Electric machine unit, vehicle and method for operating electric machine unit

Abstract

The invention relates to an electric machine unit having an electric machine and a rectifier, in which the electric machine has a plurality of conventional phase windings and an additional inductance connected to at least one of the plurality of conventional phase windings, in which the rectifier has a plurality of half-bridges, each half-bridge being connected to one of the plurality of conventional phase windings of the electric machine; the motor unit has a DC voltage connection for connection to an energy store and a DC voltage side switch; the DC voltage side connecting parts of the plurality of half-bridges are connected with each other and can be connected to or separated from the corresponding DC voltage connecting part through one of the DC voltage side switches; the motor unit has first DC voltage charging connections to one of which the additional inductor is connected and one side of the DC voltage side connection of the plurality of half bridges is connected to another of the first DC voltage charging connections; the motor unit has second DC voltage charging connections to which the DC voltage side connections are connected.

Description

Technical Field

[0001] The invention relates to a motor unit having an electric machine and a rectifier, a vehicle having such a motor unit and a method for operating such a motor unit. Background Art

[0002] In electric machines, in particular electric machines used as motors and / or generators, and in particular when used in vehicles, inverters (rectifiers) are used to rectify the alternating current generated or to invert the direct current present. For this purpose, in particular, an energy store, such as a battery, is also provided, which can be charged or from which energy can be drawn for operating the electric machine. In particular when the electric machine is (also) used as a traction drive of a vehicle, it is often necessary to be able to charge the energy store from an external source, for example from a (public or private) power grid. Summary of the invention

[0003] According to the invention, a motor unit, a vehicle and a method for operating a motor unit are proposed having the features of the independent patent claims. Advantageous developments are the subject matter of the dependent claims and of the following description.

[0004] The present invention relates to an electric machine and an associated rectifier or inverter and their operation. Within the scope of the present invention, the combination of an electric machine and an associated rectifier is also referred to as an electric machine unit. Typically, the rectifier is in this case mounted or attached to the electric machine. The electric machine unit can here be part of a vehicle and in particular also serve as a traction drive. Examples of electric machines that come into consideration are synchronous machines, synchronous reluctance machines, induction machines, permanent magnet machines, etc. The rectifier and the electric machine or electric machine unit and their operation will be described in detail below.

[0005] For example, a typical electric motor has three or more phases; although the present invention is mainly explained with respect to electric motors with three phases, this also applies to different numbers of phases, such as six, nine, twelve or fifteen phases. Usually, three phases in each case form a group (phase group). Each phase of the electric motor has a phase winding (phase and phase winding are usually used synonymously).

[0006] The multi-phase windings of the electric machine (and possibly each group) can also be connected to one another, for example in a star or delta connection. In the case of a star connection, there is a so-called neutral point, to which all phase windings are connected. The phase windings are inserted into the stator of the electric machine (they thus form the stator winding). In principle, the electric machine can also have only one or two phases.

[0007] Furthermore, the electric machine has a rotor which can be permanently and / or externally excited.Preferred use is also in so-called high-voltage applications, in which the electric machine is operated at voltages of, for example, 48 V, 60 V or higher.

[0008] The rectifier has a plurality of half-bridges, usually one for each phase of the motor, i.e. the rectifier is thus designed for a specific number of phases of the motor with which it is to be used. For this purpose, the rectifier may have a plurality of phase connections, to which one of the plurality of phase windings of the motor is to be connected respectively. In general, each of the plurality of half-bridges is connected respectively to one of the plurality of phase windings of the motor, i.e. at the center tap of the respective half-bridge.

[0009] The half-bridge in turn comprises two switches or switching elements (e.g. MOSFETs or IGBTs), whose center taps (the taps between the two switches) are connected to the associated phase connections as described above. The other two connections of the half-bridge (the DC voltage side connections) are usually connected together to the (positive or negative) DC voltage connection, respectively. Thus, the rectifier or usually the motor unit has a DC voltage connection, which in turn is provided for connection to an energy storage device such as a battery. Usually, an intermediate circuit capacitor is also provided between the DC voltage connections. Such a rectifier is preferably bidirectional, i.e. it can convert a DC voltage into an AC voltage (for motor operation of the motor) and vice versa (for generator operation and possible recovery operation of the motor).

[0010] It should be mentioned at this point that a connection or a connection in the context of the present invention is to be understood in particular as an electrical or electrically conductive connection or an electrical or electrically conductive connection.

[0011] Typically, the half-bridges are here electrically (directly) connected (via their center taps) to the associated phase connections and then via them to the associated phases. However, in order to be able to charge an energy store arranged in the vehicle, for example from the outside and not only by generator-like operation of the electric machine, a connection option for an external voltage source can be provided. Basically, both on-board (integrated in the vehicle) and off-board (provided separately from the vehicle) charging devices or chargers come into consideration here. An on-board charging device is preferred, in particular on the basis of cost savings and weight reduction.

[0012] As already mentioned at the outset, in particular when the electric machine is (also) used as traction drive for the vehicle, it is usually necessary to be able to charge the energy store from an external source, for example from a (public or private) grid or a charger, typically an electricity supply system.

[0013] Power flow in an electric power system can be either unidirectional or bidirectional. In modern applications, bidirectional power systems are often superior to unidirectional charging because they are able to use the energy stored in the battery to support the power system or grid. Injecting power from electric vehicle (EV) batteries into the grid (V2G) can improve grid stability, improve power quality, and restore grid voltage in the event of a grid fault.

[0014] However, as has been shown, the problem here is that the charging infrastructure available in different geographical locations can support different voltages. For example, some fixed charging stations may support 400V DC, while others may support 800V DC.

[0015] The typical topology of integrated chargers is usually suitable for connection to AC voltage grids, although it is usually not possible to connect them to DC voltage grids. The trend now is that the battery and rectifier (inverter) use 800V nominal voltage, because electric vehicles usually operate at 800V nominal voltage. Therefore, a 400V charging station cannot charge an 800V electric vehicle.

[0016] The solution is to replace any 400V charging stations with higher voltage charging stations, or to install an adapted DC-DC converter in the 400V charging station to boost the charging station's 400V to 800V, both of which result in higher costs and significant investments in available 400V charging stations.

[0017] However, within the context of the present invention, the possibility of supporting different voltages of a charging station or power supply system with the motor unit is proposed.

[0018] Here, the inductance of the phase winding is also insufficient, since the rectifier usually operates at a low switching frequency, for example less than 30 kHz. Therefore, operating the rectifier in DC-DC mode results in high DC input currents.

[0019] In this context, it is proposed that in addition to a plurality of phases (e.g. three phases) with a phase winding per phase, the electric machine also has an additional inductance. In particular, the additional inductance can also be a winding (additional winding), so that the phase windings of the phases of the electric machine will be referred to as conventional phase windings hereinafter. When a plurality of conventional phase windings are connected to one another at a neutral point, the additional inductance is connected to at least one of the plurality of conventional phase windings.

[0020] In particular, exactly one additional inductance or additional winding is provided, ie a three-phase motor then has a total of four windings (or winding strands). A 3n-phase motor has a total of 3n+1 windings (or winding strands).

[0021] Although the rectifier can be designed essentially as described above, the motor unit has a first direct voltage charging connection (usually two) and a second direct voltage charging connection (usually also two).

[0022] The additional inductance is here connected or connectable to one of the first DC voltage charging connections, preferably the positive first DC voltage charging connection. This first DC voltage charging connection is thus connected via the additional inductance (via the neutral point) to one or more conventional phase windings and then to the center tap of the semiconductor bridge. One side (usually the negative side) of the DC voltage side connection of a plurality of half bridges is connected or connectable to another of the first DC voltage charging connections.

[0023] The first DC voltage charging connection can be connected to a corresponding charging contact in a charging socket of the vehicle or in a common charging interface, for example. Likewise, the second DC voltage charging connection can be connected to a corresponding charging contact in a (different) charging socket of the vehicle or in a common (different) charging interface, for example.

[0024] Furthermore, the motor unit, in particular the rectifier, has a DC voltage connection at the DC voltage-side switches; these switches can be, for example, semiconductor switches, such as MOSFETs or IGBTs, or, for example, also electromechanical switches. As described above, the DC voltage-side connections of a plurality of half-bridges are all connected to one another, and each half-bridge is connected or connectable to a corresponding one of the DC voltage connections via one of the DC voltage-side switches in the closed state of the switch and is disconnected or disconnectable therefrom (i.e. from a corresponding one of the DC voltage connections) in the open state of the switch.

[0025] In this way, the rectifier can be used not only for conventional operation of the electrical machine, i.e. in particular for motor and / or generator operation, but also for energy transmission between the energy store and the external DC voltage system, i.e., for example, for charging the energy store. Depending on the type of the external DC voltage system or its voltage level, the energy store can be charged directly, for example, by connecting the external DC voltage system to the second DC voltage charging connection; this is advantageous, for example, if the external DC voltage system has the same or approximately the same voltage level as the energy store (e.g. 800 V).

[0026] Likewise, the energy store can be charged via the additional inductance, at least one of the phase windings and the rectifier via the connection of the external DC voltage system to the first DC voltage charging connection; this is advantageous, for example, if the external DC voltage system has a different voltage level than the energy store, for example 400 V in the case of an 800 V energy store. The rectifier or the associated half-bridge can be used as a step-up converter. In principle, it is also possible to convert the voltage from a higher voltage level to a lower voltage level and also to have different voltage levels. For this purpose, the rectifier must be controlled accordingly. In principle, energy transmission without voltage conversion is also conceivable, for example for emergency operation.

[0027] When the switch is closed in the above-described operating mode, energy can be transferred between two different external DC voltage systems by opening the switch, one of which is connected to the first DC voltage charging connection and one of which is connected to the second DC voltage charging connection. Here, the two external DC voltage systems can also have different voltage levels; it is also conceivable here that the two external DC voltage systems have the same or approximately the same voltage level, wherein the second external DC voltage system generally has a slightly higher voltage. Even so, energy transfer is possible.

[0028] As already mentioned, it may happen that the inductance of the phase winding is insufficient, since the rectifiers usually operate at a low switching frequency, for example less than 30 kHz. Now using an additional inductance, said inductance can be adapted. By arranging the additional inductance as part of the electrical machine, in particular the stator, an inductive (or generally electromagnetic) coupling of the additional inductance with at least one of the phase windings is achieved. Depending on the requirements, the additional inductance can be arranged in a suitable manner to achieve a greater or lesser inductive coupling. The additional inductance can be directly inductively coupled to at least one of the plurality of conventional phase windings, but the additional inductance can also be reversely inductively coupled to at least one of the plurality of conventional phase windings. For example, the additional inductance can be designed as an additional winding and can be arranged in the stator like the plurality of conventional phase windings.

[0029] This coupled additional inductance is particularly effective in reducing disruptive current ripple. By arranging the additional inductance in the motor, the entire system is also more compact and does not require external access to the neutral point of the motor.

[0030] In one embodiment, the additional inductor is connected to the neutral point and is connected thereto to a plurality of conventional phase windings. In another embodiment, the additional inductor is connected to one of the plurality of conventional phase windings on the side of the conventional phase winding away from the neutral point. In this way, a total of three inductors, the additional inductor, one of the plurality of conventional phase windings to which the additional inductor is connected, and one of the other conventional phase windings can be connected in series, which means that the additional inductor can be designed to be smaller if necessary.

[0031] The invention also relates to a vehicle having an electric motor unit according to the invention. The electric motor unit can be used as a traction drive, but another use is also conceivable for small machines. The vehicle can then have a charging contact which is provided for connection to a counterpart, in particular a charging plug or a charging socket, in particular for two different DC voltages, in particular both simultaneously, i.e. for example two charging sockets.

[0032] Further advantages and improvements of the invention are apparent from the description and the accompanying drawings.

[0033] The invention is schematically illustrated in the drawings using exemplary embodiments and is described below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A preferred embodiment of a vehicle according to the invention is schematically shown;

[0035] Figure 2 Schematically shows a preferred embodiment of the motor unit according to the present invention;

[0036] Figure 3a , 3b 3c schematically shows parts of a motor unit according to the present invention in various preferred embodiments;

[0037] Figure 4 shows the different operating modes Figure 2 The motor unit in

[0038] Figure 5 shows the different operating modes Figure 2 The motor unit in

[0039] Figure 6 shows the different operating modes Figure 2 The motor unit in. DETAILED DESCRIPTION

[0040] Figure 1 A preferred embodiment of a vehicle 100 according to the invention is schematically shown. 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 here by an electric machine 130 with a stator 132 and a rotor 134. The electric machine 130 thus acts as a traction drive. It goes without saying that the front axle or both axles can also be driven.

[0041] The electric machine 130 is connected to a rectifier or inverter 140 (shown here only schematically; for a more detailed description, please refer to the following figures). The rectifier 140 is in turn connected to an energy storage 150, such as a battery, possibly via an intermediate circuit capacitor 142 (which can be part of the rectifier 140). Via the rectifier 140, the DC voltage provided by the battery 150 can be converted into an AC voltage for the motor-like operation of the electric machine 130. Likewise, vice versa, during the generator-like operation of the electric machine 130, the AC voltage generated therein can be converted into a DC voltage via the (thus bidirectional) rectifier 140 in order to charge the battery 150.

[0042] As already mentioned at the outset, the electric motor 130 and the rectifier 140 are here part of a motor unit 160 .

[0043] In addition, a first charging interface 170.1, i.e. a DC charging interface for direct current voltage, is provided on the vehicle 100. The first charging interface 170.1 can be connected to a direct current voltage source 178.1, such as a power grid, an external power supply or another direct current voltage system, for example, via a charging cable 172.1 having a plug 174.1 and via a socket 176.1. In this way, the energy storage device or the battery 150 can be charged. It should be noted that the specific connection method of the DC charging interface 170.1 and the motor unit 160 or the battery 150 is not shown here; please refer to the figure below.

[0044] In addition, a second charging interface 170.2 is provided on the vehicle 100, i.e., a DC charging interface which is also a DC voltage. The second charging interface 170.2 can be connected to a DC voltage source 178.2, such as a power grid, an external power supply or another DC voltage system, for example, via a charging cable 172.2 with a plug 174.2 and via a socket 176.2. In this way, the energy storage device or the battery 150 can be charged. It should be noted that the specific connection method of the DC charging interface 170.2 and the motor unit 160 or the battery 150 is not shown here; please refer to the figure below.

[0045] As will be explained in more detail below, the first charging interface 170 . 1 and the second charging interface 170 . 2 are particularly intended for different voltage levels of a DC voltage source to be connected, for example 400 V and 800 V.

[0046] exist Figure 2 In the figure, a preferred embodiment of the motor unit 160 according to the present invention is schematically shown; it can be Figure 1 In addition, a rectifier 140 and a battery 150 are shown, which may also be Figure 1 In a preferred embodiment, the rectifier 140 may be a rectifier according to the present invention.

[0047] In the case of the motor 130, three phases U, V and W are shown here, each comprising a phase winding 136U, 136V, 136W. It should be noted that the terms "phase" and "phase winding" may also be used synonymously, wherein a "phase winding" generally (only) refers to a winding or coil within the stator. The phase windings 136U, 136V, 136W are part of the stator (see Figure 1 ); the rotor is not shown here. The phase windings 136U, 136V, 136W are also (electrically) connected to each other at a neutral point 138; it can be a so-called star connection.

[0048] In addition, the motor 130 has an additional inductance 136X designed as an additional winding. In order to better distinguish them from the additional winding 136X, the phase windings 136U, 136V, 136W should also be referred to as conventional phase windings. The conventional phase windings 136U, 136V, 136W and the additional inductance or additional winding 136X can be arranged in the stator in particular, that is, the conventional phase windings 136U, 136V, 136W and the additional winding 136X can be wound on the stator teeth in the same way.

[0049] By arranging the additional winding together with the conventional phase windings 136U, 136V, 136W in the motor 130, in particular in its stator, a particularly good inductive (or electromagnetic) coupling between the additional winding and the conventional phase windings is possible. The additional winding 136X can have a connection (phase connection) on the motor just like the conventional phase windings 136U, 136V, 136W.

[0050] In the electric machine 130 , the additional winding 136X is here for example (directly) connected to the neutral point 138 and via it (analogously) connected to the conventional phase windings 136U, 136V, 136W.

[0051] In the example shown, the connection is such that the additional winding 136X is directly inductively coupled to the conventional phase windings 136U, 136V, 136W. This is shown by the dots on the conventional phase windings 136U, 136V, 136W and the additional winding 136X.

[0052] exist Figure 3a In the Figure 2 0 , where the inductive (or electromagnetic) coupling between the additional winding and the conventional phase winding is indicated by arrows.

[0053] Figure 3b A motor 130b is shown, which may substantially correspond to Figure 2 or Figure 3a 136W, but the additional winding 136X is reversely (or indirectly) inductively coupled to the conventional phase windings 136U, 136V, 136W. This is shown by the points on the conventional phase windings 136U, 136V, 136W and the additional winding 136X. To this end, the various windings can be connected in different ways.

[0054] Figure 3c A motor 130c is shown, which corresponds substantially to Figure 2 and Figure 3aThe motor 130 in FIG. 1 is a motor 130 in FIG. 1 , but the additional winding 136X is connected to the normal phase winding 136W on the side of the normal phase winding 136W away from the neutral point 138. In this way, the additional winding 136X is connected in series with the normal phase winding 136W and then connected to the other two normal phase windings 136U and 136V via the neutral point 138.

[0055] The arrangement of the additional winding 136X and the conventional phase windings 136U, 136V, 136W in the motor or stator itself can be similar to Figure 3a , 3b , but the circuit can be adapted accordingly.

[0056] In the motor 130c, the additional winding 136X is directly inductively coupled to the conventional phase windings 136U, 136V, and optionally also to 136W, but reverse (indirect) inductive coupling can also be provided here. The additional winding 136X can, for example, simply be connected in series with the conventional phase winding 136W, which does not cause or causes negligible inductive coupling. Similarly, the additional winding 136X can also be purposefully inductively coupled to the conventional phase winding 136W (for example in addition to 136U, 136V).

[0057] See again Figure 2 For a three-phase motor, the rectifier 140 has six switches or switching elements, for example transistors such as MOSFETS or IGBTs, of which two switches each form a half bridge and are assigned to one phase. Alternatively, a half bridge with three or more stages can also be used instead of such a two-stage half bridge. For example, the switching element for the U phase is designated as T U_H and T U_L (high side and low side), for V phase it is designated as T V_H and T V_L (high side and low side), and for the W phase is specified as T W_H and T W_L (high side and low side), wherein the two switching elements of each phase form a half bridge designated as 144U, 144V or 144W. The center tap 145U, 145V, 145W of the half bridge can be connected or connected to the associated phase U, V, W or the corresponding phase winding 136U, 136V or 136W.

[0058] Furthermore, a control circuit 148 for the switches or switching elements of the half bridge is shown, for example a so-called gate driver circuit. This can control the switches or switching elements to open and close in a suitable manner in order to control the rectifier for rectification. In this case, the control circuit 148 can receive control signals, for example, from a motor control unit (not shown here); it is also conceivable that the control circuit 148 is part of the engine control unit.

[0059] The DC voltage side connections of the half bridges 144U, 144V and 144W are each interconnected or connected and are collectively designated as 146+ or 146-. The DC voltage side connection can be connected to the DC voltage connection B+ or B- of the rectifier. For this purpose, two switches 180+ and 180- are provided, wherein when the switch 180+ is in the closed state, the DC voltage side connection 146+ is connected to the DC voltage connection B+ via the switch 180+. Correspondingly, when the switch 180- is in the closed state, the DC voltage side connection 146- is connected to the DC voltage connection B- via the switch 180-. When the switches 180+ and 180- are in the open state, the DC voltage side connection 146+ or 146- is separated from the DC voltage connection B+, B-, respectively.

[0060] For example, the opening and closing of switches 180+, 180- can be controlled via a control circuit 182 of rectifier 140. Here, the control circuit 182 can receive control signals, for example, from a motor control unit (not shown here); it is also conceivable that the control circuit 148 is part of the engine control unit.

[0061] The switches 180+, 180- mentioned can each be, for example, one or more transistors, such as MOSFETs or IGBTs. Alternatively, the switches can also be designed, for example, as electromechanical switches.

[0062] An intermediate circuit capacitor 142 is connected in parallel to the DC voltage side connection, and the rectifier 140 is connected or can be connected to an energy store or battery 150 via the DC voltage connections B+ and B−.

[0063] Furthermore, the motor unit 160 has two first DC voltage charging connections 172.1+, 172.1-. These can be connected to the first charging interface 170.1. For easier allocation, the first charging interface 170.1 is Figure 2 For example, it is shown as being located at or near the first DC voltage charging connection 172 . 1+, 172 . 1 −.

[0064] The additional winding 136X is connected, for example, to a first DC voltage charging connection 172 . 1+, while the negative side 146 − of the DC voltage side connections of a plurality of half bridges is connected to the first DC voltage charging connection 172 . 1 −.

[0065] Furthermore, the motor unit 160 has two second DC voltage charging connections 172.2+, 172.2-. These can be connected to the second charging interface 170.2. For easier allocation, the second charging interface 170.2 is Figure 2 For example, it is shown as being located at or near the second DC voltage charging connection 172 . 2+, 172 . 2 −.

[0066] The DC voltage side connection 146+ of the plurality of half bridges is connected to the second DC voltage charging connection 172.2+, and the DC voltage side connection 146- of the plurality of half bridges is connected to the second DC voltage charging connection 172.2-. The connection of the second DC voltage charging connection is hereby realized in such a way that by opening the switches 180+, 180-, the second DC voltage charging connection is separated from the DC voltage connections B+, B-, but not from the DC voltage side connections 146+, 146- of the plurality of half bridges. Furthermore, for example, a protective device, in particular a mechanical protective device, can be provided which, if necessary, prevents an external DC voltage source from being connected to one of the charging connections; this is particularly advantageous in the (motor or generator) operation of the electric machine.

[0067] The first DC voltage charging connections 172.1+, 172.1- can be part of the rectifier or integrated therein. It is important to ensure that one of the two first DC voltage charging connections must be connected to the additional winding 136X. In addition to the electrical connection between the rectifier and the conventional phase winding, additional electrical connections may be required here.

[0068] The second DC voltage charging connection 172 . 2+, 172 . 2 − can also be part of the rectifier or be integrated therein.

[0069] from Figure 3b , 3c It can be seen that the motors 130b and 130c shown therein can be Figure 2 The electric machine 130 shown is substituted. The external connections of the electric machine for the rectifier may be similar, only the internal connections or possibly also the arrangement of the conventional phase windings and the additional phase windings may be different.

[0070] for Figure 2 The motor unit 160 shown can now have multiple operating modes. Figure 2 In the illustrated situation (switches 180+, 180- in closed position), conventional operation of the electric machine 130 as a motor and generator is possible. The rectifier 140 or the half-bridge with its switches can be operated in the usual way to rectify (convert) between direct voltage and alternating voltage.

[0071] Current flows between the electric machine and the rectifier, and current flows between the energy storage device and the rectifier. It is important to ensure that no external DC voltage system is connected to the first DC voltage charging connection and no external DC voltage system is connected to the second DC voltage charging connection. For this purpose, for example, the protective device already mentioned can be provided.

[0072] Figure 4 Shows Figure 2Another operating mode of the motor unit 160 in the embodiment is energy transmission between the battery and an external DC voltage system, such as a DC voltage source 178.1, which is connected to the first charging interface 170.1, for example, external charging of the battery 150. The motor unit 160 corresponds to Figure 2 The motor unit in the , therefore not all parts are labeled or described again here; in this regard, reference is made to Figure 2 and related descriptions.

[0073] Switches 180+, 180- are in the closed position. Rectifier 140 or half-bridge and its switches can be controlled to convert a DC voltage between a first voltage level provided by first DC voltage source 178.1 (ie between the first DC voltage charging connections) and a second voltage level of the energy storage.

[0074] Here, the current I ch The current I flows from the DC voltage source 178.1 via the additional winding, the neutral point and the normal phase winding to the half bridge. ch In each phase, it is divided into individual currents I1, I2, I3. The voltage can be adapted accordingly by suitable actuation of the half bridge or its switches, whereby the corresponding current I bat flows to the battery 150 .

[0075] The half bridges can be controlled in such a way that they act as DC-DC converters in order to load the battery 150 with a current I bat This means, for example, that a battery with 800 V can be charged with a 400 V DC voltage. Likewise, energy can be transferred from the battery 150 to the DC voltage source 178 . 1 . It is important here to ensure that no external DC voltage system is connected to the second DC voltage charging connection.

[0076] Figure 5 Shows Figure 2 , i.e., energy transmission between a first external DC voltage system (e.g., a DC voltage source 178.1 connected to the first charging interface 170.1) and another external DC voltage system (e.g., a DC voltage source 178.2 connected to the second charging interface 170.2). The motor unit 160 corresponds to Figure 2 The motor unit in the , therefore not all parts are labeled or described again here; in this regard, reference is made to Figure 2 and related descriptions.

[0077] Switches 180+, 180- are in the open position, disconnecting the battery 150 from the rectifier 140. The rectifier 140 or half-bridge and its switches can be controlled to convert a DC voltage between a first voltage level provided by the first DC voltage source 178.1 (i.e., between the first DC voltage charging connections) and a second voltage level provided by the second DC voltage source 178.2 (i.e., between the second DC voltage charging connections).

[0078] Here, the current flows from the DC voltage source 178.1 via the additional winding, the neutral point and the normal phase winding to the half bridge. The current is divided into individual currents I1, I2, I3 in each phase. The voltage can be adapted accordingly by appropriate control of the half bridge or its switches, so that the corresponding current I DC Flows to DC voltage source 178.2.

[0079] The half bridges can be controlled in such a way that they act as DC-DC converters in order to supply a current I to a DC voltage source 178.2. DC This means, for example, that a 400 V DC voltage can be used to power another 800 V DC voltage source. Likewise, energy can be transferred from DC voltage source 178.2 to DC voltage source 178.1.

[0080] Figure 6 Shows Figure 2 Another operating mode of the motor unit 160 in the embodiment is energy transmission between the battery and an external DC voltage system (such as a DC voltage source 178.2), which is connected to the second charging interface 170.2, for example, to externally charge the battery 150. The motor unit 160 corresponds to Figure 2 The motor unit in the , therefore not all parts are labeled or described again here; in this regard, reference is made to Figure 2 and related descriptions.

[0081] The switches 180+, 180- are in the closed position. The rectifier 140 or its half-bridge is not actively needed here. The current I DC Here, the flow from the DC voltage source 178.2 directly to the battery 150. This means, for example, that the battery can be charged directly at 800 V using a DC voltage of 800 V. Energy can also be transferred from the battery to the DC voltage source 178.2. It is important here to ensure that no external DC voltage system is connected to the first DC voltage charging connection.

Claims

1. A motor unit (160), comprising a motor (130, 130b, 130c) and a rectifier (140), in, The motor (130) has a plurality of phases (U, V, W), each phase having a normal phase winding (136U, 136V, 136W) and an additional inductance (136X), wherein the plurality of normal phase windings are connected to each other at a neutral point (138), and wherein the additional inductance (136X) is connected to at least one of the plurality of normal phase windings, The rectifier (140) has a plurality of half-bridges (144U, 144V, 144W), wherein each of the plurality of half-bridges is connected to one of a plurality of conventional phase windings of the motor at a center tap (145U, 145V, 145W) of the corresponding half-bridge, The motor unit (160), in particular the rectifier, has a DC voltage connection (B+, B-) and a DC voltage-side switch (180+, 180-), wherein the DC voltage connection (B+, B-) is provided for connection to an energy storage device (150), The DC voltage side connections (146+, 146-) of the plurality of half bridges are connected to each other and can be connected to the corresponding DC voltage connection (B+, B-) via one of the DC voltage side switches (180+, 180-) when the switch is in a closed state, or can be separated from the corresponding DC voltage connection (B+, B-) when the switch is in an open state. The motor unit (160) has a first DC voltage charging connection (172.1+, 172.1-), the additional inductance (136X) is connected or connectable to one of the first DC voltage charging connections, and one side of the DC voltage side connections (146-) of the plurality of half bridges is connected or connectable to another of the first DC voltage charging connections, The motor unit (160) has a second DC voltage charging connection (172.2+, 172.2-), wherein the DC voltage side connections of a plurality of half bridges are connected or connectable to a corresponding one of the second DC voltage charging connections.

2. The motor unit (160) according to claim 1, wherein: The additional inductor (136X) is connected to the neutral point (138) and is connected to a plurality of conventional phase windings (136U, 136V, 136W) via the neutral point.

3. The motor unit (160) according to claim 1, wherein: The additional inductor (136X) is connected to one of the plurality of normal phase windings on a side of the normal phase winding away from the neutral point.

4. The motor unit (160) according to any one of the preceding claims, wherein: The additional inductor is inductively coupled to at least one of the plurality of conventional phase windings.

5. The motor unit (160) according to claim 4, wherein: The additional inductance is directly inductively coupled to at least one of the plurality of conventional phase windings.

6. The motor unit (160) according to claim 4, wherein: The additional inductor is reversely inductively coupled to at least one of the plurality of conventional phase windings.

7. The motor unit (160) according to any one of the preceding claims, wherein: The electric machine has a stator, wherein the additional inductance is designed as an additional winding and wherein a plurality of conventional phase windings and the additional winding are arranged in the stator.

8. The motor unit (160) according to any one of the preceding claims, wherein: The motor has three phases with three conventional phase windings.

9. The motor unit (160) according to any one of the preceding claims, wherein: The rectifier (140) is designed to be bidirectional.

10. The electric motor unit (160) according to any one of the preceding claims, which is designed as a traction drive of a vehicle (100).

11. A vehicle (100) having an electric motor unit (160) according to any one of the preceding claims and having an energy storage device (150), in particular a battery, wherein: The energy store is connected to the DC voltage connections (B+, B-).

12. A method for operating a motor unit (160) according to any one of claims 1 to 10 or a vehicle according to claim 11, in, The rectifier (140) and / or the DC voltage side switches (180+, 180-) are controlled depending on the operating mode.

13. The method according to claim 12, wherein: For operation of the electrical machine (130), in particular motor and / or generator operation, the DC voltage side switch is controlled to assume a closed state, and In this case, the rectifier is controlled to rectify between a direct voltage and an alternating voltage.

14. The method according to claim 12 or 13, wherein: In order to transfer energy between the connected energy storage device (150) and an external DC voltage system (178.1) to be connected or already connected via a first DC voltage charging connection, the DC voltage-side switch is actuated to assume a closed state, and Therein, a rectifier (140) is activated to convert a DC voltage between a first voltage level between a first DC voltage charging connection and a second voltage level of the energy store.

15. The method according to any one of claims 12 to 14, wherein: In order to transfer energy between an external DC voltage system (178.1) to be connected or already connected to the first DC voltage charging connection and another external DC system (178.2) to be connected or already connected via the second DC voltage charging connection, the DC voltage side switch is controlled to assume the open state, and The rectifier (140) is controlled to convert the DC voltage between a first voltage level between the first DC voltage charging connection and a second voltage level between the second DC voltage charging connection.

16. The method according to any one of claims 12 to 15, wherein: In order to transfer energy between a connected energy storage device (150) and an external DC voltage system (178.2) to be connected or already connected via a second DC charging connection, the DC voltage-side switch is actuated to assume a closed state.

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