DE102019006266A1 - Storage device for an electrically operable motor vehicle with a switching device for controlling two sub-strands of an electrical energy store and method for operating such a storage device - Google Patents

Abstract

The invention relates to a storage device (1) for an electrically operated motor vehicle, with at least one electrical energy store (2), which has at least two partial strings (3, 4) connected in series for storing electrical energy, at least one charging connection (8) and one Switching device (5), the switching device (5) being electrically connected to the series connection of the partial strands (3, 4) and at least one intermediate tap (9) between the partial strands (3, 4), the switching device (5) having at least two semiconductor switches ( S1, S2, S3) for distributing the electrical energy from the charging device to the sub-strands (3, 4). In order to enable improved charging at different voltage levels of charging devices, the switch device (5) additionally has a voltage converter (6), which is designed by switching the at least two semiconductor switches (S1, S2, S3) to generate a different charging voltage for charging at least one of the sub-strands (3, 4) from a voltage of the charging device.

Description

The invention relates to a storage device for an electrically operable motor vehicle with at least one electrical energy store, which has at least two partial strings connected in series for storing electrical energy, at least one charging connection, via which the partial strings connected in series can be connected to a charging device and by which Charging device provided energy can be supplied and thereby be charged, and a switching device, the switching device being electrically connected to the series connection of the partial strands and at least one intermediate tap between the partial strands, the switching device being at least two semiconductor switches for distributing the electrical energy from the charging device to the partial strands having. A second aspect of the invention relates to a method for operating a storage device, in particular the storage device mentioned above.

An electrically operated motor vehicle, in particular an electric vehicle or a hybrid vehicle, usually has an electrical energy store with a predetermined voltage level. The voltage level of the electrical energy store can be nominally 400 volts or 800 volts, for example. Charging devices, for example so-called charging stations or charging stations, usually have a certain voltage level. The voltage level of different charging devices can vary depending on the charging standard and / or regionally different norms. For example, the voltage level of a charging station can be nominally 400 volts, 500 volts, 750 volts or 800 volts. For example, direct current charging devices customary in Asia have a maximum charging voltage of 750 volts. With these, charging an electrical energy store with a voltage level of 800 volts is not readily possible.

To work around this problem, the DE 10 2018 000 490 A1 a storage device for a motor vehicle, in which at least two partial strings connected in series for storing electrical energy can be switched into different switching states by a switching device. This would make it possible, for example, to connect two sub-strings, each with a nominal voltage level of 400 volts, in parallel to provide electrical energy for driving a motor vehicle, to achieve a nominal voltage level of 800 volts, and to charge in parallel on a charging station with 750 volts switch to reach a nominal voltage level of 400 volts. Using an exemplary charging station with a nominal voltage level of 750 volts, however, the maximum charging speed is greatly reduced.

Through the DE 10 2018 000 491 A1 Such a storage device is further developed by a galvanically isolating on-board charger, which enables the on-board electrical system to be supplied with charging devices at different voltage levels.

It is an object of the present invention to enable improved charging of an electrical energy store in an electrically operated motor vehicle at different voltage levels.

According to the invention, this object is achieved by the subject matter of the independent claims. Advantageous embodiments with appropriate further developments are the subject of the dependent claims.

In order to further develop a storage device in accordance with the preamble of patent claim 1 in such a way that improved charging can be made possible with charging devices at different voltage levels, it is provided according to the invention that the switching device additionally has a voltage converter which is designed to switch the at least two semiconductor switches appropriately to generate a different charging voltage for charging at least one of the partial strands from a voltage of the charging device. In other words, the at least two semiconductor switches are supplied with a double benefit. Switching the at least two semiconductor switches makes it possible, for example, to electrically connect only a first of the partial strands to the charging device in a first switching state of the at least two semiconductor switches, to connect only a second of the partial strands to the charging device in a second switching state, and in a third Switching state two, several or all of the sub-strands to connect to the switching device. In particular, the first, the second and the third switching state relate to a state in which the storage device is connected to the charging device via the at least one charging connection. In addition, the corresponding switching of the semiconductor switches makes it possible to generate the different charging voltage for charging the at least one of the sub-strands from the voltage of the charging device. In particular, it is possible to generate the different charging voltage in the first, the second and / or the third switching state. The different charging voltage can be generated by repeated, in particular periodic, opening and closing of at least one of the at least two semiconductor switches. The switching device thus enables the same semiconductor switch at the same time the division of the electrical energy into the sub-strands and the generation of the different charging voltage. Of course, the switching device can also be used in such a way that no charging voltage deviating from the voltage of the charging device is generated, but at least one of the sub-strands is charged directly with the voltage of the charging device.

In particular, it is provided that each of the at least two semiconductor switches is connected in parallel to exactly one of the respective sub-strands, a respective interposed diode being designed to prevent a short circuit of the sub-strands when the respective parallel-connected semiconductor switch is closed. In particular, exactly one of the at least two semiconductor switches is connected in parallel to each of the sub-strands. Closing one of the semiconductor switches then bridges the respective sub-strand to which the closed semiconductor switch is connected in parallel. As a result, a portion of the voltage of the charging device or the charging voltage deviating therefrom, which is applied to the bridged sub-strand, is reduced to almost zero. The remaining portion is reduced in accordance with the ratio of the internal resistance of the semiconductor switch to all components which are connected in series.

In order to further develop a method according to the preamble of claim 5 to enable improved charging at different voltage levels of a charging device, it is provided according to the invention that the switching device is additionally designed as a voltage converter and, by switching the at least two semiconductor switches accordingly, a different one from a voltage of the charging device Charging voltage for charging at least one of the sub-strands is generated.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and from the drawings. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the combination indicated in each case, but also in other combinations or on their own, without the scope of Leaving invention.

• 1 eine erste Ausführungsform einer Speichereinrichtung, bei welcher der Spannungswandler als Abwärtswandler ausgeführt ist; und
• 2 einen Schaltplan einer zweiten Ausführungsform der Speichereinrichtung, bei dem der Spannungswandler aus Aufwärtswandler ausgeführt ist.

Show:

• 1 a first embodiment of a memory device in which the voltage converter is designed as a step-down converter; and
• 2nd a circuit diagram of a second embodiment of the memory device, in which the voltage converter is implemented by step-up converter.

The 1 and 2nd each show different exemplary embodiments of a memory device 1 for an electrically operated motor vehicle. The electrically operated motor vehicle is in particular a passenger car or a truck. The electrically operated motor vehicle has an electric drive, for example a synchronous machine or an asynchronous machine. The storage device is designed to supply such an electrical drive of an electrically operable motor vehicle with electrical energy. The electrically operated motor vehicle can be designed, for example, as an electric vehicle or as a hybrid vehicle.

In the 1 and 2nd there is a charging port on the left side 8th shown. In the figures is the charging connection 8th each with the equivalent circuit diagram of a real voltage source comprising an ideal voltage source U_DC as well as an internal resistance R_DC represents. Using the charging port 8th is the storage device 1 can be connected to a charging device and can be supplied with electrical energy provided by the charging device. The charging device can be a charging station, a charging station or an inductive charging device. As a result, the connection can be either conductive or inductive. The ideal voltage source U_DC represents a voltage that the storage device receives from the charging device. In other words, a voltage provided by the charging device is through the ideal voltage source U_DC represents. In addition, the storage devices 1 Both versions have in common that the respective loader 7 are arranged both in the plus line and in the minus line. In other words, both poles of the charging port 8th via a respective charging contactor 7 with the rest of the storage device 1 electrically connected. In addition, the storage device is in both exemplary embodiments 1 an input capacitor C in parallel to both poles of the charging connection 8th or arranged parallel to the loading device.

The storage device 1 has an electrical energy storage 2nd on which in the present case two partial strings connected in series 3rd , 4th having. Other embodiments can split the electrical energy store 2nd in more than two branches 3rd , 4th provide. The two branches 3rd , 4th are each from a respective voltage source U_B1 , U_B2 as well as a respective internal resistance R_B1 , R_B2 represents. In the partial strands 3rd , 4th it is essentially a respective partial store of the electrical energy store 2nd . The partial strands 3rd , 4th can each comprise one or more battery cells or battery cells. The two branches 3rd , 4th are related to the charging device or the charging connection 8th connected in series. Between the partial strands 3rd , 4th is an intermediate tap 9 arranged. The intermediate tap 9 is between the minus pole of the branch 3rd and the positive pole of the partial strand 4th arranged.

Parallel to the partial strands 3rd , 4th is a respective semiconductor switch S2 , S3 switched. The semiconductor switch S2 is between the plus pole of the charging connector 8th and the intermediate tap 9 arranged. The semiconductor switch S3 is between the intermediate tap 9 and the minus pole of the charging connection 3rd arranged. By closing the respective semiconductor switch S2 , S3 can the partial strand connected in parallel 3rd , 4th be bridged. This can be done by closing the semiconductor switch S2 the partial strand 3rd be bridged. By closing the semiconductor switch S3 can the partial strand 4th be bridged. A short circuit in the event of bridging one of the sub-strands 3rd , 4th to prevent is between the semiconductor switch S2 , S3 and the partial strand connected in parallel 3rd , 4th a respective diode D1 , D2 arranged. The diodes D1 , D2 are for a charging current from the charging device or from the charging connection 8th arranged in the flow direction. The diode D1 is with respect to a voltage of the first partial strand 3rd switched in the reverse direction. The diode D2 is with respect to a tension of the partial strand 4th switched in the reverse direction.

At the storage facility 1 according to 1 is the voltage converter 6 as a step-down converter, also referred to as a "step-down converter" or "buck converter". The following are different. The semiconductor switch is in a first switching state S2 opened and the semiconductor switch S3 closed. In this case, the second strand is 4th bridged. As a result, a charging voltage or the voltage at the charging connection drops 8th only on the first branch 3rd from. In other words, only the first partial strand is in the first switching state 3rd supplied with electrical energy. In the first switching state, therefore, only the first partial strand can 3rd to be charged. In a second switching state, the semiconductor switch is reversed S2 closed and the semiconductor switch S3 open. The first sub-strand is thus in the second switching state 3rd bridged and the second strand 4th can be supplied with electrical energy or charged. The semiconductor switches are in a third switching state S2 and S3 open. In this third switching state, both sub-strands can 3rd , 4th be charged at the same time. The semiconductor switch S1 is for lowering the tension U_DC at the charging port 8th intended.

In the first, the second and the third switching state, there can be a change in the voltage U_DC at the charging port 8th be provided or not. In other words, it can be provided that the partial strands to be loaded in each case in accordance with the switching state 3rd , 4th directly with the tension U_DC at the charging port 8th to load or lower it. In the latter case, the semiconductor switch S1 be opened and closed alternately. This results in a reduction in the tension on the part of the partial strands 3rd , 4th in other words, the voltage of the charging device, which is at the charging connection 8th is present, a different, in the present case lower, voltage is generated. For example, the voltage U_DC less than the added voltage ( U_B1 + U_B2 ) of both branches 3rd , 4th but higher than the single voltage of one of the two strands 3rd , 4th or both sub-strands 3rd , 4th . In this case, the storage device 1 be switched to the first or the second switching state. By clocking the circuit of the semiconductor switch S1 becomes the voltage on the partial strand active in the respective switching state 3rd , 4th reduced to an appropriate value.
In another example is the tension U_DC greater than the added voltage ( U_B1 + U_B2 ) of both branches 3rd , 4th . In this example, the storage device 1 be switched to the third switching state. This allows both partial strands 3rd , 4th be loaded at the same time. The voltage U_DC is thereby by the voltage converter 6 or by clocking the operation of the semiconductor switch S1 to the added voltage ( U_B1 + U_B2 ) of both branches 3rd , 4th lowered.

A change between the switching states takes place in particular without current. For example, by lowering the voltage level through the voltage converter 6 the charging current is gradually reduced to enable current-free switching. When switching it is important to ensure that first the semiconductor switch S 2 and S3 assume the open state for a rapid current rise in the choke L to avoid. This allows the choke to be dimensioned L be kept small.

Corresponds to the tension U_DC either the added voltage ( U_B1 + U_B2 ) of both branches 3rd , 4th or single voltage ( U_B1 , U_B2 ) at least one of the two sub-strands 3rd , 4th , is the lowering of the tension U_DC not necessary. In such cases, the semiconductor switch S1 be permanently closed so that the voltage is not adjusted. The partial strand or strands 3rd , 4th can be loaded directly in the first, second or third switching state. For loading one of the two branches 3rd , 4th becomes the tension U_DC on the charging device, in particular on the individual voltage ( U_B1 , U_B2 ) of the corresponding partial strand 3rd , 4th commanded. For loading both partial strands 3rd , 4th becomes the tension U_DC on the charging device in particular on the added voltage (U_B1 + U_B2) of both sub-strands 3rd , 4th commanded. When changing between the loading of the individual partial strands 3rd , 4th are both semiconductor switches S2 and S3 open. Then the charging device can first be switched to the single voltage ( U_B1 , U_B2 ) of the other partial strand to be loaded 3rd , 4th to be commanded. Then, by closing the corresponding semiconductor switch S2 , S3 the loading process of the other branch 3rd , 4th be started.

At the storage facility 1 according to 2nd is the voltage converter 6 as a step-up converter, also known as a “step-up converter” or “boost converter”. In this embodiment, too, the first partial strand 3rd , the second strand 4th or both strands 3rd , 4th be charged simultaneously when the voltage U_DC either the added voltage (U_B1 + U_B2) of both branches 3rd , 4th or single voltage ( U_B1 , U_B2 ) at least one of the two sub-strands 3rd , 4th corresponds.

Analogous to the first embodiment, one of the sub-strands can be bridged 3rd , 4th by closing the corresponding semiconductor switch S2 or S3 respectively.

The control in this case is carried out analogously to the embodiment of 1 .

1. a) U_DC < U_B1 + U_B2: Der Halbleiterschalter S2 wird taktend betrieben, der Halbleiterschalter S3 ist dauerhaft geöffnet. Über den Duty-Cycle des Halbleiterschalters S2 kann der Strom über die Drossel L geregelt werden. Während S2 geschlossen ist, wird der zweite Teilstrang 4 geladen. Dabei steigt der Strom in der Drossel L an. Anschließend wird S2 geöffnet. Durch den Strom in der Drossel L werden nun beide Teilstränge 3, 4 geladen, wobei sich der Strom wieder reduziert. Insgesamt wird das Laden des zweiten Teilstrangs 4 verstärkt.
2. b) U_DC < U_B1 + U_B2: Der Halbleiterschalter S3 wird taktend betrieben, der Halbleiterschalter S2 ist dauerhaft geöffnet. Über den Duty-Cycle des Halbleiterschalters S3 kann der Strom über die Drossel L geregelt werden. Während S3 geschlossen ist, wird der erste Teilstrang 3 geladen. Dabei steigt der Strom in der Drossel L an. Anschließend wird S3 geöffnet. Durch den Strom in der Drossel L werden nun beide Teilstränge 3, 4 geladen, wobei sich der Strom wieder reduziert. Insgesamt wird das Laden des ersten Teilstrangs 3 verstärkt.
3. c) U_DC < U_B1: Der Halbleiterschalter S2 wird taktend betrieben. Der Halbleiterschalter S3 ist dauerhaft geschlossen, der zweite Teilstrang 4 ist dadurch gebrückt. Über den Duty-Cycle des Halbleiterschalters S2 kann der Strom über die Drossel L geregelt werden. Während S2 geschlossen ist, wird nicht geladen. Dabei steigt der Strom in der Drossel L an. Anschließend wird S2 geöffnet. Durch den Strom in der Drossel L wird nun der erste Teilstrang 3 geladen, wobei sich der Strom wieder reduziert. Insgesamt wird nur der erste Teilstrang 3 geladen.
4. d) U_DC < U_B2: Der Halbleiterschalter S3 wird taktend betrieben. Der Halbleiterschalter S2 ist dauerhaft geschlossen, der erste Teilstrang 3 ist dadurch gebrückt. Über den Duty-Cycle des Halbleiterschalters S3 kann der Strom über die Drossel L geregelt werden. Während S3 geschlossen ist, wird nicht geladen. Dabei steigt der Strom in der Drossel L an. Anschließend wird S3 geöffnet. Durch den Strom in der Drossel L wird nun der zweite Teilstrang 4 geladen, wobei sich der Strom wieder reduziert. Insgesamt wird nur der zweite Teilstrang 4 geladen.

Is the tension U_DC at the charging port 8th less than the added voltage (U_B1 + U_B2) of both branches 3rd , 4th or the single voltage ( U_B1 , U_B2 ) at least one of the two sub-strands 3rd , 4th , so the voltage through the voltage converter 6 increase. The advantage of this embodiment is that the semiconductor switch S2 and S3 a double function for switching between the sub-strands 3rd , 4th as well as adjusting the tension U_DC have. In this embodiment there are essentially 4th different operating modes with voltage adjustment:

1. a) U_DC <U_B1 + U_B2: The semiconductor switch S2 is operated clocked, the semiconductor switch S3 is permanently open. About the duty cycle of the semiconductor switch S2 can the current through the choke L be managed. While S2 is closed, the second branch 4th loaded. The current in the choke increases L on. Then will S2 open. Through the current in the choke L are now both sub-strands 3rd , 4th charged, whereby the current is reduced again. Overall, the loading of the second strand 4th reinforced.
2. b) U_DC <U_B1 + U_B2: The semiconductor switch S3 is operated clocked, the semiconductor switch S2 is permanently open. About the duty cycle of the semiconductor switch S3 can the current through the choke L be managed. While S3 is closed, the first branch 3rd loaded. The current in the choke increases L on. Then will S3 open. Through the current in the choke L are now both sub-strands 3rd , 4th charged, whereby the current is reduced again. Overall, the loading of the first strand 3rd reinforced.
3. c) U_DC <U_B1: The semiconductor switch S2 is operated clocked. The semiconductor switch S3 is permanently closed, the second branch 4th is bridged by it. About the duty cycle of the semiconductor switch S2 can the current through the choke L be managed. While S2 is closed, is not loaded. The current in the choke increases L on. Then will S2 open. Through the current in the choke L now becomes the first branch 3rd charged, whereby the current is reduced again. Overall, only the first sub-strand 3rd loaded.
4. d) U_DC <U_B2: The semiconductor switch S3 is operated clocked. The semiconductor switch S2 is permanently closed, the first branch 3rd is bridged by it. About the duty cycle of the semiconductor switch S3 can the current through the choke L be managed. While S3 is closed, is not loaded. The current in the choke increases L on. Then will S3 open. Through the current in the choke L now becomes the second branch 4th charged, whereby the current is reduced again. Overall, only the second strand 4th loaded.

Through the two presented embodiments of the storage device 1 it is possible to charge vehicles at charging devices, in particular charging stations, even if the added voltage ( U_B1 + U_B2 ) of both branches 3rd , 4th is higher than the maximum output voltage of the charging device. For this purpose, the switching device 5 both the functionality of a pure switching network and a voltage converter 6 on.

By switching on the voltage of the intermediate tap 9 can dimension the components of the voltage converter 6 be kept small. The refurbishment of the throttle L is determined by the transformation ratio of the voltage converter 6 certainly. It can be small thanks to the small voltage differences due to the switching network be kept and thus be inexpensive and take up little space. The components, especially the semiconductor switches S2 and or S3 , can be designed for a low clock frequency. This enables inexpensive components with low transmission losses. The same applies to the diodes D1 , D2 .

In operation with sole use of the switching network, components can only be used for the voltage converter 6 are agile, to be dispensed with. A further reduced installation space is therefore necessary. Switch-over batteries via contactors to implement a charging function with low DC charging voltages can be avoided. In addition, challenges in dealing with switchover batteries (equalizing currents, no switchover / connection possible if the voltage differences in partial batteries are too great) can be avoided.

The charging power can be increased by increasing the DC charging voltage. Limiting the charging power can be counteracted by the current carrying capacity of the charging plug, especially when the charging voltages are low. Switching between the sub-strands 3rd , 4th can be done practically without interruption, since semiconductor switches and no contactors are provided and no compensation currents occur.

The partial voltages U_B1 , U_B2 the partial strands 3rd , 4th can be different. In this way, an additional degree of freedom is made possible compared to simple switch batteries. In addition, the semiconductor components of the switching device 5 only on the voltage level of the individual sub-strands 3rd , 4th be designed. For example, at a respective partial voltage of the partial strands 3rd , 4th low-cost 650 V components of 400 V each, which also have lower transmission and switching losses.

For example, the DC charging capacity of an 800 V vehicle can be achieved with a 500 V charging station or a 750 V charging station. In this case, a charging power can be achieved which is identical to the charging power with a switching battery (using only the switching network) or higher (using the voltage converter 6 ).

Reference list

1

Storage device

2nd

electrical energy storage

3rd

Partial strand

4th

Partial strand

5

Switching device

6

Voltage converter

7

Charging contactor

8th

Charging port

9

Intermediate tap

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102018000490 A1 [0003]
• DE 102018000491 A1 [0004]

Claims (5)

Storage device (1) for an electrically operated motor vehicle, with - at least one electrical energy store (2), which has at least two partial strings (3, 4) connected in series for storing electrical energy, - at least one charging connection (8), via which the partial strings (3, 4) connected in series can be connected to a charging device and can be supplied with electrical energy provided by the charging device and can thus be charged, and - a switching device (5), the switching device (5) being connected in series with the partial strands (3, 4 4) and at least one intermediate tap (9) between the sub-strands (3, 4) is electrically connected, wherein - the switching device (5) has at least two semiconductor switches (S1, S2, S3) for distributing the electrical energy from the charging device to the sub-strands ( 3, 4), characterized in that - the switching device (5) additionally has a voltage converter (6), which d is designed to generate a different charging voltage for charging at least one of the sub-strands (3, 4) from a voltage of the charging device by appropriately switching the at least two semiconductor switches (S1, S2, S3). Storage device (1) after Claim 1 , characterized in that the switching device (5) additionally comprises an input capacitor (C) and / or a choke inductor (L) as part of the voltage converter (6). Storage device (1) after Claim 1 or 2nd , characterized in that each of the at least two semiconductor switches (S1, S2, S3) is connected in parallel to exactly one of the respective partial strands (3, 4), a respective interposed diode (D1, D2) being formed, a short circuit of the partial strands ( 3, 4) when closing the respective parallel connected semiconductor switch (S1, S2). Memory device (1) according to one of the preceding claims, characterized in that the voltage converter (6) is designed as a step-down converter, in particular as a buck converter, or as a step-up converter, in particular as a boost converter. Method for operating a storage device (1) which has at least one electrical energy store (2) with at least two partial strings (3, 4) connected in series for storing electrical energy, for an electrically operated motor vehicle, comprising the steps: - connecting the electrical Energy store (2) via a charging connection (8) of the storage device (1) with a charging device and supplying the electrical energy storage device (2) with electrical energy provided by the charging device, - splitting the electrical energy from the charging device into the sub-strands (3, 4) by means of a switching device (5), which comprises at least two semiconductor switches (S1, S2, S3), the switching device (5) with the series connection of the partial strands (3, 4) and at least one intermediate tap (9) between the partial strands (3, 4 ) is electrically connected, characterized in that - the switching device (5) additionally as a voltage switch dler (6) and by switching the at least two semiconductor switches (S1, S2, S3) from a voltage of the charging device, a different charging voltage for charging at least one of the sub-strands (3, 4) is generated.

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