DE102011113079A1 - Method for operating vehicle, particularly hybrid vehicle by control device, involves operating electric machine in secondary operating mode with kinetic energy, and storing electric energy generated from electric machine - Google Patents

Abstract

The method involves decoupling of an electric machine (2) from the drive wheels (5,6), and operating the electric machine in a primary operating mode with electric energy from an electric energy storage unit (8) while the electric machine is decoupled from the drive wheels. The electric machine is operated in a secondary operating mode with the kinetic energy, which is generated during operation of the electric machine in the primary operating mode. The electric energy generated from the electric machine in the secondary operating mode is stored in the electric energy storage unit.

Description

The present invention relates to a method for operating a vehicle, which has an electrical machine and an electrical energy store. The vehicle may in particular comprise a hybrid vehicle, which comprises an internal combustion engine in addition to the electric machine for driving the vehicle, or an electric vehicle with a so-called range extender, d. h., An internal combustion engine, which provides electrical energy for operating the electric drive machine of the vehicle. The present invention further relates to a corresponding control device for a vehicle having an electric machine and an electrical energy store, and a vehicle having such a control device, in particular a hybrid vehicle or an electric vehicle with a range extender.

Electric energy storage of electric or hybrid vehicles, such as lithium-ion batteries or lithium iron phosphate batteries, have high internal resistance at low temperatures. This reduces the maximum removable power of the electrical energy storage. For example, when an internal combustion engine of a hybrid vehicle with lithium-ion batteries is to be started at very low temperatures, the internal resistance may be so high that the output power of the battery is insufficient to accelerate the internal combustion engine to the required rotational speed to be started can. The discharge current during this process heats the battery and lowers the internal resistance of the battery, increasing the maximum power output. As a result, the speed of the internal combustion engine increases until it is high enough to start the internal combustion engine. However, the battery is discharged constantly. If the existing capacity of the battery is not sufficient to provide the energy for starting the internal combustion engine for the duration of the heating, the vehicle can not be started and thus can not be operated.

In this context is from the DE 10 2009 016 259 A1 a voltage detection device with a voltage controlled oscillator and a battery state control system known. According to one embodiment, battery monitoring to a hybrid controller sends a temperature increase instruction when the temperature of the battery is low based on a value measured by a temperature sensor. The hybrid controller performs a temperature increase control in response to the temperature increase instruction. The temperature increase control adjusts drive signals to thereby oscillate an output voltage of a DC converter in the form of, for example, a pseudosinusoidal wave. With the oscillation of the output voltage of the DC converter, an energy stored in a capacitor is changed. Charges corresponding to the changes of the electric energy stored in the capacitor are transported between the capacitor and the battery. This allows power to be cyclically charged into the battery and cyclically discharged therefrom, such that a charge and discharge current oscillates with respect to the battery. The oscillating charging and discharging current flows through an internal resistance of the battery, resulting in generation of heat in the battery. The generated heat causes the temperature of the battery to rise.

Object of the present invention is to heat an electric energy storage of a vehicle, in particular a hybrid vehicle or electric vehicle with range extender, loss.

According to the present invention, this object is achieved by a method for operating a vehicle according to claim 1, a control device for a vehicle according to claim 7 and a vehicle according to claim 9. The dependent claims define preferred and advantageous embodiments of the invention.

According to the present invention, a method for operating a vehicle is provided. The vehicle includes an electric machine, an electrical energy storage and a clutch. The electrical machine is capable of generating kinetic energy from electrical energy in a first operating mode and generating electrical energy from kinetic energy in a second operating mode. The clutch is used to selectively couple the electric machine with drive wheels of the vehicle. In the method, the electric machine is decoupled from the drive wheels by means of the clutch and operated in a first mode with electrical energy from the electrical energy storage, while the electric machine is decoupled from the drive wheels. Thereafter, the electric machine is operated in the second mode. In this case, kinetic energy, which was generated during operation of the electric machine in the first operating mode, is used for operating the electric machine, while the electric machine is decoupled from the drive wheels. As a result, the electric machine generates electrical energy in the second operating mode, which is returned to the electrical energy store and stored. This method may preferably be performed before starting an internal combustion engine of the vehicle. Thus, the electrical energy storage is not discharged by Starting the internal combustion engine heated, but by charging and discharging cycles, in which electrical energy is converted into rotational energy in the electric machine and this rotational energy is converted back into electrical energy and stored in the electrical energy storage. As a result, a low-loss heating of the electrical energy storage can be achieved. By decoupling the electric machine from the drive wheels and possibly also a decoupling of the electric machine from the internal combustion engine, only small energy losses occur. On the other hand, a significant amount of electrical energy can be converted into kinetic energy and back, whereby the heating of the electrical energy storage can be done in a relatively short time, so that the electrical energy storage is ready after a short time to start the engine.

The kinetic energy generated in the first mode includes, for example, a rotational energy of a rotor of the electric machine. The electrical energy is thus used to accelerate the rotor of the electric machine and then recovered by braking the rotor again. Due to the usually high efficiency of the electric machine of an electric or hybrid vehicle occur in these energy conversions only small loss. As a result, the electrical energy store can already be brought to a desired temperature with a small amount of electrical energy. Since the electrical energy storage is heated by charging and discharging, the electrical energy storage is heated by the electrodes from the inside, which already small amounts of energy sufficient to put the electrical energy storage in a powerful state.

According to one embodiment, a temperature of the electrical energy store is determined and the electric machine is operated in the first and second operating modes as a function of the determined temperature. In this case, the operation of the electric machine in the first operating mode and in the second operating mode can be repeated cyclically until the temperature has reached a predetermined threshold value. By cyclically operating the electric machine in the charging and discharging mode, the electric machine can be operated in a speed range, which is perceived by a user of the vehicle as not disturbing, so that the heating process of the electrical energy storage is not perceived by a user as unpleasant ,

In addition, it may be displayed on a display unit of the vehicle that the method is performed to heat the electrical energy storage. As a result, additional understanding of the time delay and the operation of the electric machine before starting the internal combustion engine at the user of the vehicle can be awakened.

According to one embodiment, the vehicle is, for example, a hybrid vehicle with the electric machine and an internal combustion engine. The vehicle additionally comprises a further clutch, which serves for selectively coupling the internal combustion engine with the electric machine. In the method, the electric machine is decoupled from the internal combustion engine when the electric machine of the first or second mode is operated to heat the energy storage. By decoupling the electric machine from the internal combustion engine, the electric machine can be used as a low-loss buffer for kinetic energy to provide, as described above, low-loss charge and discharge cycles for the electrical energy storage to heat this example, at low temperatures.

In an electric vehicle with a so-called Ranger Extender, the internal combustion engine of the range extender is usually not coupled via a further coupling with the electric machine, but includes its own starter and its own electric generator for generating electrical energy for operating the vehicle. Since the range extender is usually started with electrical energy from the electrical energy storage, it may also be necessary in this type of electric vehicles to heat the electrical energy storage by the method described above. Thus, a physical decoupling of the range extender of the electric machine is not required, but it is sufficient to decouple the electric machine from the drive wheels.

According to the present invention, there is further provided a control device for a vehicle. The vehicle includes an electric machine, an electrical energy storage and a clutch. The electrical machine is capable of generating kinetic energy from electrical energy in a first operating mode and generating electrical energy from kinetic energy in a second operating mode. The clutch is used to selectively couple the electric machine with drive wheels of the vehicle. The control device is coupled to the electric machine, the electrical energy storage and the clutch. The control device controls the clutch such that the electric machine is decoupled from the drive wheels and operates the electric machine in the first operating mode with electrical energy the electrical energy storage, while the electric machine is decoupled from the drive wheels. As a result, the electric machine is idling and thus stores kinetic energy through its rotation. Then, the control device operates the electric machine in the second operating mode with the kinetic energy that was generated during operation of the electric machine in the first operating mode. The electric machine is also decoupled from the drive wheels in operation in the second mode. The electrical energy generated by the electric machine in the second mode is supplied to the electrical energy storage for storage.

The control device can be designed to carry out the methods described above and therefore comprises the advantages of the previously described methods.

Finally, according to the present invention, a vehicle is provided which comprises an electric machine, an electrical energy store and the control device described above. The electric machine can generate kinetic energy from electrical energy in a first operating mode and generate electrical energy from kinetic energy in a second operating mode. The clutch is used to selectively couple the electric machine with drive wheels of the vehicle. Thus, the vehicle is suitable for carrying out the method described above and therefore also includes the advantages of the method described above. The vehicle is, for example, a hybrid vehicle with an additional internal combustion engine. The electric machine is used for driving the vehicle and for starting the internal combustion engine.

The present invention will be described below in detail with reference to the drawings.

The sole figure shows a vehicle according to an embodiment of the present invention.

The figure shows a vehicle 1 , For example, a hybrid vehicle, with an electric drive machine 2 and an internal combustion engine 3 , The electric drive machine 2 is via a first clutch 4 with wheels 5 . 6 mechanically coupled. About a second clutch 7 are the electric drive machine 2 and the internal combustion engine 3 coupled together. The vehicle 1 further includes a battery 8th , which have power electronics 11 electrically with the electric drive machine 2 is coupled. The power electronics 11 serves to control the electric drive machine 2 , The electric drive machine 2 can optionally, depending on the electrical control, as an electric generator or as an electric motor work. If the electric drive machine 2 As an electric motor, it converts electrical energy from the battery 8th into kinetic energy. This kinetic energy can, for example, when the clutch is closed 4 to the drive wheels 5 . 6 be directed to the vehicle 1 drive. Furthermore, the kinetic energy when the clutch is closed 7 used to the internal combustion engine 3 to start. If the electric drive machine 2 As an electric generator, it converts kinetic energy into electrical energy, which is used to store the battery 8th is supplied. The kinetic energy can in this case with the clutch closed 4 over the wheels 5 . 6 from kinetic energy of the vehicle 1 be won. With the clutch closed 7 Can kinetic energy to generate the electrical energy from the internal combustion engine 3 to be provided. The vehicle 1 further comprises a control device 9 , which are used to control the flow of energy between the drive wheels 5 . 6 , the electric drive machine 2 , the internal combustion engine 3 and the battery 8th with the electric drive machine 2 , the internal combustion engine 3 , the battery 8th and the two clutches 4 . 7 connected is. Furthermore, the vehicle includes 1 an ad 10 which, for example, in a dashboard of the vehicle 1 is arranged and a driver of the vehicle a current flow of energy between the battery 8th , the electric drive machine 2 , the internal combustion engine 3 and the wheels 5 . 6 represents.

To ensure reliable operation of the vehicle 1 ensure the vehicle is 1 especially at a low energy level in the battery 8th from the internal combustion engine 3 driven. To the internal combustion engine 3 To get started, the clutch becomes 7 closed and the internal combustion engine 3 with the help of the electric drive machine 2 started. This is done by electrical energy from the battery 8th used. The battery 8th For example, a rechargeable lithium-ion battery, but has a high internal resistance at low temperatures. If now the internal combustion engine 3 At low temperatures, it may be that the internal resistance of the battery 8th so high is that the output power of the battery 8th is not enough to the internal combustion engine 3 to accelerate to the required speed so that it can be started. Due to the discharge current at this start attempt, the battery 8th Although heated up and the internal resistance of the battery drops, whereby the maximum output power increases, however, the battery is also discharged steadily and strongly. If the energy stored in the battery is insufficient to heat up and heat up for the duration of the heating the turning of the internal combustion engine 3 available, the vehicle can not be started.

To avoid this, the controller determines 9 before starting the internal combustion engine 3 in the battery 8th Existing amount of energy and the temperature of the battery 8th , If the temperature is correspondingly low and only a small amount of electrical energy in the battery 8th is stored, the internal combustion engine 3 not immediately started, but first a heating process of the battery 8th carried out. For this purpose, the battery is taken from electrical energy and fed back, as the battery 8th automatically heated during discharging and charging. Advantageously, this heating occurs during discharging and charging in the interior of the battery, so that only a small amount of heat is required to increase the performance of the battery. One or more discharge and charge cycles are realized as follows.

First, the controller controls 9 the couplings 4 and 7 such that the electric drive machine 2 both from the drive wheels 5 . 6 as well as from the internal combustion engine 3 is disconnected. Then the electric drive machine 2 operated as a motor and with electrical energy from the battery 8th accelerated from standstill to a predetermined speed, whereby a rotor of the electric drive machine 2 is rotated and thus stores kinetic energy in the form of rotational energy. Then the electric drive machine 2 operated as an electric generator and the stored kinetic energy stored in the rotor by braking the rotor back into electrical energy, which to the battery 8th is returned and stored there. This acceleration and deceleration is performed so often until the temperature of the battery has risen so high that the internal resistance of the battery is sufficiently low to provide a required energy for a quick start of the internal combustion engine 3 provide. Due to the high efficiency of the electric drive machine 2 occur during acceleration and deceleration of the electric drive machine 2 only low energy losses. Because the clutches 4 . 7 in hybrid vehicles in general anyway, no costly additional components are needed for the realization of the discharge and charging cycles.

The predetermined speed to which the electric drive machine 2 can be set so that it is not perceived as unpleasant or disturbing for a user of the vehicle. The acceleration and deceleration of the electric drive machine 2 For example, it can also be carried out with a predetermined acceleration profile, for example a sinusoidal speed curve. The cycle times for accelerating and decelerating the electric drive machine may typically be in the range of a few seconds, for example in the range of 4 to 8 seconds. The cycle times can, for example, from a rotational mass of the electric drive machine 2 , the mass of the parts of the couplings 4 and 7 , which rotate together with the electric drive machine, and a maximum torque of the electric drive machine 2 be determined. On the display unit 10 can be displayed to a user that the electric drive machine 2 for heating the battery 8th is cyclically accelerated and decelerated before a starting process of the internal combustion engine 3 is initiated.

The method described above can be used in hybrid vehicles, plug-in hybrid vehicles, which have an additional connection for charging the battery 8th equipped with energy from a power grid, and used in electric vehicles with a range extender. In addition, the method described above can also be used in conjunction with other battery technologies as lithium-ion batteries.

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 102009016259 A1 [0003]

Claims (10)

Method for operating a vehicle, wherein the vehicle ( 1 ) an electric machine ( 2 ), an electrical energy store ( 8th ) and a clutch ( 4 ), wherein the electric machine ( 2 ) generates kinetic energy from electrical energy in a first operating mode and generates electrical energy from kinetic energy in a second operating mode, wherein the clutch ( 4 ) for selectively coupling the electric machine ( 2 ) with drive wheels ( 5 . 6 ) of the vehicle ( 1 ), the method comprising: - decoupling the electric machine ( 2 ) of the drive wheels ( 5 . 6 ), - operating the electric machine ( 2 ) in the first operating mode with electrical energy from the electrical energy store ( 8th ) while the electric machine ( 2 ) of the drive wheels ( 5 . 6 ) is decoupled, - operating the electric machine ( 2 ) in the second operating mode with kinetic energy, which during operation of the electric machine ( 2 ) was generated in the first mode while the electric machine ( 2 ) of the drive wheels ( 5 . 6 ) is decoupled, wherein in the second mode of operation of the electric machine ( 2 ) generated electrical energy in the electrical energy storage ( 8th ) is stored. Method according to claim 1, wherein the kinetic energy generated in the first operating mode comprises a rotational energy of a rotor of the electric machine ( 2 ). The method of claim 1 or 2, further comprising: - determining a temperature of the electrical energy store ( 8th ), wherein the operation of the electric machine ( 2 ) is performed in the first and second modes depending on the determined temperature. The method of claim 3, wherein the operation in the first mode and the operation in the second mode is repeated until the temperature has reached a predetermined threshold. Method according to one of the preceding claims, further comprising: - displays on a display unit ( 10 ) of the vehicle ( 1 ) that the process is carried out to the electrical energy storage ( 8th ) to heat. Method according to one of the preceding claims, wherein the vehicle ( 1 ) further an internal combustion engine ( 3 ) and another coupling ( 7 ), wherein the further coupling ( 7 ) for selectively coupling the internal combustion engine ( 3 ) with the electric machine ( 2 ), the method further comprising: - decoupling the electric machine ( 2 ) of the internal combustion engine ( 3 ), when the electric machine ( 2 ) is operated in the first or second mode. Control device for a vehicle, wherein the vehicle ( 1 ) an electric machine ( 2 ), an electrical energy store ( 8th ) and a clutch ( 4 ), wherein the electric machine ( 2 ) generates kinetic energy from electrical energy in a first operating mode and generates electrical energy from kinetic energy in a second operating mode, wherein the clutch ( 4 ) for selectively coupling the electric machine ( 2 ) with drive wheels ( 5 . 6 ) of the vehicle ( 1 ) is configured, wherein the control device ( 9 ) with the electric machine ( 2 ), the electrical energy storage ( 8th ) and the clutch ( 4 ) and is configured, - the electric machine ( 2 ) by means of the coupling ( 4 ) of the drive wheels ( 5 . 6 ), - the electric machine ( 2 ) in the first operating mode with electrical energy from the electrical energy store ( 8th ) while the electric machine ( 2 ) of the drive wheels ( 5 . 6 ) is decoupled, - the electric machine ( 2 ) in the second operating mode with kinetic energy, which during operation of the electric machine ( 2 ) was generated in the first mode, while the electric machine ( 2 ) of the drive wheels ( 5 . 6 ) is decoupled, whereby by the electrical machine ( 2 ) generated in the second mode electrical energy for storage in the electrical energy storage ( 8th ) to the electrical energy storage ( 8th ). Control device according to claim 7, wherein the control device ( 9 ) is configured for carrying out the method according to one of claims 1-6. Vehicle comprising: - an electric machine ( 2 ), which generates kinetic energy from electrical energy in a first operating mode and generates electrical energy from kinetic energy in a second operating mode, - an electrical energy store ( 8th ), - a coupling ( 4 ) for selectively coupling the electric machine ( 2 ) with drive wheels ( 5 . 6 ) of the vehicle ( 1 ), and - a control device ( 9 ) according to claim 7 or 8. Vehicle according to claim 9, wherein the vehicle ( 1 ) a hybrid vehicle with the electric machine ( 2 ) and an internal combustion engine ( 3 ), wherein the electric machine ( 2 ) to driving of the vehicle ( 1 ) and for starting the internal combustion engine ( 3 ) is configured.

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