DE102021212316A1 - Arrangement for impedance analysis of a battery pack, battery system, method for impedance analysis of a battery pack - Google Patents

Abstract

The invention relates to an arrangement (60) for impedance analysis of a battery pack (5), which has an internal voltage source (Vi), an internal resistance (Ri), an internal inductance (Li), a positive pole (22) and a negative pole (21 ), wherein the arrangement (60) comprises a capacitor (CA) which has a positive terminal (CA+) and a negative terminal (CA-), a first switching element (61) and a second switching element (62), wherein a first Connection of the first switching element (61) is electrically connected to a node (25) which can be electrically connected to one of the poles (21, 22) of the battery pack (5), a second connection of the first switching element (61) is electrically connected to one of the terminals (CA+, CA-) of the capacitor (CA), a first terminal of the second switching element (62) is electrically connected to the other of the terminals (CA+, CA-) of the capacitor (CA) and electrically to the other of the poles ( 21, 22) of the battery pack (5) can be connected, and a second terminal of the second switching element (62) is electrically connected to the node (25). According to the invention, the arrangement (60) is set up such that different modulated currents (I) are generated by changing the pulse duty factor of the first and second switching elements (61, 62).

Description

The invention relates to an arrangement for impedance analysis of a battery pack which has an internal voltage source, an internal inductance, a positive pole and a negative pole, the arrangement having a capacitor which has a positive terminal and a negative terminal, a first switching element and a second Switching element includes, wherein a first terminal of the first switching element is electrically connected to a node that is electrically connected to one of the poles of the battery pack, a second terminal of the first switching element is electrically connected to one of the terminals of the capacitor, a first terminal of the second switching element is electrically connected to the other of the terminals of the capacitor and is electrically connectable to the other of the poles of the battery pack, and a second terminal of the second switching element is electrically connected to the node.
The invention also relates to a method for analyzing the impedance of a battery pack.

State of the art

It is becoming apparent that more and more electrically powered vehicles will be used in the future. Such electrically powered vehicles, such as hybrid vehicles and electric vehicles, each include a battery system, such as a 48V battery system, for powering or traction of the vehicle.

In order to determine the state of health (state of heat, SOH), the state of charge (state of charge, SOC) or the internal resistance of the battery system, an impedance analysis of the battery system is usually carried out. There are many ways to record impedance analysis in the laboratory. According to the current state of the art, however, this is always done with an additional device, since a current or voltage source/sink is also required.

The document US 2014/0268959 A1 describes a bi-directional power converter that can be used in an electric vehicle to perform AC-DC power conversion to charge the battery of the electric vehicle and DC-AC power conversion to output power to operate external electrical loads.

Disclosure of Invention

An arrangement for impedance analysis of a battery pack is proposed, which has an internal voltage source, an internal resistance, an internal inductance, a positive pole and a negative pole. The battery pack can include a battery cell or a number of battery cells that are connected to one another in parallel and/or in series. The battery cells are preferably designed as lithium-ion cells. The battery cells simulate electrical voltage sources with internal resistances. Electrical lines within the battery pack also have electrical resistance and inductance. The electrical voltage sources of the battery cells form the internal voltage source of the battery pack. The internal resistance of the battery cells and the resistance of the electrical lines form the internal resistance of the battery pack. The inductance of the electrical lines forms the internal inductance of the battery pack. Optionally, the battery module can also have a coil with an additional inductance.

In this case, the arrangement comprises a capacitor which has a positive terminal and a negative terminal, a first switching element and a second switching element. The switching elements each have three connections, with a switching path being formed between a first connection and a second connection, which can be controlled by means of a third connection. The battery pack can be electrically connected to the capacitor and also separated from the capacitor by means of the first and the second switching element.

A first connection of the first switching element is electrically connected to a node that can be electrically connected to one of the poles of the battery pack, and a second connection of the first switching element is electrically connected to one of the terminals of the capacitor. A first terminal of the second switching element is electrically connected to the other of the terminals of the capacitor and electrically connectable to the other of the poles of the battery pack, and a second terminal of the second switching element is electrically connected to the node.

For example, the node that is electrically connected to the first terminal of the first switching element may be connected to the positive terminal of the battery pack, and the second terminal of the first switching element is connected to the positive terminal of the capacitor. The first connection of the second switching element is then connected to the negative pole of the battery pack and to the negative terminal of the capacitor. The negative pole of the battery pack is electrically connected to the negative terminal of the capacitor.

The interconnection of the switching elements of the arrangement enables several switching states of the Battery packs when the arrangement is electrically connected to the battery pack, ie the node is electrically connected to one of the poles of the battery pack, while the first terminal of the second switching element is electrically connected to the other pole of the battery pack. For example, in a first switching state, when the first switching element is open and the second switching element is closed, a current can flow through the internal inductance of the battery pack, but not to the capacitor. In a second switching state, when the first switching element is closed and the second switching element is open, a current can flow through the internal inductance of the battery pack and through the capacitor. In a third switching state, when the first switching element is open and the second switching element is open, no current can flow through the battery.

According to the invention, the arrangement is set up such that different modulated currents are generated by changing the pulse duty factor of the first and second switching elements. The switching frequency of the switching elements is usually at least 100 kHz and can reach into the megahertz range. This allows low-frequency signal forms, such as a sine wave, to be modulated. This sinusoidal signal is swept through several frequencies to record the impedances. The frequency range here is usually in the range from 0.1 Hz to 50 kHz. The switching frequency must always be higher than the modulated frequency. The resulting current flow and the cell/battery voltage are measured and thus the impedance and phase angle for each frequency are determined in order to record an impedance spectrum of the battery pack. Preferably, amplitude modulation such as PWM modulation is used in generating various modulated currents. This allows different frequencies or amplitudes to be run through in order to record the impedance spectrum. A sinusoidal signal is preferably modulated. When recording the impedance spectrum, current, voltage and temperature are measured and monitored.

If the arrangement according to the invention is designed as a separate device for impedance analysis, the battery pack is electrically connected to the arrangement in order to carry out the impedance analysis. The capacitor should then be pre-charged in order to avoid high inrush currents and thus protect the components. With smaller capacitor capacities, this may not be necessary. After charging the capacitor, the voltage of the capacitor is at the same level as that of the battery pack. Different modulated currents are then generated by changing the duty cycles of the first and second switching elements. The arrangement can be controlled in such a way that during a first phase the first switching element is opened and the second switching element is closed, during a second phase the first switching element is closed and the second switching element is open and during a third phase the first switching element is closed and the second Switching element is open. The first phase, the second phase and the third phase are repeated cyclically. After that, an impedance spectrum is recorded based on the different modulated currents.

However, it is also conceivable that the arrangement according to the invention for the impedance analysis of a battery pack is permanently installed in a battery system. In this case, the capacitor can always be electrically connected to the battery pack in normal operation of the battery pack or battery system, so that the voltage of the capacitor is at the same level as that of the battery pack. In this case, the impedance analysis can advantageously be carried out immediately following a driving cycle or charging cycle.

The first and second switching elements are preferably in the form of semiconductor switches. For example, the first switching element and the second switching element can be in the form of field effect transistors and each have a SOURCE connection, a DRAIN connection and a GATE connection. The switching elements are interconnected in such a way that the first connection is the SOURCE connection, the second connection is the DRAIN connection and the third connection is the GATE connection. For example, the switching elements are MOSFETs, in particular n-channel MOSFETs of the enhancement type.

The arrangement according to the invention preferably also includes a precharging circuit, a first connection of the precharging circuit being electrically connected to the node or to the first connection of the first switching element and a second connection of the precharging circuit being electrically connectable to one of the poles of the battery pack. In this case, the other pole of the battery pack can be electrically connected to the first connection of the second switching element. With the pre-charge circuit, a capacitor with a larger capacity can be selected. The pre-charging circuit can be in the form of a MOSFET. The MOSFET is used in linear mode, which switches on after the capacitor has been precharged. Linear operation means that the MOSFET is operated in the saturation range. This MOSFET can fail if the second switching element can also be used as a redundant switch to prevent a permanent short circuit of the battery pack or the battery cells in the event of a fault. The pre-charging circuit can also consist of a switchable resistor that reduces the current flow in the capacitor.

The arrangement according to the invention preferably also comprises a third switching element. In this case, a first connection of the third switching element is electrically connected to the node and a second connection of the third switching element can be electrically connected to one of the poles of the battery pack. In this case, the other pole of the battery pack can be electrically connected to the first connection of the second switching element. This third switching element can, depending on the component's own switching, also take over the pre-charging.

Preferably, the third switching element is also designed as a semiconductor switch, such as a field effect transistor.

The arrangement according to the invention preferably also includes an additional inductance. In this case, a first connection of the additional inductance is electrically connected to the node or, if present, electrically connected to the second connection of the precharging circuit and/or the second connection of the third switch. A second connection of the additional inductance can be electrically connected to one of the poles of the battery pack. In this case, the other pole of the battery pack can be electrically connected to the first connection of the second switching element.

A battery system is also proposed. The battery system proposed according to the invention comprises a battery pack and an arrangement according to the invention.

A further aspect of the invention is the provision of a method for impedance analysis of a battery pack using the arrangement according to the invention. Accordingly, features described in the context of the arrangement and the battery system apply to the method and vice versa, features described in the context of the method apply to the arrangement and the battery system.

• - Verbinden des Knotenpunkts elektrisch mit einem der Pole des Batteriepacks;
• - Verbinden des ersten Anschlusses des zweiten Schaltelements elektrisch mit dem anderen der Pole des Batteriepacks;
• - Erzeugen verschiedener modulierter Ströme durch Veränderung der Tastverhältnisse des ersten und zweiten Schaltelements, wobei die Anordnung derart angesteuert wird, dass während einer ersten Phase das erste Schaltelement geöffnet und das zweite Schaltelement geschlossen ist, während einer zweiten Phase das erste Schaltelement geschlossen und das zweite

The method proposed according to the invention comprises the following steps:

• - electrically connecting the node to one of the poles of the battery pack;
• - electrically connecting the first terminal of the second switching element to the other of the poles of the battery pack;
• - Generating different modulated currents by changing the duty cycle of the first and second switching element, the arrangement being controlled in such a way that during a first phase the first switching element is opened and the second switching element is closed, during a second phase the first switching element is closed and the second

• - Aufzeichnen eines Impedanzspektrum basierend auf den verschiedenen modulierten Strömen.

Switching element is opened and during a third phase the first switching element is closed and the second switching element is opened, and wherein the arrangement is controlled in such a way that the first phase, the second phase and the third phase are cyclically repeated;

• - Recording an impedance spectrum based on the different modulated currents.

During the process, an LC resonant circuit, which is also referred to as a resonant circuit, is formed by the battery pack, the internal inductance and, if present, the additional inductance and the capacitor.

After the arrangement according to the invention has been connected to the battery pack, the capacitor should be precharged in order to avoid high inrush currents and thus to protect the components. With smaller capacitor capacities, this may not be necessary.

The arrangement is preferably controlled in such a way that the first switching element is open and the second switching element is open during a first intermediate phase between the first phase and the second phase. It is also conceivable that the first switching element is open and the second switching element is open during a second intermediate phase between the third phase and the first phase. With the first and the second intermediate phase, high losses caused by the closing and opening of the switching elements can be avoided.

The invention also relates to a device for impedance analysis of a battery pack, which includes the arrangement according to the invention and/or which is set up to carry out the method according to the invention. The device according to the invention can be used as a separate device for carrying out an impedance analysis of any battery pack or can be attached to the battery pack.

Furthermore, a vehicle is proposed that includes the arrangement according to the invention and/or the battery system according to the invention and/or which is set up to carry out the method according to the invention.

Advantages of the Invention

The present invention enables impedance analysis within a battery system. The arrangement according to the invention can be installed within the battery system, in particular close to the battery pack. As a result, the switching elements can advantageously be designed for smaller currents.

With the arrangement according to the invention, the impedance analysis can be carried out after a driving cycle or charging cycle.

The parts of the battery system that are already present and/or the electrical consumers connected to them can advantageously be used, thereby saving costs.

character list

Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

• 1 eine schematische Darstellung eines Batteriesystems mit einer erfindungsgemäßen Anordnung gemäß einer ersten Ausführungsform,
• 2 eine schematische Darstellung eines Batteriesystems mit einer erfindungsgemäßen Anordnung gemäß einer zweiten Ausführungsform,
• 3 eine schematische Darstellung eines Batteriesystems mit einer erfindungsgemäßen Anordnung gemäß einer dritten Ausführungsform,
• 4 eine schematische Darstellung eines Batteriesystems mit einer erfindungsgemäßen Anordnung gemäß einer vierten Ausführungsform,
• 5 eine schematische Darstellung eines erfindungsgemäßen Batteriesystems,
• 6 eine schematische Darstellung des Batteriesystems während einer ersten Phase des erfindungsgemäßen Verfahrens,
• 7 eine schematische Darstellung des Batteriesystems während einer zweiten Phase des erfindungsgemäßen Verfahrens und
• 8 eine schematische Darstellung des Batteriesystems während einer dritten Phase des erfindungsgemäßen Verfahrens.

Show it:

• 1 a schematic representation of a battery system with an arrangement according to the invention according to a first embodiment,
• 2 a schematic representation of a battery system with an arrangement according to the invention according to a second embodiment,
• 3 a schematic representation of a battery system with an arrangement according to the invention according to a third embodiment,
• 4 a schematic representation of a battery system with an arrangement according to the invention according to a fourth embodiment,
• 5 a schematic representation of a battery system according to the invention,
• 6 a schematic representation of the battery system during a first phase of the method according to the invention,
• 7 a schematic representation of the battery system during a second phase of the method according to the invention and
• 8th a schematic representation of the battery system during a third phase of the method according to the invention.

Embodiments of the invention

In the following description of the embodiments of the invention, the same or similar elements are denoted by the same reference symbols, with a repeated description of these elements being dispensed with in individual cases. The figures represent the subject matter of the invention only schematically.

1 shows a schematic representation of a battery system 10 with an arrangement 60 according to the invention according to a first embodiment. The battery system 10 comprises a battery pack 5, a positive terminal 12, a negative terminal 11, a circuit breaker 14 and an inventive arrangement 60 for impedance analysis of the battery pack 5.

The battery pack 5 comprises a plurality of battery cells, not shown here, which can be connected to one another both in series and in parallel within the battery pack 5 . Each of the battery cells simulates an electrical voltage source with an internal resistance (not shown). The electrical voltage sources of the battery cells form an internal voltage source Vi. The internal resistances of the battery cells and an electrical resistance of electrical lines form an internal resistance Ri, inductances of the electrical lines and battery cells form an internal inductance Li, which is connected in series with the internal resistance Ri. Optionally, a coil with an additional inductance can also be provided. In this case, the inductances of the electrical lines and the battery cells together with the inductance of the coil form the internal inductance Li.

The battery pack 5 thus has the internal voltage source Vi and the internal inductance Li. The battery pack 5 also has a positive pole 22 and a negative pole 21 . When idling, a voltage supplied by the internal voltage source Vi is present between the positive pole 22 and the negative pole 21 . Present in 1 the positive terminal 12 can be electrically connected to the positive pole 22 via the isolating switch 14 . The negative terminal 11 is firmly electrically connected to the negative pole 21 . The circuit breaker 14 can include a main pre-charging circuit.

The arrangement 60 according to the invention includes a first switching element 61, a second switching element 62, a pre-charging circuit 63, an additional inductance Lz and a capacitor CA, which includes a positive terminal CA+ and a negative terminal CA-. The switching elements 61, 62 each have three terminals, with between a first terminal and a second connection a switching path is formed, which can be controlled by means of a third connection.

In the present case, the first switching element 61 and the second switching element 62 are embodied as field effect transistors. The switching elements 61, 62 each have a SOURCE connection, a DRAIN connection and a GATE connection. The switching elements 61, 62 are interconnected in such a way that the first connection is the SOURCE connection, the second connection is the DRAIN connection and the third connection is the GATE connection.

In the present case, the switching elements 61, 62 are n-channel MOSFETs of the enhancement type. The switching elements 61, 62 each have a switching path and an inverse diode connected in parallel with the switching path. The inverse diode, which is also referred to as the body diode, is created in every MOSFET due to its internal structure and is not an explicit component.

The first connection of the first switching element 61 is connected to a node 25 . The second terminal of the first switching element 61 is connected to the positive terminal CA+ of the capacitor CA. The first terminal of the second switching element 62 is connected to the negative pole 21 of the battery pack 5 and to the negative terminal CA- of the capacitor CA. The second connection of the second switching element 62 is connected to the node 25 . The node 25 is connected to the positive pole 22 of the battery pack 5 via the series connection of the additional inductance Lz and the pre-charging circuit 63 . In this case, the pre-charging circuit 63 can be in the form of a MOSFET. The MOSFET is used in linear mode, which turns on after the capacitor CA has been precharged.

By means of the positive terminal 12 and the negative terminal 11, the battery system 10 can be connected to electrical consumers, such as an on-board network of a motor vehicle. However, the battery system 10 should be disconnected from electrical loads during the impedance analysis.

The arrangement 60 according to the invention can be installed within the battery system 10, in particular close to the battery pack 5. Advantageously, the switching elements 61, 62 can be designed for smaller currents. In this case, the capacitor CA can always be electrically connected to the battery pack 5 in normal operation of the battery pack 5 or battery system 10 so that the voltage of the capacitor CA is at the same level as that of the battery pack 5 . In this case, the impedance analysis can advantageously be carried out immediately following a driving cycle or charging cycle.

2 and 3 each show a schematic representation of a battery system 10 with an arrangement 60 according to the invention. The battery system 10 comprises a battery pack 5, a positive terminal 12, a negative terminal 11, a circuit breaker 14 and an arrangement 60 according to the invention for impedance analysis of the battery pack 5.

The representations of the battery system 10 of 2 and 3 differ from the representation of the battery system 10 of FIG 1 in that the arrangement 60 according to the invention also has a third switching element 64, which is present in 2 and 3 is formed as a MOSFET has.

The third switching element 64, together with the first switching element 61, assumes the task of the isolating switch 14, which in 1 was presented.

The capacitor CA is, for example, an intermediate circuit capacitor which is electrically connected to an on-board network of a motor vehicle. The battery pack 5 can have a further capacitor, which then forms the capacitor CA together with the intermediate circuit capacitor.

The pre-charging circuit 63 can be connected in parallel with the third switching element 64, see FIG 2 , or connected in parallel to the second and the third switching element 62, 64, see 3 , be.

The arrangement 60 according to the invention, which is 2 and 3 is shown may be partially part of the battery system 10 . For example, the switching elements 61, 62, 64 and the pre-charging circuit 63 can be components of the battery system 10, while the capacitor CA is an intermediate circuit capacitor of an electrical machine connected to the battery system 10 and is located outside of the battery system 10. The already existing parts of the battery system 10 and/or the electrical consumers connected to it can advantageously be used and the costs can be saved as a result.

4 shows a schematic representation of a battery system 10 with an arrangement 60 according to the invention according to a further embodiment. The arrangement 60 according to the invention is designed as a separate device. The battery system 10 includes a battery pack 5, a circuit breaker 14, a positive terminal 12 and a negative terminal 11. By means of the terminals 11, 12 and the isolating switch 14, the arrangement 60, which is designed as a separate device, can be electrically connected to the battery pack 5 and separated from the battery pack 5.

The arrangement 60 according to the invention includes, the same as 1 , a first switching element 61, a second switching element 62, a pre-charging circuit 63, an additional inductor Lz and a capacitor CA which comprises a positive terminal CA+ and a negative terminal CA-. The switching elements 61, 62 each have three connections, with a switching path being formed between a first connection and a second connection, which can be controlled by means of a third connection.

5 shows a schematic representation of a battery system 10. The battery system 10 comprises a battery pack 5, a capacitor CA and an inventive arrangement 60 for impedance analysis of the battery pack 5.

The battery pack 5 also includes a number of battery cells, not shown here, which can be connected to one another both in series and in parallel within the battery pack 5 . Each of the battery cells simulates an electrical voltage source with an internal resistance. The electrical voltage sources of the battery cells form an internal voltage source Vi. The internal resistances of the battery cells and an electrical resistance of electrical lines form an internal resistance Ri. Inductances of the electrical lines and battery cells form an internal inductance Li. Optionally, a coil with an additional inductance can also be provided. In this case, the inductances of the electrical lines and the battery cells together with the inductance of the coil form the internal inductance Li.

The arrangement 60 according to the invention has a first switching element 61 , a second switching element 62 and a pre-charging circuit 63 . The first and second switching elements 61, 62 are each designed as a MOSFET. Present in 3 For example, the pre-charge circuit 63 is also a MOSFET, which is used in linear operation and turns on after the capacitor CA has been pre-charged.

6 , 7 and 8th each show a battery system 10 according to the invention during a phase of the method according to the invention. To simplify the illustration, the first and second switching elements 61, 62 shown in 5 were shown as MOSFETs, and the precharge circuit 63 shown in 5 also represented as a MOSFET, in 6 , 7 and 8th each shown as a switch. During the method according to the invention, the node 25 is electrically connected to the positive pole 22 via the pre-charging circuit 63 designed as a MOSEFT. That is, the pre-charge circuit 63 formed as a MOSFET turns on after pre-charging the capacitor CA during the process. In 6 , 7 and 8th this is represented by a closed switch.

6 shows a schematic representation of the battery system 10 during a first phase of the method according to the invention. During the first phase, the first switching element 61 is open and the second switching element 62 is closed. A current I flows through the internal voltage source Vi, through the internal resistance Ri, through the internal inductance Li, through the pre-charging circuit 63 and through the second switching element 62 during the first phase.

After the end of the first phase, the second switching element 62 is opened and a first intermediate phase begins, in which the first switching element 61 and the second switching element 62 are open. After the end of the first intermediate phase, the first switching element 61 is closed and a second phase begins.

7 shows a schematic representation of the battery system 10 during the second phase of the method. During the second phase, the first switching element 61 is closed and the second switching element 62 is open. A current I flows through the internal voltage source Vi, the internal resistor Ri, the internal inductance Li, the pre-charging circuit 63, the first switching element 61 and the capacitor CA during the second phase.

8th shows a schematic representation of the battery system 10 during a third phase of the method. During the third phase, the first switching element 61 is closed and the second switching element 62 is open. A current I flows through the internal voltage source Vi, the internal resistor Ri, the internal inductor Li, the precharge circuit 63, the first switching element 61, and the capacitor CA during the third phase. However, the current I flows in the opposite direction during the third phase as during the second phase.

After the end of the third phase, the first switching element 61 is opened and a second intermediate phase begins, in which the first switching element 61 and the second switching element 62 are open. After the end of the second intermediate phase, the second switching element 62 is closed and another first phase begins.

The invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, within the range specified by the claims, a large number of modifications are possible, which are within the scope of expert action.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• US 2014/0268959 A1 [0004]

Claims (12)

Arrangement (60) for impedance analysis of a battery pack (5), which has an internal voltage source (Vi), an internal resistance (Ri), an internal inductance (Li), a positive pole (22) and a negative pole (21), wherein the arrangement (60) comprises a capacitor (CA) having a positive terminal (CA+) and a negative terminal (CA-), a first switching element (61) and a second switching element (62), a first terminal of the first switching element (61) is electrically connected to a node (25) which can be electrically connected to one of the poles (21, 22) of the battery pack (5), a second connection of the first switching element (61) is electrically connected to one of the terminals (CA+, CA -) of the capacitor (CA), a first terminal of the second switching element (62) is electrically connected to the other of the terminals (CA+, CA-) of the capacitor (CA) and electrically to the other of the poles (21, 22) of the battery pack (5) can be connected, and a second terminal of the second switching element (62) is electrically connected to the node (25), characterized in that the arrangement (60) is set up such that by changing the duty ratios of the first and second switching element (61, 62) different modulated currents (I) are generated. Arrangement (60) after claim 1 , characterized in that the first and second switching element (61, 62) are designed as semiconductor switches. Arrangement (60) after claim 1 or 2 , further comprising a pre-charging circuit (63), wherein a first terminal of the pre-charging circuit (63) is electrically connected to the node (25) or to the first terminal of the first switching element (61) and a second terminal of the pre-charging circuit (63) is electrically connected to a the poles (21, 22) can be connected. Arrangement (60) after claim 3 , characterized in that the pre-charging circuit (63) is designed as a MOSFET. Arrangement (60) according to one of Claims 1 until 4 , further comprising a third switching element (64), wherein a first terminal of the third switching element (64) is electrically connected to the node (25) and a second terminal of the third switching element (64) is electrically connected to one of the poles (21, 22) of Battery packs (5) can be connected. Arrangement (60) after claim 5 , characterized in that the third switching element (64) is designed as a semiconductor switch. Arrangement (60) according to one of Claims 1 until 6 , further comprising an additional inductor (Lz), wherein a first terminal of the additional inductor (Lz) is electrically connected to the node (25) or, if present, electrically connected to the second terminal of the pre-charging circuit (63) and / or the second terminal of the third switching element (64) and a second connection of the additional inductance (Lz) can be electrically connected to one of the poles (21, 22) of the battery pack (5). Battery system (10) comprising a battery pack (5) and an arrangement (60) according to one of Claims 1 until 7 . Method for impedance analysis of a battery pack (5) with an internal voltage source (Vi), an internal resistance (Ri), an internal inductance (Li), a positive pole (22) and a negative pole (21), using an arrangement (60 ) after one of the Claims 1 until 7 , comprising the following steps: - connecting the node (25) electrically to one of the poles (21, 22) of the battery pack (5); - Connecting the first terminal of the second switching element (62) electrically to the other of the poles (21, 22) of the battery pack (5); - charging of the capacitor (CA); - Generating different modulated currents (I) by changing the duty cycle of the first and second switching element (61, 62), the arrangement (60) being controlled in such a way that during a first phase the first switching element (61) is opened and the second switching element ( 62) is closed, during a second phase the first switching element (61) is closed and the second switching element (62) is open and during a third phase the first switching element (61) is closed and the second switching element (62) is open, and wherein the Arrangement (60) is controlled in such a way that the first phase, the second phase and the third phase are cyclically repeated; - Recording an impedance spectrum based on the different modulated currents (I). procedure after claim 9 , characterized in that the arrangement (60) is controlled in such a way that during a first intermediate phase between the first phase and the second phase the first switching element (61) is opened and the second switching element (62) is opened and/or during a second intermediate phase between the third phase and the first phase the first switching element (61) is open and the second switching element (62) is open. Device for impedance analysis of a battery pack (5) having an arrangement (60) according to one of Claims 1 until 7 includes and / or is set up, according to a method claim 9 or 10 to perform. Vehicle having an arrangement (60) according to one of Claims 1 until 7 and/or a battery system 10 according to claim 8 includes and / or is set up, according to a method claim 9 or 10 to perform.

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