the potential specific cost value ( 13 ) a relation between an additional emission of pollutants to an additional amount of charge of the energy store ( 6 ). Method according to claim 1, characterized in that the potential specific saving value ( 14 ) a relation between a lower pollutant emission to a lower charge amount of the energy accumulator ( 6 ).