WO2011160995A1

WO2011160995A1 - Method for operating an electric vehicle

Info

Publication number: WO2011160995A1
Application number: PCT/EP2011/059997
Authority: WO
Inventors: Hubert Friedl; Günter Fraidl
Original assignee: Avl List Gmbh
Priority date: 2010-06-24
Filing date: 2011-06-16
Publication date: 2011-12-29
Also published as: AT508065A3; AT508065A2; AT508065B1

Abstract

The invention relates to a method for operating an electric vehicle (1) comprising at least one electric drive motor (2), at least one electrical energy store (4), and at least one power generating device formed by an internal combustion engine (5), wherein the internal combustion engine is activated as a function of the charge state (SOC) of the electrical energy store (4), wherein at least one exhaust treatment device (7) is associated with the exhaust tract (6) of the internal combustion engine (5). The emissions can be reduced decisively if the exhaust treatment device (7) is heated to operating temperature prior to activating the internal combustion engine (5).

Description

Method for operating an electric vehicle

The invention relates to a method for operating an electric vehicle, which has at least one electric drive machine, at least one electrical energy storage and at least one power generating device formed by an internal combustion engine, wherein the internal combustion engine is activated in dependence of the state of charge of the electrical energy storage, wherein in the exhaust system of the internal combustion engine at least one Aftertreatment device is assigned. Furthermore, the invention relates to a device for carrying out the method.

It is known, with Range Extender units, which consist of an internal combustion engine and a generator unit, to extend the range of electric vehicles gene by no longer sufficient battery charge, the electrical energy for the electric motor drive by a, formed by an internal combustion engine, so-called range extender is generated. To be able to provide sufficient electrical power under all operating conditions, the power of the range extender would have to be designed similarly to the electrical drive power. However, this requires comparatively high weight, cost and dimensions of the range extender unit. However, since the range extender is generally only a fraction of the total operating time of an electric vehicle in active mode and the majority of the operating life of the electric vehicle is only an inactive additional weight, minimizing the size and weight of the range extender unit is a very important goal.

This can be done, for example, that the range-extender power is not designed for the maximum power of the electric traction drive, but only to the much lower average required drive power or the power required to reach the maximum speed limit. Any additional energy demand is covered by a stored energy reserve. However, this energy reserve must be designed in such a way that a performance shortage can never occur in practical driving (for example, on long freeways, passages, etc.). The more accurately this peak demand can be predicted, the smaller and thus more cost-effective and cost-effective, both the range extender unit and the energy storage of the electric vehicle can be designed.

Two types of range extender control are known: So-called SOC-based range extender control:

The switch-on strategy is primarily determined by the state of charge of the electrical energy store (SOC ... State of charge). The range extender is switched on and off between two predefined thresholds. In refined variants, this threshold is adapted depending on additional variables (for example, the previous energy / power requirement, battery temperature, etc.).

Active GPS-based Range Extender Control:

After actively entering the destination, the route is calculated and the energy demand for the route is calculated using the expected speed and altitude profile. Thus, the switch-on of the range extender can be set so that on the one hand, even at low power of the range extender on long gradients no power shortage occurs, on the other hand, the operating life of the range extender and thus the consumption of fossil fuels is minimized. However, in practice, as drivers generally do not input known destinations into the GPS (Global Positioning System) system, the actual benefit of such control is limited.

From AT 506.272 A a method for operating an electric vehicle is known in which a power generating device is activated from a defined state of charge of the electrical energy storage. The power generating device is designed for a mean power requirement of the electric drive machine at a defined continuous speed of the electric vehicle in the plane, the power generating device is activated before reaching a lower technical operating limit of the state of charge of the electric energy storage at a defined Einschaltladezustand, which is such that in relation to the lower technical operating limit, an energy reserve remains in the electrical energy storage in order to cover peak output. The Einschaltladezustand can be set flexibly depending on a destination and / or a planned route.

From EP 1 225 074 A2 a series hybrid vehicle with an electric motor, a generator and an internal combustion engine driving the generator is known. In this case, the vehicle is operated purely electrically with deactivated internal combustion engine within a zero-emission zone. Both shortly before entering the emission-free zone and when leaving the emission-free zone, the electrical energy storage is charged by the internal combustion engine. WO 2005/082663 A1 discloses a portable power unit for electric vehicles, which is designed to extend the range of the electric vehicle.

From US 2009/015202 A, a method for charging control in a hybrid vehicle is known, wherein a nominal state of charge is defined as the mean value of the charging area. The energy flow is controlled so that the nominal state of charge is maintained. By operating the electric drive motor of the hybrid vehicle, the state of charge is lowered from a desired value and raised again by generating electrical energy with the internal combustion engine.

WO 2008/128416 A1 discloses an energy management for hybrid vehicles with a load prediction system, with which a future load level is calculated based on input parameters and by means of a self-learning system to determine an optimal future output power, a battery state of charge and an optimal vehicle speed based on the load request. On the basis of this optimal future power estimation, the internal combustion engine, the generator and the electrical energy store of the hybrid vehicle are coordinated.

JP 2008-201165 A describes a control unit for a hybrid vehicle, wherein the switch-on of the engine depending on the state of charge of the energy storage is determined based on the recorded data of completed rides and due to the demonstrated driving characteristics of an identified driver.

From EP 2 172 740 A it is known to determine a range profile by means of a navigation system on the basis of the state of charge of an energy store in a hybrid vehicle.

JP 2008 290610 A describes a navigation device for a hybrid vehicle, which simulate all possible routes between input start and a destination input and determines the fuel consumption of the internal combustion engine at each route.

Due to the concept, range extenders are only used for range expansion and are only activated when the temperature falls below a predefined state of charge of the electrical energy store. Thus, there may be a long time between turning off and activating the range extender. This means that range extenders must generally be started in the cold state, in which neither the internal combustion engine nor the exhaust aftertreatment devices in the exhaust system of the internal combustion engine have the required operating temperature. This results in the problem that without additional Measures must be expected when cold starting a range extender with relatively high exhaust emissions.

From DE 10 2007 025 19 AI a method for driving a motor vehicle with an exhaust gas heater is known, at least one operating parameter of the exhaust system detects at least one influence value of the heater determines and the influence value is compared with a target parameter of the exhaust system, whereupon the heater is activated so that the operating parameter reaches the target parameter.

DE 10 2005 003 469 A1 describes an abnormality determination apparatus for an electrically heatable catalyst for a plug-in hybrid vehicle that includes a battery that is charged by connecting an external charging device to an external electric power supply. An abnormality determination means performs a determination of an abnormality in the electrically heatable catalyst when the external charging device is connected to the external electric power supply.

The object of the invention is to avoid the disadvantages mentioned and to reduce emissions in an electric vehicle whose energy storage can be charged by an internal combustion engine.

According to the invention, this is achieved by heating at least one exhaust aftertreatment device to operating temperature before activating the internal combustion engine, wherein preferably the internal combustion engine - and thus also the heating device of the exhaust aftertreatment device - is activated as a function of the driving route.

It is particularly advantageous if, starting from a reference point which preferably corresponds to a starting point of the travel route, all possible relevant travel routes, preferably all possible travel routes, are simulated within a defined viewing horizon, and for each of the simulated travel routes a prospective switch-on time of the internal combustion engine and / or the heating device of the exhaust gas aftertreatment device is determined so that when the viewing horizon is reached, a defined state of charge of the energy store is maintained.

Relevant routes are defined as those that influence the operating strategy of the range extender differently.

As a result, even without active input of a destination all lying within the defined viewing horizon, such as the total vehicle range possible driving routes and the resulting most favorable Switching time of the internal combustion engine and / or the heating device of the exhaust gas aftertreatment device calculated. The procedure is similar to that of a chess computer, which also calculates every possible move in advance and calculates the best possible solution.

The calculation of all possible relevant routes is updated at each potential route change. In this case, there is a permanent adjustment of the calculated and the actual energy demand.

The simulation of all possible relevant routes are advantageously based on speed profiles which are determined as a function of the road type, the road condition, the topography, the traffic situation, the outside temperatures, the weather conditions and / or the time of day. It is particularly advantageous if a prospective energy consumption profile is created for all possible driving routes and the operation of the internal combustion engine and / or the heating device of the exhaust gas aftertreatment device is planned on the basis of this energy consumption profile, wherein the current and the prospective energy consumption at each travel route is preferably used when the energy consumption profile is generated is taken into account. Furthermore, the previous energy consumption can be used on the traveled section of the route to determine the vehicle load from the known topography. The driver-specific energy consumption, as well as all other additional consumers such as air conditioning requirements based on outside temperature, light, windscreen wipers, windscreen and seat heating etc. are used for the most accurate prediction of energy requirements.

It is preferably provided that the simulation of the travel routes is based on a defined driver profile, wherein preferably the driver profile is derived from the driving operation of past journeys.

The total vehicle range can be used as the observation horizon. In order to reduce the simulation effort and shorten the computing time, it can be provided that the viewing horizon is estimated on the basis of the length, duration and destination of past journeys. But it is also possible to manually specify or preset the event horizon.

In a particularly preferred embodiment of the invention, it is provided that the respective current location of the electric vehicle is assigned to a new reference point, and a new simulation of all possible routes on the basis of the new reference point takes place. The viewing horizon can be the original viewing horizon. It is but also conceivable that the viewing horizon as the viewpoint is changed dynamically.

A new assignment of the viewpoint and a new simulation of all possible routes should be performed at least when each node or branch point of the road network.

The best results can be achieved in the context of the invention in that the simulation of the routes takes place with the involvement of a vehicle navigation system and / or a navigation satellite system.

In this case, the switch-on time of the internal combustion engine is determined prospectively as a function of the charge state of the electrical energy store and the travel route and, taking into account a heat-up function of the exhaust gas aftertreatment device, determines a switch-on time of the heater at a defined heat output and the heater is switched on at a time prior to starting the internal combustion engine, so that Activation time of the internal combustion engine, the exhaust aftertreatment device has a defined operating temperature.

The invention will be explained in more detail below with reference to FIGS. Show it :

Fig. 1 is an electric vehicle with an electrical energy storage for

Implementation of the method according to the invention;

Fig. 2 is a diagram of the method according to the invention; and

Fig. 3 is a route.

Fig. 1 shows an electric vehicle 1 with an electric drive machine 2 for driving drive wheels 3, the electric drive machine 2 being fed by an electrical energy store 4. To extend the range, a range extender formed by an internal combustion engine 5 is provided, which charges the electrical energy store 4. The internal combustion engine 5 has an exhaust gas line 6 with at least one exhaust gas aftertreatment device 7 formed by a catalytic converter, wherein a heating device 8 is provided for heating the exhaust gas aftertreatment device 7. By a control unit 9, the operation of the internal combustion engine 5 and the heater 8 is controlled.

Fig. 2 shows the operating strategy for heating the exhaust aftertreatment device 7. In the normal electric driving mode 100, the drive is effected by the electric vehicle 2 via the electrical energy store 4, the internal combustion engine 5 being switched off. The control unit 9 monitors in step 200 permanently the state of charge SOC of the electric energy storage 4 and checks whether the state of charge SOC requires a charge by means of the internal combustion engine 5. If this is the case, it is checked in step 300 whether the internal combustion engine 5 is switched on. In this case (Y), steps 400 and 500 are skipped. If the internal combustion engine 5 is deactivated, the heating device 8 is switched on in step 400 and all preparations for starting the internal combustion engine 5 are made. The starting of the internal combustion engine 5 takes place in step 500. After starting the internal combustion engine 5, the heating power of the heating device 8 is adjusted to the operating state of the internal combustion engine 5 in step 600. In addition, the heating power can also be adjusted as a function of the state of charge SOC of the energy store 4 of the ambient temperature, the whereabouts of the electric vehicle 1 or the like in order to charge the energy store 4 as little as possible.

The activating of the heating device 8 takes place prospectively, which means that the activation of the heating device 8 is set as a function of the anticipated specific point in time for switching on the internal combustion engine 5.

An example of a prospective switching on of the internal combustion engine and subsequently the heating device 8 is shown in FIG. 3 shown.

The Fig. 3 schematically shows a road map with a travel route R actually driven by the electric vehicle, where P _{0 is} the starting point, Pi is a characteristic node and P _{z is} the destination. If the system does not know the destination, a simulation will be performed for all possible routes. In this case, the instantaneous location of the electric vehicle 1 is used as the reference point for the simulation at the starting point P ₀ . Starting from this reference point, all possible routes within the observation horizon H are taken into account. For each of the simulated travel routes, a switch-on instant of the power generation device is prospectively determined, so that a defined state of charge of the energy accumulator 4 is maintained when the operating horizon H is reached. The line 10 indicates the technical limit of purely electric driving. Field 20 indicates the area in which the simulation provides the activation of the range extender in order not to fall below a defined state of charge SOC within the observation horizon H at the destination.

By simulating all possible routes even without active input of a destination all within the defined observation horizon H, for example, the total vehicle range, lying possible driving routes and the resulting most favorable switch-on of the power generation device is calculated. The calculation of all possible routes becomes It is updated at each potential route change, ie in each node or branch point Pi of the road network on the actually driven route R. In this case, there is a permanent adjustment of the calculated and the actual energy demand.

The simulation of all possible routes is based on speed profiles, which are determined depending on the type of road, the road conditions, the topography, the traffic situation, the outside temperatures, the weather conditions and / or the time of day. For each possible route, a prospective energy consumption profile is created and the operation of the internal combustion engine 5 is planned on the basis of this energy consumption profile, taking into account the current and the prospective energy consumption for each route when the energy consumption profile is generated. In this case, the driver-specific energy consumption, as well as all other additional consumers such as air conditioning requirements based on outside temperature, light, windscreen wipers, windscreen and seat heating, heating device 8 for the exhaust aftertreatment device 7 etc. are used for the most accurate prediction of energy requirements. The information about road conditions, traffic conditions, weather, etc. can be provided via Internet, traffic, telematics or the like.

The simulation of the routes can be based on a defined driver profile, wherein the driver profile can be derived automatically from the driving operation of past trips, manually entered or detected by a personal identification device.

As a viewing horizon H, for example, the total vehicle range can be used. However, it is also possible to estimate the viewing horizon H on the basis of the length, duration and destination of past journeys or to preselect them manually.

In particular, at crossing points Pi along the route traveled, the respective current location of the electric vehicle 1 can be assigned to a new reference point, and a new simulation of all possible routes on the basis of the new reference point. As the viewing horizon, the original viewing horizon H can be used further. However, it is also conceivable that the viewing horizon is changed dynamically together with the viewing point.

Expediently, the simulation of the travel routes takes place with the involvement of a vehicle navigation system and / or a navigation satellite system. The method described makes it possible, without the driver having to enter information about the destination, to minimize the size of the energy store as well as of the internal combustion engine without resulting in reduced driving performance. Nevertheless, the use of the range extender remains to a minimum necessary extent and allows the maximization of the purely mains-powered battery operation.

In particular, in metropolitan areas such as large cities with a large number of relatively close neighboring intersections, a simplification of the method may be useful in order to keep the computational effort and the calculation time within reasonable limits. It is sufficient if only such possible relevant routes are calculated, which influence the operation of the range extender. For example, in particular travel routes with different topography, traffic situation or type of road (for example city highways) are taken into account.

The field 30 in Fig. 3 indicates the area in which the heater 8 is activated when the internal combustion engine 5 is turned on at the point P ₂ . By prospective fixing of the hiring device 8 of the exhaust gas aftertreatment device 7 it is achieved that the Bgas aftertreatment device has the required operating temperature even at a longer standstill of the internal combustion engine 5 at the time of starting the internal combustion engine 5. In this way, the emissions, in particular when starting the internal combustion engine 5 can be substantially reduced.

Claims

PATENT APPLICATIONS

1. A method for operating an electric vehicle (1) which has at least one electric drive machine (2), at least one electrical energy store (4) and at least one power generating device formed by an internal combustion engine (5), wherein the internal combustion engine as a function of the state of charge (SOC) the electric energy storage device (4) is activated, wherein in the exhaust line (6) of the internal combustion engine (5) at least one exhaust aftertreatment device (7) is assigned, characterized in that before activating the internal combustion engine (5) the exhaust aftertreatment device (7) is heated to operating temperature ,

2. The method according to claim 1, characterized in that the internal combustion engine (5) is activated as a function of the route.

3. The method according to claim 2, characterized in that starting from a reference point, which preferably corresponds to a starting point (P ₀ ) of the route (R), within a defined viewing horizon (H) all possible relevant routes, preferably all possible routes are simulated , and that for each of the simulated travel routes a prospective switch-on time (P ₂ ) of the internal combustion engine (5) is determined so that a defined state of charge (SOC) of the energy store (4) is maintained when the viewing horizon (H) is reached.

4. The method according to any one of claims 1 to 3, characterized in that the switch-on time exhaust aftertreatment device (7) is determined prospectively taking into account a heating function of the exhaust aftertreatment device (7) at a defined heat output so that the exhaust aftertreatment device (7) at the switching-on of the internal combustion engine ( 5) has a defined operating temperature.

5. The method according to any one of claims 1 to 4, characterized in that the heating power for heating the exhaust gas aftertreatment device (7) in dependence on the operating state of the internal combustion engine (5), the ambient temperature, the state of charge (SOC), the energy store (4) and / or depending on the whereabouts of the electric vehicle (1) is adjusted.

6. Apparatus for carrying out the method for operating an electric vehicle (1), which has at least one electric drive machine (2), at least one electrical energy store (4), and at least one by an internal combustion engine (5) formed power generating device, wherein the internal combustion engine (5) depending on the state of charge of the electrical energy store (4) is activated, wherein the exhaust line (6) of the internal combustion engine (5) at least one exhaust aftertreatment device (7) is arranged according to a of claims 1 to 4, characterized in that the exhaust gas aftertreatment device (7) comprises a heating device (8), wherein the exhaust gas aftertreatment device (7) can be heated to an operating temperature before the activation of the internal combustion engine.

7. The device according to claim 6, characterized in that the heating device by means of a control unit (9) is activated, which is adapted to the switch-on of the internal combustion engine (5) in dependence of the state of charge (SOC) of the electrical energy store (4) and the route (R).

8. Apparatus according to claim 6 or 7, characterized in that the control unit (9) is adapted to the heating power of the heating device (8) in dependence on the ambient temperature, the operating state of the internal combustion engine (5), the state of charge (SOC) of the electrical energy store (4) and / or the whereabouts of the electric vehicle (1).

2011

Fu / Sc