Circuit arrangement and method for generating an alternating voltage

Abstract

The present invention relates to a method for generating an alternating voltage (U AC ). The circuit arrangement comprises at least one modular inverter (7) which is designed as a cascade of a plurality of inverter units (8); a control device (11) for configuring the inverter units (8); and a data transmission system (12) for transmitting signals between the control device (11) and the inverter units (8). Each inverter unit (8) can be connected to a separate DC voltage source (6), and each inverter unit (8) has a control input (S IN ) and data output terminal (S OUT ) and according to the control input (S IN ) is set by a control signal received from the control device (1) so that a specified DC voltage source (6) can be used to generate an AC voltage (U AC ) or cannot be used to generate AC voltage (U AC According to the invention, the data transmission system (12) comprises a control line (S) connected to the control device (11) and at least one data line (D) connected to the control device (11), wherein the control line (S) is additionally connected to a control input (S) of the inverter unit (8). IN ), and at least one data line (D) is connected to a data output terminal (S) of the inverter unit (8) OUT The inverter units (8) are configured to transmit status information relating to the respectively assigned DC voltage source (6) to the control device (11) via at least one data line (D), wherein the control device (11) is configured to transmit control signals for configuring the inverter units (8) based on the received status information. The data transmission system (12) also has a clock generator line (CLK) and / or a synchronization line (SYNC) connected to the control device (11) and all the inverter units (8).

Description

[0001] This application claims the benefit of European Patent Application No. 21192613.4, the contents of which are incorporated herein in their entirety by reference. Technical Field

[0002] The invention relates to a circuit arrangement for generating an alternating current (AC) voltage, the circuit arrangement comprising at least one modular inverter in the form of a cascade of a plurality of inverter units, a control device for configuring the inverter units, and a data transmission system for signal transmission between the control device and the inverter units.

[0003] The invention also relates to a power supply system and an electric load device, in particular an electric vehicle or a household power grid.

[0004] The invention also relates to a method for generating an alternating voltage by means of a modular inverter in the form of a cascade of a plurality of inverter units, wherein each inverter unit is connected to a dedicated direct current (DC) voltage source. Background Art

[0005] In power supply systems, battery storage systems are sometimes used, such as photovoltaic home storage systems ("solar cells") for storing surplus power from photovoltaic systems, or drive batteries ("high voltage storage systems") for powering electric motors or drive units of electric vehicles. Such battery storage systems sometimes require a battery voltage of several hundred volts. However, since the battery voltage of a single battery cell is only a few volts (e.g., 3.7V for lithium-ion batteries), many single battery cells must be connected in series to form a battery pack (hereinafter also referred to as a "battery").

[0006] Due to manufacturing factors, each cell of the battery exhibits different characteristics, such as battery capacity, self-discharge rate, and temperature characteristics. Over time, aging effects further exacerbate these differences. As a result, during the charging process, some cells have not yet reached their maximum charge, while others are fully charged. Overcharging a fully charged cell will eventually cause damage or even destruction to the cell. To prevent this, the charging process must be terminated early.

[0007] The discharge process proceeds in a similar manner. While some battery cells are completely discharged, other battery cells sometimes still store enough energy to continue driving an electric vehicle, for example. In the case of an electric vehicle, the driving operation must eventually be terminated prematurely, otherwise the weaker battery cells will be deeply discharged, resulting in their destruction.

[0008] To ensure that the charging and discharging process proceeds smoothly, a battery management system (BMS) is used to balance the charges between the various battery cells, see J. Qi, D. Lu., “Review of Battery Cell Balancing Techniques”, Australasian Universities Power Engineering Conference, AUPEC 2014, Curtin University, Perth, Australia, Sept. 28 Oct. 1, 2014.

[0009] The most common method currently is the so-called passive charge balancing. In this case, the already fully charged battery cells are discharged through resistors, while the other battery cells continue to charge. An obvious disadvantage of this method is that valuable electrical energy is lost, and this method also does not provide a solution for the discharge process.

[0010] The problem of passive charge balancing can be solved by active charge balancing. However, this technique requires complex circuits with power electronics and sophisticated controls.

[0011] To generate three-phase voltages, such as for motors or electric motors in electric vehicles, self-commutated inverters are often used. Usually, such inverters consist of six power electronic valves that are interconnected to form a three-phase bridge. In this "two-point inverter", the sinusoidal AC voltage is composed of a series of three voltage levels (0, ±U DC ) is generated. The level of the voltage pulse depends on the battery voltage U DC , and is therefore constant. To generate an AC voltage, the duration of the voltage pulse can be varied as an actuating element. This is usually calculated using the pulse width modulation (PWM) method. In this case, however, higher interference voltages appear in the AC voltage of the superimposed frequency. In order to reduce the harmonics of the voltage, it is known to increase the clock frequency of the inverter. Modern inverters therefore usually have clock frequencies between a few kHz and 100 kHz. The switching losses of the inverter increase in proportion to its clock frequency.

[0012] To avoid these problems, a modular inverter (such as proposed in DE102011004248A1) can be used. In this technology, the individual battery cells are not directly connected in series, but in series through a power electronic H-bridge circuit. This principle may be applicable to single-phase loads or even to three-phase loads. A three-phase modular inverter can be formed by two single-phase modular inverters connected in series, such as proposed in DE102018003642A1.

[0013] A major challenge when generating an AC voltage from a plurality of individual DC voltage sources is the closed-loop control and the resulting necessary communication between a central open-loop control unit and / or a closed-loop control unit (hereinafter referred to as "control device") and the individual inverter units connected to the respective DC voltage sources.

[0014] The scientific publication "Marquez A.et al.: "Communications scheme of a modular power conversion system", 2015IEEE International Conference on Industrial Technology (ICIT), March 17, 2015, pages 3034-3039" relates to a universal data bus system for modular inverters. In particular, it proposes an asynchronous master-slave communication system, in which the individual inverter units respond to the call of the central control device by transmitting the corresponding request data. In conjunction with another bus system for controlling the inverter units, the required AC voltage can ultimately be generated. However, the proposed overall system requires a large number of separate lines and is also severely limited in terms of the achievable transmission speed, making it difficult to use for a large number of inverter units.

[0015] The switching states and rated voltages of the individual DC voltage sources are preferably calculated by a control device, which also requires appropriate indication or configuration of the inverter units. In order to generate a high-precision AC voltage, in particular in order to also be able to utilize very small voltage steps, the applicable switching states, rated voltage values ​​and other commands need to be transmitted from the control device to the individual inverter units at high speed. In order to generate the AC voltage, the control device also requires state information of the individual DC voltage sources, in particular information about the current charging state of the DC voltage sources that is as accurate as possible, which needs to be transmitted from the individual inverter units to the control device at high speed.

[0016] In order to generate AC voltage with higher accuracy or smaller voltage steps, a large number of DC voltage sources or inverter units must be provided. Therefore, the data transmission system not only needs to be suitable for bidirectional transmission at high data rates, but also needs to facilitate communication between a large number of communication partners.

[0017] The quality or standard of the generated AC voltage, i.e. the accuracy with which the generated AC voltage approaches a pure sinusoidal signal, depends crucially on the communication capabilities between the control device and the inverter units and thus essentially on the technical characteristics of the data transmission system. Therefore, a suitable data transmission system is required for the communication between a central control device and a plurality of inverter units for generating the AC voltage. Summary of the invention

[0018] In view of the known prior art, the object of the invention is to provide a circuit arrangement for generating an alternating voltage which can generate an alternating voltage to a particularly high standard or which can generate an alternating voltage which approximates a pure sinusoidal signal as accurately as possible.

[0019] Another object of the invention is to provide a power supply system for generating an AC voltage from a plurality of DC voltage sources, which power supply system is capable of generating an AC voltage to a particularly high standard or of generating an AC voltage which approximates a pure sinusoidal signal as accurately as possible.

[0020] Furthermore, it is an object of the present invention to provide an electrical load device, the main load of which is supplied by an AC voltage which is generated by a plurality of DC voltage sources to a particularly high standard or which approximates a pure sinusoidal signal as accurately as possible.

[0021] Another object of the invention is to provide a method for generating an AC voltage from a plurality of DC voltage sources, which method can be used to generate the AC voltage to a particularly high standard, or to approximate the AC voltage to a pure sinusoidal signal as accurately as possible.

[0022] A circuit arrangement is provided for generating an alternating voltage, which is used in particular for supplying an electrical load (also referred to below as “primary load”) which can be connected to the circuit arrangement.

[0023] The main load can be connected to the circuit device in any manner. For example, the circuit device can have terminals to connect the main load or to a power line or busbar connected to the main load. In some cases, the circuit device can also be mechanically connected to the main load, such as by press fit, form fit and / or material bonding with the housing part of the main load.

[0024] Preferably, a main load is not to be understood as a component of the circuit arrangement.

[0025] The main load may be any electrical load, or even a group of multiple electrical loads. The main load is preferably a motor, a drive and / or at least one electrical load within a low voltage network, in particular a household network.

[0026] The alternating voltage generated by the circuit arrangement is preferably a single-phase alternating voltage. However, the circuit arrangement can also be provided to generate a multi-phase alternating voltage, in particular a three-phase current. During operation, the amplitude, phase and / or frequency of the alternating voltage can be adjustable (e.g., in order to specify the speed of an electric motor), or can be constant (e.g., in order to operate a household appliance).

[0027] According to the invention, the circuit arrangement comprises at least one modular inverter which is in the form of a cascade of a plurality of inverter units.

[0028] Therefore, at least one inverter can be designed to generate an AC voltage. To this end, the inverter can have, for example, a first main supply terminal and a second main supply terminal, between which an AC voltage is present. The electrical load to be worked or the main load can then be connected to the first main supply terminal and the second main supply terminal, or can be attached to the main supply terminals.

[0029] A cascade of inverter cells is intended to be understood to mean in particular an output-side series arrangement formed by the inverter cells.

[0030] In principle, any desired number of inverter units may be provided, for example up to 10 inverter units, up to 20 inverter units, up to 50 inverter units, up to 100 inverter units, up to 200 inverter units, up to 500 inverter units or even more inverter units.

[0031] It should be pointed out here that, for example, in order to increase the maximum possible output current, it is also possible in principle to connect an inverter unit in parallel with other inverter units.

[0032] According to the invention, the circuit arrangement further comprises a control device for configuring the inverter unit and a data transmission system for transmitting signals between the control device and the inverter unit.

[0033] The control means may be in the form of a microprocessor. Alternatively, the control means may be implemented by any other means, such as an arrangement of one or more discrete electrical devices on a printed circuit board, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), or another programmable circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), and / or a commercially available computer. The control means may also be present as a combination of multiple electronic devices in a locally distributed arrangement in the circuit arrangement.

[0034] The control device can also be a functional module of a superordinate control unit, for example a functional module of a battery management system mentioned below, a functional module of a DC voltage source or a functional module of a control unit of an electrical load operated by AC voltage.

[0035] According to the invention, each inverter unit can be connected to at least one dedicated DC voltage source, each inverter unit has a control input and a data output, and is designed to use the control signal received from the control device via the control input as a command to make the associated DC voltage source (in some cases +U DC or -U DC ) can be used to generate an AC voltage or cannot be used to generate an AC voltage at the output end.

[0036] The connection between the individual inverter units and the at least one DC voltage source can be realized, for example, by means of suitable power supply lines and / or busbars. However, a direct connection to the DC voltage source can also be provided. In some cases, the circuit arrangement can also be mechanically connected to the at least one DC voltage source by means of a press fit, a form fit and / or a material bond, for example, to a housing part of the at least one DC voltage source (for example, a housing part of a battery).

[0037] Preferably, the at least one DC voltage source is not to be understood as a component of the circuit arrangement.

[0038] In particular, the DC voltage source can be a single cell of a battery or a battery pack consisting of a plurality of interconnected cells ("battery module"). However, in some cases, the DC voltage source can also be a complete battery or a combination of multiple batteries.

[0039] "Battery" in the present case is to be understood as meaning both rechargeable storage devices (i.e. "accumulators" / "batteries"), the individual cells of which are also referred to as "secondary cells", and non-rechargeable storage devices. In some cases, a battery or battery pack may also consist of only a single cell. The present invention is therefore intended to be understood as not necessarily being limited to batteries having a plurality of interconnected cells. Furthermore, a battery in the present invention may also refer to electrical energy storage devices which are not or are not entirely electrochemical in design, such as capacitors.

[0040] In principle, however, the DC voltage source can be any DC voltage source, that is to say, for example, also a DC voltage provided by an electronic component, for example, a DC voltage provided by a rectifier and / or a DC chopper on the output side. For simplicity, the DC voltage source hereinafter and above refers essentially to a battery cell of a common battery, but this does not imply a restriction but is merely an example.

[0041] According to the present invention, a single DC voltage source, such as a single battery cell, can be connected in series through a single inverter unit as required. Therefore, the oscillating output voltage of the inverter is generated by adding the individual voltages of the individual DC voltage sources, and the individual voltages present a staircase pattern with small steps. The level of the minimum voltage step can correspond to the output voltage of the corresponding DC voltage source (e.g., the cell voltage of the battery cell, such as 3.7V).

[0042] Cascading inverter cells can significantly reduce the high clock frequencies necessary for pulse width modulated output voltages and the associated switching losses.

[0043] In addition, it is possible to use DC voltage sources of different ages, different states and different types in the same power supply system, since they can be combined flexibly. In addition, this great flexibility allows the use time of battery blocks, such as those in a photovoltaic storage system for a home or in a high-voltage storage system for an electric vehicle, to be significantly extended.

[0044] According to the invention, the data transmission system has a control line connected to the control device and at least one data line connected to the control device. The control line is connected to the control input of the inverter unit and the at least one data line is connected to the data output of the inverter unit. The inverter unit is designed to transmit status information about the respectively associated DC voltage source to the control device using the at least one data line. In turn, the control device is designed to transmit control signals to configure the inverter unit based on the received status information.

[0045] Thus, the control line can be used to transmit information and control signals from the control device to all inverter units simultaneously. The control device can combine all control information required for generating the AC voltage and send it to the inverter units in the form of a data block. Correspondingly, data transmission from the inverter units to the control device can take place via at least one data line, which is preferably used by only one inverter unit at a specific time to transmit data, preferably only when requested by the control device.

[0046] The aforementioned status information may in particular be information relating to the current charge state, the current temperature and / or the current “state of health” of the DC voltage source.

[0047] The DC voltage sources can each have a control module or a common control module, which collects status information related to each DC voltage source, for example using suitable sensors (temperature sensors, ammeters and / or voltmeters, etc.) and / or reading status information from separate circuits. At least one control module can transmit applicable status information to the inverter unit for further processing and / or transmission to the control device. The control module can be a battery management system for the battery in particular. The battery management system can be used to monitor and / or control the battery (sometimes also called a power management system (PMS)), and can use analog and / or digital methods to transmit information about the current state (e.g., charging state and / or temperature state) and / or design or characteristic parameters related to each battery and its battery cells (e.g., rated voltage, end-of-charge voltage and / or identification data).

[0048] The control line is preferably used for unidirectional signal transmission from the control device to the inverter unit, and the at least one data line is used for unidirectional data transmission from the individual inverter units to the control device.

[0049] In general, two (unidirectional) transmission paths, ie one control line and the other at least one data line, can be used to provide an advantageous bidirectional signal and data transmission.

[0050] The proposed data transmission system can be used to provide fast data transmission between communication partners using only a few power lines.

[0051] Finally, the data transmission system is used to provide an advantageous data bus system in which the control device can be in the form of a master and the inverter units can be in the form of slaves. The prior art discloses various data bus systems, such as an SPI (Serial Peripheral Interface) bus or a CAN (Controller Area Network) bus. However, none of the currently known data bus systems is suitable for use as a data transmission system between the control device and the inverter unit to generate a particularly high-quality AC voltage, in particular since, in the present case, extremely precise synchronization of the individual inverter units or slaves with the control device or the master may be required.

[0052] The control device and / or the inverter unit can have respective data processing modules for coordinating or triggering communications, forwarding of data and signals, in particular configuration of the inverter unit (eg connection and / or disconnection of a DC voltage source).

[0053] It can be provided that the inverter or its inverter unit is designed to adjust the amplitude, phase and / or frequency on the output side to provide an AC voltage specified by the control device. Therefore, the inverter or its inverter unit can be flexibly configured according to the specification of the control device, for example, in order to specify, control and / or adjust the operating behavior of the main load.

[0054] In a refinement of the invention, it can be particularly provided that the inverter units each have an H-bridge circuit, which includes four power electronic switching elements that can be configured by the control device. For an exemplary embodiment of such an H-bridge circuit, reference is made to DE 10 2018 003 642 A1, the disclosure of which is fully incorporated into this specification by this reference.

[0055] For example, in each case, the outputs of two of the power electronic switching elements can be connected to form a series arrangement and can form a corresponding common connection path of the H-bridge circuit. Two such connection paths can be set. On each of the two connection paths, the power electronic switching element can have an output terminal of an inverter unit attached between them. The respective end points of the connection path can be connected to each other, and the input terminal of the inverter unit is attached to each end point; therefore, the two connection paths can be connected in parallel. According to the wiring of the H-bridge, the output voltage of each inverter unit can preferably adopt three voltage values ​​(0, ±U DC )one of the.

[0056] The configurable power electronic switching element can be provided in the form of a bipolar transistor or preferably in the form of a MOSFET. However, in principle any switching element can be used, in particular a semiconductor element. The configurable power electronic switching element can also be in the form of a relay. In principle, the design of the configurable power electronic switching element is non-restrictive for the present invention.

[0057] In an advantageous embodiment of the invention, the control device can be arranged to configure the inverter unit via a control line (in particular to configure the inverter unit periodically) to generate an AC voltage from the individual voltages of the DC voltage source (preferably in steps or at least approximately in steps).

[0058] The control device can also be designed to load the inverter units differently depending on the respective charge states of the applicable DC voltage sources, which are transmitted to the control device as status information for balancing the charges between the DC voltage sources.

[0059] Since each DC voltage source can be connected or disconnected via an independent inverter unit, charge balancing between the DC voltage sources is possible, that is to say, charge balancing between a plurality of battery cells is possible, for example.

[0060] For example, it can be provided that a DC voltage source with a higher charge state participates in generating the AC voltage more frequently and / or for a longer time than the other DC voltage sources, so that the charge states of all DC voltage sources are consistent with each other over time.

[0061] According to one embodiment of the present invention, the control device can be further designed to at least temporarily or intermittently exclude the inverter unit from participating in the generation of AC voltage based on the charging state, temperature state and / or fault state of the applicable DC voltage source, and the charging state, temperature state and / or fault state are transmitted to the control device as status information.

[0062] For example, a faulty or overheated DC voltage source can be excluded. In particular, deeply discharged battery cells can also be excluded.

[0063] For example, in the event of a permanent or temporary failure of a DC voltage source, the inverter can continue to operate using the still functioning DC voltage source. The availability of the corresponding power supply system can thus be much higher than with conventional technologies of direct and naturally inflexible series arrangement of DC voltage sources.

[0064] Defective DC voltage sources (e.g. defective battery cells) can be switched off and bypassed. Furthermore, they can be safely replaced even during operation.

[0065] According to one embodiment of the present invention, it may be provided that the inverter unit is designed to transmit the status information only when requested by the control device.

[0066] The control device can be designed to request status information of the corresponding inverter unit by transmitting a unique identifier associated with the applicable inverter unit, in particular via a control line (but in some cases also via another line, such as the synchronization line mentioned below or even via a wireless communication channel).

[0067] In one embodiment of the invention, it can be provided that the inverter units each have an output switching element which is connected to the data line via a data output and which is capable of placing the data output in a high impedance state if the applicable inverter unit does not transmit status information.

[0068] The output switching element can be used to avoid conflicts between logical or binary states (0 / 1) on the data line particularly easily. For example, the output switching element can be provided with the known output connections "open collector", "open drain" or "tri-state".

[0069] According to a first variant of the invention, provision is made for the data transmission system to additionally have a clock generator line which is connected to the control device and all inverter units.

[0070] Preferably, the control device is designed to generate a clock signal for synchronizing the signal transmission between the control device and the inverter unit on the clock generator line. However, in principle, the clock signal does not necessarily have to be generated by the control device, but can also be generated by another electrical unit or component, for example by one of the inverter units.

[0071] In this context, it should be mentioned that the clock generator line or the clock signal is not absolutely necessary for the synchronization of the signal transmission between the control device and the inverter unit. In principle, the communication can also take place asynchronously. A clock recovery process can also be provided.

[0072] The use of a clock generator circuit with a suitable clock signal is particularly preferred, since this allows the transmission speed and the reliability of the data and signal transmission to be increased. In particular, clock frequencies above 1 MHz can be achieved using a clock signal.

[0073] According to a second variant of the invention, as an alternative or in addition to the first variant of the invention, the data transmission system also has a synchronization line connected to the control device and all inverter units.

[0074] The control device can be designed to generate a synchronization signal on the synchronization line. However, in principle, the synchronization signal does not necessarily have to be generated by the control device, but can also be generated by another electrical unit or component, for example, by one of the inverter units.

[0075] The synchronization signal can be used to facilitate precise synchronization of all inverter units to produce an AC voltage of a particularly high standard, or to approximate it to a sinusoidal voltage with particularly low harmonics.

[0076] Therefore, the inverter units can be designed to synchronize switching time, that is, when the AC voltage is being generated, the time when the output side voltage of each inverter unit changes is synchronized with the time when the synchronization signal is received, or the switching time is directly dependent on the time when the synchronization signal is received.

[0077] Optionally, the synchronization signal can also be used to identify the beginning and end of a data block transmitted from the control device to the inverter unit via the control line.

[0078] Furthermore, the inverter unit can optionally be designed to transmit the requested data packets synchronously with a synchronization signal on the data line.

[0079] Preferably, the data transmission system has not only a control line and at least one data line, but also a clock line and a synchronization line. Thus, at least four lines can preferably be implemented.

[0080] In one embodiment of the present invention, the control device and the inverter unit may be provided with respective potential isolation elements to facilitate signal transmission in an isolated manner via control lines, at least one data line, a clock generator line and / or a synchronization line based on different voltage levels.

[0081] Since the voltage potentials of the individual DC voltage sources are usually different (the voltage potentials may sometimes differ by more than 100 Volts), it may be advantageous to manufacture the data transmission system in an isolated form, in particular with a high isolation voltage.

[0082] Furthermore, potential isolation significantly improves immunity to inductive and capacitive coupling, especially when using floating conductors with double potential isolation (i.e., potential isolation at both ends or at all connection points of each conductor).

[0083] The potential isolation element allows DC isolation to be achieved, thereby preventing current from flowing between the two ends of the line while facilitating unimpeded data transmission. The proposed electrical isolation may be particularly beneficial for preventing voltages or currents caused by overvoltages or ground loops, especially because the grounds of systems isolated by particularly long lines are sometimes not at the same potential, and the different potentials mean that ground currents that may adversely affect signal quality may flow between the two ends of the line. Therefore, the proposed isolation further improves data transmission.

[0084] The potential isolation element is preferably a digital isolator, a transformer, a coupling capacitor and / or an optocoupler.

[0085] In an advantageous embodiment of the invention, provision can be made for a plurality of instances of an inverter unit to be combined to form a common module group.

[0086] Preferably, the circuit arrangement has multiple instances of module groups, for example at least two module groups, preferably up to 5 module groups or more module groups, for example up to 10 module groups, up to 20 module groups, up to 50 module groups, up to 100 module groups, up to 200 module groups, up to 500 module groups or even more module groups.

[0087] It can be provided that each module group has the same number of inverter units. However, this is not absolutely necessary. For example, each module group can have exactly 2 inverter units, can have up to 5 inverter units, can have up to 10 inverter units, can have up to 20 inverter units, can have up to 50 inverter units, can have up to 100 inverter units, can have up to 200 inverter units, can have up to 500 inverter units or can have even more inverter units.

[0088] Each module group may have a module control input connected to all control inputs of the inverter units in the module group and a module data output connected to all data outputs of the inverter units in the module group.

[0089] In order to reduce the line lengths within the data transmission system, it may be advantageous to form a module group from a plurality of inverter units. The line lengths within the module group can be relatively short. Since long line lengths are particularly associated with high line capacitances, reducing the line lengths can increase the transmission rate of the data transmission system. This is particularly advantageous (but not exclusively) for data lines if the inverter units have the above-described output switching elements.

[0090] In an advantageous embodiment of the invention, provision can be made for the data transmission system to have exactly one data line for each module group.

[0091] The control device can have a logic input gate, preferably an OR gate, whose input side is connected to the individual data lines of the module group and whose output side provides the individual combined data lines for further processing within the control device.

[0092] The input gates can thus be used to regroup data lines in the control device that originally ran in parallel.

[0093] In an advantageous embodiment of the present invention, each module group may have a logic output gate, preferably an OR gate, whose input side is connected to the respective data outputs of the inverter units in the module group and whose output side is connected to the module data outputs of the module group.

[0094] This can further improve the transmission rate of communication between the inverter unit and the control line.

[0095] In order to reduce the influence of the load current, according to an improvement of the present invention, a buffer can be optionally provided in the line or between the line and the input and output of the inverter unit and the control device. However, the buffer is not absolutely necessary, it is just another option to improve the data transmission system.

[0096] In one embodiment of the invention, a modular inverter may be provided having at least two inverter modules, wherein inverter units of the inverter are evenly distributed over the at least two inverter modules, and wherein the inverter modules are connected to form a series arrangement in order to jointly generate an AC voltage between main supply terminals of a main load connectable to the circuit arrangement.

[0097] In particular, a corresponding first power output terminal and a second power output terminal may be provided on each inverter module. In order to connect the inverter modules to form a series arrangement, the second power output terminal of the first inverter module is preferably connected to the first power output terminal of the second inverter module, and the AC voltage for supplying power to the main load can ultimately be generated between the first power output terminal of the first inverter module and the second power output terminal of the second inverter module.

[0098] Many electrical load arrangements have not only a primary load, but also one or more secondary loads. For example, electric vehicles require not only the drive motor, which can be considered the primary load, but also secondary loads such as air conditioning systems, headlights, entertainment systems or radios. Powering such secondary loads is usually done with a secondary voltage that is lower than the AC operating voltage, which is usually 12V or 48V DC in electric vehicles. In addition to providing the AC operating voltage, providing the secondary voltage is also relatively complex.

[0099] According to an improved embodiment of the present invention, the inverter modules may optionally have secondary power supply terminals arranged between them. Finally, the control device may be designed to configure the inverter units of the inverter modules in such a way that a secondary voltage is generated between the secondary power supply terminals and one of the primary power supply terminals to supply power to a secondary load that may be connected to the circuit device.

[0100] Preferably, the control device may be designed to regulate the secondary voltage independently of the AC voltage generated by the primary load by appropriately configuring the inverter module or its inverter unit.

[0101] The secondary load can in principle be any electrical load or a group of electrical loads. The secondary load is preferably an electrical load that can be operated independently of the primary load.

[0102] The secondary load can be connected to the secondary power supply terminal and at least one primary power supply terminal by any means. For example, the secondary load can be directly attached to the power supply terminal, or can be attached to the power supply terminal by a wire or busbar connected to the secondary load. In some cases, the circuit device can also be mechanically connected to the secondary load, for example, by press fit, form fit and / or material bonding with the housing portion of the secondary load.

[0103] Preferably, the secondary load is not to be understood as a component of the circuit arrangement.

[0104] The secondary load is preferably an electrical load which can be operated with a DC voltage, preferably a secondary load of an electric vehicle, in particular an electric vehicle, such as an air conditioning system, a headlight or an entertainment system.

[0105] The secondary voltage is preferably a voltage having a lower amplitude than the amplitude of the AC voltage supplying the primary load.

[0106] The proposed circuit arrangement can be used to generate a secondary voltage in order to supply the secondary load independently of the AC voltage of the primary load. This is very advantageous, since the AC voltage of the primary load usually depends on the current operating state of the primary load - for example, in the case of an electric motor of an electric vehicle, on the driving speed. Even in the case of a low AC voltage amplitude and / or a low AC voltage frequency, the proposed improved circuit arrangement can be used to continue to ensure reliable power supply to the secondary load. Thus, for example, even when the electric vehicle is traveling at a very low speed or is at a standstill, the secondary load of the electric vehicle can still be reliably operated at the first secondary voltage by means of the proposed circuit arrangement.

[0107] According to an improved embodiment of the present invention, a second inverter may be provided in the circuit arrangement, wherein the second inverter has a third main power supply terminal and a fourth main power supply terminal, between which a second AC voltage for supplying power to the main load exists.

[0108] Preferably, the third main supply terminal of the second inverter is connected to the second main supply terminal of the aforementioned first inverter.Thus, the inverters can be connected in series.

[0109] Thus, the main load can be connected to the first main supply terminal, the second main supply terminal (which is connected to the third main supply terminal) and the fourth main supply terminal, or attached thereto, in particular enabling three-phase operation.

[0110] In principle, the second inverter can be of any form. Therefore, the second inverter does not have to be configurable. However, preferably, the second inverter has the same design as the aforementioned first inverter. The features and advantages described above and below for one of the inverters can also be transferred to the other inverter. In principle, this also applies to the inverter modules of the inverter and the inverter units of the inverter modules.

[0111] Preferably, it is possible to provide a symmetrical three-phase voltage for supplying the main loads between the main supply terminals of the inverter.

[0112] In a further embodiment of the invention, a circuit arrangement with a rectifier can be provided, the rectifier being used to provide a DC voltage for supplying power to the secondary load. In principle, the secondary load can also be operated directly with an AC voltage, but this depends on the application or type of the secondary load. However, the secondary load preferably uses a DC voltage, for example a DC voltage between 12 volts and 48 volts. The input side of the rectifier can be connected to a first main supply terminal, a second main supply terminal, a fourth main supply terminal, a secondary supply terminal and / or another secondary supply terminal of one of the inverters in order to generate a DC voltage from one or more potential differences generated between the supply terminals connected to the input side.

[0113] The rectifier can be provided in the form of an electronic valve device or a valve device, which is connected to the supply terminals attached to the input side. The electronic valve device is used to ensure that the maximum potential difference generated between the supply terminals is always available to the output side to supply the secondary load. In particular, a diode can be provided for producing the electronic valve device. However, the use of a diode as a valve element should be understood as merely illustrative and not restrictive. As an alternative, a rectifier based on a thyristor or a rectifier of a different design can also be provided, for example.

[0114] Finally, the control device can be designed to always configure the inverter unit to firstly provide an AC voltage for supplying the primary load and secondly a potential difference between at least two supply terminals greater than the voltage required to operate the secondary load. Active charge balancing between DC voltage sources (e.g. battery cells) can be performed particularly easily if as many potential differences as possible are already independently large enough to operate the secondary load.

[0115] In a further development of the invention, the circuit arrangement can additionally be provided with a DC chopper, the input side of which is connected to the output side of the rectifier providing the DC voltage, and the output side of which provides the rated operating voltage for the operation of the secondary load. The DC chopper can be used to generate a stable DC voltage and to provide it to the secondary load. However, the use of a DC chopper is not absolutely necessary, in particular if the secondary load can also be operated with an unregulated DC voltage or the secondary voltage can already be regulated by the control device.

[0116] The invention also relates to a power supply system comprising a circuit arrangement according to the above and below and a DC voltage source.

[0117] Particularly advantageous applications of the proposed power supply system relate to supplying power to a low voltage grid or to primary loads of an electric vehicle.

[0118] In particular, the power supply system can be provided with an energy storage component comprising individual DC voltage sources. However, the DC voltage sources can also be independent of one another and do not necessarily need to be arranged in a common energy storage component.

[0119] In particular, it can be provided that the energy storage component has a battery or is in the form of a battery, and that the individual DC voltage sources are in the form of battery cells.

[0120] Advantageously, modular generation of the AC voltage enables selective active charge state control and thermal management based on the current battery charge state and / or temperature data, by involving individual battery cells or battery modules in the generation of the AC voltage, or by at least intermittently deactivating individual battery cells or battery modules based on instructions from a control device.

[0121] The invention also relates to an electrical load arrangement, in particular an electric vehicle or a household electrical network, comprising a power supply system according to the description above and below and at least one main load operated with an alternating voltage.

[0122] In principle, an electrical load device can be any load device having at least one main load that can be operated using an AC voltage. For example, the load device can be a building that needs to be powered.

[0123] The present invention is particularly suitable for use in providing electricity to homes or industrial facilities using solar cells.

[0124] The invention also relates to a method for generating an alternating voltage, comprising at least the following method steps:

[0125] - operating a modular inverter which is a cascade of multiple inverter units, each of which is connected to a dedicated DC voltage source; and

[0126] - operating a control device for configuring the inverter units, wherein each inverter unit uses the instructions of the control device as a basis for making the associated DC voltage source available or unavailable for generating an AC voltage on the output side, wherein the inverter units transmit status information about the respectively associated DC voltage source to the control device via data lines of a data transmission system, and wherein the control device sends control signals to the inverter units via control lines of the data transmission system to configure the inverter units based on the received status information, wherein the data transmission system uses clock generator lines and / or synchronization lines connected to the control device and all inverter units.

[0127] The proposed method can be used to generate an approximately sinusoidal AC voltage with very low harmonics by adding individual DC voltages of DC voltage sources, in particular based on the proposed signal transmission technology for fast and simple control of modular inverters.

[0128] The invention is particularly advantageously suitable for supplying power to an electric motor or to an electrical network which contains a battery as energy storage.

[0129] The proposed modular inverter can also be used to charge the battery via an external DC or AC power source.

[0130] Finally, the invention also relates to a computer program comprising control commands which, when a control device (in particular the aforementioned control device) executes the program, cause the control device to carry out the method described above.

[0131] Features that have been described in conjunction with one of the subjects of the present invention, in particular features provided by the circuit arrangement, the power supply system, the load arrangement, the method and the computer program, can also be advantageously implemented in other subjects of the present invention. Similarly, advantages that have been mentioned in connection with one of the subjects of the present invention can also be understood with respect to other subjects of the present invention.

[0132] It should be noted that the terms "connected" or "connection" used in this specification can describe both direct electrical connection of components and indirect electrical connection of components (for example, through further electrical lines or electronic devices such as resistors, inductors and / or capacitors). On the other hand, the term "attachment" generally indicates direct connection of components.

[0133] It should also be noted that terms such as "including", "having" or "with" do not exclude other features or steps. In addition, terms such as "one" or "the" that represent steps or features in the singular form do not exclude multiple features or steps, and vice versa.

[0134] However, in a pure embodiment of the present invention, it may also be provided that the features introduced by the terms "comprises", "has" or "with" are exhaustively listed in the present invention. Therefore, in the context of the present invention, one or more listings of features may be considered independent.

[0135] It should be noted that labels such as “first” or “second” are mainly used to distinguish the respective device or method features, and are not necessarily used to indicate that the features are interdependent or related to each other.

[0136] Furthermore, it should be emphasized that the values ​​and parameters described in the present case concomitantly include deviations or variations of ±10% or less, preferably ±5% or less, more preferably ±1% or less, very particularly preferably ±0.1% or less of the respectively mentioned value or parameter, as long as these deviations are not excluded in the embodiment of the present invention. The specification of a range by means of starting and ending values ​​also includes all those values ​​and fractions comprised by the respectively mentioned range, in particular the starting and ending values ​​and the respective mean values.

[0137] The invention also relates to a circuit device for generating a periodic output voltage, the circuit device comprising at least one modular function generator in the form of a cascade of a plurality of inverter units, a control device for configuring the inverter units and a data transmission system for signal transmission between the control device and the inverter units, wherein each inverter unit can be connected to a dedicated DC voltage source, each inverter unit has a control input and a data output, and the inverter unit is designed to receive a control signal from the control device via the control input and use this as a basis for making the associated DC voltage source available or unavailable for generating an output voltage on the output side, the output voltage having a curve shape specified by the control device, wherein the data transmission system has a control line connected to the control device and at least one data line connected to the control device, wherein the control line is additionally connected to the control input of the inverter unit and at least one data line is connected to the data output of the inverter unit, wherein the inverter unit is designed to use at least one data line to transmit status information related to the respectively associated DC voltage source to the control device, and wherein the control device is designed to transmit control signals based on the received status information to configure the inverter unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0138] Exemplary embodiments of the present invention are described in more detail below based on the accompanying drawings.

[0139] The accompanying drawings show preferred exemplary embodiments, in which the various features of the present invention are shown in combination with each other. The features of the exemplary embodiments can also be realized independently of other features of the same exemplary embodiment, and can therefore be easily combined with the features of other exemplary embodiments by a person skilled in the art to form further advantageous combinations and sub-combinations.

[0140] In the figures, functionally identical elements are provided with the same reference symbols.

[0141] According to the diagram:

[0142] 1 shows an electrical load device according to the invention having a power supply system according to the invention, the power supply system having a circuit device according to a first embodiment of the invention;

[0143] FIG. 2 shows an H-bridge circuit of an exemplary inverter unit of an inverter of a circuit arrangement according to the present invention;

[0144] FIG. 3 shows an electrical load device according to the invention having a power supply system according to the invention having a circuit device according to a second embodiment of the invention; and

[0145] FIG. 4 shows an electrical load arrangement according to the invention with a power supply system according to the invention having a circuit arrangement according to a third embodiment of the invention. DETAILED DESCRIPTION

[0146] FIG1 shows an electrical load device 1, which may be, for example, a household electrical grid or an electric vehicle (particularly an electric vehicle). The load device 1 has a power supply system 2 for supplying power to at least one primary load 3 and optionally to at least one secondary load 4. In principle, the primary load 3 may be a device that can be supplied with an AC voltage u AC Any load that can be operated by a power source, such as a light source, an electrical circuit, a heat source and / or an electric motor. In particular, the primary load 3 can be a conventional household appliance or multiple household appliances. The secondary load 4 can also be operated with an AC voltage, but in some cases a DC voltage u DC run.

[0147] The power supply system 2 has a circuit device 5 and a plurality of DC voltage sources 6. The DC voltage source 6 shown in dashed lines in FIG1 may be part of a common energy storage component. Such energy storage components are preferably batteries or battery packs, in particular solar cells, and a single DC voltage source 6 is in the form of a battery cell of a battery or battery pack. In particular, the DC voltage source 6 may be a battery cell of a photovoltaic home storage system or a battery cell of a high-voltage storage system of an electric vehicle. In the following text, the energy storage component is sometimes referred to as a battery, and the DC voltage source 6 is referred to as a battery cell. However, this is merely a preferred application and should not be construed as restrictive.

[0148] Therefore, the circuit arrangement 5 is mainly used to generate an AC voltage u for supplying power to the main load 3. AC , and for this purpose the circuit arrangement 5 has at least one modular inverter 7 in the form of a cascade of a plurality of inverter units 8. For this purpose, each inverter unit 8 can be connected to a dedicated DC voltage source 6. Thus, appropriate connection or disconnection of the individual DC voltage sources 6 within the series arrangement formed by the inverter units 8 can be used to generate the AC voltage u AC , the AC voltage u AC Preferably the voltage is as close to a sinusoidal oscillation as possible.

[0149] In order to supply power to the main load 3, the inverter 7 shown in FIG. 1 has a first main power supply terminal 9 and a second main power supply terminal 10, between which a first AC operating voltage u AC .

[0150] The circuit arrangement 5 has a control device 11 for configuring the inverter units 8 and a data transmission system 12 for transmitting signals between the control device 11 and the inverter units 8. Each inverter unit 8 has a control input s IN and data output terminals OUT , and is designed to be controlled via the input terminal s IN Receives a control signal from the control device 11 and uses it as a control signal to enable the associated DC voltage source 6 to generate an AC voltage u on the output side. AC or cannot be used to generate an AC voltage u AC Instructions.

[0151] The data transmission system 12 has a control line S connected to the control device 11 and at least one data line D connected to the control device 11, wherein the control line S is additionally connected to the control input s of the inverter unit 8. IN , and at least one data line D is connected to the data output terminal s of the inverter unit 8 OUT The inverter unit 8 is designed to transmit status information about the respectively associated DC voltage source 6 to the control device 11 using at least one data line D, and the control device 11 is further designed to transmit control signals for configuring the inverter unit 8 based on the received status information.

[0152] The status information may be, in particular, information about the current state of charge, the current temperature or the current “state of health” of the respective DC voltage source 6 or battery cell. To determine the status information, the energy storage assembly including the DC voltage source 6 or the battery may have a battery management system which records the status information and makes it available to the individual inverter units 8.

[0153] In particular, the control device 11 can be designed to periodically configure the inverter unit 8 through the control line S to obtain the voltage U of the DC voltage source 6. DC Generates AC voltage u ACIn particular, the control device 11 may be designed to load the inverter unit 8 differently based on the respective charging states of the applicable DC voltage sources 6, the respective charging states being transmitted to the control device 11 as state information, so that a charge balance is generated between the DC voltage sources 6. The control device 11 may also be configured to at least temporarily exclude the inverter unit 8 from participating in the generation of the AC voltage based on the charging state, temperature state and / or fault state of the applicable DC voltage source 6, the charging state, temperature state and / or fault state being transmitted to the control device 11 as state information.

[0154] A particularly advantageous communication between the control device 11 and the inverter unit 8 can be achieved if the inverter unit 8 transmits status information only upon request by the control device 11. To this end, the control device 11 can transmit a unique identifier associated with the applicable inverter unit 8 via the control line S, one of the other lines mentioned below, or in other ways, thereby requesting the status information of the respective inverter unit 8.

[0155] In order to reduce the influence of the load current, optional buffers 13 may be provided between the corresponding lines and the input and output of the inverter unit 8 and the control device 11 .

[0156] Finally, each inverter unit 8 also has an output switching element 14, which is connected to the output terminal s OUT connected to the data line D and, if the applicable inverter unit 8 does not transmit status information, the output switching element 14 can switch the data output terminal s OUT In this way, conflicts between logic states on the data line D can be avoided particularly easily.

[0157] In order to increase the data rate of signal and data transmission between the control device 11 and the inverter unit 8, a clock generator line CLK may be provided to provide a synchronous data transmission system 12. Preferably, the control device 11 generates a suitable clock signal to synchronize the signal transmission on the clock generator line CLK.

[0158] Furthermore, the data transmission system 12 can have a synchronization line SYNC connected to the control device 11 and all inverter units 8. The control device 11 can be designed to generate a suitable synchronization signal on the synchronization line SYNC, wherein the inverter units 8 are designed to eventually synchronize or couple the switching time, i.e. when the AC voltage u AC During the generation, the timing at which the output side voltage of each inverter unit 8 changes is synchronized with the timing at which the synchronization signal is received.

[0159] Preferably, the data transmission system 12 therefore has four line types, which are indicated as “control line S”, at least one “data line D”, “clock generator line CLK” and “synchronization line SYNC”.

[0160] In order to further improve signal transmission, the control device 11 and the inverter unit 8 can be provided with respective potential isolation elements 15, preferably digital isolators or optocouplers, so as to facilitate signal transmission in an isolated manner through the control line S, at least one data line D, the clock generator line CLK and / or the synchronization line SYNC, while the two sides of these lines have different voltage levels.

[0161] The inverter unit 8 and the control device 11 can have a data processing module 16 in order to generate and evaluate the communication signals and connect the H bridge mentioned again below according to the provisions of the control device. The data processing module 16 of the control device 11 can be in the form of a master device, and the data processing modules 16 of the inverter unit 8 can each be in the form of a slave device.

[0162] The proposed data transmission system 12 can be used to provide particularly advantageous communication capabilities between the control device 11 and the inverter unit 8 (or their corresponding data processing modules 16), which means that a particularly high-quality AC voltage u can be generated due to the advantageous precise synchronization capabilities. AC .

[0163] Optionally, in particular, if the secondary voltages u1, u2 are to be provided not only for the main load 3 but also for the secondary load 4, the modular inverter 7 can be decomposed into at least two inverter modules 17, the inverter units 8 are distributed on the inverter modules 17 (preferably evenly distributed), and the inverter modules 17 are connected to each other to form a series arrangement, so as to jointly generate an AC voltage u1 between the main power supply terminals 9, 10 for the main load 3. AC The inverter module 17 may have a secondary power supply terminal 18 arranged therebetween. The control device 11 may ultimately be designed to configure the inverter unit 8 of the inverter module 17 so that at least one secondary voltage u1, u2 is generated between the secondary power supply terminal 18 and one of the main power supply terminals 9, 10 to supply power to the secondary load 4.

[0164] If the operation of the secondary load 4 requires a DC voltage u DC , then preferably a rectifier 19 may also be provided, the input side of the rectifier 19 being connected to the first main power supply terminal 9, the second main power supply terminal 10 and the secondary power supply terminal 18, so as to generate potential differences u1, u2, u3 between the power supply terminals 9, 10, 18 connected to the input side. AC One or more of the required DC voltage u is generated DCPreferably, the rectifier 19 may have an electronic valve device, which may in particular use a diode as a valve unit. In some cases, a DC chopper may also be provided to generate a stable DC voltage.

[0165] In principle, the cascaded inverter units 8 can be connected in any manner in order to connect the DC voltage sources 6 to one another as specified. An exemplary design is shown in FIG2 . Each inverter unit 8 can have a power supply line 20 that can be connected to a battery unit or a DC voltage source 6. In addition, the inverter unit 8 has a communication line 21 that can be connected to the data processing module 16 of the inverter unit 8 and / or the control device 11 of the circuit arrangement 5.

[0166] In particular, each inverter unit 8 can have an H-bridge circuit 22, which includes four power electronic switching elements 23 that can be configured by the control device 11 or the control module 16. By way of example, the power electronic switching elements 23 can be in the form of semiconductor devices, in particular in the form of MOSFETs as shown in FIG. 2. A suitable configuration of the switching elements 23 can be used to specify three possible voltage levels (0, +U, and +V) on the output side in each case. DC and -U DC ).

[0167] A disadvantage of the proposed output switching element 14 may be a lower transmission rate of the data line D, in particular for longer line lengths, since relatively high line capacitances may occur. To increase the data transmission rate, a plurality of inverter units 8 may be combined in a common module group 24, as shown in FIG.

[0168] For the sake of simplicity, some details are not shown in FIGS. 3 and 4 , in particular details on the output side, such as the interconnection with the primary load 3 and the optional secondary load 4 .

[0169] The circuit arrangement 5 may have a plurality of instances of a module group 24, each module group 24 having all control inputs s connected to the inverter units 8 of the module group 24. IN The module control input terminal M IN and all data outputs s of the inverter units 8 connected to the module group 24 OUT The module data output terminal M OUT The line length within the corresponding module group 24 can be significantly reduced. The individual data output terminals s of the inverter units 8 of the module group 24 OUT The modules can be easily combined or interconnected within the module group 24 .

[0170] Preferably, exactly one data line D is provided in the data transmission system 12 for each module group 24. Finally, the control device 11 can have a logic input gate 25, preferably an OR gate, whose input side is connected to the individual data lines D of the module groups 24 and whose output side provides a single combined data line for further processing in the control device 11.

[0171] This allows the data transmission via the data line D to be significantly accelerated overall.

[0172] In order to further increase the transmission rate through the data line D, a further improvement can be provided. As shown in FIG. 4 , according to the improved embodiment, each module group 24 has a logic output gate 26, preferably an OR gate, whose input side is connected to the respective data output terminals s of the inverter unit 8 of the module group 24. OUT , whose output side is connected to the module data output terminal M of the module group 24 OUT .

Claims

1. A method for generating an alternating voltage (u AC ) of the invention, comprising: at least one modular inverter (7) in the form of a cascade of a plurality of inverter units (8); A control device (11) for configuring the inverter unit (8); and A data transmission system (12) for transmitting signals between the control device (11) and the inverter unit (8), Each inverter unit (8) can be connected to a dedicated DC voltage source (6), and each inverter unit has a control input terminal (s IN ) and data output terminal (s OUT ), and the inverter unit is designed to pass the control input terminal (s IN ) receives a control signal from a control device (11) as an instruction, so that the relevant DC voltage source (6) can be used to generate an AC voltage (u AC ) or cannot be used to generate AC voltage (u AC ), wherein the data transmission system (12) has a control line (S) connected to the control device (11) and at least one data line (D) connected to the control device (11), wherein the control line (S) is additionally connected to a control input (s) of the inverter unit (8) IN ), and at least one data line (D) is connected to a data output terminal (s) of the inverter unit (8) OUT ), wherein the inverter units (8) are designed to use at least one data line (D) to transmit status information related to the respectively associated DC voltage source (6) to the control device (11), and wherein the control device (11) is designed to transmit a control signal based on the received status information to configure the inverter unit (8), The invention is characterized in that a plurality of inverter units (8) are combined to form a common module group (24), wherein the circuit arrangement (5) has a plurality of module groups (24) and wherein each module group (24) has a control input (s) connected to all the inverter units (8) in the module group (24). IN ) connected to the module control input (M IN ) and all data output terminals (s) of the inverter units (8) in the module group (24) OUT ) connected to the module data output terminal (M OUT ), wherein the data transmission system (12) has exactly one data line (D) for each module group (24), wherein the control device (11) has a logic input gate (25) whose input side is connected to the data line (D) and whose output side provides a single combined data line for further processing in the control device (11), and wherein each module group (24) has a logic output gate (26) whose input side is connected to the respective data output (s) of the inverter unit (8) in the module group (24). OUT ), whose output side is connected to the module data output terminal (M OUT ).

2. The circuit arrangement (5) according to claim 1, characterized in that The control device (11) is designed to cyclically configure the inverter unit (8) via a control line (S) to generate an AC voltage (u) from each voltage of the DC voltage source (6). AC ), wherein the control device (11) is also designed to load the inverter unit (8) differently based on the corresponding charging state of the applicable DC voltage source (6), and the charging state is transmitted to the control device (11) as state information so that the charge between the DC voltage sources (6) is balanced.

3. The circuit arrangement (5) according to claim 1, characterized in that The control device (11) is designed to cyclically configure the inverter unit (8) via a control line (S) to generate an AC voltage (u) from each voltage of the DC voltage source (6). AC ), wherein the control device (11) is further designed to at least temporarily exclude the inverter unit (8) from participating in the generation of the AC voltage (u AC ), the charging state, temperature state and / or fault state are transmitted to the control device (11) as state information.

4. The circuit arrangement (5) according to claim 1, characterized in that The inverter unit (8) is designed to transmit status information only when requested by the control device (11), wherein the control device (11) is designed to request the status information of the corresponding inverter unit (8) by transmitting a unique identifier associated with the applicable inverter unit (8) via the control line (S).

5. The circuit arrangement (5) according to claim 1, characterized in that Each inverter unit (8) has an output switching element (14) which is connected to the inverter via a data output terminal (s OUT ) is connected to the data line (D), and if the applicable inverter unit (8) does not transmit status information, the output switching element (14) is capable of switching the data output terminal (s OUT ) is placed in a high impedance state.

6. The circuit arrangement (5) according to claim 1, characterized in that The data transmission system (12) also has a clock generator line (CLK) connected to the control device (11) and all inverter units (8), wherein the control device (11) is designed to generate a clock signal in order to synchronize the signal transmission between the control device (11) and the inverter units (8) on the clock generator line (CLK).

7. The circuit arrangement (5) according to claim 1, characterized in that The data transmission system (12) also has a synchronization line (SYNC) connected to the control device (11) and all inverter units (8), wherein the control device (11) is designed to generate a synchronization signal on the synchronization line (SYNC), and wherein the inverter units (8) are designed to synchronize the switching time, i.e. when the AC voltage (u AC ) is being generated, the timing at which the output side voltage of each inverter unit (8) changes is synchronized with the timing at which the synchronization signal is received.

8. The circuit arrangement (5) according to claim 7, characterized in that The control device (11) and the inverter unit (8) have respective potential isolation elements (15) so that signals are transmitted in an isolated manner via a control line (S), at least one data line (D), a clock generator line (CLK) and / or a synchronization line (SYNC) based on different voltage levels.

9. The circuit arrangement (5) according to claim 1, characterized in that A modular inverter (7) has at least two inverter modules (17), wherein the inverter units (8) of the modular inverter (7) are evenly distributed over the at least two inverter modules (17), and wherein the inverter modules (17) are connected to form a series arrangement in order to jointly generate an AC voltage (U) between two main supply terminals (9, 10) on the output side of a main load (3) connectable to a circuit arrangement (5). AC ), wherein the inverter modules (17) have secondary supply terminals (18) arranged between them, and wherein the control device (11) is designed to configure the inverter unit (8) of the inverter module (17) so that a secondary voltage (u2) is generated between the secondary supply terminal (18) and one of the main supply terminals (9, 10) to supply power to a secondary load (4) that can be connected to the circuit device (5).

10. A power supply system (2) comprising a circuit arrangement (5) according to any one of claims 1 to 9 and a DC voltage source (6).

11. An electric load device (1), comprising a power supply system (2) according to claim 10 and a power supply device (2) using an alternating voltage (u AC ) operates at least one main load (3).

12. A method for generating an alternating voltage (u AC ), comprising at least the following steps: Operating a modular inverter (7) which is a cascaded form of a plurality of inverter units (8), wherein each inverter unit (8) is connected to a dedicated DC voltage source (6); A control device (11) for configuring the inverter units (8) is operated, wherein each inverter unit (8) uses the instructions of the control device (11) as a command to make the associated DC voltage source (6) available for generating an AC voltage (u AC ) or cannot be used to generate AC voltage (u AC ), and wherein the inverter units (8) transmit status information about the respectively associated direct current voltage sources (6) to the control device (11) via data lines (D) of the data transmission system (12), and wherein the control device (11) sends control signals to the inverter units (8) via control lines (S) of the data transmission system (12) to configure the inverter units (8) based on the received status information; and A plurality of inverter units (8) are combined to form a common module group (24), wherein the circuit arrangement (5) has a plurality of module groups (24) and wherein each module group (24) has a control input (s) connected to all the inverter units (8) in the module group (24). IN ) connected to the module control input (M IN ) and all data output terminals (s) of the inverter units (8) in the module group (24) OUT ) connected to the module data output terminal (M OUT ), wherein the data transmission system (12) has exactly one data line (D) for each module group (24), wherein the control device (11) has a logic input gate (25) whose input side is connected to the data line (D) and whose output side provides a single combined data line for further processing in the control device (11), and wherein each module group (24) has a logic output gate (26) whose input side is connected to the respective data output (s) of the inverter unit (8) in the module group (24). OUT ), whose output side is connected to the module data output terminal (M OUT ).

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