Grid-connectable multilevel converter, multilevel converter system and charging system

Abstract

Proposed is a grid-connectable multilevel converter (112) configured for at least temporarily interfacing a three-phase electrical network (106) and / or for at least temporarily providing a direct current mode; a multilevel converter (112) includes: at least a first modular energy storage string having a plurality of energy sources and at least one power converter module, the at least one power converter module including at least two switching elements; at least two switching elements configured for selectively switching each of the plurality of energy sources to operate the at least first modular energy storage string in an alternating current mode in which the at least first modular energy storage string is connectable to a first phase of a three-phase power grid (106); and the at least two switching elements are configured to selectively switch each of the plurality of energy sources to operate the at least first modular energy storage string in a direct current mode.

Description

Technical Field

[0001] The present invention relates to a grid-connected multilevel converter, a multilevel converter system, and a charging system. Background Art

[0002] With the increasing integration of (renewable) energy and the growing demand for grid stability, the need for reliable and efficient energy storage solutions has increased significantly. Against this backdrop, the concept of an AC battery (also known as a battery-powered multilevel converter) operating on the grid has emerged as a promising technology. Such a system combines the benefits of an energy storage battery with the flexibility and functionality of a multilevel converter, enabling seamless integration and operation within an alternating current (AC) grid.

[0003] The battery-powered multilevel converter serves as a bridge between the grid and the energy storage battery, facilitating bidirectional power flow and ensuring optimal utilization of the stored energy. By leveraging a multilevel converter architecture composed of multiple power converter modules with varying voltage levels, the system achieves enhanced voltage quality, reduced harmonic distortion, and improved power flow control.

[0004] The core component of the system is the energy storage battery, which serves as a reliable and efficient power source. For example, the battery is designed to store excess energy during periods of low demand or high renewable energy generation and then release the stored energy during periods of peak demand or low energy availability. By operating within the AC grid, the battery-powered multilevel converter provides dynamic support to the grid, contributing to grid stability, load balancing, and frequency regulation.

[0005] Furthermore, in the field of electric vehicles (EVs) and their charging infrastructure, the demand for faster charging times and increased driving ranges continues to drive innovation. A fundamental component of the ECO system is the DC charger, which allows for efficient and rapid charging of the EV battery. To optimize the charging process, traditional battery boosters have been developed as a key technology to enhance the performance of the DC charger.

[0006] Traditional battery boosters for DC chargers are devices specifically designed to enhance the charging capacity of DC charging systems. They are used to overcome limitations associated with the distribution network, grid constraints, and the capacity of the charging station infrastructure. By integrating a battery booster into the charging system, the charging power can be significantly increased, thereby reducing the charging time and improving user convenience.

[0007] Traditional battery boosters operate by storing energy from the grid during periods of low demand or excess generation. This stored energy is then utilized to provide an additional power boost during high-demand periods or when rapid charging is required. By effectively managing the power flow and providing a temporary energy buffer, battery boosters enable DC chargers to operate at higher power levels without overloading the grid or compromising the stability of the power source.

[0008] This technology benefits EV owners not only by reducing charging times and increasing the availability of charging stations, but also by addressing challenges associated with the entire grid infrastructure. Traditional battery boosters for DC chargers play a crucial role in the transition to sustainable transportation by optimizing the charging process, improving the charging experience, and facilitating the widespread adoption of electric vehicles.

[0009] However, traditional battery boosters for DC chargers typically connect the battery to be charged directly to the DC link. This configuration results in harmful microcirculation, which leads to reduced battery life. Alternatively, the battery is connected via a DC / DC converter, which is typically configured as a cascaded DC / DC converter. However, the efficiency of this cascaded DC / DC converter is low and thus not preferred for the overall efficiency of the boost function provided. In addition, traditional DC charger topologies do not allow bidirectional power / energy flow. Summary of the Invention

[0010] In this context, the aim is to provide an improved multilevel converter, and / or a corresponding improved multilevel converter system. Furthermore, an object of the present invention is to provide an improved charging system.

[0011] This object is achieved by a grid-connected multilevel converter having the features of claim 1. Furthermore, this object is achieved by a multilevel converter system having the features of claim 12. Furthermore, this object is achieved by a charging system having the features of claim 13.

[0012] Advantageous embodiments of the present disclosure are the subject of the dependent claims. Any and all combinations of at least two features disclosed in the description, claims, and / or drawings fall within the scope of the present disclosure. Naturally, the explanations given in connection with the grid-connected multilevel converter equivalently apply to the multilevel converter system and / or charging system according to the present disclosure without redundantly mentioning them in their context. In particular, within the scope of common language practice, linguistically common paraphrases and / or similar substitutions of corresponding terms, especially the use of synonyms supported by generally recognized linguistic literature, are of course included in the current content of the present disclosure without having to explicitly mention each variation.

[0013] According to a first aspect, a grid-connected multilevel converter is configured to at least temporarily interface, in particular, with a three-phase power grid and / or to at least temporarily provide a DC mode. The multilevel converter includes at least a first modular energy storage string having a plurality of energy sources and at least one power converter module, the at least one power converter module including at least two switching elements. The at least two switching elements are configured to selectively switch each of the plurality of energy sources, preferably relative to each other, to operate at least the first modular energy storage string in an AC mode, in which at least the first modular energy storage string can be connected to a first phase of a three-phase power grid, in particular. Further, the at least two switching elements are configured to selectively switch each of the plurality of energy sources to operate at least the first modular energy storage string in a DC mode.

[0014] Thus, the present application relates to a grid-connected multilevel converter that is designed to interface with a three-phase power grid, in particular, and to provide a DC mode when needed. The multilevel converter includes a first modular energy storage string consisting of a plurality of energy sources and at least one power converter module. The power converter module includes a set of at least two switching elements. These switching elements are preferably strategically configured to selectively switch each of the energy sources, thereby allowing the first modular energy storage string to operate in an AC mode or in a DC mode, in which the first modular energy storage string can be connected to a first phase of a three-phase power grid, in particular. Thus, in the present context, a technical solution for the above object is provided. In particular, the grid-connected multilevel converter can operate on the power grid and can provide a power boost and / or charging function in the DC mode, preferably for a plurality of different and / or selectable voltage levels. Thereby, the grid-connected multilevel converter can be operated on the power grid in the AC mode and / or used for charging and / or discharging and / or boosting in the DC mode. Thus, the multilevel converter proposed herein preferably provides a direct DC link to an electrical energy storage device to be charged or for charge boosting. Thus, no additional power conversion, such as a DC / DC converter, is required. The multilevel converter proposed herein is preferably a single-star multilevel converter and / or a modular multilevel converter. Thus, in particular due to the at least two switching elements, the circuit of the plurality of energy sources can be reconfigured for different purposes, such as AC grid operation and / or DC charging boost, preferably providing for different voltage levels. AC grid operation can be to provide support services and / or energy trading functions and / or self-charging functions for the multilevel converter. The claimed grid-connected multilevel converter presents a novel and effective solution for integrating energy sources into an existing power grid while enabling flexible operating modes.

[0015] The claimed multilevel converter is preferably configured to operate on a three-phase electrical grid, in particular, and furthermore to operate in a DC mode, where the multilevel converter is preferably reconfigurable such that at least one phase can be disconnected from the three-phase electrical grid, in particular, to provide at least two direct current (DC) terminals. In other words, the grid-connected multilevel converter can be configured at least temporarily to interface with a three-phase electrical grid and / or to provide a DC output in a DC mode (also referred to hereinafter as the DC mode). In this DC mode, the grid-connected multilevel converter can preferably be configured to provide a power boost function and / or a charging function for the DC charging operation of an electrical DC load connectable to the at least two DC terminals of the grid-connected multilevel converter.

[0016] The electrical grid can be considered a single-phase or a multiphase electrical grid. Thus, without departing from the scope of the claims, the term "three-phase electrical grid" can be replaced by a single-phase or a multiphase electrical grid. Such a multiphase electrical grid can have at least two phases. Thus, the claimed three-phase electrical grid should not be construed as narrowing the scope of the claims.

[0017] It should be noted that multiple energy sources can preferably be connected in series at least temporarily. The multiple energy sources can be connected in series positive and / or in series negative at least temporarily. Furthermore, in particular depending on the setup of the power converter module, the multiple energy sources can be connected in parallel or bypassed at least temporarily. Such a setup of the power converter module can include at least three switches to provide a parallel connection. The connection options can depend on the topology of the power converter module and / or the number of switching elements. A topology with two switching elements can be configured for series positive and / or bypass connection. A topology with three switching elements can be configured for parallel connection, particularly preferably with unipolarity. A topology with four switching elements can be configured for series positive, series negative, and / or bypass connection. A topology with five or more switching elements can be configured for series positive, series negative, bypass, and / or parallel connection. The energy source can be any kind of energy source, such as a battery and / or a photovoltaic cell and / or a fuel cell and / or an electromechanical power converter and / or a capacitive energy source.

[0018] The "grid-connected multilevel converter" preferably refers to a device designed to facilitate the connection and / or interaction between an electrical grid and an energy storage system, preferably allowing bidirectional power flow and / or the exchange of electrical energy. The converter can preferably adapt to the voltage and / or frequency requirements of the electrical grid and preferably achieve seamless integration and / or operation.

[0019] "Three-phase power grid" preferably refers to a power distribution system consisting of three alternating current (AC) voltage sources, preferably generated and / or transmitted with a 120-degree phase separation from each other. Of course, the three-phase power grid can have fewer than three phases, such as one or two phases, or more than three phases. The three-phase power grid is a common configuration for large-scale power transmission and / or distribution, preferably providing efficient and balanced power delivery.

[0020] "DC mode" preferably refers to the operating mode in which the multilevel converter supplies and / or receives direct current (DC) power. In this mode, the energy sources within the multilevel converter are preferably configured to provide and / or receive a continuous current flow with a constant polarity.

[0021] "First modular energy storage string" preferably refers to a group of interconnected energy sources (or energy storage units) arranged in a modular manner. The multiple energy sources preferably together form the main energy storage / delivery component within the multilevel converter. The multiple energy sources are preferably designed to store and / or provide electrical energy as needed for use and power support.

[0022] "Energy source" preferably refers to the individual components or units that store and / or deliver electrical energy within the first modular energy storage string. These sources can include batteries, supercapacitors, or any other energy storage device capable of storing and delivering electricity.

[0023] "Power converter module" preferably refers to a module within the multilevel converter that facilitates the conversion and / or control of electrical power. It includes circuits, such as switching elements, to manipulate the flow of electrical energy and regulate voltage and current levels.

[0024] "Switching element" preferably refers to an electronic device used within the power converter module to control the flow of current, such as a transistor or thyristor. These elements can be selectively turned on or off to enable or interrupt the current path and facilitate the desired energy transfer or conversion.

[0025] "AC mode" preferably refers to the operating mode in which the multilevel converter operates in synchronization with the AC waveform of the power grid. The switching elements are preferably configured to selectively switch the energy sources, preferably allowing the multilevel converter to supply and / or receive AC power, which preferably matches the characteristics of the AC voltage and / or frequency of the power grid.

[0026] "Capable of connecting to the first phase of a three-phase power grid" preferably refers to the ability of the first modular energy storage string to be electrically connected to one of the three phases of a three-phase power grid. This connection preferably enables the multilevel converter to interface with the power grid, exchange power, and / or contribute to the operation of the power grid while maintaining synchronization with the voltage and / or phase of the power grid.

[0027] In an embodiment, at least two switching elements are configured to selectively switch each of a plurality of energy sources preferably at least temporarily relative to one another into a series positive and / or series negative and / or positive bypass state and / or negative bypass state and / or parallel connection in order to operate at least a first modular energy storage string in an AC mode. Alternatively or additionally, at least two switching elements are configured to selectively switch each of a plurality of energy sources at least temporarily into a series positive and / or series negative and / or positive bypass state and / or negative bypass state and / or parallel connection in order to operate at least a first modular energy storage string in a DC mode. Of course, at least one power converter module may have a switching configuration that includes more than two switches. "Series positive / negative" preferably means that the switching element allows the energy sources to be connected in a series positive configuration or a series negative configuration. Series positive preferably means connecting the positive terminal of one energy source (i.e., the first module) to the negative terminal of an adjacent energy source (i.e., the second module). Series negative preferably means connecting the negative terminal of one energy source (i.e., the first module) to the positive terminal of an adjacent energy source (i.e., the second module).

[0028] "Positive bypass / negative bypass" preferably means that the switching element enables a positive bypass state or a negative bypass state. Positive bypass preferably means using the positive current rail for bypassing an energy source (i.e., the energy source of the first module or the second module). Negative bypass preferably means using the negative current rail for bypassing an energy source (i.e., the energy source of the first module or the second module). It can apply to both current polarities. "Parallel operation" preferably means that the switching element facilitates the parallel connection of the energy sources (i.e., the first module and the second module). This preferably means that the positive terminals of the sources can be connected and the negative terminals can be connected, thereby allowing them to work together.

[0029] In another embodiment, the multilevel converter further comprises at least a second modular energy storage string and / or a third modular energy storage string, the second modular energy storage string and / or the third modular energy storage string being equivalently configured to at least the first modular energy storage string, wherein, in AC mode, the second modular energy storage string can be connected to a second phase of a three-phase grid, in particular, and / or wherein, in AC mode, the third modular energy storage string can be connected to a third phase of the three-phase grid; wherein, in DC mode, the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string are configured to provide a charging function for a DC charging operation and / or a power boosting function for a DC charging operation, separately or cumulatively. The "charging function" preferably means that the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string are configured to provide a charging function. The charging function preferably means a self-charging function. This preferably means that they are designed to receive electrical energy from an external source and store it within the energy storage module. This claim does not specify the specific nature of the charging operation or the electrical energy source. The "power boosting function" preferably means that the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string are also configured to provide a power boosting function. This preferably means that the energy storage string can increase the output current and / or power of a charger unit for charging an electrical load. The "DC charging operation" preferably means that the charging function and / or the power boosting function of the modular energy storage string are preferably respectively intended for a direct current (DC) charging operation. This preferably indicates that the provided multilevel converter is designed to facilitate the charging of a DC receiving device or system. The cumulative function preferably means that the above features, including the charging function and the power boosting function, can be utilized individually or in combination. The claim indicates that the first modular energy storage string, the second modular energy storage string, and the third modular energy storage string can perform these functions individually or together, allowing flexibility and adaptability in different charging scenarios and / or voltage levels for charging.

[0030] The second modular energy storage string preferably has a plurality of energy sources and at least one power converter module, the at least one power converter module preferably including at least two switching elements. The at least two switching elements are configured to selectively switch each of the plurality of energy sources, preferably relative to each other, to operate at least the second modular energy storage string in AC mode, in which at least the second modular energy storage string can be connected to a second phase of a three-phase grid, in particular. Additionally, the at least two switching elements are configured to selectively switch each of the plurality of energy sources to operate at least the second modular energy storage string in DC mode.

[0031] The third modular energy storage string preferably has a plurality of energy sources and at least one power converter module, which preferably includes at least two switching elements. The at least two switching elements are configured to selectively switch each of the plurality of energy sources, preferably relative to each other, to operate at least the third modular energy storage string in an AC mode, in which at least the third modular energy storage string can be connected to a third phase, in particular a three-phase power grid. In addition, the at least two switching elements are configured to selectively switch each of the plurality of energy sources to operate at least the third modular energy storage string in a DC mode.

[0032] In another embodiment, the first modular energy storage string is connected to or can be connected to the second modular energy storage string via at least a first string contactor. Alternatively or additionally, the second modular energy storage string is connected to or can be connected to the third modular energy storage string via at least a second string contactor. Alternatively or additionally, the first modular energy storage string is connected to or can be connected to the third modular energy storage string via at least a third string contactor. Alternatively or additionally, the first to third modular energy storage strings are connected to or can be connected to a common star point. Here, the contactor can also describe any kind of switch and / or any kind of switch matrix suitable for performing the connection between the corresponding strings. It can be considered that the connection to the common star point is achieved if the first string contactor and the second string contactor are closed. However, if there are no optional string contactors, the first and / or second and / or third modular energy storage devices can be permanently connected to the common star point, which means that the first and / or second and / or third modular energy storage devices can be provided in a star connection configuration. The connection between the first phase string and the second phase string can be performed via the common star point. The (common) star point in the electrical system preferably refers to a central reference point or connection point. It is preferably used in configurations in which a plurality of components or elements are connected in a star or radial pattern. In this context, the first and / or second and / or third modular energy storage strings can be interconnected or linked to a shared central connection point called the common star point. This configuration preferably allows the merging or convergence of the electrical connections from these energy storage strings. It preferably enables them to share a common reference point, which can have various advantages in terms of electrical distribution, control, and / or monitoring within a multilevel converter and / or a multilevel converter system and / or a charging system.

[0033] In a further embodiment, the first modular energy storage string may be connected in series with at least a second modular energy storage string via at least a fourth string contactor. Alternatively or additionally, the second modular energy storage string may be connected in series and / or in parallel with at least a third modular energy storage string via at least a fifth string contactor. It is also possible that the first modular energy storage string may be connected in series with at least a third modular energy storage string via a sixth string contactor. Here, the contactor may also describe any kind of switch and / or any kind of switch matrix suitable for performing the connection between the respective strings.

[0034] In another embodiment, at least the first modular energy storage string may be connected to a first phase of a three-phase power grid via a preferably phase-independent first grid contactor; and / or wherein at least the second modular energy storage string may be connected to a second phase of the three-phase power grid via a preferably phase-independent second grid contactor; and / or wherein at least the third modular energy storage string may be connected to a third phase of the three-phase power grid via a preferably phase-independent third grid contactor. Here, the contactor may also describe any kind of switch and / or any kind of switch matrix suitable for performing the connection between the respective strings. According to the embodiment, the respective grid contactors are preferably placed at the top grid track of the respective phase of a preferably three-phase power grid. By this placement, copper savings can be achieved compared to the placement of the contactor and the grid connection side of at least one multilevel converter and / or at least one multilevel converter system. Of course, the multilevel converter may have more than three phases, especially if the power grid also includes more than three phases.

[0035] In another embodiment, the first modular energy storage string includes at least two terminal connections configured to provide a DC input and / or output in DC mode, preferably for power boosting and / or charging and / or discharging functions; and / or wherein the second modular energy storage string includes at least two terminal connections configured to provide a DC output in DC mode, preferably for power boosting and / or charging and / or discharging functions; and / or wherein the third modular energy storage string includes at least two terminal connections configured to provide a DC output in DC mode, preferably for power boosting and / or charging and / or discharging functions. Multiplexing and / or routing can be used to switch between the terminal connections, especially if the voltage level to be provided between two corresponding terminal connections can be changed. "Terminal connection" preferably refers to a specific point and / or connector on the first and / or second and / or third modular energy storage string where an external connection can be made or a connection to the outside of a multilevel converter can be made. The claims state that there are at least two terminal connections, preferably suggesting that there are two separate points on the corresponding string for making external connections. "DC output" preferably refers to the terminal connection on the first and / or second and / or third modular energy storage string configured to provide a direct current (DC) output. In the DC operating mode, the corresponding string is designed to deliver electrical energy in the form of direct current. This output can be used to power other devices or systems that require a DC input and / or for boost charging and / or charging. By having at least two terminal connections on the corresponding modular energy storage string, the system allows the DC output to be transmitted to external components or devices, preferably enabling the stored energy to be utilized in the DC operating mode.

[0036] In another embodiment, in particular, the corresponding first terminal connection of at least two terminal connections in each string is provided on the grid connection side of the corresponding first modular energy storage string and / or second modular energy storage string and / or third modular energy storage string, and wherein the corresponding second terminal connection of at least two terminal connections is provided at a common star point. In other words, at least one of at least two corresponding terminal connections in each string can be arranged at the common star point, while the other of at least two corresponding terminal connections in each string can be arranged on the grid side of the corresponding modular energy storage string. "Grid connection side" preferably means that the corresponding terminal connection is located on the side where the energy storage string is connected or can be connected to the grid.

[0037] In another embodiment, each of at least two terminal connections of the corresponding first modular energy storage string and / or second modular energy storage string and / or third modular energy storage string can be operated via a corresponding terminal contactor. Here, the contactor can also describe any kind of switch and / or any kind of switch matrix suitable for performing the connection between the corresponding strings. A "terminal contactor" preferably refers to a device or component capable of operating or controlling a terminal connection. Each of at least two terminal connections in the corresponding modular energy storage string can be operated via a corresponding terminal contactor. This means that there can be contactors preferably associated with each terminal connection, preferably allowing independent operation and / or control of the corresponding terminal connection.

[0038] In another embodiment, the first energy storage string includes a first grid filter, which is arranged between the first grid contactor and the corresponding first energy source among a plurality of preferably serially connected energy sources of the first energy storage string; and / or wherein, the second energy storage string includes a second grid filter, which is arranged between the second grid contactor and the corresponding first energy source among a plurality of preferably serially connected energy sources of the second energy storage string; and / or wherein, the third energy storage string includes a third grid filter, which is arranged between the third grid contactor and the corresponding first energy source among a plurality of preferably serially connected energy sources of the third energy storage string. A "grid filter" preferably refers to a component positioned between the first grid contactor and a specific energy source within the first energy storage string. The grid filter is preferably designed to filter and / or regulate electrical signals and / or power flowing between the grid contactor and the designated energy source and / or string. These filters can be used to remove noise and / or harmonics and / or other undesirable components from electrical signals and / or energy flows. A "grid contactor" preferably refers to a device and / or component capable of connecting the corresponding energy storage string to the grid and / or disconnecting it from the grid. It preferably controls the electrical connection between the corresponding energy storage string and the grid.

[0039] In another embodiment, at least one terminal filter is provided on at least one of the terminal connections of the corresponding first modular energy storage string and / or second modular energy storage string and / or third modular energy storage string.

[0040] In another embodiment, at least one of at least two terminal connections of the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string is connected to at least partially bypass the first grid filter and / or the second grid filter and / or the third grid filter. In other words, the bypass configuration can allow current to at least partially bypass or at least partially avoid the corresponding filter in the circuit. In this case, at least one of the terminal connections associated with the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string can be connected in a manner that partially or fully bypasses the first grid filter and / or the second grid filter and / or the third grid filter. This means that current can flow directly from the terminal connection to another part of the circuit of the multilevel converter without passing through the corresponding grid filter or only passing through a part of the corresponding grid filter. It should be understood that the first grid filter and / or the second grid filter and / or the third grid filter can be only partially bypassed. The grid filter can be used for filtering or can be bypassed according to the operating mode, particularly the modulation mode or the stabilization mode. The modulation operating mode can have an AC output voltage and thus may require the use of a filter. During the stabilization operating mode, which has a constant or only slowly changing output voltage, the filter can be bypassed. It should be noted that the grid filter can be designed to filter out modulation noise and the grid filter can be the same in each phase or string, particularly when connected in series. Therefore, it may not be necessary to connect three filters in series as it may add additional conduction and core losses to the entire system. In such a configuration, the corresponding grid connection side terminal connections can be placed such that only a part of the first and / or second and / or third grid filter is utilized. In such a configuration, not the entire corresponding grid filter but only a part of it is used for DC mode operation. The main advantage of providing the option to bypass the first and / or second and / or third grid filter is that, depending on the setup and / or configuration of the multilevel converter and / or the corresponding energy storage string, string-specific filters and / or string-independent filters can be used. Thus, not every energy storage string needs to be provided with the same filter. This can be advantageous in terms of capital cost. Additionally, bypassing redundant filters or filter stages can reduce conduction and / or core losses.

[0041] In another embodiment, in AC mode, when at least a first modular energy storage string is connected to a first phase of a three-phase power grid, the at least first modular energy storage string is configured to operate in an energy trading mode, wherein, in the energy trading mode, electrical energy is transferable and / or interchangeable between a plurality of energy sources of the at least first modular energy storage string and at least the first phase of the three-phase power grid; and / or wherein, in AC mode, when at least a first modular energy storage string is connected to a first phase of a three-phase power grid, the at least first modular energy storage string is configured to operate in a grid support mode, wherein, in the grid support mode, electrical energy is transferable and / or interchangeable between a plurality of energy sources of the at least first modular energy storage string and at least the first phase of the three-phase power grid for supporting grid frequency control operations and / or for supporting reactive power compensation. It should be understood that these features equally apply to the second and / or third modular energy storage strings. In particular, the three-phase power grid may be part of a charging system including at least one of the claimed multilevel converters.

[0042] In another embodiment, in AC mode, when at least a first modular energy storage string is connected to a first phase of a three-phase power grid, the at least first modular energy storage string is configured to operate in a self-charging mode, wherein, in the self-charging mode, electrical energy can be transferred from at least the first phase of the three-phase power grid to a plurality of energy sources of the at least first modular energy storage string.

[0043] According to a second aspect, there is provided a multilevel converter system. The multilevel converter system includes at least two multilevel converters as claimed before and after herein. The at least two multilevel converters can be connected via at least one multilevel converter contactor. Here, the contactor may also describe any kind of switch and / or any kind of switch matrix adapted to perform the connection between the corresponding strings. Considering the technically smallest possible entity, at least one multilevel converter contactor may be configured to connect the corresponding first strings of the corresponding multilevel converters together.

[0044] In an embodiment of the multilevel converter system, at least one multilevel converter contactor is configured to connect at least two multilevel converters to a common star point, wherein, in DC mode, the output voltage of the common DC output of the at least two multilevel converters increases, particularly for providing a power boost and / or a charging function.

[0045] According to a third aspect, there is provided a charging system for DC charging or discharging an electrical energy storage device of at least one electrical consumer (preferably an electric vehicle). The system includes: at least one electrical consumer including an electrical energy storage device; preferably a three-phase power grid; a front-end converter unit capable of being connected to the preferably three-phase power grid and configured to convert and / or rectify the alternating current of the preferably three-phase power grid into direct current for charging the electrical energy storage device; and a DC charging unit capable of being connected to the front-end converter unit; an electrical energy storage device at least temporarily capable of being connected to the DC charging unit to perform a DC charging operation; and at least one multilevel converter and / or at least one multilevel converter system according to any one of the embodiments presented herein. It should be understood that the energy flow of the charging system can be bidirectional. Thus, energy can be charged into the electrical energy storage device and / or energy can be released from the electrical energy storage device, for example to provide the released energy to at least one phase of the preferably three-phase power grid. For example, the charging system (especially the electrical energy storage device) can be charged from any suitable direct current (DC) source such as a mobile power source or a power wall, etc., wherein the charging energy is provided directly or indirectly to at least one phase of the preferably three-phase power grid. In such a configuration, at least one multilevel converter and / or at least one multilevel converter system can be configured to provide the energy flow to at least one phase of the preferably three-phase power grid in an AC configuration. This can be considered a reverse mode, in which at least one multilevel converter and / or at least one multilevel converter system converts and / or transfers and / or pushes energy from the electrical energy storage device into at least one phase of the preferably three-phase power grid.

[0046] In an embodiment of the charging system, in DC mode, at least one multilevel converter and / or at least one multilevel converter system is at least temporarily capable of being connected in parallel to the DC charging unit for providing a power boost function and / or a charging function for the DC charging operation; or wherein, in DC mode, at least one multilevel converter and / or at least one multilevel converter system is at least temporarily capable of being connected in parallel to the front-end converter unit for providing a power boost function and / or a charging function for the DC charging operation. The expression "capable of being connected in parallel" preferably means that at least one current of the charging unit and at least one current of at least one multilevel converter and / or at least one multilevel converter system are added and / or summed together. In other words, "capable of being connected in parallel" or "connected in parallel" means that the corresponding outputs of at least two devices connected in parallel are in parallel connection. Alternatively, at least one multilevel converter and / or at least one multilevel converter system can be connected in parallel with the front-end converter. The front-end converter can be considered a rectifier.

[0047] In an embodiment of the charging system, the system includes a transformer unit that can be interconnected between a preferably three-phase power grid and at least one multilevel converter and / or at least one multilevel converter system. Such a transformer can be applied for current isolation. Therefore, when such isolation is not required, such a transformer may be redundant.

[0048] All aspects and embodiments described above can be combined as considered appropriate by those skilled in the art.

[0049] In the present context, "a / an" should not be construed as being limited to only one element. More precisely, multiple elements can also be provided, such as for example two, three, or more. Any other numbers used herein should also not be construed as having the effect of imposing a limitation on the exact number of elements stated. On the contrary, numerical deviations upwards and downwards are possible unless there is an indication to the contrary.

[0050] Other possible embodiments of the present invention also include combinations of any features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In such cases, those skilled in the art will also add the respective aspects as improvements or supplements to the corresponding basic forms of the present invention. Description of the Drawings

[0051] Figure 1 Shows a first schematic example of a charging system;

[0052] Figure 2 Shows a second schematic example of a charging system;

[0053] Figure 3 Shows a first improvement of a multilevel converter system and a power grid;

[0054] Figure 4 Shows a further improvement of a multilevel converter system;

[0055] Figure 5 Shows a further improvement of a multilevel converter system;

[0056] Figure 6 Shows a further improvement of a multilevel converter system and a power grid;

[0057] Figure 7 Shows a further improvement of a multilevel converter system and a power grid;

[0058] Figure 8 Shows a further improvement of a multilevel converter system and a power grid;

[0059] Figure 9 Shows a further improvement of a multilevel converter system and a power grid;

[0060] Figure 10 Shows a further improvement of a multilevel converter system and a power grid;

[0061] Figure 11 Shows a further improvement of a multilevel converter system and a power grid;

[0062] Figure 12 Shows a further improvement of a multilevel converter system and a power grid;

[0063] Figure 13 Shows a further improvement of a multilevel converter system and a power grid;

[0064] Figure 14 Shows a further improvement of a multilevel converter system and a power grid;

[0065] Figure 15 Shows a further improvement of a multilevel converter system and a power grid;

[0066] Figure 16 Shows a further improvement of a multilevel converter system and a power grid;

[0067] Figure 17 Shows a further improvement of a multilevel converter system and a power grid;

[0068] Figure 18 Shows a further improvement of a multilevel converter system and a power grid;

[0069] Figure 19 Shows a further improvement of a multilevel converter system and a power grid;

[0070] Figure 20 Shows a further improvement of a multilevel converter system and a power grid;

[0071] Figure 21 Shows a further improvement of a multilevel converter system and a power grid;

[0072] Figure 22 Shows a further improvement of a multilevel converter system and a power grid;

[0073] Figure 23 Shows a further improvement of a multilevel converter system and a power grid;

[0074] Figure 24 Shows a further improvement of a multilevel converter system and a power grid;

[0075] Figure 25 Shows a further improvement of a multilevel converter system and a power grid;

[0076] Figure 26Shows further improvements to a multilevel converter system and the power grid;

[0077] Figure 27 Shows further improvements to a multilevel converter system and the power grid; and

[0078] Figure 28 Shows a schematic improvement of a power converter module. Detailed Description

[0079] Unless otherwise indicated, identical or functionally identical elements are given the same reference numerals in the figures. It should also be noted that the illustrations in the figures are not necessarily drawn to scale.

[0080] Figure 1 Shows a schematic diagram of a charging system 100. The charging system 100 is particularly but not exclusively used for and / or suitable for the DC charging and / or discharging of an electrical energy storage device 102 of at least one electrical consumer 104. The electrical consumer 104 can be a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV). The energy storage device 102 can be a battery, particularly a traction battery or an energy wall battery.

[0081] The charging system 100 further includes preferably a three-phase power grid 106, a front-end converter unit 108, which is at least temporarily connectable to the preferably three-phase power grid 106 and is configured to rectify the alternating current of the power grid 106 and / or to invert DC current, preferably for charging the electrical energy storage device 102. In addition, the charging system 100 can include a DC charging unit 110, which can be at least temporarily connectable to the front-end converter unit 108. Of course, it should be understood that in other embodiments, there can be more conversion stages, such as isolated DC-DC conversion through an additional DC-DC converter. According to the shown improvement, the electrical energy storage device 102 is at least temporarily connectable to the DC charging unit 110 to perform a DC charging operation for charging the electrical energy storage device 102. To support and / or boost and / or at least partially replace the DC charging unit 110, especially during the charging operation, the charging system 100 includes at least one multilevel converter 112 and / or at least one multilevel converter system 114 including at least two multilevel converters 112. The multilevel converter 112 can be considered an AC battery storage device (AC battery) adapted to at least temporarily switch to at least one DC mode.

[0082] Optionally only, the charging system 100 may further include a DC / DC converter 116, which may be interconnected on the output side of at least one multilevel converter 112 and / or at least one multilevel converter system 114, and the DC / DC converter 116 is between at least one multilevel converter 112 and / or at least one multilevel converter system 114 and the front-end converter unit 108.

[0083] According to Figure 1 , in the DC mode, at least one multilevel converter 112 and / or at least one multilevel converter system 114 (especially its corresponding output 115) is at least temporarily connected in parallel to the front-end converter unit 108, especially the corresponding output 118 of the front-end converter unit 110, for providing a power boost function and / or a charging function for DC charging operation.

[0084] According to Figure 2 , a charging system 100 according to another improvement is shown. Compared with Figure 1 , in the DC mode, at least one multilevel converter 112 and / or at least one multilevel converter system 114 (especially its corresponding output terminals 115) is at least temporarily connected in parallel to the DC charging unit 110, especially the corresponding output 200 of the DC charging unit 110, for providing a power boost function and / or a charging function for DC charging operation. In this configuration, the output 200 of the DC charging unit 110 can be directly boosted by the energy / current that can be delivered from at least one multilevel converter 112 and / or at least one multilevel converter system 114.

[0085] Figure 3 A multilevel converter system 114 in potential improvements is shown. The multilevel converter system 114 exemplarily includes two multilevel converters 112. Each of the two multilevel converters 112 is configured as a grid-connected multilevel converter 112.

[0086] The corresponding multilevel converter 112 is configured for at least temporarily interfacing with preferably a three-phase power grid 106 and / or for at least temporarily providing the DC mode indicated above. The corresponding multilevel converter 112 includes at least a first modular energy storage string 300, which has a plurality of energy sources 302 and at least one power converter module 304. At least one power converter module 304 may be included among the plurality of energy sources 302. For clarity, only one of the corresponding energy sources of each string is marked in Figure 3 . At least one power converter module 304 includes at least two switching elements 2800 (for more details, see the description in the last paragraph of the specification in Figure 28 ).

[0087] At least two switching elements 2800 are configured to selectively switch each of a plurality of energy sources 302 to operate at least a first modular energy storage string 300 in an AC mode, wherein at least the first modular energy storage string 300 is connectable to a first phase 306 of a three-phase power grid 106. Additionally, at least two switching elements 2800 are configured to selectively switch each of a plurality of energy sources 302 to operate at least the first modular energy storage string 300 in at least one DC mode. At least two switching elements 2800 are configured to selectively switch each of a plurality of energy sources 302 to at least temporarily be in a series positive and / or series negative and / or positive bypass state and / or negative bypass state and / or parallel to operate at least the first modular energy storage string 300 in an AC mode. Alternatively or additionally, at least two switching elements 2800 are configured to selectively switch each of a plurality of energy sources 302 to at least temporarily be in a series positive and / or series negative and / or positive bypass state and / or negative bypass state and / or parallel to operate at least the first modular energy storage string 300 in a DC mode.

[0088] The corresponding multilevel converter 112 further includes at least a second modular energy storage string 308 and / or a third modular energy storage string 310. The second modular energy storage string 308 preferably has a plurality of energy sources 312 and at least one power converter module 314, and the at least one power converter module 314 preferably includes at least two switching elements 2800 (consider Figure 28 ). At least two switching elements are configured to selectively switch each of a plurality of energy sources 312, preferably relative to each other, to operate at least the second modular energy storage string 308 in an AC mode, wherein at least the second modular energy storage string 308 is connectable to a second phase 316 of, in particular, a three-phase power grid 106. Additionally, at least two switching elements 2800 are configured to selectively switch each of a plurality of energy sources 312 to operate at least the second modular energy storage string 308 in a DC mode.

[0089] The third modular energy storage string 310 preferably has a plurality of energy sources 318 and at least one power converter module 320, and the at least one power converter module 320 preferably includes at least two switching elements 2800 (consider Figure 28)。At least two switching elements 2800 are configured to selectively switch each of the plurality of energy sources 318, preferably relative to each other, to operate at least the third modular energy storage string 310 in an AC mode, wherein the at least third modular energy storage string 310 can be connected to a third phase 322 of a three-phase power grid 106 in particular. Furthermore, at least two switching elements 2800 are configured to selectively switch each of the plurality of energy sources 318 to operate at least the third modular energy storage string 310 in a DC mode. The plurality of energy sources 302, 312, 318 can be of the same type of energy source, or can include different types of energy sources. Furthermore, the respective power converter modules 304, 314, 320 of the respective modular energy storage strings 300, 308, 310 can be of the same type, or can include different types of power converter modules. However, in Figure 3 and further Figures 4 to 28 the case of, the second and third modular energy storage strings 308, 310 are equivalently configured as at least the first modular energy storage string 300.

[0090] In the AC mode, the first modular energy storage string 300 can be connected to a first phase 306 of the three-phase power grid 106 via a first grid contactor 324. Alternatively or additionally, in the AC mode, the second modular energy storage string 308 can be connected to a second phase 316 of the three-phase power grid 106 via a second grid contactor 326. Alternatively or additionally, in the AC mode, the third modular energy storage string 310 can be connected to a third phase 322 of the three-phase power grid 106 via a third grid contactor 328.

[0091] In the DC mode, the first and / or second and / or third modular energy storage strings 300, 308, 310 are configured to respectively at least provide a charging function for DC charging operation and / or at least provide a power boosting function for DC charging operation. In particular, each of the strings 300, 308, 310 can be individually configured to provide such additional functions for DC charging operation. Alternatively or additionally, at least two of the at least three strings 300, 308, 310 can be connected to provide such additional functions for DC charging operation and / or to obtain the possibility of providing such additional functions at a plurality of different voltage levels.

[0092] According to Figure 3 , the first to third modular energy storage strings 300, 308, 310 can be connected to each other on the grid connection side of the respective multilevel converters 112. To provide such connectability between the modular energy storage strings 300, 308, 310, Figure 3Two different options are shown, one option for the lower multilevel converter 112 and an alternative or equivalent option for the upper multilevel converter 112. These two options are named A and B in Figure 3 the following.

[0093] According to the series connection option A, the first modular energy storage string 300 can be connected to the second modular energy storage string 308 via at least a first string contactor 330. Additionally, the second modular energy storage string 308 can be connected to the third modular energy storage string 310 via at least a second string contactor 332. Further, according to Figure 3 , the corresponding first to third modular energy storage strings 300, 308, 310 are connected to a common star point 334. The contactors 330 and 332 are directly placed between the corresponding strings 300, 308, 310 on the grid connection side of the upper multilevel converter 112. A first terminal connection 333 is led out from the first modular energy storage string 300, and the first terminal connection 333 includes a terminal contactor 335 for opening or closing the first terminal connection 333. A second terminal connection 336 is led out from the common star point 334. The second terminal connection 336 can also be used to interconnect the two multilevel converters 112 to a multilevel converter system 114. Thus, a multilevel converter contactor 337 can be provided at the second terminal connection 336, particularly for interconnecting at least two multilevel converters 112 to the common star point 334 to provide the multilevel converter system 114.

[0094] According to the series connection option B, the first modular energy storage string 300 can be connected to the second modular energy storage string 308 via a first string contactor 330 and a second string contactor 332 (specifically, by closing both the first and second string contactors 330, 332). Additionally, the second modular energy storage string 308 can be connected to the third modular energy storage string 310 via at least a second string contactor 332 and a third string contactor 338 (specifically, by closing both the second and third string contactors 332, 338). Further, the first modular energy storage string 300 can be connected to the third modular energy storage string 310 via at least a first string contactor 330 and a third string contactor 338 (specifically, by closing both the first and third string contactors 330, 338). According to the shown option B, on the grid connection side of the lower multilevel converter 112, the contactors 330, 332, and 338 are pulled or moved outwards towards the first terminal connection 333 via corresponding current taps on the grid connection side of the respective strings. Additionally, as already mentioned for option A, a second terminal connection 336 is led out from the common star point 334. According to option B, the string contactors 330, 332, 338 can be used as respective string individual terminal contactors, preferably for opening and / or closing the terminal connection 333 in a string individual manner.

[0095] Further reference is made to Figure 3 such that the first energy storage string 300 of the corresponding multilevel converter 112 includes a first grid filter 340 which is arranged between the first grid contactor 324 and the corresponding first energy source among the plurality of energy sources 302 of the first energy storage string 300, as seen from the grid connection side. The second energy storage string 308 includes a second grid filter 342 which is arranged between the second grid contactor 326 and the corresponding first energy source among the plurality of energy sources 312 of the second energy storage string 308. The third energy storage string 310 includes a third grid filter 344 which is arranged between the third grid contactor 328 and the corresponding first energy source among the plurality of energy sources 318 of the third energy storage string 310. According to Figure 3 the corresponding string contactors 330, 332, 338 are positioned between the corresponding grid contactors 324, 326, 328 and the corresponding grid filters 340, 342, 344.

[0096] It should be understood that the detailed structure of the multilevel converter 112 is shown in Figure 3 in combination with Figure 28 and that, for the sake of clarity, not all of the reference numerals shown in Figures 6 to 28 are shown again below. Only the main components are shown. In addition, the features that are different from each other and / or in particular different from Figure 3 are discussed and shown in detail in the drawings. Figure 3

[0097] Figure 4 and Figure 5 show two further improvements of the multilevel converter system 114 which is connected or connectable to the three-phase grid 106. Figure 4 and Figure 5 Each of the multilevel converters 112 shown in Figure 3 can be configured as at least one of the multilevel converters 112 of the multilevel converter system 114 of

[0098] According to Figure 4 at least two multilevel converters 112 can be interconnected and can thus interact with each other, in particular for synchronization and / or power connection purposes. In a further improvement, more than two multilevel converters 112 can interact as subsystems. Each multilevel converter 112 is provided with an exemplary pair of terminal connections 400, 402. It should be noted that the terminal connections 400, 402 can be combined and / or interconnected across the subsystems of the multilevel converter 112 by pairing and / or aggregating.

[0099] Figure 5 ​An improvement is shown in which the respective multilevel converters 112 of the multilevel converter system 114 are not interconnected and / or paired and / or aggregated into a subsystem multilevel converter 112.

[0100] Figure 6 An improvement of the multilevel converter system 114 is shown including two multilevel converters 112 corresponding to the multilevel converters 112 presented in the lower part of Figure 3 . Thus, the description provided for the multilevel converter generally also applies here. The two multilevel converters 112 can be connected to a common star point 334 via the multilevel converter contactors 337. The grid contactors 324, 326, 328 (see Figure 3 ) are collectively represented as a grid contactor arrangement 600. In the same manner, the string contactors 330, 332, 338, which serve as string individual terminal contactors, are collectively represented as a string contactor arrangement 602. In the same manner, the grid filters 340, 342, 344 are collectively represented as a grid filter arrangement 604. In Figure 6 the improvement shown, all the contactors are in the open position. Thus, the multilevel converters 112 are not connected to each other and are not connected to the grid 106. In addition, the corresponding terminals 333 are open. Therefore, no voltage (represented by 0V) can be measured between the terminal connections 333, 336.

[0101] Figure 7 Generally shows Figure 6 an improvement in which the respective grid contactors of the grid contactor arrangement 600 are closed. Thus, Figure 7 shows the switch configuration for the AC operation of the multilevel converter system 114. By way of example only, a transformer unit 700 is provided on the grid 106. It should be noted that such a transformer unit 700 can be applied to each embodiment disclosed herein. The transformer unit 700 can interconnect the three-phase grid 106 with at least one multilevel converter 112 and / or at least one multilevel converter system 114.

[0102] According to Figure 8 shows Figure 6 an improvement in which all the grid contactors 324, 326, 328 of the respective multilevel converters 112 are open, all the string contactors 330, 332, 338 are closed, and the multilevel converter contactor 337 remains open. In this setting, a ±X volt DC voltage can be measured between each of the terminals 333, 336 of the respective multilevel converters 112. The DC voltage can be used for DC charging operations and / or for providing a DC boost for such charging operations.

[0103] According to Figure 9 , with Figure 8In contrast, the multilevel converter contactor 337 is in the closed position. Thereby, the two multilevel converters are connected to the common star point 334. In particular, if the energy sources of the corresponding strings 300, 308, 310 of one of the multilevel converters 112 are connected in series negatively, while the energy sources of the corresponding strings 300, 308, 310 of the other multilevel converter 112 are connected in series positively, a voltage of 2X volts can be measured between the two terminals 333 (represented by Figure 9 -X V and +X V in

[0104] Figure 10 ). This generally corresponds to the improvement shown in Figure 6 . However, compared with Figure 6 , the improvement of the multilevel converter system 114 shows a configuration in which the terminal connection 333 is provided with a corresponding terminal filter 1000. The terminal filter 1000 can be configured to filter the output current and / or output voltage at the corresponding terminal. The terminal filter is provided after the corresponding string contactor arrangement 602. In addition, Figure 10 different from the improvement shown in Figure 6 , one of the grid filter arrangements 604 is placed directly between the grid contactor arrangement 600 and the string-independent power tap to the terminal connection 333. In this way, at least one of the grid filters 340, 342, 344 of the grid filter arrangement 604 can be at least partially bypassed.

[0105] Figure 11Shows an improvement to the multilevel converter system 114, where a first modular energy storage string 300 can be connected in series with at least a second modular energy storage string 308 via at least a fourth string contactor 1100, and where the second modular energy storage string 308 can be connected in series with at least a third modular energy storage string 310 via at least a fifth string contactor 1102. According to this improvement, the first modular energy storage string 300 includes at least two terminal connections 1104, 1106, which are configured to provide a DC output in DC mode. In addition, the second modular energy storage string 308 includes at least two terminal connections 1108, 1110, which are configured to provide a DC output in DC mode. In addition, the third modular energy storage string 310 includes at least two terminal connections 1112, 1113, which are configured to provide a DC output in DC mode. The corresponding first terminal connections 1104, 1108, 1112 are provided on the grid connection side of the corresponding first and / or second and / or third modular energy storage strings 300, 308, 310. The corresponding second terminal connections 1106, 1110, 1113 are provided at a common star point 334. In this way, a DC output can be provided separately for each modular energy storage string 300, 308, 310. Instead of the string contactor arrangement 602 shown in the previous figures, in Figure 11 In the improvement, each of the terminal connections 1104, 1108, 1112 includes at least one terminal contactor (not shown separately). The terminal contactors are collectively referred to as the terminal contactor arrangement 1114. In other configurations, the terminal contactor arrangement 1114 may include only one terminal contactor instead of multiple terminal contactors.

[0106] Figure 12 Generally shows Figure 11 In the improvement, the corresponding grid contactors of the grid contactor arrangement 600 are closed. Therefore, Figure 12 Shows the switching configuration for the AC operation of the multilevel converter system 114. In addition, the fourth and fifth string contactors 1100, 1102 are closed so that the modular energy storage strings 300, 308, 310 are connected to the common star point 334. The corresponding terminal contactor arrangements 1114 of the corresponding multilevel converters 112 remain open. The multilevel converter contactor 337 remains open. In this configuration, each multilevel converter 112 is connected to the grid 106. For clarity, the individual string terminal connections are not shown again in Figure 12 In this context, explicit reference is made to Figure 11 .

[0107] Figure 13 Generally shows Figure 11Improvements are made, in which the corresponding grid contactors of the grid contactor arrangement 600 are opened. Accordingly, the corresponding multilevel converters 112 are disconnected from the grid 106. In addition, the fourth and fifth string contactors 1100, 1102 are opened. The corresponding terminal contactor arrangements 1114 of the corresponding multilevel converters 112 are closed. The multilevel converter contactor 337 remains open. In this way, for each modular energy storage string 300, 308, 310, a DC power output can be provided between each pair of terminal connections of each modular energy storage string 300, 308, 310. Accordingly, for each multilevel converter 112, 3.0 times X volts can be provided for the charging function and / or the boost function.

[0108] It should be noted that X volts can be the maximum output voltage that each modular energy storage string 300, 308, 310 can provide, respectively.

[0109] Figure 14 Generally shows Figure 13 Improvements are made, in which, in the left multilevel converter 112, the fourth string contactor 1100 is closed and the fifth string contactor 1102 is open, and in which, in the right multilevel converter 112, the fourth string contactor 1100 is open and the fifth string contactor 1102 is closed. In addition, the multilevel converter contactor 337 is closed. In this configuration, a voltage of X volts can be obtained at the corresponding terminal outputs. In this way, the first and second modular energy storage strings 300, 308 of the left multilevel converter 112 are connected in series, where an output voltage of 2.0 times X volts can be obtained between the terminal connections 1104, 1108 of the left multilevel converter. In addition, the third modular energy storage string 310 of the left multilevel converter 112 is connected to the first modular energy storage string 300 of the right multilevel converter 112 via the multilevel converter contactor 337, where an output voltage of 2.0 times X volts can be obtained between the terminal 1104 of the right multilevel converter 112 and the terminal connection 1112 of the left multilevel converter 112. In addition, the second and third modular energy storage strings 308, 310 of the right multilevel converter 112 are connected in series, where an output voltage of 2.0 times X volts can be obtained between the terminal connections 1108, 1112 of the right multilevel converter 112.

[0110] Figure 15 Shows the same setup as Figure 14 except that the voltage outputs of the respectively connected modular energy storage strings are indicated in a different way for enhanced clarity.

[0111] Figure 16 Shows a further improvement of the multilevel converter system 114. The corresponding multilevel converters 112 are in the same way as Figure 11configured in a similar manner as shown and described. However, compared to the Figure 11 improvement shown in, no multilevel converter contactor 337 is provided between the two exemplary multilevel converters 112 shown. Instead, two grid contactor arrangements 600 are placed at the top side of the grid, preferably directly at the respective phases 306, 316, 322 of the grid 106. One grid contactor arrangement 600 (also referred to as the left grid contactor arrangement) is placed before the respective power taps of the modular energy storage strings 300, 308, 310 for the left multilevel converter 112. The second grid contactor arrangement 600 (also referred to as the right grid contactor arrangement) is placed before the respective power taps of the modular energy storage strings 300, 308, 310 for the right multilevel converter 112. In this way, if the grid contactors of the left grid contactor arrangement 600 are opened, the multilevel converter system 114 is disconnected from the grid as a whole. Additionally, if at least one grid contactor of the right grid contactor arrangement 600 is closed, at least one of the modular energy storage strings 300, 308, 310 of the left multilevel converter 112 can be connected to at least one of the modular energy storage strings 300, 308, 310 of the right multilevel converter 112. Thus, the left grid contactor arrangement 600 can replace the function of the multilevel converter contactor 337. Additionally, according to the Figure 16 improvement shown, the respective multilevel converters 112 include not only a terminal contactor arrangement 1114 on the grid connection side of the respective multilevel converters 112, but also another terminal contactor arrangement 1600 provided at the respective terminals at the common star point side of the respective multilevel converters 112. The respective fourth and fifth string contactors 1100, 1102 are opened. The respective terminal contactors of the respective terminal contactor arrangements 1114, 1600 remain open.

[0112] Figure 17 is generally shown Figure 16 of the improvement, where the respective grid contactors of the two grid contactor arrangements 600 are closed. Thus, Figure 17 shows the switching configuration for the AC operation of the multilevel converter system 114. Additionally, the respective fourth and fifth string contactors 1100, 1102 are closed. The respective terminal contactors of the respective terminal contactor arrangements 1114, 1600 remain open. In this way, the two multilevel converters 112 are in grid connection. The respective modular energy storage strings 300, 308, 310 are connected to the common star point 334.

[0113] Figure 18 is generally shown Figure 16 of the improvement, where the respective terminal contactors of the respective terminal contactor arrangements 1114, 1600 are closed.

[0114] In this way, for each modular energy storage string 300, 308, 310, for each multilevel converter, a DC power output can be provided between each pair of terminal connections of each modular energy storage string 300, 308, 310. Thus, for each multilevel converter 112, 3.0 times X volts can be provided for the charging function and / or the boost function.

[0115] Figure 19 Is generally shown Figure 16 An improvement of, in which the corresponding grid contactors of the right grid contactor arrangement 600 are closed, while the corresponding grid contactors of the left grid contactor arrangement 600 remain open, so that the multilevel converter system 114 is disconnected from the grid. The corresponding terminal contactors of the corresponding terminal contactor arrangement 1114 are open, while the corresponding terminal contactors of the corresponding terminal contactor arrangement 1600 are closed. The corresponding fourth and fifth string contactors 1100, 1102 are open. In this way, the first modular energy storage string 300 of the left multilevel converter 112 is connected in series with the first modular energy storage string 300 of the right multilevel converter 112 via the grid contactors of the right grid contactor arrangement 600. In addition, the second modular energy storage string 308 of the left multilevel converter 112 is connected in series with the second modular energy storage string 300 of the right multilevel converter 112 via the grid contactors of the right grid contactor arrangement 600. In addition, the third modular energy storage string 310 of the left multilevel converter 112 is connected in series with the first modular energy storage string 310 of the right multilevel converter 112 via the grid contactors of the right grid contactor arrangement 600. In this way, a DC power output can be provided between the corresponding closed terminal connections of the interconnected modular energy storage strings. Thus, 3.0 times 2X volts can be provided for the charging function and / or the boost function.

[0116] Figure 20 Is generally shown Figure 3 An improvement of the multilevel converter system 114 shown in. However, similar to Figure 16 , the multilevel converter contactor 337 is replaced by another right grid contactor arrangement 600. In addition, similar to Figure 16 , the left grid contactor arrangement 600 is placed exactly before the corresponding power taps of the modular energy storage strings 300, 308, 310 for the left multilevel converter 112. As already for Figure 3Explained in detail, the left multi-level converter 112 includes a series contactor arrangement 602, which includes series contactors 332, 334, 338, and the left multi-level converter 112 includes series contactors 332, 334. The series contactors 332, 334 together with the terminal contactor 335 of the left multi-level converter can be summarized as a series contactor arrangement 2000. The series contactor arrangements 602 and 2000 refer to technically equivalent options.

[0117] Figure 21 An improvement of the multi-level converter system 114 is shown, where the left multi-level converter corresponds to Figure 20 the configuration of the right multi-level converter 112, especially corresponding to the configuration of the series contactor arrangement 602. In addition, at the common terminal connection on the common star point side of the corresponding multi-level converter 112, another terminal contactor 2100 is provided.

[0118] Figure 22 Generally shows Figure 21 an improvement, where the corresponding series contactors of the corresponding series contactor arrangement 602 are closed. In addition, the corresponding terminal contactor 2100 is closed. The corresponding grid contactors of the corresponding grid contactor arrangement 600 remain open. In this way, the first to third modular energy storage strings 300, 308, 310 of the corresponding multi-level converter 112 are connected in parallel, and a DC output voltage of X volts can be obtained at the corresponding two terminal connections of the corresponding multi-level converter 112.

[0119] Figure 23 Generally shows Figure 21An improvement, wherein the corresponding string contactor of the corresponding string contactor arrangement 602 is disconnected. The corresponding terminal contactor 2100 is closed. In addition, the corresponding grid contactor of the right grid contactor arrangement 600 is closed. In this way, the first modular energy storage string 300 of the left multilevel converter 112 is connected in series with the first modular energy storage string 300 of the right multilevel converter 112 via the grid contactor of the right grid contactor arrangement 600. In addition, the second modular energy storage string 308 of the left multilevel converter 112 is connected in series with the second modular energy storage string 300 of the right multilevel converter 112 via the grid contactor of the right grid contactor arrangement 600. In addition, the third modular energy storage string 310 of the left multilevel converter 112 is connected in series with the first modular energy storage string 310 of the right multilevel converter 112 via the grid contactor of the right grid contactor arrangement 600. The first modular energy storage string 300 connected in series is connected in parallel with the second modular energy storage string 308 and the third modular energy storage string 310 connected in series. In this way, a DC power output may be provided between the corresponding closed terminal connections 2100 of the two multi-level converters 112. Thus, 1.0 times 2X volts may be provided for a charging function and / or a boost function.

[0120] Figure 24 A further development of the multilevel converter system 114 is shown. The left-hand multilevel converter 112 corresponds to the right-hand multilevel converter 112. Each multilevel converter 112 comprises a grid contactor arrangement 600, which is exemplarily placed after the respective power tapping from the first to third phases 306, 316, 322 of the grid 106 to the first to third modular energy storage strings 300, 308, 310 (similar to Figure 6)。In addition, the corresponding first modular energy storage string 300 includes a terminal connection 2400 that is tapped immediately after the grid contactor 324 of the first phase 306. The terminal connection 2400 includes a terminal contactor 2402. In addition, on the grid connection side of the corresponding multilevel converter 112, the second modular energy storage string 308 can be connected to the third modular energy storage string 310 via an additional string contactor 2404. In addition, on the common star point side of the corresponding multilevel converter 112, the second modular energy storage string 308 can be connected to the third modular energy storage string 310 via an additional string contactor 2406. In this way, the corresponding first to third modular energy storage strings 300, 308, 310 can be connected in series (i.e., by closing the string contactor 2404) and / or the second and third modular energy storage strings 308, 310 can be connected in parallel (i.e., by closing both string contactors 2404, 2406) and / or at least one of the second or third modular energy storage strings 308, 310 can be bypassed (i.e., by closing the string contactor 2406). It should be understood that the contactor 2406 can be configured to disconnect the third modular energy storage string 310 from the common star point 334. In addition, in the grid connection of the corresponding multilevel converter 112, by closing the corresponding string contactor 2406 and keeping the corresponding string contactor 2404 open, the corresponding first to third modular energy storage strings 300, 308, 310 can be connected to the common star point 334 (see Figure 25 ).

[0121] Figure 26 is generally shown Figure 24 an improvement, in which the corresponding grid contactors of the corresponding grid contactor arrangement 600 are open. The corresponding terminal contactors 2100, 2402 are closed. The corresponding string contactor 2404 is closed while the string contactor 2406 is open. In this way, the corresponding first to third modular energy storage strings 300, 308, 310 are connected in series. In this way, a DC power output can be provided between the corresponding pair of closed terminal connections 2100, 2402 of the two multilevel converters 112. Therefore, 2.0 times 3X volts can be provided for the charging function and / or the boosting function.

[0122] Figure 27 shows a further improvement of the multilevel converter system 114. The general configuration of the corresponding multilevel converter 112 corresponds to Figures 24 to 26. However, in the configuration of the left multilevel converter 112, the string contactor 2404 is placed after the corresponding grid filter of the grid filter arrangement 604. In this way, at least one of the grid filters of the grid filter arrangement 604 provided at the second and third modular energy storage strings 308, 310 of the left multilevel converter 112 can be at least partially bypassed by closing the string contactor 2404. In addition, in the configuration of the right multilevel converter 112, the terminal connection 2400 is placed after the grid filter of the grid filter arrangement 604 arranged at the first modular energy storage string 300. In this way, the grid filter provided at the first modular energy storage string 300 (preferably before the first energy storage module) can be at least partially bypassed.

[0123] Figure 28 A potential switch arrangement of a power converter module 304 is shown which exemplarily includes four switch elements 2800. Each module string 2802, 2804 of the exemplary power converter modules 304 connected in series provides two respective switch elements 2800. A respective further terminal connection 2806, 2808 is provided between each of the two switch elements of each string 2802, 2804. The terminal connections 2806, 2808 may be used to modularly connect a plurality of power converter modules 304 together.

[0124] It should be noted that the switching topology can be selected with respect to the filtering requirements on the AC and DC sides of the multilevel converter system. The greater the filtering capability required on the DC side, the more inductors may be involved in the DC configuration. Reference numerals list 100 Charging System 102 Electrical energy storage device 104 Electrical appliances 106 Power Grid 108 Front-end converter unit 110 DC charging unit 112 Multilevel Converter 114 Multilevel Converter System 115 Output 116DC / DC Converter 118 Output 200 Output 300 Modular Energy Storage Strings 302 Multiple Energy Sources 304 Power Converter Module 306 Phase 308 Modular Energy Storage String 310 Modular Energy Storage String 312 Multiple energy sources 314 Power converter module 316 Phase 318 Multiple energy sources 320 Power converter module 322 Phase 324 Grid contactor 326 Grid contactor 328 Grid contactor 330 String contactor 332 String contactor 333 Terminal connection 334 Star point 335 Terminal contactor 336 Terminal connection 337 Multilevel converter contactor 338 String contactor 340 Grid filter 342 Grid filter 344 Grid filter 400 Terminal connection 402 Terminal connection 600 Grid contactor arrangement 602 String contactor arrangement 604 Grid filter arrangement 800 Transformer unit 1000 Terminal filter 1100 String contactor 1102 String contactor 1104 Terminal connection 1106 Terminal connection 1108 Terminal connection 1110 Terminal connection 1112 Terminal connection 1113 Terminal connection 1114 Terminal contactor arrangement 1600 Terminal contactor arrangement 2100 Terminal contactor 2400 Terminal connection 2402 Terminal contactor 2404 String contactor 2406 String contactor 2800 Switch element 2802 Module string 2804 Module string 2806 Terminal connection 2808 Terminal connection

Claims

1. A grid-connectable multilevel converter, configured for at least temporarily interfacing with a three-phase grid and / or for at least temporarily providing a direct current mode; The multi-level converter comprises: at least a first modular energy storage string having a plurality of energy sources and at least one power converter module, the at least one power converter module including at least two switching elements; The at least two switching elements are configured to selectively switch each of the plurality of energy sources to operate the at least first modular energy storage string in an AC mode in which the at least first modular energy storage string is connectable to a first phase of the three-phase grid; as well as The at least two switching elements are configured to selectively switch each of the plurality of energy sources to operate the at least a first modular energy storage string in the DC mode.

2. The multilevel converter according to claim 1, in, The at least two switching elements are configured to selectively switch each of the plurality of energy sources at least temporarily into a series positive and / or series negative and / or positive bypass state and / or negative bypass state and / or parallel connection to operate the at least first modular energy storage string in an AC mode; and / or Wherein, the at least two switching elements are configured to selectively switch each of the multiple energy sources at least temporarily to series positive and / or series negative and / or positive bypass state and / or negative bypass state and / or parallel to operate the at least first modular energy storage string in DC mode.

3. The multilevel converter according to claim 1 or 2, further comprising: at least a second modular energy storage string and / or a third modular energy storage string, The second modular energy storage string and / or the third modular energy storage string are configured equivalently to the at least first modular energy storage string, wherein, in AC mode, the second modular energy storage string is connectable to the second phase of the three-phase grid, and / or wherein, in AC mode, the third modular energy storage string is connectable to the third phase of the three-phase grid; In which, in DC mode, the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string are configured to provide a charging function for DC charging operation and / or a power boost function for DC charging operation, respectively.

4. The multilevel converter according to claim 3, in, The first modular energy storage string is connectable to the second modular energy storage string via at least a first string contactor; and / or wherein the second modular energy storage string is connectable to the third modular energy storage string via at least a second string contactor; and / or wherein the first modular energy storage string is connectable to the third modular energy storage string via at least a third string contactor; and / or Wherein, the first to the third modular energy storage strings are connected to or can be connected to a common star point.

5. The multilevel converter according to claim 3 or 4, in, The first modular energy storage string is connectable in series with at least the second modular energy storage string via at least a fourth string contactor; and / or Therein, the second modular energy storage string is capable of being connected in series and / or in parallel with at least the third modular energy storage string via at least a fifth string contactor.

6. A multilevel converter according to any one of the preceding claims, in, The at least first modular energy storage string is connectable to a first phase of the three-phase grid via a first grid contactor; and / or wherein the at least a second modular energy storage string is connectable to a second phase of the three-phase grid via a second grid contactor; and / or Therein, the at least third modular energy storage string is connectable to a third phase of the three-phase grid via a third grid contactor.

7. A multilevel converter according to any one of the preceding claims, in, The first modular energy storage string comprises at least two terminal connections configured to provide a DC output in a DC mode; and / or wherein the second modular energy storage string comprises at least two terminal connections, the terminal connections being configured to provide a DC output in a DC mode; and / or Wherein, the third modular energy storage string includes at least two terminal connections, and the terminal connections are configured to provide a DC output in a DC mode.

8. The multilevel converter according to claims 4 and 7, in, A respective first terminal connection of the at least two terminal connections is arranged on a grid connection side of the respective first modular energy storage string and / or second modular energy storage string and / or third modular energy storage string, and Therein, a corresponding second terminal connection of the at least two terminal connections is arranged at the common star point.

9. The multilevel converter according to claim 7 or 8, in, Each of the at least two terminal connections of the respective first modular energy storage string and / or second modular energy storage string and / or third modular energy storage string is operable via a respective terminal contactor.

10. The multilevel converter according to claim 6, in, The first energy storage string comprises a first grid filter arranged between the first grid contactor and a respective first energy source of the plurality of energy sources of the first energy storage string; and / or wherein the second energy storage string comprises a second grid filter, the second grid filter being arranged between the second grid contactor and a corresponding first energy source of the plurality of energy sources of the second energy storage string; and / or wherein the third energy storage string comprises a third grid filter, the third grid filter being arranged between the third grid contactor and a corresponding first energy source of the plurality of energy sources of the third energy storage string; and / or Wherein, at least one of the at least two terminal connections of the first modular energy storage string and / or the second modular energy storage string and / or the third modular energy storage string is connected to at least partially bypass the first grid filter and / or the second grid filter and / or the third grid filter.

11. The multilevel converter according to any one of claims 7 to 9, in, At least one terminal filter is arranged on at least one of said terminal connections of the respective first modular energy storage string and / or second modular energy storage string and / or third modular energy storage string.

12. A multilevel converter system comprising at least two multilevel converters according to any one of the preceding claims, in, The at least two multilevel converters can be connected via at least one multilevel converter contactor.

13. A charging system for direct current charging and / or discharging of an electrical energy storage device of at least one electrical consumer, The charging system comprises: said at least one electrical consumer comprising said electrical energy storage device; Three-phase power grid; a front-end converter unit connectable to the three-phase grid and configured to invert the alternating current of the three-phase grid into direct current for charging the electric energy storage device; and a DC charging unit, connectable to the front-end converter unit; The electrical energy storage device is at least temporarily connectable to the DC charging unit to perform a DC charging operation; as well as At least one multilevel converter according to any one of claims 1 to 11 and / or at least one multilevel converter system according to claim 12.

14. The charging system according to claim 13, in, In the DC mode, the at least one multilevel converter and / or the at least one multilevel converter system is at least temporarily connectable in parallel to the DC charging unit for providing a power boost functionality for the DC charging operation; or Therein, in the DC mode, the at least one multilevel converter and / or the at least one multilevel converter system can be at least temporarily connected in parallel to the front-end converter unit for providing a power boost function for the DC charging operation.

15. The charging system according to claim 13 or 14, The charging system comprises a transformer unit, The transformer unit can be interconnected between the three-phase network and the at least one multilevel converter and / or the at least one multilevel converter system.

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