Electrical machine unit, vehicle and method for operating an electrical machine unit

Abstract

The invention relates to an electrical machine unit (160) having an electrical machine (130) with two phase groups (P1, P2) and with a power converter (140), wherein the power converter has first and second switches, wherein the electrical machine unit has first DC charging contacts (190.1, 192.1), wherein DC-side connections of the half-bridges of the first half-bridge group (146.1) are connected to one another and electrically to one of the first DC charging contacts (190.2, 192.2), wherein DC-side connections of the half-bridges of the second half-bridge group (146.2) are connected to one another, wherein each first and second switch, in a first switch position (S1), electrically connects the respective DC-side connections of the half-bridges of the half-bridge group to the respective DC voltage connection (B+, B-) via the respective switch and separates them from the respective DC voltage connection (B+, B-) in a second switch position (S2), wherein the electrical machine unit is configured to: in a machine operating mode, bring the first switches and the second switches each into the first switch position (S1), in a first energy transfer mode, bring the first switches into the first switch position (S1) and the second switches into the second switch position (S2), and in a second energy transfer mode, bring the first switches into the second switch position (S1) and the second switches into the first switch position.

Description

[0001] The present invention relates to an electrical machine unit with an electrical machine and a power converter, a vehicle and a method for operating such an electrical machine unit.

[0002] WO 2013 / 077221 A1 discloses a charging system for vehicles that focuses on the integration of chargers and battery management systems. A method is described in which a charging port is connected to the battery controller via communication protocols such as CAN or PLC to ensure safe and efficient energy transfer. The technology enables optimization of the charging processes through voltage balancing and central control of the charging processes. JP 2013-132197 A describes a comparable system. Document CN 1 12 810 467 A describes an energy conversion device that provides efficient charging and discharging for high-voltage batteries in vehicles. It comprises an AC motor, a bidirectional PWM inverter, and a switching module.

[0003] DE 10 2019 218 375 A1 describes a method and device for controlling the charging of high-voltage batteries via multiple charging terminals. The focus is on preventing sparking and inrush currents by balancing the voltage between the charging terminals. Background of the invention

[0004] In electrical machines, particularly those used as motors and / or generators, and particularly when used in vehicles, inverters are used to rectify the generated alternating current or to convert the applied direct current. For this purpose, an energy storage device such as a battery is provided, which can be charged via it or from which energy can be drawn to operate the electrical machine. Particularly when an electrical machine is (also) used as a traction drive for a vehicle, it is usually necessary to be able to charge the energy storage device externally, for example from a (public or private) power grid. Disclosure of the invention

[0005] According to the invention, an electrical machine unit, a vehicle, and a method for operating such an electrical machine unit are proposed, having the features of the independent patent claims. Advantageous embodiments are the subject of the subclaims and the following description.

[0006] The invention relates to electrical machines and associated power converters or inverters, as well as their operation. The combination of electrical machine and associated power converter shall be referred to as an electrical machine unit within the scope of the invention. Typically, the power converter is attached to the electrical machine. The electrical machine unit can be part of a vehicle, and in particular can also be used as a traction drive. Examples of electrical machines that can be considered include synchronous machines, synchronous reluctance machines, induction machines, permanent magnet machines, and others. The electrical machine unit and its operation will be described in detail below.

[0007] Typical electrical machines have, for example, three phases or a multiple thereof; in the context of the present invention, electrical machines with at least two galvanically isolated phase groups of three phases each are of particular interest, for example with six, nine, twelve or 15 phases. Typically, three phases form a group (phase group); the three phases of a group are also connected to one another, for example in a star or delta connection. The phases (or phase windings) are incorporated into a stator of the electrical machine (they thus form a stator winding). In principle, however, the invention can also be used with two galvanically isolated phase groups, each with at least one phase.

[0008] In addition, the electric machine has a rotor that can be permanently excited and / or separately excited. A preferred use is also in so-called high-voltage applications, where the electric machine is operated at a voltage of, for example, 48 V or higher.

[0009] The power converter has a half-bridge for each phase connection of the electrical machine. Whereas with three phases in a phase group each phase is assigned a phase connection, with only one or two phases in a phase group two phase connections are provided. Each phase group is assigned a half-bridge group. With two phase groups with three phases each there are therefore two half-bridge groups with three half-bridges each. A half-bridge in turn comprises two switches or switching elements (e.g. MOSFETs or IGBTs) whose center tap (tap between the two switches) is to be connected to the corresponding phase connection. The other two connections - the DC side connections - of the half-bridges are each connected, typically together, to a (positive or negative) DC voltage connection.The power converter thus has DC voltage connections, which in turn are configured for connection to an energy storage device such as a battery. Typically, an intermediate circuit capacitor is also provided between the DC voltage connections, possibly also for each half-bridge group. Such a power converter is preferably bidirectional, meaning it can convert both DC voltage into AC voltage (for motor operation of the electric machine) and vice versa (for generator and possibly recuperative operation of the electric machine).

[0010] The half-bridges, and thus also the power converter, can be designed as so-called two-level half-bridges, but also as multi-level half-bridges with more than two, e.g. three, levels; here not only two, but three or more voltage levels can be generated

[0011] Typically, the half-bridges are electrically connected (directly) to the corresponding phase or phase connection (via their center tap). In order to charge the energy storage device, which is located in a vehicle, for example, externally—and not only via the generator operation of the electric machine—a connection option for an external voltage source must be provided. Generally, on-board (integrated in the vehicle) and off-board (provided separately from the vehicle) charging devices or chargers are possible. On-board charging devices are preferred, particularly due to cost and weight savings.

[0012] The electric machine unit further comprises first DC charging contacts. In one embodiment, the electric machine unit also comprises second DC charging contacts. The DC-side terminals of the half-bridges of the first half-bridge group are connected to one another and electrically connected to the first DC charging contact; the DC-side terminals of the half-bridges of the second half-bridge group are also connected to one another and, if provided, electrically connected to the second DC charging contact.

[0013] The first DC charging contacts, in turn, can be connected, for example, to a first DC charging port of a corresponding vehicle or be encompassed by it, wherein the first DC charging port is configured for connection to a counterpart, in particular a charging plug or a charging socket. Likewise, the second DC charging contacts, if provided, can be connected, for example, to a second DC charging port of the corresponding vehicle or be encompassed by it, wherein the second DC charging port is configured for connection to a counterpart, in particular a charging plug or a charging socket.

[0014] In addition, the electrical machine unit has first and second switches - semiconductor switches such as MOSFETs or IGBTs can be used, for example. Electromechanical switches or relays can also be considered, as these have low power loss. Each first and / or second switch can also comprise several separate semiconductor switches. Each first switch is designed such that in a first switch position the respective DC-side connections of the half-bridges of the first half-bridge group are electrically connected to the respective DC voltage connection via the respective first switch, and in a second switch position the respective DC-side connections of the half-bridges of the first half-bridge group are disconnected from the respective DC voltage connection.

[0015] Likewise, each second switch is designed such that in a first switch position the respective DC-side terminals of the half-bridges of the second half-bridge group are electrically connected to the respective DC voltage terminal via the respective second switch, and in a second switch position the respective DC-side terminals of the half-bridges of the second half-bridge group are separated from the respective DC voltage terminal.

[0016] A (first) external direct voltage or direct voltage source, e.g., a power or energy supply network, can then be connected to the first DC charging contacts or the first DC charging connection. A (second) external direct voltage or direct voltage source, e.g., a power or energy supply network, can also be connected to the second DC charging contacts or the second DC charging connection. This can be done, for example, via a plug that is inserted into a socket (or generally the DC charging connection). It is also conceivable that a plug is provided on the vehicle (e.g., connected directly via a cable). When the electrical machine unit is in operation, the first and second switches can be set to the first or second switch position (e.g., via a corresponding control device) depending on the operating mode (in particular, all first switches and / or all second switches must always be of the same type).

[0017] The first and / or second switches as well as the first and / or second DC charging contacts can be arranged or installed, for example, inside the power converter (if sufficient additional space is available) or outside the power converter. An arrangement on the housing is conceivable, for example.

[0018] To operate the electric machine, in particular for motor and / or generator operation, i.e. a machine operating mode, the first and second switches are moved to the first switch position. This electrically connects the half-bridges of the first and second half-bridge groups to the energy storage device. The first and possibly the second DC charging contacts are connected, but as long as no external DC voltage source is connected, they are inoperative. This allows normal operation, for example to drive the vehicle electrically or to recuperate. In one embodiment, it can also be provided that a protective mechanism is present which prevents the connection of an external DC voltage source in such cases, i.e. in particular in the machine operating mode.

[0019] In one embodiment, however, it can also be provided that an external DC voltage source is still connected in the machine operating mode, e.g. via an overhead line, and also supplies energy, e.g. to charge the battery and / or supply the electric machine.

[0020] For energy transfer between a connected energy storage device and an external DC voltage system - e.g., for external charging of the energy storage device from a DC voltage source as a DC voltage system or for feeding energy from the energy storage device into a consumer with a DC voltage supply as a DC voltage system - the first switches can remain in the first switch position or be set to this position in a first energy transfer mode. Optionally, the second switches can be set to the second switch position, e.g., for safety reasons, if a (second) external DC voltage system is connected to the second DC charging contacts (if present).

[0021] In this way, an external DC voltage system, e.g., the DC voltage source, can be connected to the first DC voltage terminals, e.g., using a suitable charging plug. For example, when used in a vehicle, the second switches are automatically moved to the second switch position (e.g., via a corresponding control device) when the charging plug is inserted. However, switching (possibly manual) to an external charging or feed-in mode can also be provided.

[0022] The current thus flows, for example, from the external DC voltage source via the first switches directly into the connected energy storage device. This variant allows the connection of a DC voltage source that is compatible with the voltage level of the energy storage device, e.g., 800 V.

[0023] For energy transfer between a connected energy storage device and an external DC voltage system - e.g. for external charging of the energy storage device from a DC voltage source as a DC voltage system or for feeding energy from the energy storage device into a consumer with a DC voltage supply as a DC voltage system - the first switches can also be moved to the second switch position in a second energy transfer mode; the second switches can remain in the first switch position or be moved to it.

[0024] In this way, an external DC voltage system, e.g., the DC voltage source, can be connected to the first DC voltage terminals or the first charging contacts, e.g., using a suitable charging plug. For example, it is conceivable that, when used in a vehicle, the first switches are automatically moved to the second switch position (e.g., via a corresponding control device) when the charging plug is inserted. However, a (possibly manual) switch to an external charging or feed-in mode can also be provided.

[0025] The current thus flows, for example, from the external DC voltage source via the first half-bridge group, the first phase group, and the second phase group of the electrical machine, and then via the second half-bridge group into the connected energy storage device. In this context, it should be noted that if the first phase group and the second phase group of the electrical machine, or their respective phase windings, have a different number of turns, the two phase groups act as a transformer, and thus the voltage can be increased or reduced depending on the ratio of the number of turns.

[0026] This variant allows the connection of a DC voltage source that is not compatible with the voltage level of the energy storage device, e.g. 400 V.

[0027] In an electrical machine, the phases of the first phase group are galvanically isolated from the remaining phases (typically, the three phases of each phase group are each galvanically isolated from the remaining phases). This creates a transformer, so that the alternating voltage applied to the phases or phase windings of the first phase group induces a corresponding alternating voltage in the remaining phases—in a six-phase machine, this is the remaining three phases or phase windings. The phase windings of the first phase group thus function as the primary windings of the transformer, and the remaining phase windings as the secondary windings. The transformed alternating voltage is then applied to the half-bridges of the second half-bridge group.

[0028] For this purpose, the two half-bridge groups and the two phase groups can be used as DC-DC converters, a so-called active double bridge. However, (only) the half-bridges of the first half-bridge group can also function as inverters or DC-AC converters to generate the aforementioned alternating voltage. The second half-bridge group can remain passive, i.e., be used as a passive rectifier.

[0029] For energy transfer between a first external DC voltage system and a second external DC voltage system - e.g. for energy transfer between two external DC voltage systems with, e.g., two different voltage levels - according to the invention, in a third energy transfer mode, the first switches and the second switches are each brought into the second switch position.

[0030] In this way, a first external DC voltage system, e.g., the DC voltage source, can be connected to the first DC voltage terminals, e.g., using a corresponding charging plug. The same applies to a second external DC voltage system.

[0031] The current flow is thus, for example, from the first external DC voltage source via the first half-bridge group, the first phase group and the second phase group of the electrical machine, and further via the second half-bridge group to the second external DC voltage source.

[0032] This variant allows to connect two DC voltage sources with different voltage levels, e.g. 400 V and 800 V.

[0033] Here, as in the second energy transfer mode, the phases of the electric machine serve as a transformer. For this purpose, the two half-bridge groups and the two phase groups can be used as DC-DC converters, a so-called active double bridge. However, (only) the half-bridges of the first half-bridge group can also function as inverters or DC-AC converters to generate the aforementioned alternating voltage. The second half-bridge group can remain passive, i.e., be used as a passive rectifier.

[0034] In one embodiment, the electrical machine unit has a third switch, wherein the third switch is designed such that in a first switch position (closed) the first phase group and the second phase group (or the neutral points of the respective phase windings) are electrically connected to one another, and that in a second switch position (open) the first phase group and the second phase group are electrically separated from one another. In the second switch position, the two phase groups are not connected, but can be used as a transformer in the second energy transfer mode, as described above, optionally with different numbers of turns. The second switch position (open) can then be a standard position, which is used, for example, in the machine operating mode.

[0035] With the first switch position (closed), however, a fourth and fifth energy transfer mode are possible, in which the phase groups do not act as transformers, but as series-connected inductors. The fourth energy transfer mode can correspond to the second energy transfer mode, and the fifth energy transfer mode to the third energy transfer mode. However, the phase groups are not used as transformers. Instead, the corresponding half-bridges can be used as DC-DC converters, e.g., buck or boost converters, with the phase windings connected in series and acting as inductors.

[0036] The invention also relates to a vehicle with an electric machine unit according to the invention. This can be used as a traction drive, but other uses are also conceivable—with a smaller machine. As already mentioned, the vehicle can then have a charging port configured for connection to a counterpart, in particular a charging plug or charging socket, which then also has the AC voltage connections.

[0037] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0038] The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing. Short description of the drawings Fig. 1 schematically shows a vehicle in one embodiment. Fig. 2 shows schematically an electrical machine unit in one embodiment. Fig. 3 shows the electrical machine unit from Fig. 2 in a different operating mode. Fig. 4 shows the electrical machine unit from Fig. 2 in a different operating mode. Fig. 5 shows the electrical machine unit from Fig. 2 in a different operating mode. Fig. 6 shows an electrical machine unit in a further embodiment. Embodiment(s) of the invention

[0039] In Fig. 1 shows a roughly schematic representation of a vehicle 100 in one embodiment. The vehicle 100 has a front axle 110 with wheels 112 and 114, and a rear axle 120 with wheels 122 and 124. The rear axle 120 is driven by an electric machine 130 with a stator 132 and rotor 134. The electric machine 130 thus serves as a traction drive. It is understood that instead of the rear axle 120, the front axle 110 can also be driven by the electric machine 130, or possibly both axles. This is intended only for explanatory purposes.

[0040] The electric machine 130 is connected to a power converter or inverter 140 (shown only schematically here; for a more detailed illustration, reference is made to the following figures). The power converter 140, in turn, is connected, if necessary via an intermediate circuit capacitor 142 (the intermediate circuit capacitor 142 can be part of the power converter 140), to an energy storage device 150, such as a battery. The power converter 140 can convert the direct voltage provided by the battery 150 into alternating voltage for the motor operation of the electric machine 130. Conversely, when the electric machine 130 is in generator operation, the alternating voltage generated there can also be converted into direct voltage via the (thus bidirectional) power converter 140 in order to charge the battery 150.

[0041] The electrical machine 130 and the power converter 140 are part of an electrical machine unit 160, as already mentioned at the beginning.

[0042] Additionally, a first DC charging port 170.1 is provided on the vehicle 100, which can be connected, for example, via a charging cable 172.1 with plug 174.1 and via a socket 176.1 to a (first) DC voltage source 178.1, e.g., a power grid, an external power supply, or another DC voltage system. This can be a DC voltage source with a corresponding plug and socket. In this way, the energy storage device or the battery 150 can be charged. It should be noted that the specific interconnection of the first DC charging port 170.1 with the electric machine unit 160 or the battery 150 is not shown here; reference is made to the following figures for this purpose.

[0043] Additionally, a second DC charging port 170.2 is provided on the vehicle 100, which can be connected, for example, via a charging cable 172.2 with plug 174.2 and via a socket 176.2 to a (second) DC voltage source 178.2, e.g., a power grid, an external power pack, or another DC voltage system. This can be a DC voltage source with a corresponding plug and socket. In this way, the energy storage device or the battery 150 can be charged. It should be noted that the specific interconnection of the first DC charging port 170.2 with the electric machine unit 160 or the battery 150 is not shown here; reference is made to the following figures for this purpose.

[0044] In Fig. 2 schematically shows an electrical machine unit 160 in one embodiment; this may be the electrical machine unit 160 of Fig. 1. Also shown are the power converter 140 and the battery 150, which are also those from Fig. 1 can act.

[0045] The electric machine 130 is shown as having six phases U1, V1, W1, U2, V2, and W2, each comprising a phase winding 136 (designated only once). It should be noted that the terms phase and phase winding can also be used synonymously, with phase winding usually referring (only) to the winding or coil within the stator. The phase windings 136 are part of the stator (see FIG. Fig. 1); the rotor is not shown here. The phases U1, V1, W1 form a first phase group P1 and the phases U2, V2, W2 form a second phase group P2 (the numbering of the phase group is ultimately for explanatory purposes only).

[0046] The power converter 140 has - for the six-phase electrical machine - twelve switching elements, e.g. transistors such as MOSFETS or IGBTs, with two switching elements each forming a half-bridge and being assigned to one phase.

[0047] For example, for phase U1 the switching elements with T U1,H and T U1,L (highside and lowside), which form a half-bridge designated 144, with a center tap connected to phase U1 or its phase winding or a corresponding phase terminal. For phase U2, the switching elements are designated T U2,H and T U2,Lwhich also form a half-bridge. The same applies to the switching elements and half-bridges of the remaining phases. The half-bridges for the first phase group P1 are combined into the first half-bridge group 146.1, and the half-bridges for the second phase group P2 are combined into the second half-bridge group 146.2. Each half-bridge group could also be referred to as a separate power converter or inverter, which then serves only one of the phase groups.

[0048] The DC-side terminals of the half-bridges of the first half-bridge group 146.1 are interconnected and connected to DC terminals B+ and B- via first switches 180.1, 182.1. A first intermediate circuit capacitor 142.1 is connected in parallel to the DC-side terminals. The phase terminals of the first phase group P1 are each connected to the corresponding half-bridge of the first half-bridge group 146.1 at a center tap of the respective half-bridge.

[0049] The half-bridges of the second half-bridge group 146.2 are interconnected and connected to the DC voltage terminals B+ and B- via second switches 180.2, 182.2. A second intermediate circuit capacitor 142.2 is connected in parallel to the DC voltage side terminals. The phase terminals of the second phase group P2 are each connected to the corresponding half-bridge of the second half-bridge group 146.2 at a center tap of the respective half-bridge.

[0050] The power converter can be connected to the energy storage unit or battery 150 via the DC voltage terminals B+ and B-.

[0051] The first switches 180.1, 182.1 and the second switches 180.2, 182.2 can each be, for example, arrangements with multiple transistors such as MOSFETs or IGBTs, with each switch being capable of being set to two different switch positions (like a changeover switch). In this case, they should, in particular, be bidirectional switches. Alternatively, the first and / or second switches can also be designed as electromechanical switches, for example.

[0052] Each first switch 180.2, 182.2 is configured such that, in a first switch position, the respective DC-side terminals of the half-bridges of the first half-bridge group 146.1 are electrically connected to the respective DC voltage terminal B+, B- via the respective first switch, and in a second switch position, the respective DC-side terminals of the half-bridges of the first half-bridge group are disconnected from the respective DC voltage terminal. Similarly, each second switch 180.2, 182.2 is configured such that, in a first switch position, the respective DC-side terminals of the half-bridges of the second half-bridge group 146.1 are electrically connected to the respective DC voltage terminal B+, B-.2 are electrically connected to the respective DC voltage terminal B+, B- via the respective second switch, and in a second switch position the respective DC voltage side terminals of the half-bridges of the second half-bridge group are separated from the respective DC voltage terminal.

[0053] Furthermore, the electric machine unit 160 has, for example, a control device 186 which is configured to selectively move the first switches into the first switch position or into the second switch position, and to selectively move the second switches into the first switch position or into the second switch position. By way of example, Fig. 2 shows the first switch position S1 (closed) for the second switch 182.2. This applies equally to the first and the other second switches. With the Fig. In the situation shown in Figure 2, a machine operating mode is possible, i.e., the first and second switches are each in the first switch position. This allows regular operation of the electric machine 130, both in motor and generator mode.

[0054] In Fig. 3, the electrical machine unit 160 is made of Fig. 2 in a different operating mode, namely a first energy transfer mode for energy transfer between the battery and the (first) DC voltage source, e.g. external charging of the battery 150. The electric machine unit 160 corresponds to that of Fig. 2, so that not all components are explained again here; in this respect, the Fig. 2 and the associated description.

[0055] Unlike in Fig. 2, the second switches 180.2, 182.2 are in the second switch position S2 (open), while the first switches 180.1, 182.1 remain in the first switch position S1 (closed). A (first) external DC voltage source 178.1 is now connected to the first DC charging connection 170.1 (see also Fig. 1).

[0056] With the Fig. The situation shown in Figure 3 is possible as an energy transfer between the external DC voltage source 178.1 and the battery 150. This can be charging the battery or supplying the external DC voltage source 178.1 from the battery. A current I flows. bat directly between the battery and the external DC voltage source 178.1.

[0057] This first energy transfer mode can be used in particular when the voltage level of the energy storage device and the external DC voltage system are at least substantially the same. This is the case, for example, with an 800 V compatible battery when an 800 V DC voltage source (or a DC voltage source compatible with 800 V) is available.

[0058] At this point it should be mentioned in general that, especially with batteries, the actual voltage level of e.g. 800 V can sometimes drop significantly during discharging, but such a battery can still be supplied by a DC voltage source of e.g. 800 V.

[0059] In Fig. 4, the electrical machine unit 160 is made of Fig. 2 in a different operating mode, namely a second energy transfer mode for energy transfer between the battery and the (first) DC voltage source, e.g. external charging of the battery 150. The electric machine unit 160 corresponds to that of Fig. 2, so that not all components are explained again here; in this respect, the Fig. 2 and the associated description.

[0060] Unlike in Fig. 2, the first switches 180.1, 182.1 are in the second switch position S2 (open), while the second switches 180.2, 182.2 remain in the first switch position S1 (closed). A (first) external DC voltage source 178.1 is now connected to the first DC charging connection 170.1 (see also Fig. 1).

[0061] With the Fig. The situation shown in Figure 4 is possible as an energy transfer between the external DC voltage source 178.1 and the battery 150. This can be charging the battery or supplying the external DC voltage source 178.1 from the battery.

[0062] Unlike in Fig. 3, however, no current flows directly between the battery and the external DC voltage source 178.1, but rather a current flows through the first half-bridge group 146.1, the first phase group P1, the second phase group P2, and the second half-bridge group 146.2. The two phase groups P1 and P2 serve as a transformer. The first half-bridge group 146.1 can be operated, for example, as a DC-AC converter; likewise, the two half-bridge groups with the phase groups can be operated as DC-DC converters. Thus, currents I U1 , I V1 , I W1 , I U2 , I V2 , I W2 as shown, as well as the current I bat to or from the battery.

[0063] As already mentioned, the number of turns of the phases or phase windings of the first phase group P1 and the second phase group P2 can be different, so that the voltage can be raised or lowered depending on the ratio of the turns. The specific number of turns can be selected as needed, for example, one to two or two to one.

[0064] In Fig. 5, the electrical machine unit 160 is made of Fig. 2 in a different operating mode, namely a third energy transfer mode for energy transfer between the (first) DC voltage source and another (second) DC voltage source. The electric machine unit 160 corresponds to that of Fig. 2, so that not all components are explained again here; in this respect, the Fig. 2 and the associated description.

[0065] Unlike in Fig. 2, the first switches 180.1, 182.1 and the second switches 180.2, 182.2 are in the second switch position S2 (open). A (first) external DC voltage source 178.1 is connected to the first DC charging connection 170.1, and a (second) external DC voltage source 178.2 is connected to the second DC charging connection 170.2 (see also Fig. 1).

[0066] With the Fig. The situation shown in Figure 5 is possible as an energy transfer between the external DC voltage source 178.1 and the external DC voltage source 178.2. In particular, the two DC voltage sources can have different voltage levels, e.g., 400 V and 800 V.

[0067] Similar to Fig. 4, a current flows through the first half-bridge group 146.1, the first phase group P1, the second phase group P2, and the second half-bridge group 146.2, and then to the second DC voltage source 178.2. The two phase groups P1 and P2 serve as a transformer. The first half-bridge group 146.1 can be operated, for example, as a DC-AC converter; likewise, the two half-bridge groups with the phase groups can be operated as DC-DC converters. This causes currents I to flow. U1 , I V1 , I W1 , I U2 , I V2 , I W2 as shown, as well as the current I DC1 to or from the DC voltage source 178.1 and the current I DC2 to or from the DC voltage source 178.2.

[0068] Here, too, as already mentioned, the number of turns of the phases or phase windings of the first phase group P1 and the second phase group P2 can be different, so that the voltage can be raised or lowered depending on the ratio of the turns. The specific number of turns can be selected as needed, e.g., one to two or two to one.

[0069] In Fig. 6, an electrical machine unit 160' is shown in a further embodiment. The electrical machine unit 160' corresponds to the electrical machine unit 160 according to Fig. 2 to 5, but with the difference that a third switch 184 is provided in the electrical machine 130', by means of which the first phase group P1 and the second phase group P2, or the respective phases, can be connected via their respective neutral points. The third switch 184 can be part of the electrical machine or provided externally, but then as part of the electrical machine unit 160'.

[0070] If the third switch 184 is open (second switch position), the operation does not change compared to the explanations for the Fig. 2 to 5. This means that, for example, the machine operating mode as well as the first, second and third energy transfer modes can be used.

[0071] However, if the third switch 184 is closed (first switch position), a fourth and fifth energy transfer mode can be used.

[0072] The fourth energy transfer mode corresponds to that in Fig. 4, with the switch positions shown there for the first and second switches, however, the third switch 184 is closed, ie the phase windings of the two phase groups are connected, they act as a series-connected inductance. As in Fig. 4, a (first) external DC voltage source 178.1 can be connected to the first DC charging connection 170.1.

[0073] Here, a current flows through the first half-bridge group 146.1, the first phase group P1, the second phase group P2, and the second half-bridge group 146.2. However, the two phase groups P1 and P2 do not serve as transformers here, but rather as a (common) inductance. Together with the half-bridges, the phase windings serve as a DC-DC converter, for example, as a buck or boost converter.

[0074] For example, the high-side switches of the first half-bridge group 146.1 (just one or two of them, or even three - or more, if present - depending on the current intensity and / or required inductance) can be closed. The current then flows from the DC voltage source via these closed high-side switches into the first phase group P1 and the second phase group P2 connected in series with it. From there, the current can then flow via the second half-bridge group 146.2 into the energy storage device. The switches of the second half-bridge group 146.2 can be controlled accordingly, e.g., as a boost converter to increase the voltage of the DC voltage source.

[0075] Alternatively, however, only the first half-bridge group 146.1 could be controlled accordingly, while the switches of the second half-bridge group 146.2 remain passive, so that the first half-bridge group 146.1 or its switches together with the inductances of the phase windings serve as a buck converter in order to reduce the voltage of the DC voltage source.

[0076] The fifth energy transfer mode corresponds to the Fig. 4, with the switch positions shown there for the first and second switches, however, the third switch 184 is closed, ie the phase windings of the two phase groups are connected, they act as a series-connected inductance. As in Fig. 5, a (first) external DC voltage source 178.1 can be connected to the first DC charging port 170.1, and a (second) external DC voltage source 178.2 can be connected to the second DC charging port 170.2.

[0077] Here, a current flows through the first half-bridge group 146.1, the first phase group P1, the second phase group P2, and the second half-bridge group 146.2. However, the two phase groups P1 and P2 do not serve as transformers here, but rather as a (common) inductance. Together with the half-bridges, the phase windings serve as a DC-DC converter, for example, as a buck or boost converter.

[0078] For example, the high-side switches of the first half-bridge group 146.1 (just one or two of them, or even three - or more, if present - depending on the current intensity and / or required inductance) can be closed. The current then flows from the first DC voltage source via these closed high-side switches into the first phase group P1 and the second phase group P2 connected in series with it. From there, the current can then flow via the second half-bridge group 146.2 into the second DC voltage source. The switches of the second half-bridge group 146.2 can be controlled accordingly, e.g., as a boost converter to increase the voltage of the first DC voltage source.

[0079] Alternatively, however, only the first half-bridge group 146.1 could be controlled accordingly, while the switches of the second half-bridge group 146.2 remain passive, so that the first half-bridge group 146.1 or its switches together with the inductances of the phase windings serve as a buck converter in order to reduce the voltage of the first DC voltage source.

Claims

[1] Electrical machine unit (160) with an electrical machine (130) with two phase groups (P1, P2) each of at least one phase (U1, V1, W1; U2, V2, W2) and with a power converter (140), wherein the power converter has two half-bridge groups each comprising at least one half-bridge, wherein each phase group is assigned a half-bridge group, so that one half-bridge (144) is provided for each phase connection of the electrical machine, wherein the power converter has DC voltage connections (B+, B-) which are designed for connection to an energy store (150), wherein the power converter has first switches (180.1, 182.1) and second switches (180.2, 182.2), wherein the electric machine unit has first DC charging contacts (190.1, 192.1), wherein the phase terminals (U1, V1, W1) of a first phase group (P1) of the two phase groups in the electrical machine are each connected to the associated half-bridge (144) of a first half-bridge group (146.1) of the two half-bridge groups, at a center tap of the respective half-bridge, wherein the phase terminals (U2, V2, W2) of a second phase group (P2) of the two phase groups are each connected to the associated half-bridge of a second half-bridge group (146.2) of the two half-bridge groups, at a center tap of the respective half-bridge, wherein DC-side terminals of the half-bridges of the first half-bridge group (146.1) are connected to each other and electrically to one of the first DC charging contacts (190.2, 192.2), wherein DC-side terminals of the half-bridges of the second half-bridge group (146.2) are connected to each other, wherein each first switch (180.1, 182.1) is designed such that in a first switch position (S1), the respective DC-side terminals of the half-bridges of the first half-bridge group are electrically connected to the respective DC voltage terminal (B+, B-) via the respective first switch, and in a second switch position (S2), the respective DC-side terminals of the half-bridges of the first half-bridge group are separated from the respective DC voltage terminal, wherein each second switch (180.2, 182.2) is designed such that in a first switch position (S1), the respective DC-side terminals of the half-bridges of the second half-bridge group are electrically connected to the respective DC voltage terminal (B+, B-) via the respective second switch, and in a second switch position (S2), the respective DC-side terminals of the half-bridges of the second half-bridge group are separated from the respective DC voltage terminal, and wherein the electrical machine unit is designed to: in a machine operating mode, to bring the first switches and the second switches each into the first switch position (S1), in a first energy transfer mode, to bring the first switches into the first switch position (S1) and the second switches into the second switch position (S2), and in a second energy transfer mode, to bring the first switches into the second switch position (2) and the second switches into the first switch position, and wherein the electric machine unit (160) further comprises second DC charging contacts, wherein the DC-side terminals of the half-bridges of the second half-bridge group are further electrically connected to one of the second DC charging contacts (190.2, 192.2), and wherein the electrical machine unit is designed to: in a third energy transfer mode, to bring the first switches and the second switches each into the second switch position (S2). [2] Electrical machine unit (160) according to claim 1, wherein the phases of the first phase group (P1) are galvanically separated from the phases of the second phase group (P2). [3] Electrical machine unit (160) according to one of the preceding claims, wherein the half-bridges are each designed as two-level half-bridges or as multi-level half-bridges with more than two levels. [4] Electrical machine unit (160) according to one of the preceding claims, wherein the power converter (140) is bidirectional. [5] Electrical machine unit (160) according to one of the preceding claims, further comprising a control device which is configured to selectively bring the first switches (180.1, 182.1) into the first switch position (S1) or into the second switch position (S2), and to selectively bring the second switches (180.2, 182.2) into the first switch position (S1) or into the second switch position (S2). [6] Electric machine unit (160) according to one of the preceding claims, wherein a number of turns of the phases of the first phase group (P1) and the number of turns of the phases of the two phase groups are different from each other. [7] Electrical machine unit (160') according to one of the preceding claims, which has a third switch (184), wherein the third switch (184) is designed such that in a first switch position the first phase group (P1) and the second phase group (P2) are electrically connected to one another, and that in a second switch position the first phase group (P1) and the second phase group (P2) are electrically separated from one another, and wherein the electrical machine unit is designed to: in a fourth energy transfer mode, to bring the first switches into the second switch position (S2) and the second switches into the first switch position (S1) and the third switch (184) into the first switch position, and in a fifth energy transfer mode, to bring the first switches into the second switch position (S2) and the second switches into the second switch position (S1) and the third switch (184) into the first switch position. [8] Electric machine unit (160) according to one of the preceding claims, which is designed as a traction drive of a vehicle (100). [9] Vehicle (100) with an electric machine unit (160) according to one of the preceding claims and with an energy storage device (150), in particular a battery, which is electrically connected to the DC voltage terminals (B+, B-) of the power converter (150). [10] Vehicle (100) according to claim 9, further comprising a first DC charging connection (170.1) which is configured for connection to a counterpart, in particular a charging plug or a charging socket, and which is connected to or has the first DC charging contacts, and / or a second DC charging connection (170.2) which is configured for connection to a counterpart, in particular a charging plug or a charging socket, and which is connected to or has the second DC charging contacts. [11] Method for operating an electrical machine unit (160) according to one of claims 1 to 8 or a vehicle according to claim 9 or 10, wherein the first switches and the second switches are brought into the first switch position (S1) or into the second switch position (S2) depending on the operating mode, and wherein, in particular, with reference back to claim 8, the third switch is brought into the first switch position (S1) or into the second switch position (S2) depending on the operating mode. [12] Method according to claim 11, wherein the machine operating mode is used for operation, in particular motor and / or generator operation, of the electric machine (130). [13] The method of claim 12, wherein during the machine operating mode, energy is further provided from an external DC voltage system that is or will be connected to the first DC charging contacts for a connected energy storage device (150) and / or the electric machine (130). [14] Method according to one of claims 11 to 13, wherein the first energy transfer mode is used for energy transfer between a connected energy storage device (150) and an external DC voltage system which is or will be connected to the first DC charging contacts. [15] Method according to one of claims 11 to 14, wherein the second energy transfer mode is used for energy transfer between a connected energy storage device (150) and an external DC voltage system which is or will be connected to the first DC charging contacts, and wherein the power converter is controlled to convert a voltage. [16] Method according to one of claims 11 to 15, wherein the third energy transfer mode is used for energy transfer between a first external DC voltage system which is or will be connected to the first DC charging contacts and a second external DC voltage system which is or will be connected to the second DC charging contacts, and wherein the power converter is controlled to convert a voltage. [17] Method according to one of claims 11 to 16, with reference back to claim 7, wherein the fourth energy transfer mode is used for energy transfer between a connected energy storage device (150) and an external DC voltage system which is or will be connected to the first DC charging contacts, and wherein the power converter is controlled to convert a voltage. [18] Method according to one of claims 11 to 17, with reference back to claim 7, wherein the fifth energy transfer mode is used for energy transfer between a first external DC voltage system which is or will be connected to the first DC charging contacts and a second external DC voltage system which is or will be connected to the second DC charging contacts, and wherein the power converter is controlled to convert a voltage.

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