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 a DC voltage-side connection of a half-bridge is connected to a respective DC voltage connection, the electric machine unit having one or more phase switches for connecting or disconnecting a respective phase connection to a respective half-bridge, the motor unit has one or more inductors and one or more inductor switches to connect or disconnect the respective inductor to the respective half-bridge, the motor unit having a first and a second DC charging contact, the first DC charging contact being connected to one of the DC voltage terminals, the motor unit having a charging switch, the second DC charging contact being connected to the other of the DC voltage terminals, and the charging switch being connected to the other of the DC voltage terminals. The charging switch is designed in such a way that, in a first switching position, the second DC charging contact is connected to the other of the DC voltage terminals, and, in a second switching position, the second DC charging contact is connected to the one or more inductors.

Description

Field of the Invention

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

[0002] In an electric machine, especially in an electric machine used as an engine and / or a generator, and especially when used in a vehicle, an inverter (rectifier) is used to rectify the generated alternating current or to invert the applied direct current. In particular, an energy storage device such as a battery is also provided, which can be charged or from which energy can be drawn for the operation of the electric machine. In particular, when the electric machine (also) serves as a traction drive of a vehicle, it is usually necessary to be able to charge the energy storage device from the outside, for example, from a (public or private) power grid. Summary of the Invention

[0003] According to the present invention, an electric machine unit, a vehicle, and a method for operating such an electric machine unit having the features of the independent patent claims are proposed. Advantageous embodiments are the subject matter of the dependent claims and the following description.

[0004] The present invention relates to an electric machine and the associated rectifier or inverter and their operation. Within the scope of the present invention, the combination of the electric machine and the associated rectifier is referred to as an electric machine unit. Here, the rectifier is usually arranged on the electric machine. The electric machine unit can be a part of a vehicle and, in particular, can also be used as a traction drive. As the electric machine, a synchronous machine, a synchronous reluctance machine, an induction machine, a permanent magnet machine, etc. can be considered. The electric machine unit and its operation will be described in detail below.

[0005] Typical electric machines have three phases or a multiple thereof, for example, six, nine, twelve, or fifteen phases. Here, three phases usually form a group (phase group); the three phases in a group are also connected to each other, for example, by a star or delta connection method. These phases (or phase windings) are inserted into the stator of the electric machine here (thus forming a stator winding). Although the present invention will be mainly described for three phases below, the present invention can also be used for a single phase or a case of more than three phases.

[0006] In addition, the rotor of the electric machine can be permanent magnet and / or separately excited. In addition, a preferred application is a so-called high-voltage application, in which the electric machine operates at a voltage of, for example, 48 V or higher.

[0007] Here, the rectifier has a half-bridge at each phase terminal of the electric machine. For example, in the case of three or more phases, each phase is assigned a phase terminal, while in the case of only one or two phases, two phase terminals are provided. Each phase terminal is here assigned a half-bridge. In the case of three phases, there are for example three half-bridges. The half-bridge in turn consists of two switches or switching elements (such as MOSFETs or IGBTs), the center tap (the tap between the two switches) of which is connected to the respective phase terminal.

[0008] The other two terminals of the half-bridge - the terminals on the DC voltage side - are usually connected together and respectively to the (positive or negative) DC voltage terminals. Thus, the rectifier has DC voltage terminals, which in turn are arranged to be connected to an energy storage device such as a battery. Usually, an intermediate circuit capacitor is also provided between the DC voltage terminals. Preferably, such a rectifier is here bidirectional, i.e. it can convert DC voltage into AC voltage (for engine-like operation of the electric machine), and vice versa (for generator-like operation of the electric machine and, if necessary, recuperation operation).

[0009] Not only the half-bridge but also the rectifier can be designed as a so-called two-level half-bridge, or can be designed as a multi-level half-bridge with more than two levels (such as three levels); thus here, not only two voltage levels can be generated, but also three or more voltage levels.

[0010] Usually, the half-bridge (via its center tap) is here connected (directly) to the respective phase or phase terminal.

[0011] However, within the scope of the present invention, the electric machine unit has one or more phase switches, wherein at least one of the one or more phase switches is respectively assigned to a phase terminal and is configured to: in a first switch position (closed), the respective phase terminal is connected to the center tap of the respective half-bridge, and in a second switch position (open), the respective phase terminal is disconnected from the center tap of the respective half-bridge.

[0012] In one embodiment, at least one phase terminal is not assigned a phase switch. Then, the at least one phase terminal is connected (i.e., directly or permanently) to the center tap of the respective half-bridge.

[0013] A specific example is in the case of three phases or phase terminals, where three phase switches are provided, i.e. one phase switch is assigned to each phase terminal, or only two phase switches are provided, i.e. one phase terminal is directly connected. This will be explained in detail in the description of the drawings.

[0014] In order to be able to charge the energy storage device arranged in the vehicle from the outside - and not just by the generator operation of the electric machine - the option of connecting an external voltage source must be provided. In principle, both on-board (integrated in the vehicle) and off-board (separate from the vehicle) charging devices or charging equipment are conceivable here.

[0015] An integrated onboard charger (OBC) with a rectifier or inverter is a device that combines the functions of an onboard charger and a rectifier or inverter in a single device. This integration helps reduce the size, weight, and cost of the electric vehicle's drive train. An integrated OBC with a rectifier / inverter can also provide bidirectional current, meaning it can convert DC power from the battery to AC power to support AC loads (V2L), grid power (V2G), and even other electric vehicles.

[0016] Within the scope of the invention, the motor unit has a first DC charging contact and a second DC charging contact for this purpose. In addition, the motor unit also has one or more inductors, in particular coupled inductors, and one or more inductive switches. In this case, each of the one or more inductors is respectively assigned to a half-bridge, wherein at least one of the one or more inductive switches is respectively assigned to an inductor and is configured such that in a first switching position, the respective inductor is connected to the center tap of the respective half-bridge, and in a second switching position, the respective inductor is disconnected from the center tap of the respective half-bridge. Coupled inductors have particular advantages here, because on the one hand they have a smaller structural size than a single inductor and on the other hand they suppress current fluctuations better than a single inductor.

[0017] Such an inductor is used to charge the energy store via a half-bridge. A specific example is that in the case of three phases or phase terminals with three phase switches, three inductors are provided, i.e. one inductor is assigned to each phase terminal, but only two of the inductors are assigned an inductor switch. The third inductor can then be connected directly to the center tap of the associated half-bridge. In the above example with two phase switches, for example, only two inductors are provided, i.e. one inductor is assigned to each phase terminal with a phase switch; however, only one of the two inductors is assigned an inductor switch. This will be explained in more detail in the description of the figures.

[0018] As mentioned above, the motor unit has a first DC charging contact and a second DC charging contact for this purpose. In this case, the first DC charging contact (for example, the negative contact) is connected to one of the DC voltage terminals (for example, the negative DC voltage terminal). In addition, the motor unit has a charging switch, wherein the charging switch is designed such that in a first switch position, the second DC charging contact is connected to the other of the DC voltage terminals (for example, the positive DC voltage terminal) and in a second switch position, is connected to the one or more inductors.

[0019] The DC charging contact can also be connected to, or included in, the DC charging terminal of the corresponding vehicle, where the DC charging terminal is configured to connect to a mating device, in particular a charging plug or a charging socket.

[0020] Then, a (first) external DC voltage or DC voltage source (such as a power supply or an energy supply network) can be connected to the DC charging contact or the DC charging terminal. For example, this can be done by inserting a plug into a socket (or a general DC charging terminal). It is also conceivable to provide a plug on the vehicle accordingly (for example, directly connected by a wire).

[0021] During the operation of the motor unit, various switches (such as via corresponding control devices) can be placed in a first switch position or a second switch position according to the operating mode. Here, the phase switch and / or the inductance switch and / or the charging switch can be selectively placed in the first switch position or the second switch position independently of each other. This applies not only to different types of switches but also to the same type of switches. For example, the phase switch can be placed in different switch positions.

[0022] It should be noted here that terms such as phase switch, inductance switch, and charging switch are only used here to distinguish switches with different functions, uses, or settings at different positions. The switches themselves can have the same or similar structures, but this is not necessary. For example, semiconductor switches such as MOSFETs or IGBTs can be used. Here, an independent switch can also include a plurality of individual semiconductor switches, especially to make the switch bidirectional. However, it is also preferred that these switches or only some of them are designed as electromechanical switches, especially electromechanical switches with low resistance.

[0023] The switch and the DC charging contact can be arranged or mounted, for example, within the rectifier (if there is sufficient additional space here), or outside the rectifier. It is conceivable to be arranged, for example, on the housing.

[0024] To operate the motor, especially for the operation of the engine and / or the generator (i.e., the machine operation mode), multiple phase switches are respectively placed in the first switch position (closed), and the one or more inductance switches are respectively placed in the second switch position (open). This means that the phase or the motor is normally connected, but the inductance is disconnected, so that there will be no unwanted current flow or circulation here. Although these DC charging contacts are themselves connected, they do not work unless an external DC voltage source is connected. In this context, it is appropriate to place the charging switch in the first switch position. This thus allows normal operation, such as the electric driving or rest of the vehicle.

[0025] For transferring energy between a connected energy storage device and an external DC voltage system - i.e., for example, for externally charging the energy storage device from a DC voltage source as the DC voltage system, or for feeding energy from the energy storage device to a user having a DC voltage supply device as the DC voltage system - various energy transfer modes can be considered.

[0026] For this purpose, for example, it can be envisaged that in the case of use in a vehicle, when the charging plug is inserted, the switch is automatically (e.g., by means of a corresponding control device) placed in the relevant switch position according to the operating mode. However, it is also possible to switch (manually if necessary) to the external charging or feeding mode.

[0027] In the first energy transfer mode, the charging switch is placed in the first switch position. In this way, the external DC voltage system can be directly connected to the energy storage device. Thereby, for example, current flows directly from the external DC voltage source into the connected energy storage device. This is thus appropriate in the case where the voltage levels of the energy storage device and the external DC voltage system at least substantially correspond to each other. For example, if a DC voltage source with 800 V (or a DC voltage source compatible with 800 V) is available, then this is the case for a battery compatible with 800 V.

[0028] In this regard, it is generally necessary to note that: especially when charging a battery, for example, the actual voltage level of 800 V sometimes drops significantly, but such a battery can still be supplied by the DC voltage source at, for example, 800 V. Therefore, if the charging voltage is higher than the battery voltage, the external charging device can limit the current until the battery voltage is increased by charging.

[0029] Conversely, if the voltage levels of the energy storage device and the external DC voltage system at least substantially do not correspond to each other, for example, if a DC voltage source with 400 V (or a DC voltage source compatible with 400 V) is available in a battery compatible with 800 V, then the second or third energy transfer mode can be considered.

[0030] In the second energy transfer mode, the charging switch is placed in the second switch position, and the one or more inductive switches are each placed in the first switch position (closed). The phase switches can each be placed in the second switch position (open). The latter is suitable for disconnecting the motor or its phases from the rectifier.

[0031] Thus, current flows, for example, from an external DC voltage source through an inductor and a half-bridge (especially the high-side switch of the half-bridge, although the low-side switch can also be switched according to the switching and / or control strategy of the DC-DC converter operation) into the connected energy storage device. Here, the half-bridge can be used as a DC-DC converter or be correspondingly controlled. Thus, it is feasible, for example, to convert the 400V voltage of the DC voltage source into the 800V voltage required by the battery, and vice versa. It should be noted that the two values of 400V and 800V are only examples, and different selections are also possible.

[0032] In the third energy transfer mode, the charging switch is placed in the second switch position, and the one or at least one inductor switch is respectively placed in the first switch position (closed). The phase switches are respectively placed in the first switch position (closed). In the case of multiple inductor switches, for example, only one or two or more than two switches (if any) can be placed in the first switch position (closed). The inductor switches not placed in the first switch position (closed) are then placed in the second switch position (open) or remain in that position.

[0033] Thus, current flows, for example, from an external DC voltage source through an inductor, then through the phases of the motor, and then through a half-bridge (especially the high-side switch of the half-bridge, although the low-side switch can also be switched) into the connected energy storage device. The half-bridge can also be used as a DC-DC converter or be correspondingly controlled here.

[0034] Thus, it is also feasible, for example, to convert the 400V voltage of the DC voltage source into the 800V voltage required by the battery, and vice versa. However, different from the second energy transfer mode, here not only the (separate) inductor is used, but also the phases of the motor - which are also inductors, of course. Thus, if desired or necessary, the charging inductor can be adjusted; this may be required, for example, by an external DC voltage system (when this is a special charging station). However, this may also be the case, for example, when the inductance of the motor is insufficient to increase the switching frequency, and a smaller inductor is required.

[0035] Depending on how many inductor switches are placed in the first switch position (closed), in the case of three phases, the current flows into, for example, two phases, then into the third phase, and then through the half-bridge assigned to that phase; or it flows into one phase, then into the other two phases, and then through the half-bridges assigned to these phases. This will be explained by specific examples in the accompanying drawings.

[0036] Especially in the second and third energy transfer modes, the high-side switch and the low-side switch of the involved half-bridge can be switched at a switching frequency of, for example, several kilohertz, that is, operate using a so-called buck or boost converter to convert the voltage.

[0037] The subject matter of the present invention also relates to a vehicle having a motor unit according to the present invention. The motor unit can be used here as a traction drive, but other uses are also conceivable, for example in the case of smaller machines. As already mentioned, the vehicle can then have a charging terminal which is configured to be connected to a mating device, in particular a charging plug or a charging socket, and which also has a DC voltage terminal. Description of the Drawings

[0038] Further advantages and embodiments of the invention can be derived from the description and the appended drawings.

[0039] The invention is schematically illustrated on the basis of embodiments in the drawings and will be described below with reference to the drawings.

[0040] Figure 1 A vehicle in one embodiment is schematically illustrated.

[0041] Figure 2 A motor unit in one embodiment is schematically illustrated.

[0042] Figure 3 A motor unit in one embodiment is schematically illustrated.

[0043] Figure 4 Shows Figure 2 the motor unit in another operating mode.

[0044] Figure 5 Shows Figure 2 the motor unit in another operating mode.

[0045] Figure 6 Shows Figure 2 the motor unit in another operating mode.

[0046] Figure 7 Shows Figure 2 the motor unit in another operating mode. Detailed Description

[0047] In Figure 1 a vehicle 100 in one embodiment is schematically illustrated. 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 means of an electric machine 130 having a stator 132 and a 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 be driven by means of the electric device 130, or both axles can be driven if necessary. This is only for explanation here.

[0048] The electric motor 130 is connected to a rectifier or an inverter 140 (only schematically shown here; for a more detailed illustration, please refer to the subsequent figures). The rectifier 140 is in turn connected, if necessary, via an intermediate circuit capacitor 142 (the intermediate circuit capacitor 142 can be part of the rectifier 140) to an energy storage device 150 such as a battery. The DC voltage provided by the battery 150 can be converted into an AC voltage by the rectifier 140 for the engine operation of the electric motor 130. Conversely, when the electric motor 130 is in generator operation, the AC voltage generated here can also be converted into a DC voltage by the rectifier 140 (and thus bidirectionally) to charge the battery 150.

[0049] As mentioned earlier, the electric motor 130 and the rectifier 140 are here part of the electric motor unit 160.

[0050] As a supplement, a DC charging terminal 170 is also provided on the vehicle 100, which can be connected via a charging cable 172 with a plug 174 and via a socket 176 to a DC voltage source 178 (such as the power grid, an external power supply device or another DC voltage system). This can be a DC voltage source with corresponding plugs and sockets. In this way, the energy storage device or the battery 150 can be charged. It should be noted here that the specific connection of the DC charging terminal 170 to the electric motor unit 160 or the battery 150 is not shown here; for this, please refer to the subsequent figures.

[0051] In Figure 2 an embodiment of the electric motor unit 160 is schematically shown; this can be the Figure 1 electric motor unit 160. The rectifier 140 and the battery 150 are also shown, and they can also be the Figure 1 ones in

[0052] Three phases U, V, W in the electric motor 130 are shown here, and these phases each include a phase winding 136 (only marked once). It should be noted here that the two terms "phase" and "phase winding" can also be used synonymously, where the phase winding usually (only) designates the winding or coil within the stator. Here, the phase winding 136 is part of the stator (see Figure 1 ); the rotor is not shown here.

[0053] For a three-phase electric motor, the rectifier 140 has six switching elements, such as transistors like MOSFETS or IGBTs, where every two switching elements form a half-bridge and are assigned to one phase. Exemplarily, the switching elements of phase U are respectively marked as T U_H and T U_L(High side and low side), which form a half-bridge labeled 144, where the center tap can be connected to phase U or its phase winding or the corresponding phase terminal. Correspondingly, it applies to the switching elements and half-bridges of the remaining phases V and W.

[0054] The terminals on the DC voltage side of the half-bridge are connected to each other or joined and connected to the DC voltage terminals B+ and B-. The rectifier can be connected to the energy storage or battery 150 via the DC voltage terminals B+ and B-. The intermediate circuit capacitor 142 is connected in parallel with the terminals on the DC voltage side.

[0055] Exemplarily, the motor unit 160 or the rectifier 140 also has three phase switches 184U, 184V, 184W, which are respectively assigned to a phase terminal and thus also to a phase here. Here, each of the three phase switches 184U, 184V, 184W is configured such that: in the first switch position, the corresponding phase terminal is connected to the center tap of the corresponding half-bridge, and in the second switch position, the corresponding phase terminal is disconnected from the center tap of the corresponding half-bridge. In Figure 2 the illustrated case, the phase switches 184U, 184V, 184W are respectively in the first switch position S1, i.e., closed.

[0056] Furthermore, the motor unit exemplarily has three inductors 146U, 146V, 146W and exemplarily has two inductor switches 182U, 182V. Here, each of the three inductors is assigned to a half-bridge. Additionally, each of the two inductor switches is assigned to an inductor. No inductor switch is assigned to the inductor 146W. The inductor switches 182U, 182V are respectively configured such that: in the first switch position, the corresponding inductor is connected to the center tap of the corresponding half-bridge, and in the second switch position, the corresponding inductor is disconnected from the center tap of the corresponding half-bridge. In Figure 2 the illustrated case, the inductor switches 182U, 182V are respectively in the second switch position S2, i.e., open.

[0057] Therefore, the inductors 146U, 146V can be selectively connected to and disconnected from the corresponding half-bridge, while the inductor 146W is permanently connected to the respective half-bridge. Correspondingly, the inductor 146W does not require an inductor switch, thus enabling cost savings.

[0058] Furthermore, the motor unit has a first DC charging contact 190 and a second DC charging contact 192, where the first DC charging contact is connected to the DC voltage terminal B-.

[0059] The motor unit also has a charging switch 180, where the charging switch is designed such that: in the first switch position, the second DC charging contact 192 is connected to the DC voltage terminal B+, and in the second switch position, it is connected to the three inductors 146U, 146V, 146W. InFigure 2 In the illustrated case, the charging switch 180 is in the first switch position S1. The three inductors 146U, 146V, 146W (or the inductors present in general according to the quantity situation) are in particular designed as coupled inductors in this design.

[0060] The various switches described here, the phase switches 184U, 184V, 184W, the inductor switches 182U, 182V and the charging switch 180 can for example each be a device having a plurality of transistors (such as MOSFETs or IGBTs), where each switch can be placed in two different switch positions (in the form of a changeover switch). Alternatively, the switches can also be designed as electromechanical switches for example. While a changeover switch is required for the charging switch 180, the phase switches 184U, 184V, 184W and the inductor switches 182U, 182V can also use simple make-and-break switches.

[0061] Furthermore, the motor unit 160 exemplarily has a control device 186 which is configured to selectively place the phase switch and / or the inductor switch and / or the charging switch in the first switch position S1 or in the second switch position S2 independently of one another.

[0062] With the motor unit 160 according to Figure 2 it is now possible to execute or use various operating modes, which will also be explained below with reference to further figures.

[0063] To operate the motor, i.e. for engine or generator operation (i.e. motor operating mode), the phase switches are each placed in the first switch position S1 (closed) and the inductor switches are each placed in the second switch position S2 (open). This situation is shown in Figure 2 . As shown in Figure 2 , the charging switch 180 can be placed in the first switch position S1, but can also be placed in the second switch position S2 if necessary.

[0064] Although these DC charging contacts are already connected, they do not operate unless an external DC voltage source is connected. In one embodiment, it can also be provided that there is a protection mechanism which prevents the connection of an external DC voltage source in such cases (i.e. especially in the machine operating mode).

[0065] The rectifier 140 or the half-bridge then operates as a DC / AC converter or an AC / DC converter. For this purpose, the resulting currents are shown in Figure 2 , namely the current I from the battery to the half-bridge bat , and the phase currents I from the phases to the half-bridge U , I V , I W .

[0066] Since the inductance switches 182U and 182V are open, even if the inductance 182W is directly connected, no power will circulate through the inductances 182U, 182V, and 182W.

[0067] Figure 3 FIG. schematically shows a motor unit 160' in one embodiment, having a rectifier 140', a motor 130, and a battery 150. The motor unit 160' may correspond to the motor unit 160 according to Figure 2 , but there are some differences. The same elements and components are labeled with the same reference numerals. These differences will be discussed in particular below.

[0068] Compared with Figure 2 , here only two inductances 146U and 146V, one inductance switch 182U, and two phase switches 184U and 184V are provided. Therefore, phase W or its phase terminal is directly connected to the center tap of the corresponding half-bridge; no inductance is allocated to this phase or half-bridge. Compared with Figure 2 , no inductance switch is allocated to the inductance 146V either, which makes this inductance directly connected to the center tap of the corresponding half-bridge.

[0069] The machine operating mode can be the same as Figure 2 here, especially because the inductance is not necessary (or is disconnected as much as possible anyway). And all phases are connected. Here, it should be noted that: the variant shown here in Figure 3 only provides two inductances instead of three (coupled) inductances.

[0070] In Figure 4 shows Figure 2 the motor unit 160 in another operating mode, namely the first energy transfer mode, for energy transfer between the battery and the DC voltage source (for example, external charging of the battery 150). The motor unit 160 corresponds to the motor unit in Figure 2 , so not all components will be described here again; in this regard, reference can be made to Figure 2 and the related description.

[0071] In particular, all switches, namely the phase switches, inductance switches, and the charging switch 180, are also in the same switch positions as Figure 2 . However, different from the machine operating mode: for the first charging mode, it is crucial that the charging switch 180 is in the first switch position S1, as shown in Figure 4 . In contrast, it does not matter which switch positions the phase switches and inductance switches are in, which is different from Figure 2Differently, as shown here, possible current circulation is prevented by placing the inductive switches 182U, 182V in the second switch position S2 (open).

[0072] Here, the external DC voltage source 178 is now connected to the DC charging terminal 170 (see also Figure 1 ).

[0073] Thus, it is feasible to transfer energy between the external DC voltage source 178 and the battery 150. This can be charging the battery or supplying power from the battery to the external DC voltage source 178. Here, the current I ch flows directly between the battery and the external DC voltage source 178.

[0074] The first energy transfer mode can correspondingly also be implemented using the motor unit 160' according to Figure 3 . The inductive switches and the phase switches can here respectively have switch positions according to Figure 3 .

[0075] In Figure 5 is shown Figure 2 the motor unit 160 in another operating mode, namely the second energy transfer mode, for transferring energy between the battery and the DC voltage source (e.g. externally charging the battery 150). The motor unit 160 corresponds to the motor unit in Figure 2 , so not all components will be described here again; in this regard, reference can be made to Figure 2 and the relevant description.

[0076] Here, the charging switch 180 is in the second switch position S2, the inductive switches 182U, 182V are in the first switch position S1 (closed), and the phase switches 184U, 184V, 184W are in the second switch position S2 (open). Here, the open phase switches 184U, 184V, 184W ensure that the phases are disconnected or isolated from the rectifier.

[0077] The external DC voltage source 178 is connected to the DC charging terminal 170 (see also Figure 1 ), as in the first energy transfer mode.

[0078] Thus, energy transfer between the external DC voltage source 178 and the battery 150 is achieved, but not directly, but via the inductance and the half - bridge or its high - side switches. This can be charging the battery or supplying power from the battery to the external DC voltage source 178. Here, the current I chFrom an external DC voltage source 178 via inductors 146U, 146V, 146W (which are connected in parallel) and a half-bridge to the battery 150. Here, the current is divided into three paths via the three inductors and converges again after the half-bridge. However, the half-bridge allows voltage conversion, for example, from 400V to 800V here.

[0079] The second energy transfer mode can correspondingly also be implemented using the motor unit 160' according to Figure 3 . For this purpose, the inductor switch 182U must be placed in the first switch position S1 (closed), and the phase switches 184U, 184V can be in the second switch position S2 (open) as shown in Figure 5 . The switch 180 can be in the second switch position S2. But here, the current only flows through two inductors 146U, 146V and two respective half-bridges accordingly. In this case, the directly connected phase W is also irrelevant because it is not required in this mode.

[0080] In Figure 6 shows Figure 2 the motor unit 160 in another operating mode, namely the third energy transfer mode, especially in the first variant, for energy transfer between the battery and the DC voltage source (for example, external charging of the battery 150). The motor unit 160 corresponds to the motor unit in Figure 2 , so all components will not be described here again; in this regard, reference can be made to Figure 2 and the relevant description.

[0081] Here, the charging switch 180 is in the second switch position S2, the inductor switch 182U is in the first switch position S1 (closed), the inductor switch 182V is in the second switch position S2 (open), and the phase switches 184U, 184V, 184W are in the first switch position S1 (closed).

[0082] The external DC voltage source 178 is connected to the DC charging terminal 170 (see also Figure 1 ), as in the first energy transfer mode.

[0083] Thus, energy transfer between the external DC voltage source 178 and the battery 150 is achieved, but not directly, but through the inductors and the half-bridge or its high-side switches. This can be charging the battery or supplying power from the battery to the external DC voltage source 178.

[0084] Here, the current I chFrom an external DC voltage source 178, current first flows through inductors 146U, 146W (which are connected in parallel) - but not through inductor 146V because the inductor switch 182V is open - and two associated half - bridges, into the two associated phases U, W of the motor first, and then through phase V into the associated half - bridge (the high - side and low - side switches of which can be switched at a switching frequency of, for example, several kilohertz, for example to be used as a so - called boost or buck converter, while the other two half - bridges or their switches can be turned off), and then into the battery 150. The half - bridge allows voltage conversion, for example, from 400V to 800V here.

[0085] The difference from the second energy transfer mode according to Figure 5 is that the phase windings of the motor are used as additional inductors. Thus, current fluctuations can be reduced, for example. A lower switching frequency may also be required, for example.

[0086] The third energy transfer mode can correspondingly also be implemented using the motor unit 160' according to Figure 3 . For this purpose, the inductor switch 182U must be placed in the first switch position S1 (closed), and the phase switches 184U, 184V can be in the first switch position S1 (closed) as shown in Figure 6 . Here, current then flows through the two inductors 146U, 146V and the two associated half - bridges, into the two associated phases U, V of the motor first, and then through phase W into the associated half - bridge (the high - side and low - side switches of which can be switched at a switching frequency of, for example, several kilohertz, while the other two half - bridges or their switches can be turned off), and then into the battery 150. Here, the difference from the circuit according to Figure 2 or Figure 6 is only that the currents flowing through phases V and W are swapped, but this actually has no effect or does not have a significant impact.

[0087] It should be noted in this context that: in the circuit according to Figure 6 , the switch positions of the inductor switches 182U, 182V can also be swapped, so the currents flowing through phases U and V are also swapped, but this actually does not have a significant impact.

[0088] In Figure 7 shows Figure 2 the motor unit 160 in another operating mode, namely the third energy transfer mode, in a second variant, for energy transfer between the battery and the DC voltage source (for example, for external charging of the battery 150). The motor unit 160 corresponds to the motor unit in Figure 2 , so not all components will be described here again; in this regard, reference can be made to Figure 2 and the relevant description.

[0089] Here, the charging switch 180 is in the second switch position S2, the inductance switches 182U, 182V are in the second switch position S2 (open), and the phase switches 184U, 184V, 184W are in the first switch position S1 (closed).

[0090] The external DC voltage source 178 is connected to the DC charging terminal 170 (see also Figure 1 ), as in the first energy transfer mode.

[0091] Thus, energy transfer between the external DC voltage source 178 and the battery 150 is achieved, but not directly. Instead, it is transferred through an inductor and a half-bridge or its high-side switches. This can be used to charge the battery or supply power from the battery to the external DC voltage source 178.

[0092] Here, the current I ch flows from the external DC voltage source 178 through the inductor 146W - but since the inductance switches 182U, 182V are open, it does not flow through the inductors 146U, 146V - and through the associated half-bridge. First, it flows into the relevant phase W of the motor, then through phases U, V into the associated half-bridge, and then into the battery 150. The half-bridge allows voltage conversion, for example, from 400V to 800V here.

[0093] As shown in the variant according to Figure 6 , the phase windings of the motor are used as additional inductors here. However, different from the variant according to Figure 6 , only one inductor is used here instead of two, resulting in a slightly different total inductance.

[0094] This variant of the third energy transfer mode can correspondingly also be implemented using the motor unit 160' according to Figure 3 . For this purpose, the inductance switch 182U must be placed in the second switch position S2 (open), and the phase switches 184U, 184V can be in the first switch position S1 (closed) as shown in Figure 7 . Here, the current then correspondingly flows through the inductor 146V and the associated half-bridge (which is closed here and not switched), first into the relevant phase V of the motor, then through phases U, W into the associated half-bridges (the high-side and low-side switches of which can be switched at a switching frequency of, for example, several kilohertz), and then into the battery 150. Here, the difference from the circuit according to Figure 2 or Figure 7 (apart from having only two inductors as in Figure 3 ) is only that the currents flowing through phases V and W are swapped, but this actually has no effect or does not have a significant impact.

Claims

1. A motor unit (160) comprising a motor (130) with one or more phases (U, V, W) and a rectifier (140), in, The rectifier has a plurality of half-bridges, wherein one half-bridge (144) is provided for each phase terminal of the electric machine. The rectifier has DC voltage terminals (B+, B-) which are configured to be connected to an energy storage device (150). The DC voltage side terminals of the half bridge are connected to each other and to the corresponding DC voltage terminals (B+, B-). The motor unit has one or more phase switches (184U, 184V, 184W), wherein at least one of the one or more phase switches is respectively assigned to a phase terminal and is configured such that: in a first switch position (S1), the corresponding phase terminal is connected to the center tap of the corresponding half bridge, and in a second switch position (S2), the corresponding phase terminal is disconnected from the center tap of the corresponding half bridge, The motor unit comprises one or more inductors (146U, 146V, 146W) and one or more inductor switches (182U, 182V), wherein one of the one or more inductors is respectively assigned to a half-bridge, wherein at least one of the one or more inductor switches is respectively assigned to an inductor and is configured such that: in a first switch position (S1), the corresponding inductor is connected to a center tap of the corresponding half-bridge, and in a second switch position (S2), the corresponding inductor is disconnected from the center tap of the corresponding half-bridge, The motor unit has a first DC charging contact and a second DC charging contact (190, 192), wherein the first DC charging contact (190) is connected to one of the DC voltage terminals (B-), The motor unit has a charging switch (180), wherein the charging switch is designed such that in a first switch position (S1), the second DC charging contact (192) is connected to the other of the DC voltage terminals (B+), and in a second switch position (S2), it is connected to the one or more inductors (146U, 146V, 146W).

2. The motor unit (160) according to claim 1, wherein: At least one phase terminal is not assigned a phase switch, wherein the at least one phase terminal is connected to the associated half-bridge at a center tap of the half-bridge.

3. The motor unit (160) according to claim 1 or 2, configured to perform at least one of the following modes: In a machine operation mode, placing the plurality of phase switches in the first switch position (S1) respectively, and placing the one or more inductive switches in the second switch position (S2) respectively; In a first energy transfer mode, placing the charging switch in the first switch position (S1); In the second energy transfer mode, the charging switch is placed in the second switch position (S2), the one or more inductive switches are placed in the first switch position (S1), and preferably the phase switches are placed in the second switch position (S2); as well as In a third energy transfer mode, the charging switch is placed in the second switch position (S2), at least one of the one or more inductive switches is placed in the first switch position (S1), and the phase switches are placed in the first switch position (S1).

4. The motor unit (160) according to any one of the preceding claims, wherein: The half bridges are respectively designed as two-level half bridges or multi-level half bridges with more than two levels.

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

6. The motor unit (160) according to any one of the preceding claims also has a control device, which is configured to: independently and selectively place the phase switch and / or the inductance switch and / or the charging switch in the first switch position (S1) or in the second switch position (S2).

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

8. A vehicle (100) having an electric motor unit (160) according to any one of the preceding claims and having an energy store (150), in particular a battery, which is electrically connected to the DC voltage terminals (B+, B-) of the rectifier (140).

9. The vehicle (100) according to claim 8 further comprises a DC charging terminal (170), which is configured to be connected to a counterpart device, in particular a charging plug or a charging socket, and is connected to the first DC charging contact and the second DC charging contact or comprises these contacts.

10. A method for operating a motor unit (160) according to any one of claims 1 to 7 or a vehicle according to claim 8 or 9, in, The phase switch and / or the inductance switch and / or the charging switch are placed in the first switch position (S1) or the second switch position (S2) depending on the operating mode.

11. The method according to claim 10, wherein: The machine operating mode is used to operate the electric machine (130), in particular to operate the electric machine as a motor or as a generator.

12. The method according to claim 10 or 11, wherein: For energy transfer between the connected energy storage device (150) and an external DC voltage system, the external DC voltage system is connected or is to be connected to the first DC charging contact and the second DC charging contact, and When the voltage levels of the energy storage device (150) and the external DC voltage system are at least substantially consistent, a first energy transmission mode is used.

13. The method according to any one of claims 10 to 12, wherein: For energy transfer between the connected energy storage device (150) and an external DC voltage system, the external DC voltage system is connected or is to be connected to the first DC charging contact and the second DC charging contact, and The second energy transfer mode or the third energy transfer mode is used when the voltage levels of the energy store (150) and the external DC voltage system do not substantially correspond to each other at least.

14. The method according to any one of claims 13, wherein: The third energy transfer mode is used when adjustment of the charging inductance is desired or required.

Images