DE102009001705A1 - Electric vehicle with a battery charger - Google Patents

Abstract

The invention relates to 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. A starting of the internal combustion engine takes place by means of the generator operating in engine operation. The AC voltage required by the generator to start the internal combustion engine is provided by the battery charger, which converts a DC voltage derived from the traction battery into the AC voltage required by the generator to start the internal combustion engine.

Description

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

State of the art

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

Around to be able to use the advantages of an electric drive train and at the same time at most slight restrictions regarding the vehicle range has to be accepted, was developed the concept of a "range extender". This is a serial hybrid drive, which except an electric drive and an internal combustion engine and an electric generator. The internal combustion engine is driving if necessary, the electric generator to the battery of the electric car charge.

This Concept allows the capacity of the battery significantly smaller than a battery-powered one Electric vehicle is necessary. This has the advantage that the weight and also the cost of the electric car comparatively low can be. Furthermore, shorter ones Travels are covered purely electrically. Thereby Local pollutant emissions are completely avoided. Furthermore, comparatively low consumption costs arise for the driver.

Around To keep the system costs low, the generator must be designed in this way be that he is electrically connected directly to a battery charger the electric car can be connected. The generator must be at rated operating point provide a voltage with respect to their amplitude and their frequency corresponds to the respective mains voltage. Thereby An additional pulse inverter can be saved.

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

From the DE 10 2007 004 172 A1 For example, 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 bring about starting the internal combustion engine of the electric vehicle. 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 of operation to convert an AC voltage provided by an external AC mains to a DC voltage by means of which the traction battery of the electric vehicle is charged and used in a second mode of operation 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 is taken.

following becomes an embodiment of the invention explained with reference to the drawing.

The 1 shows a block diagram of an electric vehicle, in which the necessary for understanding the invention components of the electric vehicle 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 8th and an AC voltage connection 9 on.

The AC voltage connection 9 is connectable to an external AC mains to the traction battery 1 charge. The external AC mains supplies either an alternating voltage with a frequency of 50 Hz and a voltage amplitude of 230 V or an alternating voltage with a frequency of 50 Hz and a voltage amplitude of 400 V. The AC voltage supplied by the external AC mains is supplied by the battery charger 6 converted into a DC voltage of, for example, 300 V and then the traction battery 1 via the power electronics 3 fed, said DC voltage passes through the power electronics unchanged. This charging the traction battery 1 from the external AC power is done during a rest period 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, from the traction battery 1 energized. For this purpose, the traction battery 1 taken DC voltage of, for example, 300 V in the power electronics 3 having a pulse inverter, converted into an AC voltage whose amplitude is 300V. This alternating voltage is the electric machine 4 fed. Furthermore, when driving the electric car E in the power electronics 3 having for this purpose a DC-DC converter, from the traction battery 1 provided DC voltage of 12 V, the one or more DC consumers 5 of the electric car E is supplied. These DC consumers include, for example, control units of the electric car E.

In periods of vehicle life, in which no external AC power is available, but still a recharge or charging the traction battery 1 is required, a charge or recharge the traction battery 1 using the generator 7 and the internal combustion engine 8th respectively. During this charging or recharging of the traction battery 1 becomes the generator 7 operating in regenerative mode, from the internal combustion engine 8th driven. The case of the generator 7 provided AC voltage is in the battery charger 6 converted into a DC voltage of, for example, 300 V and the traction battery 1 via the power electronics 3 fed. The need to recharge the traction battery 1 is doing by the battery management system 2 detected and reported to a control unit of the electric car E, which then recharge the traction battery 1 controls.

To start the internal combustion engine 8th gets energy from the traction battery 1 made available. It is the traction battery 1 derived DC voltage of 300 V via the power electronics 3 the battery charger 6 supplied and converted in this into an AC voltage. This from the battery charger 6 provided AC voltage is the generator 7 supplied, which works in engine operation, to the internal combustion engine 8th to start.

Consequently, no separate starter and no separate pulse inverter is required for this starting. Instead, the already existing battery charger 6 for the duration of the engine operation of the generator 7 used for its control. This requires the battery charger 6 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.

One Such bidirectional battery charger converts to one direction one from an external power grid available Asked AC voltage in a DC voltage, by means of which the traction battery of the electric car is charged.

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

Alternatively, a single-phase design is feasible. To turn from the single-phase output voltage of the battery charger a rotation To generate field for the generator, 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.

There the internal combustion engine must be started only if the battery charger is not connected to the external mains connected, can be using a single battery charger both Realize functions, namely the charging of the battery from an external power grid and a generator control for starting the internal combustion engine. Through this double use of the Battery charger can be extra Cost of components for starting the internal combustion engine be saved.

The The invention described above can be particularly useful in electric cars using the concept of a range extender, d. H. a serial hybrid drive, which except one electric drive also an internal combustion engine and a having electric generator. Starting the internal combustion engine is done using the motor operating Generator, this generator from the battery charger the required AC voltage is supplied and wherein the battery charger said AC voltage generated from the derived from the traction battery DC voltage.

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 102007004172 A1 [0007]

Claims (2)

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 ( 8th ) by means of the generator operating in engine operation ( 7 ) and the generator ( 7 ) for starting the internal combustion engine ( 8th ) requires AC voltage from the battery charger ( 6 ), which is one of the traction batteries ( 1 ) derived DC voltage in the generator ( 7 ) for starting the internal combustion engine ( 8th ) converts required AC voltage. Electric vehicle according to claim 1, characterized in that the battery charger ( 6 ) has two operating modes, wherein in the first operating mode, one from an external AC mains via the AC voltage connection ( 9 ) in an AC to charge the traction battery ( 1 ) converted DC voltage and in the second mode one of the traction battery ( 1 ) derived DC voltage in the generator ( 7 ) for starting the internal combustion engine ( 8th ) converts required AC voltage.