DE102011011347A1 - Circuit-arrangement for use in electric charging station for charging battery of electric car, has energy storage device charged via direct-voltage of power supply and connected to battery of electric car in order to charge battery - Google Patents

Abstract

The circuit-arrangement has an energy storage device (105) charged via direct-voltage that is provided from a power supply with respect to a rectifier circuit (104). The energy storage device is connected to a battery (101) of an electric car (102) in order to charge the battery. The energy storage device comprises cells (106-109) that are switched in series with one another and chargeable over the direct-voltage. The energy storage device consists of a flow battery or a redox flow battery, a lead-acid battery and a lithium battery. An independent claim is also included for a method for charging a battery of an electric car.

Description

The invention relates to a circuit for charging at least one battery, a charging station and a method for charging at least one battery of an electric vehicle.

As electromobility grows, it becomes necessary to recharge batteries in a variety of electric vehicles as quickly as possible. This can be z. B. via a three-phase AC or a DC system. In particular, charging stations may be provided, at which the electric vehicles are at least partially charged. Such charging stations relate the required power, for example, from a public power grid.

So-called (redox) flow batteries or redox flow cells are known. In such energy storage electrical energy is stored in chemical compounds, the reactants are each present in a solvent: two energy-storing electrolytes are provided via two separate circuits, between which an ion exchange can take place via a membrane. The electrolytes can be stored in containers or tanks. In such electrochemical energy storage, the amount of energy and power can be scaled independently.

The power electronics to be provided for fast charging of the batteries is expensive due to the high electrical power to be provided. Furthermore arise during fast charging losses that can be summed up in particular by the fact that a plurality of batteries of several electric vehicles to be charged at the same time. The high power peaks required for fast charging can considerably burden the public power grid. To ensure the supply for such load peaks, the connection of the charging station is to be dimensioned accordingly, which in turn has a considerable effect on the cost. It is also disadvantageous that the (very high) current provided during the load peaks is expensive.

The object of the invention is to avoid the above-mentioned disadvantages and in particular to provide a solution to mitigate load peaks caused by the charging of batteries of electric vehicles for a power grid.

This object is achieved according to the features of the independent claims. Further developments of the invention will become apparent from the dependent claims.

• – mit einer Gleichrichterschaltung anhand derer aus einem Stromnetz eine Gleichspannung bereitstellbar ist,
• – mit einem Energiespeicher,
• – wobei der Energiespeicher über die Gleichspannung aufladbar ist und
• – wobei mindestens eine Batterie eines Elektrofahrzeugs mit dem Energiespeicher verbindbar und über diesen Energiespeicher aufladbar ist.

To solve the problem, a circuit for charging a battery is specified

• With a rectifier circuit on the basis of which a DC voltage can be provided from a power network,
• With an energy store,
• - Where the energy storage is charged via the DC voltage and
• - Wherein at least one battery of an electric vehicle with the energy store can be connected and charged via this energy storage.

In this case, it is of advantage that the power supply network is significantly more uniformly loaded by the buffer effect of the energy store and, in particular, that high load peaks (and possibly also load sinks) can be largely avoided.

A further development is that the energy store has a plurality of cells which are connected in series and can be charged via the DC voltage.

The cells may have leads that, individually or in combination with one another (eg, utilizing a series connection of the cells) provide electrical energy for charging the at least one battery. In particular, these connections can be flexibly connected to the terminals of the at least one battery of the electric vehicle.

Another development is that different voltages can be provided based on the plurality of cells, depending on the state of charge of the at least one battery of the electric vehicle and / or depending on the battery type of the at least one battery of the electric vehicle a suitable voltage for charging the at least one battery can be provided.

Advantageously, the voltage of the cells can thus be used to charge the at least one battery.

In particular, it is a further development that a control unit is provided which determines a required charging voltage of the at least one battery of the electric vehicle and connects this charging voltage with terminals of the at least one battery of the electric vehicle based on the cells of the energy store.

The control unit may, for example, connect the terminals of the cells individually or in combination (eg a series connection of several cells) to the terminals of the at least one battery of the electric vehicle. This can be flexible and dynamic - eg. B. depending on a charging function or a state of charge of the battery - done.

It is also a development that the at least one battery of the electric vehicle can be connected to the energy store via a converter and can be charged by the energy store.

Preferably, a converter (eg, a step-up or step-down converter or a current transformer) may be provided to connect the at least one cell of the energy store to the battery of the electric vehicle. As a result, on the one hand a voltage for charging the battery (flexible) can be adjusted, on the other hand, a charging current can be controlled.

• – einen Hochsetzsteller;
• – einen Tiefsetzsteller;
• – einen Stromwandler, insbesondere einen DC/DC-Wandler.

Furthermore, it is a development that the converter comprises at least:

• A boost converter;
• A buck converter;
• - A current transformer, in particular a DC / DC converter.

In the context of an additional development batteries of several electric vehicles can be connected to the energy storage and rechargeable via this energy storage.

In particular, the cells of the energy storage device can be flexibly connected to charge (with or without converters) the multiple batteries of the electric vehicles by means of the above-mentioned control unit.

• – eine Flussbatterie bzw. eine Redox-Flow-Batterie;
• – einen Blei-Akku;
• – eine Lithium-Batterie.

A next development is that the energy store comprises at least one of the following components:

• A flow battery or a redox flow battery;
• - a lead battery;
• - a lithium battery.

Another development is that at least part of the electrical energy stored in the energy store can be fed back into the power grid.

The above object is also achieved by a charging station for charging at least one electric vehicle comprising at least one of the circuits described herein.

• – bei dem ein Energiespeicher über eine aus einem Stromnetz gewonnene gleichgerichtete Spannung aufgeladen wird;
• – bei dem die mindestens eine Batterie anhand der in dem Energiespeicher gespeicherten elektrischen Energie aufgeladen wird.

Furthermore, the object described above is achieved by means of a method for charging at least one battery of an electric vehicle

• - In which an energy storage is charged via a rectified voltage obtained from a power grid;
• - In which the at least one battery is charged based on the stored energy in the energy store.

In particular, the at least one battery can also be charged based on the energy stored in the energy store.

• – ein Ladezustand der mindestens einen Batterie des Elektrofahrzeugs ermittelt wird und
• – abhängig von dem ermittelten Ladezustand mindestens eine Zelle des Energiespeichers direkt oder über einen Wandler mit der mindestens einen Batterie des Elektrofahrzeugs verbunden wird.

A further development is that

• - A state of charge of at least one battery of the electric vehicle is determined and
• - Depending on the determined state of charge at least one cell of the energy storage device is connected directly or via a converter with the at least one battery of the electric vehicle.

Embodiments of the invention are illustrated and explained below with reference to the drawings.

Show it:

1 a schematic diagram for (fast) charging a battery of an electric vehicle;

2 a schematic diagram for the (fast) charging of batteries of several electric vehicles.

The charging station exemplified here may include a local concentration of charging facilities for electric vehicles. For example, at least one connection for charging one (or more) electric vehicles in this sense can be understood as an electric filling station.

The electric vehicle may be any vehicle having at least one battery. The battery is a rechargeable battery. The electric vehicle may be a vehicle with an electric motor. It is also possible that the electric vehicle is a hybrid vehicle, the z. B. still has an internal combustion engine or another drive in addition to the electric motor. For example, the electric vehicle may be a motor vehicle (passenger or truck), motorcycle, bicycle, scooter, bus, rail vehicle, watercraft (eg, boat), aircraft, etc.

In particular, an energy supply to a charging station and an intermediate storage of energy for the electricity charging station are proposed as follows: A mains alternating voltage from a medium-voltage network (in Europe, for example, 10,000 V) is rectified. This can be done for example by a 3-phase bridge rectification. Alternatively or additionally, other rectification concepts and / or converters (eg step-down converters, boost converters or combinations thereof) may be used.

The DC voltage can be connected in series with any number of energy storage devices. Preferably, the energy stores, individually or in combination with one another (as, for example, a plurality of energy stores connected in series), provide a charging voltage for charging the batteries of the electric vehicles. In particular, the charging voltage for the batteries of the electric vehicles or for different electric vehicles or for different states of charge of batteries of the electric vehicles can be used as flexibly.

The energy storage devices may be connected in series with one another, wherein electrical taps may be present between the energy storage devices so that the appropriate voltages can be tapped off for the batteries of the electric vehicles to be charged up. For example, these tapped voltages via converter, z. B. on DC converters, boost converter, buck converter, etc. are used to charge the batteries.

It should be noted that the energy storage with a low power from the mains z. B. can be charged evenly and that over the energy storage power peaks that are needed to fast-charge the batteries of electric vehicles can be buffered. Thus, these power peaks do not directly affect the power grid, accordingly an operator of the charging station does not have to obtain the very high charging current directly from the power grid. This reduces the cost of electricity from the grid. Furthermore, can be ensured by the energy storage that the charging station obtains a lower maximum current from the power grid, which allows a more efficient and cost-effective dimensioning of the interface of the charging station to the power grid; For example, so the rectifier can be designed for the lower maximum current.

1 shows a schematic diagram for (fast) charging a battery 101 an electric vehicle 102 ,

A three-phase alternating current 103 a power grid is connected via a rectifier 104 converted into a direct current and an energy storage 105 a charging station provided.

The rectifier can be a bridge rectifier with diodes or IGBTs. It is also possible that a regulated rectifier circuit is used; In this case, the diodes can be replaced by semiconductor switches, for. As transistors, mosfets, circuit breakers, etc. are replaced and controlled accordingly.

The energy storage 105 includes a variety of cells 106 to 109 which are connected in series with each other. It should be noted that the energy storage may have any units (referred to herein as cells), for. As electrical and / or electro-chemical storage. Exemplary is in 1 a contacting of the positive and the negative terminal of the cell 107 shown by which the cell 107 over a converter 110 (Here, for example, a DC-DC converter) with the battery 101 connected is. Thus, the electrical energy of the cell 107 used to the battery 101 charge. Similarly, for batteries that require a different charging voltage, another one of the cells 106 to 109 or a series circuit comprising at least two of the cells 106 to 109 be used. There may be provided a control circuit connecting the terminals of the cells to the terminals of the battery 101 combines. It is also possible that, based on the control circuit, the cells can be connected as desired in series to a suitable charging voltage for the battery 101 provide. Also it is possible that the converter 110 has a boost and / or buck function, so that the voltage for the battery 101 is adjustable accordingly. Preferably, based on the converter 110 and / or the control unit, a charging current for the battery 101 be set. For example, the charging current and / or the charging voltage during the charging of the battery 101 to be changed. So it is possible that different fast charging functions can be provided.

In addition, it should be noted that the charging of the energy storage 105 and charging the battery 101 of the electric vehicle 102 can take place decoupled, so preferably that for the battery 101 required power does not affect the power grid. This can be z. B. can be achieved by the charging circuit for the energy storage 105 from the charging circuit for the battery 102 is decoupled. For example, different charging cycles can be determined during which only one of the circuits is in each case activated (this can be realized, for example, with switches which can be controlled electronically). Alternatively, another electronic decoupling of the two charging circuits can take place.

Requires the battery 101 For example, a charging voltage of 400 V, so results in a charging current of 250 A, a power of 100 kV. This power can be used for the duration of the fast charging process of the battery 101 through the energy storage 105 be buffered, so that a short-term heavy load on the power grid is prevented. Accordingly, the cells can 106 to 109 of the energy store 105 be dimensioned so that during the charging of electric vehicles, the load peaks largely from the energy storage 105 be provided and this is charged with comparatively constant and low electrical power from the mains.

It should be noted that the in 1 shown converter 110 is optional. Alternatively, this can be omitted.

2 shows a schematic diagram for (fast) charging of batteries 201 to 203 where each of the batteries 201 to 203 in an electric vehicle 204 to 206 is arranged.

A three-phase alternating current 207 a power grid is connected via a rectifier 208 converted into a direct current and an energy storage 209 a charging station provided.

The rectifier 208 can according to the comments too 1 be designed differently. With regard to the general structure and its function, reference should also be made to the explanatory notes to 1 directed.

The energy storage 209 includes a variety of cells 210 to 213 which are connected in series with each other. It should be noted that the energy storage 209 may have any units (referred to herein as cells), for. As electrical and / or electro-chemical storage. The cell is an example 210 a voltage U1 for the battery 201 of the electric vehicle 204 ready, a series connection of the cells 210 to 211 provides a voltage U2 for the battery 202 of the electric vehicle 205 ready and a series circuit comprising the cells 212 to 213 sets a voltage U3 for the battery 203 of the electric vehicle 206 ready.

Between the cells 210 to 213 and the batteries 201 to 203 can (optionally) at least one current and / or voltage converter can be arranged.

Further, it is an option that cells 210 to 213 individually or in combination via a switching network dynamically with the batteries 201 to 203 can be connected. This can be z. B. can be achieved via controllable connections by z. B. a control unit first a voltage U3 for charging the battery 203 provides and after a predetermined period of time or depending on a state of charge of the battery 203 to the voltage U2 to supply the battery 203 switches. Accordingly, the connection cables between the cells 210 to 213 and the respective charging terminals of the battery 203 be switched or connected. Also can be done as a flexible control of the charging ports, if the electric vehicle 206 the gas station leaves and another electric vehicle uses the same connections for charging.

As cells of energy storage 105 . 209 can z. B. flow batteries (eg., Redox flow) can be used. Thus, it is possible to reduce the effort to control the cells, since the amount of energy and power can be provided separately from each other. In particular, it is advantageous if containers (tanks) z. B. be used in the bottom of the charging station to receive the electrolyte for storing the electrical energy. Advantageously, it is possible to convert existing gas stations at least partially to charging stations.

Alternatively or additionally, it is possible to use as cells of the energy store: any rechargeable battery, e.g. Lead-acid batteries, lithium batteries.

The proposed solution also makes it possible to feed back at least part of the electrical energy stored in the energy store into the power grid. As a result, z. B. excess electrical energy to be sold to an electricity supplier. This can in particular be demand-dependent: for example, a charging station can provide electrical energy to the electricity provider so that the electricity supplier can cope with a temporary load peak.

The operator of the charging station can thus agree with the electricity supplier or operator of the power grid a decrease as well as a delivery of electrical power from or to the power grid. For this purpose, a device can be provided which converts the direct current accordingly (eg, chops it into an alternating current) so that the electrical energy can be fed into the alternating current network of the electricity supplier.

Preferably, the charging station is above a predetermined power threshold, z. B. 1 MW, dimensioned. In this case, the charging station operator can participate directly in the reserve power market. It is also possible that several charging stations merge to be jointly regulated as a virtual power plant or participate in the reserve power market.

The approach presented here allows a cost-effective and efficiency-optimized design of a structure of charging stations, which can be used flexibly for rapid charging of at least one electric vehicle. Due to the concept presented different voltages for charging the batteries of the electric vehicles can be provided. Electrical energy can be directly at the charging station, z. B. by means of flow batteries are cached. This makes it possible, the energy storage of the gas station with low-priced electricity z. B. to charge during periods of low load and the power at times of maximum load not (only) from the power grid, but (also) provide from the energy storage of the charging station. The approach allows the caching of volatile renewable energy sources. Furthermore, it is possible to ensure efficient regulation or utilization of the power grid.

LIST OF REFERENCE NUMBERS

101

Battery of the electric vehicle 102

102

electric vehicle

103

Power mains connections (three-phase alternating current)

104

rectifier

105

energy storage

106-109

Cells of the energy store 105

110

Converter, z. B. current transformer

207

Power mains connections (three-phase alternating current)

208

rectifier

209

energy storage

210-213

Cells of the energy store 209

Claims (12)

Circuit for charging a battery ( 101 ; 201 - 203 ) - with a rectifier circuit ( 104 ; 208 ) by means of which a DC voltage can be supplied from a power grid, - with an energy store ( 105 ; 209 ), - wherein the energy store ( 105 ; 209 ) is chargeable via the DC voltage and - at least one battery ( 101 ; 201 - 203 ) of an electric vehicle ( 102 ; 204 - 206 ) with the energy store ( 105 ; 209 ) and via this energy storage ( 105 ; 209 ) is rechargeable. Circuit according to Claim 1, in which the energy store ( 105 ; 209 ) several cells ( 106 - 109 ; 210 - 213 ), which are connected in series and can be charged via the DC voltage. Circuit according to Claim 2, in which, on the basis of the plurality of cells ( 106 - 109 ; 210 - 213 ) different voltages can be provided, depending on the state of charge of the at least one battery ( 101 ; 201 - 203 ) of the electric vehicle ( 102 ; 204 - 206 ) and / or depending on the battery type of the at least one battery ( 101 ; 201 - 203 ) of the electric vehicle ( 102 ; 204 - 206 ) a suitable voltage for charging the at least one battery ( 101 ; 201 - 203 ) is available. A circuit according to claim 3, wherein a control unit is provided which determines a required charging voltage of the at least one battery of the electric vehicle and connects this charging voltage with terminals of the at least one battery of the electric vehicle based on the cells of the energy store. Circuit according to one of the preceding claims, in which the at least one battery ( 101 ) of the electric vehicle ( 102 ) via a transducer ( 110 ) with the energy store ( 105 ) connectable and from the energy storage ( 105 ) is rechargeable. The circuit of claim 5, wherein the converter comprises at least: A boost converter; A buck converter; - A current transformer, in particular a DC / DC converter. Circuit according to one of the preceding claims, in which batteries ( 201 - 203 ) of several electric vehicles ( 204 - 206 ) with the energy store ( 209 ) and via this energy storage ( 209 ) are rechargeable. Circuit according to one of the preceding claims, in which the energy store comprises at least one of the following components: A flow battery or a redox flow battery; - a lead battery; - a lithium battery. Circuit according to one of the preceding claims, in which at least a part of the electrical energy stored in the energy store can be fed back into the power grid. Electricity charging station for charging at least one electric vehicle comprising at least one circuit according to one of claims 1 to 9. Method for charging at least one battery ( 101 ; 201 - 203 ) of an electric vehicle ( 102 ; 204 - 206 ) - in which an energy storage ( 105 ; 209 ) is charged via a rectified voltage obtained from a power grid; - where the at least one battery ( 101 ; 201 - 203 ) based on in the energy storage ( 105 ; 209 ) stored electrical energy is charged. Method according to claim 11, - in which a state of charge of the at least one battery ( 101 ; 201 - 203 ) of the electric vehicle ( 102 ; 204 - 206 ) is determined and - in which depending on the determined state of charge at least one cell ( 106 - 109 ; 210 - 213 ) of the energy store ( 105 ; 209 ) directly or via a converter ( 110 ) with the at least one battery ( 101 ; 201 - 203 ) of the electric vehicle ( 102 ; 204 - 206 ) is connected.

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