Selectively combinable electric machine and electric drive with selectable components

Abstract

An electrical machine (EM) is provided with a first and a second multiphase winding system (W1, W2). Each winding system (W1, W2) has a first end (FE1, FE2) that can be connected to an inverter output (IF1, IF2) and a second end (SE1, SE2) with a plurality of phases (U, V, W). A first switch (SW1) is connected between the second ends (FE1, FE2), a second switch (SW2) is connected between the second end (SE1) of the first winding (W1) and a first star point (S1), and a third switch (SW3) is connected between the second end (SE2) of the second winding (W2) and a second star point (S2). The first switch (SW1) is arranged between the second and third switches (SW2, SW3). Furthermore, an electric drive (ED) is provided, which has the electric machine (EM).

Description

Electric-drive vehicles typically include an accumulator (battery) that powers a polyphase inverter and a polyphase electric machine powered by the polyphase inverter. The inverter and the electric machine have a plurality of phases to generate a rotating magnetic field for driving the rotor of the electric machine.As a rule, these components are monitored and switched off in the event of a fault. The availability of the drive thus depends on the availability of all phases of all components. Increased availability would be advantageous. In addition, the optimum efficiency of an electric drive is generally achieved only in a narrow range of operating parameters. However, electric drives are operated in a variety of different operating situations, such as a maximum power range for fast driving and accelerating and a reduced power range for constant or low speed driving. It is the object of the invention to provide a drive which provides a high degree of efficiency for such different operating situations.This object is achieved by the subject matter of claim 1. Further characteristics, features, embodiments and advantages emerge from the dependent claims, the description and the figure.It is proposed to provide an electric machine having at least two polyphase winding systems, the open ends of which can be connected in series by a first switch or which can be disconnected from one another to form a separate star point for each of the winding systems. Depending on the operating parameters, the most effective configuration may be provided. In addition, in the event of a failure in one of the winding systems (or in one of the connected inverters), the configuration of individual winding systems may be provided, which enables the defective winding system to be deactivated, while the other winding system may be used for the drive. This enables an emergency operation function. Other embodiments and their advantages will be described below.An electric machine is described which has (at least) a first and a second polyphase winding system. Each winding system has a plurality of phases (3, 5, 6,... ). The number of phases of the first winding system is equal to the number of phases of the second winding system. Preferably, there are two winding systems, each of which has three phases. Each winding system has a first end connectable to an inverter output and a second end having a plurality of phases. Each winding system is an open-end winding system, i.e. it has open ends. Star points can be switchably connected to the second ends. A first switch is connected between the second ends, i.e. between the second end of the first winding system and the second end of the second winding system. The first switch is a polyphase switch. The number of phases of the switch corresponds to the number of phases of the individual winding systems. The first switch may be provided for synchronously opening / closing all phases. Further, the first switch may be provided for individually opening / closing the phases (e.g., by at least one single switching element per phase). The first switch is adapted to controllably connect the open ends of the winding together. This results in a series connection of the winding systems, i.e. the windings of the different systems. In this case, the phases of the various winding systems are individually connected to one another, phase by phase. The first switch enables a controllable establishment of a connection between the phases in series (and a controllable breaking of this connection). The first switch is connected to the ends of the winding systems opposite the ends of the winding systems located at an inverter connection interface (to be connected to the inverter output / AC side of the inverter and to the inverter output / AC side of the inverter, respectively). The first switch may be referred to as a series connection switch.There are a second and a third switch. These switches are provided to controllably connect the second ends of the winding systems to an associated neutral point. The second switch connects the first winding system to a first neutral point. The third switch connects the second winding system to a second neutral point. In other words, the second and the third switch controllably connect the phases of the associated winding system to one another, so that a star point is produced. The neutral point may be provided by an internal connection within the second and / or third switch, i.e. between the switching elements of the second and third switches.The second switch is connected between the second end of the first winding and a first neutral point. The third switch is connected between the second end of the second winding and a second neutral point. Since the electrical function is the same, this formulation includes the second and third switches selectively (by switching) providing a neutral point at the second ends connected to them. The second and / or third switch may be provided for synchronously opening / closing all phases. Furthermore, the second and / or the third switch can be provided for individually opening / closing the phases (by at least one single switching element per phase), whereby a partial star point is produced. The second and third switches may be referred to as neutral switches (as they connect the open ends of the winding systems to a neutral point or provide a neutral point if desired).The first switch is located between the second and third switches. The second switch is connected to the third switch via the first switch. The ends of the second switch opposite the first neutral point are connected to the first switch. The ends of the third switch opposite the second neutral point are connected to the first switch. These ends of the second and third switches are connected to opposite ends of the first switch. The second switch and the third switch are arranged symmetrically with respect to the first switch. The first winding system and the second winding system are arranged symmetrically with respect to the first switch.A fourth switch and a fifth switch may be provided. The fourth switch is connected between the second end of the first winding on the one hand and the first switch and the second switch on the other hand. A polyphase connection point may be present, which connects the first switch (in particular the end of the first switch facing the first winding system) to the second switch (in particular the end of the second switch facing the first winding system). The fourth switch connects the second ends of the first winding system to this polyphase connection point.The fifth switch is preferably connected between the second end of the second winding on the one hand and the first switch and the third switch on the other hand. Furthermore, an additional polyphase connection point can be present, which connects the first switch (in particular the end of the first switch facing the second winding system) to the third switch (in particular the end of the third switch facing the second winding system). The fifth switch connects the second ends of the second winding system to this additional polyphase connection point.The fourth switch connects the second end of the first winding system (in series) to the first switch. The fifth switch connects the second end of the second winding system (in series) to the first switch (but at the opposite end of the first switch). The first switch connects the fourth switch to the fifth switch. The fourth switch, the first switch, and the fifth switch form a series circuit (in this order). The second switch is connected to the connection point between the first and fourth switches. The third switch is connected to the connection point between the first and fifth switches. The fourth and the fifth switch can be referred to as isolating switches which bring about (switchable) isolation of the second ends (open ends) of the winding systems from the first switch and / or the second and third switches and / or the neutral points.The fourth and fifth switches may be provided for synchronously opening / closing all phases. Further, the fourth and fifth switches may be provided for individually opening / closing the phases (e.g., by at least one single switching element per phase).A control device that controls the switches may be provided. The control device may be part of the electric machine or the electric drive. The switches are controllably connected to the controller. The control inputs of the switches can be connected to associated control outputs of the control device. The control device can be provided as a single instance or by hierarchically arranged control elements. The control device is designed such that a combined drive mode is possible. In the combined drive mode, the control device provides the first switch in the closed state and the second switch and the third switch in the open state. The control device is configured to control the switches in this manner. In the combined drive mode, the control device is designed to connect the winding system in series, i.e. to connect the open ends (second ends) of the winding systems. In the combined drive mode, the control device is designed to separate or suppress the star points. In the combined drive mode, the controller provides the fourth and fifth switches (if present) in a closed state. In this way, the control device provides a phase-specific connection of the first switch to the second ends of the winding systems.The control device is preferably designed to provide an individual drive mode. In the individual driving mode, the control device provides the first switch in an open state and the second switch and the third switch in a closed state. In the individual drive mode, the controller provides the first star point for the first winding system at the second end of the first winding system (or connects the first star point to the second (open) end of the first winding system). In the individual drive mode, the controller provides the second star point for the second winding system at the second (open) end of the second winding system (or connects the second star point to the second end of the second winding system). In the individual drive mode, the control device provides for an electrical disconnection of the first winding system from the second winding system. In the individual drive mode, the fourth and fifth switches are closed, whereby the associated second ends are connected to the second / third switch or, in other words, to the star points.The control device preferably has an emergency drive mode. In the emergency drive mode, the control device provides the first switch in the open state and preferably either the second or the third switch in the open state, while the other of these two switches (second, third switch) is provided by the control device in the closed state. In the emergency drive mode, the control device ensures disconnection of the winding systems (by means of an open first switch), in order in particular to be able to disconnect a defective winding system or an inverter connected thereto from the rest of the drive or the machine. When the emergency drive mode reflects a fault in the first winding system (or inverter connected thereto), the third switch is closed, whereby the second winding system (and inverter connected thereto) can be activated. In this case, the second switch can be opened. When the emergency drive mode reflects a fault in the second winding system (or inverter connected thereto), the second switch is closed, whereby the first winding system (and inverter connected thereto) can be activated. In this case, the third switch can be opened.In the emergency drive mode, the control device provides the second and / or the fourth switch (if present) in the open state, while the third and / or the fifth switch (if present) is provided by the control device in the closed state. If the emergency drive mode reflects a fault in the first winding system (or in the inverter connected thereto), the control device can provide the fourth switch (if present) in the open state (while the fifth switch, if present, is preferably provided by the control device in the closed state). If the emergency drive mode reflects a fault in the second winding system (or the inverter connected thereto), the control device can provide the fifth switch (if present) in the open state (while the fourth switch, if present, is preferably provided by the control device in the closed state). If the emergency drive mode reflects a fault in the first winding system (or the inverter connected thereto), the inverter connected thereto is switched off by the control device, by a control entity connected upstream of the control device or by an entity connected downstream of a control entity connected upstream of the control device. If the emergency drive mode reflects a fault in the second winding system (or the inverter connected thereto), the inverter connected thereto is switched off by the control device, by a control entity connected upstream of the control device or by an entity connected downstream of a control entity connected upstream of the control device.The control device is designed such that it controls the first switch on the one hand and the second and the third switch on the other hand in a reversed or complementary manner. When the first switch is open, the second and third switches are closed and vice versa. This concerns several modes of the control device, apart from a shutdown mode in which all switches are provided in the open state. In the combined drive mode, the first, fourth and fifth switches are synchronously controlled and provided in the same switching state. When switching from this mode to another mode, e.g. the individual drive mode, the first switch is opened before the second and third switches are closed.Preferably, the control device has a reduced mode. In the reduced mode, the controller provides at least one switch for at least one of the phases of all switches in the closed state and for the other phase(s) in the open state. In this mode, only a part of all phases is connected, while the other(s) phase(s) is / are interrupted. In the event of a fault in one phase, the switch is provided in the open state for this phase and is provided in the closed state for all phases other than the said phase. The associated switch is designed such that it enables phase-specific switching. This also applies to the control device that controls the associated switch. In this way, in the combined drive mode or in the individual drive mode, only a portion (but not all) of the phases can be activated. In the individual drive mode, one of the winding systems can be fully activated and connected (by the switches), while the other winding system is only partially activated and has at least one phase which is isolated by the associated switch (fourth or fifth switch / / second or third switch).The control device can also have a safety or fault mode in which the control device provides all switches in the open state, in particular in order to avoid damage.The windings are preferably located in the same stator of the electric machine. The windings may be located in different stators with both stators applying force to the same drive shaft. In particular, the windings have the same dimensioning, especially with regard to winding patterns, layers, conductor diameters, winding numbers, etc. The phases of the various winding systems can be provided with an angular offset.The electric machine can be used in an electric drive. Such an electric drive can have the electric machine described in the present case. The electric drive has a first inverter. The first inverter is connected to the first winding system, in particular to the first end thereof. The electric drive has a second inverter. The second inverter is connected to the second winding system, in particular to the first end thereof. Each of the inverters has a DC (direct current) side and an AC (alternating current) side. The AC sides of the inverters may include an inverter port interface. The first winding system is connected to the inverter terminal interface of the first inverter. The second winding system is connected to the inverter terminal interface of the second inverter. The status (active / inactive) of each inverter can be controlled by the control device, by a control entity connected upstream of the control device or by a (subordinate) control entity connected downstream of a control entity, which also controls the control device.In the combined drive mode, both inverters are active and provide, for example, a common switching pattern for the inverters. In the individual drive mode, both inverters are active and, for example, each provide a switching pattern for the inverters that may be synchronized or interleaved between the inverters. In the emergency drive mode, one of the inverters is active (for all or only a portion of the phases), while the other inverter is inactive (for all or a portion of the phases). In the emergency drive mode, the active inverter is the one connected to the winding system which is connected to a closed second / third switch, i.e. has a neutral point. The first inverter, which is connected to the first winding system via the fourth switch, is active when the fourth switch is at least partially closed. The first inverter, which is connected to the first winding system via the fourth switch, is inactive when the fourth switch is open. The second inverter, which is connected to the second winding system via the fifth switch, is active when the fifth switch is at least partially closed. The second inverter, which is connected to the second winding system via the fourth switch, is inactive when the fifth switch is open. In a reduced mode, the inverter connected to the at least one switch that is in the closed state for at least one of the phases and is in the open state for the other phase(s) is active in a phase reduced mode. In a phase-reduced mode, only the phases of the inverter that are connected to the phases of the winding system for which the associated switch is in the closed state are active. The reduced mode may relate to both winding systems / inverters or only to one of the winding systems / inverters, while the other winding system / inverter is active for all phases. In the shutdown mode, the inverters are inactive (for all inverter phases).The first inverter preferably has a DC side connected to a first traction accumulator. The first traction accumulator can be part of the electric drive or can be connected to a first supply terminal of the drive, which in turn is connected to the first inverter of the drive. The second inverter preferably has a DC side connected to a second traction accumulator. The second traction accumulator can be part of the electric drive or can be connected to a second supply terminal of the drive, which in turn is connected to the second inverter of the drive. The accumulators and / or the supply connections are high-voltage / high-power components which are designed for driving a vehicle.The first traction accumulator and the second traction accumulator may be connected in parallel via an accumulator switch. When there is no fault, particularly in the combined drive mode and the individual drive mode, the accumulator switch is in the closed state. In the reduced mode (at least one / s of the inverter / winding systems is active only for a reduced number of phases), the accumulator switch can also be closed. In the emergency mode (one / s of the inverter / winding systems has failed), the accumulator switch is preferably open. In the shutdown mode, the accumulator switch is preferably open. The control device is designed to control the accumulator switch. Alternatively, a control entity connected upstream or downstream of the control device or a control entity connected downstream of a control entity connected upstream of the control device can control the accumulator switch.For controlling the accumulator switch, a control device, in particular one of the aforementioned control devices, can be provided. The control device preferably has a combined mode in which the control device provides the accumulator switch in the closed state and a disconnection mode in which the control device provides the accumulator switch in the open state. In the combined drive mode and the individual drive mode, the combined mode applies. The combined mode can also be applied in the reduced mode. In the emergency mode and the shutdown mode, the disconnection mode applies.All or a part of the switches may be provided in a switching unit connected to the winding systems. The switching unit and the winding systems (and the associated stators) can be arranged at different positions. FIG. 1 shows an embodiment of an electric drive useful for describing embodiments of the invention.The electric drive ED from FIG. 1 shows an electric machine EM having a first and a second winding system W 1, W 2 and switches SW 1 to SW 5 connected thereto. Furthermore, the electric drive ED from FIG. 1 has a first and a second inverter I 1, I 2, each inverter having an intermediate circuit capacitor C 1, C 2 and a power module PM 1, PM 2, which are each illustrated by way of example as a controllable 3-phase bridge circuit (B 6C). A first and a second accumulator (traction battery) A 1, A 2 are present. The first accumulator is connected to the first inverter I 1, which has the first intermediate circuit capacitor C 1 and the first power module PM 1. The second accumulator is connected to the second inverter I 2 that includes the second DC link capacitor C 2 and the second power module PM 2. The accumulators are connected in parallel by an accumulator switch AS, which has a first switching element E1 (for the negative voltage potential) and a second switching element E2 (for the negative voltage potential). The elements E1 and E2 are switched synchronously.The first inverter I 1 has a first inverter interface IF 1. The second inverter I 2 has a second inverter interface IF 2. An electric machine EM of the electric drive ED is connected to the inverters I 1, I 2, in particular to their interfaces IF 1, IF 2. The electric machine EM has two winding systems W 1, W 2. The first end FE 1 of the first winding system W 1 is connected to the first inverter I 1 via the first inverter interface IF 1. The first end FE 2 of the second winding system W 2 is connected to the second inverter I 2 via the second inverter interface IF 2. The first end FE 1 of the first winding system W 1 has three phases U, V, W. This also applies to the first end FE 12 of the second winding system W 2. The second ends SE 1, SE 2 of the first and second winding systems W 1, W 2 also have three phases. The second end SE 1 of the first winding system W 1 is opposite to the first end FE 1 of the first winding system W 1 with respect to the windings. The second end SE 2 of the second winding system W 2 is opposite to the first end FE 2 of the second winding system W 2 with respect to the windings. Switches are connected to the second ends SE 1, SE 2.A first switch SW 1 is provided in a switchable series connection between the second ends SE 1, SE 2. A first neutral point S 1 is connected to the first switch SW 1 (at one end thereof) via a second switch SW 2. A second neutral point S2 is connected to the first switch SW1 (at the opposite end thereof) via a third switch SW3. A fourth switch SW 4 connects (switchable) the second end SE 1 of the first winding system W 1 to both the first switch and the second switch. The fourth switch SW 4 connects the second end SE 1 of the first winding system W 1 to the side of the first switch SW 1 facing the second end SE 1 and to the side of the second switch SW 2 opposite to the end of the second switch SW 2 provided with or connected to the first neutral point S 1. A fifth switch SW 5 connects (switchable) the second end SE 2 of the second winding system W 2 to both the first switch SW 1 and the third switch SW 3. The fifth switch SW 5 connects the second end SE 2 of the second winding system W 2 to the side of the first switch SW 1 facing the second end SE 2 and to the side of the third switch SW 3 opposite to the end of the third switch SW 3 provided with or connected to the second neutral point S 2. The neutral point S 1 may be a part of the second switch SW 2. The neutral point S 2 may be a part of the third switch SW 3. The switchable series connection between the second ends SE 1, SE 2 is provided by the fourth switch SW 4 connected between the second end SE 1 and the first switch SW 1. The first switch SW 1 connects the fourth switch SW 4 and the fifth switch SW 5. The fifth switch SW 5 connects the second end SE 2 to the first switch. The series connection between SE 1 and SE 2 is provided by the switches SW 4, SW 1, and SW 5 (in this order).A control device C controls the switches AS, SW 1, SW 2, SW 3, SW 4, and SW 5. In a combined drive mode, the controller C provides SW 1, SW 4, and SW 5 in a closed state. The inverters collectively drive the first and second winding systems connected to each other. The switches SW 2 and SW 3 are open, there is no neutral point for the winding systems W 1, W 2. Rather, the winding systems W 1, W 2 are in an open-end mode. The combined drive mode is comparable to the operation of a dual inverter.In the individual drive mode, SW1 is open to have separate winding systems W1, W2. In order to provide a connection between the winding systems W 1, W 2 and the inverters I 1, I 2, SW 4 and SW 5 are closed. SW4 and 5 thus provide a phase-specific connection. In the individual drive mode, the winding systems W 1 and W 2 are provided in a star configuration by closing the switches SW 2 and SW 3. At this time, the phases of the second ends of each of the winding systems W 1, W 2 are connected, resulting in a star point configuration with the star points S 1, S 2.In the case of a fault F in one of the inverters or in one of the winding systems (in FIG. 1 : fault in the inverter I 1 as an example), an emergency drive mode is provided. In the emergency mode, the switch SW 1 is open to prevent the propagation of the fault F to the second inverter I 2 or the second winding system W 2. Further, the neutral point of the winding system having the fault or connected to the inverter 11 having the fault F is canceled. This is ensured by the switch SW 2 being in the open state. The other (fault-free) inverter and the winding system connected thereto (i.e. the winding system which neither has a fault nor is connected to an inverter with fault) are active. That is, the other inverter I 2 operates and the winding system (the fail-free winding system) connected thereto is in a neutral point configuration because the switch SW 3 is in a closed state. Thus, in the example of FIG. 1, the second winding system W 2 has a star point in the form of the second star point S 2. In the emergency drive mode, the drive may be operated by one of the winding systems and the inverter connected thereto while the other winding system and the inverter connected thereto is deactivated (since the deactivated inverter is in the open state, is not pulsed or is not powered, and there is a deactivated winding system resulting from an open neutral point, i.e., an open switch SW 2).In a reduced mode, only one phase is disabled and the remaining phases are active. In the event of a fault F in the first phase U of the first inverter I 1, this phase of the inverter is deactivated. When the reduced mode is combined with the combined drive mode, the same phase of the second inverter (generally, the other inverter) is deactivated. Furthermore, in particular when combined with the combined drive mode, the switches SW 2 and SW 3 are closed only for the error-free phases and are open for the phase(s) having a fault(s). When the reduced mode is combined with the individual driving mode, only the phase of the inverter or the winding system in which the fault occurs is deactivated. This is done by providing the associated phase of the associated inverter in the open state (not pulsed) and closing the associated star switch only for the unaffected phases. The phases of the inverter and winding system that are not affected by or connected to a failed winding or inverter (rsp.) are activated. In this context, an activated inverter provides a pulsed signal for all phases, and in an activated winding system, all phases are connected in a star configuration (with the associated star switch in the closed state for all phases). The first switch SW1 is in an open state to allow the winding systems to operate with a different number of active phases.In the shutdown mode, inverters I 1, I 2 are inactive and the switches are open (at least SW 1, SW 4, and SW 5, or SW 1, SW 2, and SW 3, or SW 1 to SW 5).In the combined mode of the accumulators, the traction accumulators A1, A2 are connected in parallel by the switch AS. In the disconnect mode, the switch AS is open, as a result of which the traction accumulators A 1, A 2 individually supply the inverters I 1, I 2.This enables a large number of different modes, since the battery modes and the electric drive modes can be combined widely.A machine concept with open-end windings can be realized on the basis of a double inverter approach by closing SW 1, 2, 3 while SW 4, 5 are open. This corresponds to the combined drive mode. However, a machine concept with open-end windings based on a dual inverter approach may be realized using only 2 phases when a complete inverter branch (one phase of the inverter) is defective, cf. the example fault F in FIG. 1 This corresponds to the reduced mode, which may be defined as a mode with a reduced number of active phases - for both inverter / winding systems or for only one / s of the inverter / winding systems (which is / is affected by the fault F). Further, a 6-phase machine with two star points can be realized in which SW 1, 3, 4, 5 are closed while SW 2 is open. In principle, an n-phase machine with m star points can be realized, wherein n is the number of phases of each inverter / winding system and m is the number of inverter / winding systems. In addition, a 3-phase machine (basically: n-phase machine) with reduced power can be provided with the first phase set (W 1) by deactivating the second inverter / the second winding system by opening SW 1, SW 5 (preferably also SW 3). Finally, a 3-phase machine (basically: n-phase machine) with reduced power can be provided with the second phase set (W 2) by deactivating the first inverter / the first winding system by opening SW 1, SW 4 (preferably also SW 2).

Claims

Electric machine (EM) having a first and a second polyphase winding system (W1, W2), each winding system (W1, W2) having a first end (FE1, FE2) which can be connected to an inverter output (IF1, IF2) and a second end (SE1, SE2) having a multiplicity of phases (U, V, W), wherein ≅ a first switch (SW1) is connected between the second ends (FE1, FE2), ≅ a second switch (SW2) is connected between the second end (SE1) of the first winding (W1) and a first neutral point (S1), ≅ a third switch (SW3) is connected between the second end (SE2) of the second winding (W2) and a second neutral point (S2), the first switch (SW1) being arranged between the second and third switches (SW2, SW3).Electric machine (EM) according to claim 1, wherein a fourth switch (SW4) is connected between the second end (SE1) of the first winding (W1) on the one hand and the first switch (SW1) and the second switch (SW2) on the other hand; and wherein a fifth switch (SW5) is connected between the second end (SE2) of the second winding (W2) on the one hand and the first switch (SW1) and the third switch (SW3) on the other hand.The electric machine (EM) according to claim 1 or 2, comprising a control device (C) that controls the switches (SW1 - SW5), wherein the control device (C) has ≅ a combined drive mode in which the control device (C) provides the first switch (SW1) in a closed state and the second switch (SW2) and the third switch (SW3) in an open state; and ≅ an individual drive mode in which the control device (C) provides the first switch (SW1) in an open state and the second switch (SW2) and the third switch (SW3) in a closed state.Electric machine (EM) according to claim 3, wherein the control device (C) has an emergency drive mode in which the control device (C) provides the first switch (SW1) in the open state and provides either the second or the third switch (SW2) in the open state, while the other (SW3) of these two switches (SW2, SW3) is provided by the control device in the closed state.Electric machine (EM) according to claim 3 or 4, wherein the control device (C) has a reduced mode in which the control device (C) provides at least one switch in the closed state for at least one of the phases of all switches and provides at least one switch in the open state for the other phase(s) in the open state.Electric machine (EM) according to one of the preceding claims, wherein the windings (W1, W2) are arranged in the same stator of the electric machine (EM) and have the same dimensioning.The electric drive (ED) with an electric machine according to any one of claims 1 to 6, wherein the electric drive (ED) has a first inverter (11) connected to the first end (FE1) of the first winding system (W1) and a second inverter (I2) connected to the first end (FE2) of the second winding system (W2).The electric drive (ED) according to claim 7, wherein the first inverter (11) has a DC side connected to a first traction accumulator (A1) of the electric drive (ED), and the second inverter (I2) has a DC side connected to a second traction accumulator (A1) of the electric drive (ED).Electric drive (ED) according to Claim 8, wherein the first traction accumulator (A1) and the second traction accumulator (A2) are connected in parallel via an accumulator switch (AS).Electric drive (ED) according to Claim 9, comprising a control device (C) which controls the accumulator switch (AS), wherein the control device (C) has ≅ a combined mode in which the control device (C) provides the accumulator switch (AS) in the closed state, and ≅ a disconnection mode in which the control device (C) provides the accumulator switch (AS) in the open state.

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