DE102011088988A1 - Method for controlling energy output of electrical energy converter in motor car i.e. passenger car, involves controlling energy output of energy converters to provide overall performance of onboard network based on environment information - Google Patents

Abstract

The invention relates to a method for controlling the energy output of at least two electrical energy converters (3, 4) in a motor vehicle (1), each of which provides different energy forms electrical energy for an electrical system (2) of the motor vehicle (1), said at least two Energy converter (3, 4) a required total electrical power for the electrical system (2) is provided, by means of a detection device (10) of the motor vehicle (1) environmental information of the motor vehicle (1) are detected and the energy output of the at least two energy converters (3, 4 ) is controlled to provide the total power depending on the detected environment information.

Description

The invention relates to a method for controlling the energy output of at least two electrical energy converters in a motor vehicle, which provide electrical energy for an electrical system of the motor vehicle from different energy forms. The at least two energy converters provide a required total electrical power for the on-board network. The invention also relates to a motor vehicle which is designed to carry out such a method.

It is already state of the art to use two different energy converters or energy sources in a motor vehicle, which generate electrical energy from different forms of energy. In the present case, the interest is preferably the combination of a conventional generator, which converts kinetic energy into electrical energy, as well as a thermoelectric generator, which provides electrical energy from thermal energy. Such a thermoelectric generator can be arranged, for example, in an exhaust system of the motor vehicle and convert the heat present there into electrical energy. The fact is exploited that the internal combustion engine of the motor vehicle provides waste heat, which can be exploited to provide electrical energy for the electrical system.

In the above-mentioned combination of the conventional generator on the one hand and the thermoelectric generator on the other hand, the internal combustion engine is in principle the primary energy source in the motor vehicle. If now the different methods of energy conversion are not optimally coordinated, the optimum efficiency of the entire vehicle electrical system is not achieved. In particular, in an internal combustion engine as a primary energy source, the provision of energy for the electrical converter is dependent on the load point of the internal combustion engine. A particular challenge therefore is to control the energy output of the electrical energy converter such that the efficiency of the overall system can be maximized.

Thermoelectric generators are already known from the prior art in a variety of configurations. For example, the document describes DE 10 2008 036 044 A1 a thermodynamic system with such a thermoelectric generator, which can be used in a motor vehicle.

From the publication DE 10 2007 039 107 A1 is a method for recuperation of energy in a motor vehicle during a recuperative operating state known in which free energy is converted into electrical or thermal energy and stored in the electrical system. Upon actuation of an operating element by the driver, a request signal is generated to change to a recuperation operating state, and due to this signal is then changed in the presence of predetermined conditions in the recuperation operating state.

It is an object of the invention to show a way, as in a method of the type mentioned the efficiency of the electrical system can be improved compared to the prior art.

This object is achieved by a method and by a motor vehicle having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figure.

A method according to the invention serves to control the energy output of at least two electrical energy converters in a motor vehicle which provide electrical energy for an electrical system of the motor vehicle from different energy forms, wherein a required total electrical power for the vehicle electrical system is provided by the at least two energy converters. According to the invention, environmental information of the motor vehicle is detected by means of a detection device of the motor vehicle, and the energy output of the at least two energy converters for providing the total power is controlled as a function of the acquired environmental information.

The effect of the invention is thus achieved in that the control of the energy output of the energy converter is performed in dependence on environmental information of the motor vehicle. In this case, the invention is based on the knowledge that different energy forms are available in different environmental scenarios or ambient conditions-for example at different height profiles of the road-which can then be converted into electrical energy. The invention is further based on the knowledge that the information about the current or ahead of the environment of the motor vehicle can be detected and thus can be determined which form of energy - be it the kinetic energy, be it the thermal energy in the exhaust system - currently primarily for Available or expected to be made available on the route ahead. Thus, the electrical energy can at least predominantly by that Energy converters are provided, which has the highest efficiency at the current time and thus ensures optimum efficiency of the entire electrical system. The following scenario is described by way of example only: If a road gradient is detected on the basis of the environmental information, the control of the energy output can already be determined in advance such that at least the greater part of the total power is generated by means of the conventional generator, namely kinetic energy while the thermoelectric generator can provide no power at all or only a small proportion of the total power. The motor vehicle can therefore be switched in the road gradient in the so-called overrun operation, in which a recuperation of kinetic energy is performed. Thus, the overall efficiency can be brought to a maximum.

In the present case, a control of the energy output is understood to mean an adjustment of the respective amount of energy that is to be delivered by the at least two electrical energy converters during operation in order to generate the required overall power. This means, for example, that the greater the proportion of the energy delivered, one of the energy converters is at a given total power, the smaller is the proportion of the energy delivered by the other energy converter. There is thus an interaction between the two energy converters, so that, given a given total power, the energy output of one of the energy converters is dependent on the other energy converter. It can also apply the relationship that the required total power is equal to the sum of the power of each energy converter.

Thus, the energy output of the at least two electric energy converters is controlled in consideration of environmental information of the motor vehicle. It proves to be particularly advantageous if the environmental information is detected by means of a navigation system of the motor vehicle and the energy output is controlled in dependence on route information of the navigation system. This has the advantage that a navigation system - a GPS receiver - provides data containing information about the current global or geographical position of the motor vehicle, so that the position of the motor vehicle is known on a map. It can thus be determined whether in the environment of the motor vehicle, a road gradient or a road increase is present and which form of energy is currently or probably available. A navigation system thus provides a lot of information about the environment of the motor vehicle. On the basis of route information can also be detected whether the motor vehicle is ahead of a curve, so that it can be determined in advance that the driver will soon brake alternately and accelerate. Thus, it can be anticipated that the kinetic and thermal energy will be alternately provided for the provision of electrical energy.

Thus, in one embodiment, it is provided that the surroundings information comprise information about a preceding environment, in particular over a section of road ahead. Then the control of the energy output of the at least two energy converters can already be determined in advance for the environment ahead. The control of the energy output by the two energy converters can thus be planned in advance. Such an approach has the particular advantage that the entire electrical system can already be conditioned in advance and, for example, additional recording options for the electrical energy can be created. For example, an electric battery of the motor vehicle can be discharged in advance in order to enable the future absorption of the electrical energy. It is also possible that an electrical load is switched on, which is initially supplied with electrical energy from the battery and then optionally with the energy emitted by the energy converters. As an electrical load, for example, a refrigerant compressor and / or a heater and / or a fan can be activated.

Information about a height profile of a road on which the motor vehicle moves, namely, in particular, about the height profile of a road section ahead of the motor vehicle, is particularly preferably detected as environmental information. In this way, it is possible, for example, to detect a road gradient or a rise in the road and to control the energy output of the electrical energy converter accordingly.

It can also be provided that information about a two-dimensional course of the road, in particular of the route section lying ahead, is detected as environmental information. For example, in this embodiment, the presence of bends can be detected, and the energy output can be controlled according to the bends. This embodiment takes advantage of the fact that, when cornering, the driver alternately accelerates and decelerates, with deceleration usually being in a coasting mode. Thus, the electric power can also alternately be generated once by a thermoelectric generator (when the driver is giving gas) and once by the conventional generator (in overrun mode). The Information about the presence of curves can be collected using the navigation system. Additionally or alternatively, however, this information can also be obtained by means of a sensor device of the motor vehicle, for example by means of a radar device and the like.

As a peripheral information, a distance between the motor vehicle and a destination selected by the driver by means of the navigation system can additionally or alternatively also be detected and taken into account in the control of the energy output. This embodiment is based on the knowledge that the fuel consumption is usually consumed as a function of the proximity of the destination or is generally saved in the vicinity of the destination. In addition, the proximity of the destination usually means that the motor vehicle is already located in a city area. This in turn means that relatively little thermal energy is provided in such a situation, so that the mechanical recuperation using the conventional generator is preferred. In this way, it is possible to further optimize the overall efficiency.

Additionally or alternatively, a type of the road on which the motor vehicle is moving and / or is likely to move may also be detected as environmental information. In particular, a distinction is made between the following types of road: a motorway and / or a highway and / or a city road. The motor vehicle is located on a highway, so the thermal recuperation is preferably in the foreground. If, therefore, it is recognized that the motor vehicle is located on a freeway, eleven predominant portions of the total electrical power can be generated from the thermal energy. In contrast, mechanical recuperation on a city road is preferred in which the available kinetic energy of the motor vehicle is converted into electrical energy. The efficiency can thus be brought to a maximum.

It can also be provided that information about a motorway access road ahead of the motor vehicle and / or a motorway exit is recorded and taken into account in the control of the energy delivery. While at a motorway entrance the driver will usually accelerate, the motor vehicle is usually operated or decelerated during a motorway exit. Consequently, at a highway entrance the thermal energy and at an exit the mechanical energy can be used to generate the electrical energy.

In the control of the energy output and at least one operating parameter of the motor vehicle can be considered. In one embodiment, it is provided that the current rotational speed of a drive motor of the motor vehicle is detected and taken into account in the control of the energy output. This embodiment takes advantage of the fact that in a thermal recuperation, the amount of heat energy provided is directly proportional to the speed of the drive motor. Also in the case of mechanical recuperation, the kinetic energy provided for the conversion is proportional to the rotational speed. These relationships can now be used to control the energy output of the two energy converters and / or to determine the required total power.

As already stated, the following components can be used as energy converters: at least one generator, which converts kinetic energy into electrical energy, as well as at least one thermoelectric generator, which converts thermal energy, in particular an exhaust gas line, into electrical energy. Depending on the ambient scenario, the electrical energy can thus be generated from different forms of energy, so that the efficiency of the vehicle electrical system can be optimized in each case.

The following steps are particularly preferably carried out in the method: If an increase in the road is detected on the basis of the ambient information, the energy output is controlled in such a way that at least a predominant proportion of the total power is provided by means of the thermoelectric generator while driving through the road. Namely, while driving uphill, the internal combustion engine must provide a great deal of mechanical energy for driving the motor vehicle, so that relatively much heat is generated in the exhaust system of the motor vehicle. This thermal energy is now tapped by the thermoelectric generator and converted into electrical energy. Thus, the thermal energy already present in this scenario is used to provide the electrical energy. For example, while traveling through the road ramp, the conventional generator may be completely turned off so that the full power is provided by means of the thermoelectric generator. Alternatively, it can also be provided that the conventional generator also provides electrical energy, for example a proportion of the total power of 5% or 10%. The efficiency of the electrical system is thus maximum.

If, on the other hand, a road gradient is detected on the basis of the environmental information, then the energy output can be controlled in such a way that at least a predominant portion of the vehicle is downhill during the journey the total power - for example, the complete total power - is provided from kinetic energy by means of the generator. This embodiment, in turn, is based on the finding that, when driving downhill, the internal combustion engine is usually operated in thrust and in the process no fuel injection takes place. In this case, the generation of electrical energy by means of mechanical recuperation takes priority in order to bring the overall efficiency to a maximum.

In one embodiment, it is provided that the driver of the motor vehicle is classified with regard to his driving style by means of a driving style recognition device. Then, in the control of the energy output of the at least two energy converters, the driving style of the driver can also be taken into account. Thus, the efficiency of the entire electrical system can be further optimized. A "sporty" driver will usually give a little more throttle, so that here the proportion of the output power of the thermoelectric generator can be increased in comparison to a less sporty driving style. Thus, for example, even while driving in a road gradient at least a portion of the total power can be provided by means of the thermoelectric generator, namely in particular in a sporty driving style of the driver. Such driving style recognition devices are already known as known from the prior art; The driving style recognition is usually carried out on the basis of a variety of information that can be tapped, for example, on a communication bus of the motor vehicle - for example CAN bus - namely, for example, based on an accelerator pedal movement, brake pedal movement, acceleration of the motor vehicle and the like.

The control of the energy output by the at least two electrical energy converters can - as already stated - already be determined in advance, for example, as a function of information about a route ahead section. Thus, the electrical system can also be "prepared" or "conditioned" accordingly. It can be created conditions in the electrical system, which make it possible to record the electrical energy of the two energy converters. The electrical system can thus be conditioned so targeted that the energy converter operated and the required total power can also be set in advance and then generated. In one embodiment, it is thus provided that at least one component of the vehicle electrical system is prepared for the direct acceptance of the emitted energy before or with the energy output by the energy converter. This targeted preparation of the component then makes it possible for the energy generated to be used directly, for example consumed, by the energy converter. In this case, two embodiments can be provided: On the one hand, an electrical energy store - for example a battery - of the electrical system can be at least partially discharged before the energy is released by the energy converter. On the other hand, at least one electrical consumer of the electrical system can be activated. As an electrical consumer, for example, the above-mentioned refrigerant compressor can be switched on. If, for example, a preceding road climb or a road gradient is detected, the electrical load can already be activated and / or the battery discharged in such a way that the excess energy can also be stored when driving to the mountain. The activation of an electrical load is particularly advantageous when the battery must not be cyclized. In this case, for example, a heater and / or a fan can be operated.

It can also be provided that the required total power is determined in advance in advance of the energy output by the energy converter. This can be done, for example, so that it is already determined in advance how many electrical loads can be activated and what power can be recorded at all. It can also be checked in advance how much energy the vehicle battery can absorb at all. If this total power is set in advance, then the control of the energy output can be made such that this total power is not exceeded.

A motor vehicle according to the invention is designed to carry out a method according to the invention.

Further features of the invention will become apparent from the claims, the figure and the description of the figures. All the features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figure can be used not only in the respectively indicated combination but also in other combinations or alone.

The invention will be explained in more detail below with reference to a preferred embodiment, as well as with reference to the accompanying drawings. The single figure in a schematic and highly abstract representation illustrates a motor vehicle according to an embodiment of the invention.

An illustrated in the figure motor vehicle 1 is for example a passenger car. The car 1 includes an electrical system 2 which includes the following components: a conventional generator 3 (also called G), a thermoelectric generator 4 (also called TEG), a battery 5 (also designated B), a front and a rear power distribution 6 . 7 , a variety of electrical consumers 8th (also denoted by V), an electronic control device nine , a GPS receiver 10 as well as a driving style recognition device 11 ,

In the embodiment, the motor vehicle 1 a conventional vehicle with an internal combustion engine. However, the invention is not limited to such a vehicle; The method according to the invention can also be applied to electric vehicles and / or hybrid vehicles.

The generator 3 is coupled to the internal combustion engine and provides electrical energy, namely kinetic energy of the internal combustion engine. The generator 3 is via an electrical generator line 12 with the battery 5 electrically connected.

The battery 5 is in the rear of the vehicle 1 arranged. It can, for example, under the rear seat or alternatively in the trunk of the motor vehicle 1 be placed. The battery 5 is with the rear power distributor 7 electrically coupled.

To the rear power distributor 7 is at least one of the electrical consumers 8th connected and can with electrical energy from the battery 5 or directly from the thermoelectric generator 4 be supplied.

The rear power distributor 7 is via a supply line 13 with the front power distributor 6 connected, which in turn in the front area of the motor vehicle 1 is arranged. About the supply line 13 So there is an energy transfer between the rear area on the one hand and the front area on the other. To the front power distributor 6 can be a variety of electrical consumers 8th be coupled, namely, for example, a heater, an air conditioner, an infotainment system, a refrigerant compressor, any driver assistance systems and the like.

The thermoelectric generator uses thermal energy in an exhaust system of the motor vehicle 1 and can convert this thermal energy into electrical energy. This is the thermoelectric generator 4 to the front power distributor 6 coupled, so that from the thermal generator 4 energy generated on the one hand to consumers 8th and on the other hand, if necessary, to the battery 5 can be delivered.

The control device nine - For example, a control unit - controls the energy output of the two generators 3 . 4 , Here are the generators 3 . 4 Energy converter in the context of the present invention. The energy output of the conventional generator 3 can be done such that the generator 3 provided electrical voltage is regulated by means of a regulator. The energy output of the thermoelectric generator 4 on the other hand, for example, using valves that can adjust the amount of thermal energy that the thermoelectric generator 4 is supplied.

The GPS receiver 10 is with the control device nine coupled, so that the control device nine Receives position data that includes information about the current global position of the motor vehicle. In the control device nine - which together with the GPS receiver 10 a navigation system forms - are also digital maps stored, so in the control device nine the current position of the motor vehicle 1 known on the map. The control device nine also receives data from the driving style recognizer 11 , which provides information about the driving style or the driving style of the driver. In the control device nine Thus, the driving style of the driver is known.

Now the interest is directed to the control of the energy output by the two generators 3 . 4 by means of the control device nine , A method according to an embodiment of the invention is described in more detail below:
The control device nine recognizes by the signals of the GPS receiver 10 that in front of the motor vehicle 1 a mountain is located. The control device nine thus recognizes a road ahead and a road slope behind it. Still during the approach to the mountain takes the control device nine a conditioning of the electrical system 2 before and prepares the electrical system 2 to an energy intake. At this point, the control device nine for example, at least one of the electrical consumers 8th activate and / or the battery 5 partly or completely discharged. In this way, the electrical system 2 specifically prepared for the acceptance of electrical energy. As an electrical consumer 8th At this point, for example, a refrigerant compressor and / or a heater and / or a fan can be activated. Alternatively, this activation can only with the energy output by the generators 3 . 4 respectively.

While approaching the mountain - so still in advance - puts the control device nine Also, the overall performance determined by the two generators 3 . 4 should be generated. For example, this total power may depend on how many consumer 8th be activated and / or how much energy the battery 5 can record.

Also in advance, the controller sets nine the control of the two generators 3 . 4 firmly. And that determines the controller nine at this point, that while driving through the road rise the largest share of the total power required by the thermoelectric generator 4 should be provided. During the journey through the road rise so a thermal recuperation should be made, ie the output thermal energy of the engine should be converted into electrical energy. In contrast, the internal combustion engine is to be operated in the thrust in the downhill, and there should be no fuel injection. The control device nine thus determines in advance that during the upcoming trip in the road gradient the required total power at least predominantly - possibly also completely - by means of the conventional generator 3 should be generated. By such a control of the energy output of the two generators 3 . 4 is the overall efficiency of the electrical system 2 maximum.

In the control of the energy output and the driving style or the driving style of the driver can be considered. Detects the controller nine For example, that the driver prefers a relatively sporty driving style, so a proportion of the total power in the road gradient by means of the thermoelectric generator 4 to be provided. Here, the generated heat of the internal combustion engine is converted into electrical energy.

Another example relates to a scenario in which the control device nine recognize a variety of leading curves based on the data from the GPS receiver. Again, the control device nine a conditioning of the electrical system 2 perform and example, an electrical consumer 8th activate and / or the battery 5 partially unloaded. During cornering, the driver namely alternately gas and brakes, so that the motor vehicle 1 alternately accelerated and braked again (especially in overrun mode). Here, the controller nine set in advance that in overrun or braking the generator 3 is to be operated while accelerating the electrical energy by means of the thermoelectric generator 4 should be provided.

Altogether, therefore, three different stages can be distinguished in the method: The first stage means the conditioning of the entire system. This is the creation of charge acceptance of the battery 5 or the activation of temporary consumers 8th , such as an electric refrigerant compressor. For this purpose, knowledge is required on which route the motor vehicle 1 moved, and how the driver uses the characteristics of the vehicle (ie driving information). In a second stage, the energy conversion by the two generators will match the route and the driving style 3 . 4 controlled or fixed. In a third stage is the distribution of the generation of electrical energy to the different generators 3 . 4 performed according to overall efficiencies.

LIST OF REFERENCE NUMBERS

1

motor vehicle

2

electrical wiring system

3

conventional generator

4

thermoelectric generator

5

battery

6

power distribution

7

power distribution

8th

electrical consumer

9

electronic control device

10

GPS receiver

11

Driving style detection device

12

generator line

13

supply line

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008036044 A1 [0004]
• DE 102007039107 A1 [0005]

Claims (15)

Method for controlling the energy output of at least two electrical energy converters ( 3 . 4 ) in a motor vehicle ( 1 ), which from different forms of energy electrical energy for a vehicle electrical system ( 2 ) of the motor vehicle ( 1 ), wherein the at least two energy converters ( 3 . 4 ) a required total electrical power for the electrical system ( 2 ), characterized in that by means of a detection device ( 10 ) of the motor vehicle ( 1 ) Environmental information of the motor vehicle ( 1 ) and the energy output of the at least two energy converters ( 3 . 4 ) is controlled to provide the total power depending on the detected environment information. A method according to claim 1, characterized in that the environmental information is detected by a navigation system and the energy output is controlled in dependence on route information of the navigation system. Method according to claim 1 or 2, characterized in that the environmental information comprises information about a preceding environment, in particular about a preceding section of the route, and the control of the energy output of the at least two energy converters ( 3 . 4 ) is set in advance for the environment ahead. Method according to one of the preceding claims, characterized in that as environment information information about a height profile of a road on which the motor vehicle ( 1 ), in particular via the height profile of a section of track ahead, are detected. Method according to one of the preceding claims, characterized in that as environment information information about a two-dimensional course of a road on which the motor vehicle ( 1 ), in particular via the two-dimensional course of a route section lying ahead, are detected. Method according to one of the preceding claims, characterized in that as environment information at least one of the following information is detected, which is taken into account in the control of the energy release: - a distance between the motor vehicle ( 1 ) and a destination selected by the driver by means of a navigation system and / or - a type of road on which the motor vehicle ( 1 ), wherein in particular a distinction is made between the following types of road: a motorway and / or a highway and / or a city center road, and / or - information about a motorway access road ahead and / or highway exit. Method according to one of the preceding claims, characterized in that as an energy converter ( 3 . 4 ) at least one generator ( 3 ), which converts kinetic energy into electrical energy, and at least one thermoelectric generator ( 4 ), which thermal energy, in particular an exhaust line of the motor vehicle ( 1 ), converted into electrical energy. A method according to claim 7, characterized in that if based on the environmental information, a road increase is detected, the energy output is controlled such that while driving through the road rise at least a major proportion of the total power by means of the thermoelectric generator ( 4 ) provided. A method according to claim 7 or 8, characterized in that if based on the environmental information, a road gradient is detected, the energy output is controlled such that while driving in the road gradient at least a predominant proportion of the total kinetic energy by means of the generator ( 3 ) provided. Method according to one of the preceding claims, characterized in that by means of a driving style recognition device ( 11 ) the driver of the motor vehicle ( 1 ) is classified in terms of its driving style and in the control of the energy tax also the driving style of the driver is taken into account. Method according to one of the preceding claims, characterized in that before or with the energy output by the energy converter ( 3 . 4 ) at least one component ( 5 . 8th ) of the vehicle electrical system ( 2 ) is prepared to accept the energy delivered. A method according to claim 11, characterized in that before the energy release by the energy converter ( 3 . 4 ) an electrical energy store, in particular an electric battery ( 5 ), of the electrical system ( 2 ) is at least partially discharged. A method according to claim 11 or 12, characterized in that before or with the Energy release by the energy converters ( 3 . 4 ) at least one electrical consumer ( 8th ) of the vehicle electrical system ( 2 ) is activated. Method according to one of the preceding claims, characterized in that before the energy output by the energy converter ( 3 . 4 ) the required total power is determined in advance. Motor vehicle ( 1 ), which is designed to carry out a method according to one of claims 1 to 14.

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