WO2010105869A1

WO2010105869A1 - Electrical vehicle having a battery charger

Info

Publication number: WO2010105869A1
Application number: PCT/EP2010/051086
Authority: WO
Inventors: Stefan Spannhake; Thorsten Raatz
Original assignee: Robert Bosch Gmbh
Priority date: 2009-03-20
Filing date: 2010-01-29
Publication date: 2010-09-23
Also published as: DE102009001705A1

Abstract

The invention relates to an electrical vehicle (E) having a traction battery (1), an electrical engine (4), a battery charger (6), an AC voltage connection (9), a generator (7) and an internal combustion engine (8). The internal combustion engine is started by means of the generator (7) operating in motorized operation. The AC voltage required from the generator (7) to start the internal combustion engine (8) is provided by the battery charger (6), which converts a DC voltage diverted from the traction battery (1) into the AC voltage required by the generator (7) to start the internal combustion engine (8).

Description

description

title

Electric vehicle with a battery charger

The invention relates to an electric vehicle with a battery charger.

State of the art

Electric vehicles, especially electric cars, are already known. Despite advances in the development of energy storage for such electric vehicles, the battery of the electric vehicle is still a bottleneck for achieving a significant market share. Due to the disadvantages in terms of cost and weight, which is not satisfactorily solved by newly developed batteries with lithium-ion technology can be, the range of battery-powered electric vehicles is still limited compared to gasoline-powered vehicles.

In order to exploit the advantages of an electric powertrain and at the same time have to accept at most slight restrictions on the vehicle range, the concept of a "range extender" was developed, which is a serial hybrid drive, which in addition to an electric drive and an internal combustion engine and an electric generator The internal combustion engine drives the electric generator as needed to charge the battery of the electric car.

This concept makes it possible to dimension the capacity of the battery significantly smaller than is necessary in a purely battery-powered electric vehicle. This has the advantage that the weight and also the cost of the electric car can be kept comparatively low. Furthermore, shorter journeys can be covered purely electrically. This will be local Pollutant emissions completely avoided. Furthermore, comparatively low consumption costs arise for the driver.

In order to keep system costs low, the generator must be designed so that it can be electrically connected directly to a battery charger of the electric car. The generator must provide a voltage at the nominal operating point which corresponds to the respective mains voltage with respect to its amplitude and frequency. As a result, an additional pulse inverter can be saved.

To start the internal combustion engine either - as in conventional motor vehicles - a starter is used or the generator is operated by a motor for the time of starting. The first alternative mentioned above involves additional costs for the starter and its integration into the overall system. The second aforementioned alternative requires the installation of an additional pulse inverter, which otherwise would not be necessary for the function of the generator in this concept.

From DE 10 2007 004 172 A1 a motor vehicle is known, which has a traction battery, a traction converter, an electric traction motor, an internal combustion engine and an internal combustion engine driven generator. The traction battery, the traction converter and the electric traction motor are connected in such a way that, in operation, the electric traction motor is driven by the electric energy of the traction battery. In the parked state of the motor vehicle of the internal combustion engine driven generator can be activated by an identification signal and / or deactivated. After activation of the internal combustion engine drive is started and it is done via a charger charging the traction battery. After deactivation, a shutdown of the internal combustion engine drive of the generator is made.

Disclosure of the invention

An electric vehicle with the features specified in claim 1 has the advantage over that it requires no additional components, in particular no starter and no additional pulse inverter, to a Start the internal combustion engine of the electric vehicle bring about. This saves space and leads to a cost reduction, since it requires no additional components to start the internal combustion engine. These advantages are achieved essentially by the fact that the already existing battery charger is used for the duration of the engine operation of the generator for the control of the internal combustion engine to start them. By means of the battery charger, an alternating voltage is generated in the motor operation of the generator from the battery voltage, with which the motor operation of the generator is possible to start the engine. For this purpose, the DC voltage of the battery in the battery charger is converted into a three-phase AC voltage and made available to the generator. The battery charger is thus a bi-directional device which is used in a first mode to convert an AC voltage provided by an external AC mains to a DC voltage by which the traction battery of the electric vehicle is charged and used in a second mode thereof to convert the DC voltage provided by the traction battery into an AC voltage required by the generator in its engine operation to start the internal combustion engine.

Hereinafter, an embodiment of the invention will be explained with reference to the drawing.

1 shows a block diagram of an electric vehicle, in which the components of the electric vehicle necessary for understanding the invention are shown. This electric vehicle is an electric car E. This has a traction battery 1, a battery management system 2, a power electronics 3, an electric machine 4, DC consumers 5, a battery charger 6, a generator 7, an internal combustion engine 8 and an AC voltage terminal 9.

The AC voltage terminal 9 is connectable to an external AC power supply to charge the traction battery 1. The external AC mains supply either an alternating voltage with a frequency of 50 Hz and a Spannungsamplitdue of 230 V or an alternating voltage with a frequency of 50 Hz and a voltage amplitude of 400 V. The exter- - A -

AC voltage supplied AC voltage is converted in the battery charger 6 in a DC voltage of, for example, 300 V and then supplied to the traction battery 1 via the power electronics 3, said DC voltage passes through the power electronics unchanged. This charging of the traction battery 1 from the external AC power system takes place during a rest phase of the electric car, for example, overnight.

During the driving operation of the electric car E, the electric machine 4, by means of which the main drive of the electric car takes place, supplied from the traction battery 1 with energy. For this purpose, the traction battery 1 is taken DC voltage of, for example, 300 V in the power electronics 3, which has a pulse inverter, converted into an AC voltage whose amplitude is 300 volts. This AC voltage is supplied to the electric machine 4. Furthermore, when driving the electric car E in the power electronics 3, which has a DC-DC converter for this purpose, from the provided by the traction battery 1 DC voltage of 12 V generated, which is one or more DC loads 5 of the electric car E is supplied. These DC consumers include, for example, control units of the electric car E.

In service life of the vehicle, in which no external AC power is available, but a recharge or charging of the traction battery 1 is required, charging or recharging of the traction battery 1 can be done using the generator 7 and the internal combustion engine 8. During this charging or recharging of the traction battery 1, the generator 7, which operates in generator mode, is driven by the internal combustion engine 8. The case provided by the generator 7 AC voltage is converted in the battery charger 6 in a DC voltage of, for example, 300 V and supplied to the traction battery 1 via the power electronics 3. The necessity of recharging the traction battery 1 is detected by the battery management system 2 and reported to a control unit of the electric car E, which then controls the recharging of the traction battery 1. To start the internal combustion engine 8 energy from the traction battery 1 is provided. The derived from the traction battery 1 DC voltage of 300 V via the power electronics 3 is supplied to the battery charger 6 and converted into this in an AC voltage. This AC voltage provided by the battery charger 6 is supplied to the generator 7, which operates in the engine mode to start the internal combustion engine 8.

Consequently, no separate starter and no separate pulse inverter is required for this starting. Instead, the already existing battery charger 6 is used for the duration of the motor operation of the generator 7 for its control. For this purpose, the battery charger 6 must be bidirectional. Such a bidirectional design of the battery charger of an electric car has the further advantage that, if necessary, an external AC voltage network can be supported by the traction battery.

Such a bidirectional battery charger converts in one direction an AC voltage provided by an external power supply to a DC voltage by means of which the traction battery of the electric car is charged.

In the other direction, the battery charger 6 converts the DC voltage provided by the traction battery 1 into a three-phase AC voltage, so that power can be supplied to an external power grid. To start the internal combustion engine, DC voltage derived from the traction battery in the battery charger 6 is converted into a three-phase AC voltage, which is then provided to the generator 7 in its motor operation to allow the generator 7 to start the internal combustion engine 8.

Alternatively, a single-phase design is feasible. To generate a rotating field for the generator from the single-phase output voltage of the battery charger, a second phase can be generated by means of a capacitor. This does not create a circular rotating field, but an elliptical rotating field. As a result, the efficiency is reduced, but this is acceptable for the short-term start of the internal combustion engine. Since the internal combustion engine only has to be started when the battery charger is not connected to the external power grid, both functions can be realized by means of a single battery charger, namely charging the battery from an external power grid and driving the generator to start the internal combustion engine. This dual use of the battery charger can save additional costs for components for starting the internal combustion engine.

The invention described above can be used in particular in electric cars which use the concept of a "range extender", ie a serial hybrid drive which, in addition to an electric drive, also has an internal combustion engine and an electric generator motor operating generator, said generator from the battery charger, the required AC voltage is supplied and wherein the battery charger generates said AC voltage from the derived from the traction battery DC voltage.

Claims

claims

An electric vehicle which has a traction battery, an electric machine, a battery charger, an AC voltage connection, a generator and an internal combustion engine, characterized in that starting of the internal combustion engine (8) by means of operating in motor operation generator (7) and the from Generator (7) for starting the internal combustion engine (8) required AC voltage from the battery charger (6) is provided, which converts one of the traction battery (1) derived DC voltage in the from the generator (7) for starting the internal combustion engine (8) required AC voltage.

2. Electric vehicle according to claim 1, characterized in that the battery charger (6) has two operating modes, wherein in the first mode one of an external AC power via the AC voltage terminal (9) related AC voltage in a for charging the traction battery (1) provided DC voltage converts and converted in the second mode from the traction battery (1) derived DC voltage from the generator (7) to start the internal combustion engine (8) required AC voltage.