Control device, electric machine and method

Abstract

The present invention discloses a control device for an electric machine having a first partial winding and a second partial winding independent of the first partial winding in each phase, having an inverter device which has at least one bridge circuit for each phase of the electric machine, and having a switching device which has at least one changeover switch for each phase of the electric machine, which is designed to electrically couple the first partial winding and the second partial winding of the corresponding phase in series with the respective bridge circuit of the inverter device or to electrically couple the first partial winding and the second partial winding of the corresponding phase in parallel with the respective bridge circuit of the inverter device. Furthermore, the present invention discloses a corresponding electric machine and a corresponding method.

Description

Field of the InventionThe present invention relates to a control device for an electric machine having a first partial winding and a second partial winding independent of the first partial winding in each phase. The present invention further relates to an electric machine and a method.Background ArtDE 10 2007 040 725 A1 discloses an electric machine having a polyphase winding which can be operated via a converter at a DC voltage source. Partial windings of the winding can be switched between series connection and parallel connection.Further electric machines are known from DE 10 2012 209 080 A1, DE 11 2006 002 603 T5, DE 692 16 062 T2, DE 199 17 419 A1 and DE 192 806 A.Electric machines or electric machines are nowadays used in a large number of applications. For example, electric machines can be used as drive motors in vehicles, e.g. rail vehicles or road vehicles. Electric machines can also be combined, for example, in a motor vehicle, in particular in a so-called hybrid vehicle, with an internal combustion engine in order to drive the respective vehicle.A disadvantage of electric machines is the power drop which these have in the upper rotational speed range. In order to increase the power of an electric machine in the upper rotational speed range, the use of more material in the stator and rotor of the electric machine is nowadays necessary. In this case, the electric machine increases in diameter or length as a result of the increased material use and thus becomes larger and heavier.Alternatively, the frequency converter can be adapted to the respective electric machine, so that the electric machine has a greater power in the upper rotational speed range. However, this means increased circuit complexity in the frequency converter.SUMMARY OF THE INVENTIONThe object of the present invention is therefore to provide a simplified possibility for increasing the power in an electric machine.This object is achieved in each case by a control device according to Claim 1, an electric machine according to Claim 6 and a method according to Claim 10.The realization on which the present invention is based is that known possibilities for increasing the power of an electric machine in the high rotational speed range are very complex.The idea on which the present invention is based is now to take this knowledge into account and to provide a possibility of carrying out a simple Y-to-YY changeover in an electric machine.For this purpose, the present invention provides a control device which has an inverter device which has a bridge circuit for each phase of the electric machine. In addition, a switching device is provided, which has a changeover switch for each of the phases, in each case, by means of which the two partial windings of the individual phases can be connected either electrically in series or electrically in parallel to the corresponding bridge circuit.This makes it possible, with suitable control of the shifting device, to increase the power, in particular in the upper rotational speed range of the electric machine, so that approximately no more power reduction is required in the upper rotational speed range.Furthermore, at low rotational speed, a high torque can already be achieved with lower currents and an over-dimensioning of the electric machine is no longer necessary in order to achieve high powers at high rotational speeds.Because the switching device has a first switch for each phase of the electric machine, which switch is respectively coupled to an output of the first partial winding of the respective phase and to a star node, a simple changeover between a series connection and a parallel connection of the partial windings is made possible.Because each bridge circuit has a second switch which is coupled to a positive supply line and to a first node, and a third switch which is coupled to the first node and to a negative supply line, the first node in each case being coupled to an input of the first partial winding of the respective phase, simple activation of the individual phases with an AC voltage is made possible.Because each of the changeover switches is respectively coupled to the input of the second partial winding of the respective phase and is designed to couple respective input to the output of the corresponding first partial winding of the respective phase or to the respective second node, the fourth switches and fifth switches do not have to be clocked in a series connection. Furthermore, the first switches need only conduct half the current when connected in parallel.Advantageous embodiments and refinements emerge from the dependent claims and from the description with reference to the figures.In one embodiment, each of the changeover switches and / or the first switches and / or the second switches and / or the third switches and / or the fourth switches and / or the fifth switches has contactors and / or relays and / or anti-parallel connected thyristors. This enables a simple adaptation of the control device to different applications.In one embodiment, each of the changeover switches and / or the first switches and / or the second switches and / or the third switches and / or the fourth switches and / or the fifth switches has a combination of at least one contactor or relay and anti-parallel connected thyristors. This makes it possible to reduce the losses in the switched-on state and at the same time to reduce the switching times.In one embodiment, the control device has a control device which is designed to control the changeover switches and / or the first switches and / or the second switches and / or the third switches and / or the fourth switches and / or the fifth switches in such a way that the first partial windings and the second partial windings are each electrically connected in series when the power of the electric machine is below a first threshold value and that the first partial windings and the second partial windings are electrically connected in parallel when the power of the electric machine is equal to the first threshold value or is above the first threshold value. This makes it possible to adapt the switching time for the switching between the series circuit and the parallel circuit to different application cases.In one embodiment, the control device is designed to actuate the second switches and / or the third switches and / or the fourth switches and / or the fifth switches in such a way that phase currents in the electric machine are zero before the control device actuates the changeover switches and / or the first switches. The electroless switching leads to a low load on the changeover switches and switches and prevents over-voltages at the partial windings of the electric machine.In one embodiment, the outputs of the second subwindings are electrically coupled together. The star connection of the outputs of the second partial winding simplifies the actuation of the individual phases of the electric machine.In one embodiment, the electric machine is designed as an asynchronous machine or a synchronous machine. This enables the present invention to be used in different applications.The above embodiments and developments can be combined with one another as desired, if appropriate. Further possible embodiments, developments and implementations of the invention also include combinations of features of the invention described above or below with respect to the exemplary embodiments, which combinations are not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.Content Indication of the DrawingsThe present invention is explained in more detail below with reference to the exemplary embodiments indicated in the schematic figures of the drawings. The following are shown: FIG. 1 shows a block diagram of an embodiment of a control device according to the invention; FIG. 2 shows a block diagram of an embodiment of an electric machine according to the invention; FIG. 3 shows a flow diagram of an embodiment of a method according to the invention; FIG. 4 is a block diagram of an embodiment of partial windings according to the invention in series; FIG. 5 is a block diagram of an embodiment of partial windings according to the invention connected in parallel; FIG. 6 is a block diagram showing a comparative example of a driving apparatus; FIG. 7 shows a block diagram of an embodiment of a control device according to the invention; and FIG. 8 shows a block diagram of a further embodiment of a control device according to the invention.In all figures, identical or functionally identical elements and devices have been provided with the same reference numerals, unless otherwise indicated.Within the scope of this patent application, an electric machine is understood to be any type of electric machine that has a plurality of electrical phases and converts electrical energy into mechanical energy.A partial winding is understood to mean a winding which, given a suitable external circuit, would also suffice solely for driving the electric machine. If, within the scope of this patent application, first and second partial windings of a phase are mentioned, this is to be understood to mean that a phase has two such partial windings, the connections of which are led out of the housing of the electric machine in such a way that at least some of the inputs and the outputs of the partial windings can be electrically contacted outside the housing. An input or output of the windings is to be understood as meaning in each case the two electrical connections of the windings. In this case, the designation as an input or output does not imply a specific arrangement. For example, an input or an output may be coupled to a positive voltage or to a negative voltage.A series connection of the first partial windings and the second partial windings can also be referred to as a Y circuit, since a single winding consisting of the first and second partial windings results in the electric machine in a series connection of the first partial windings and the second partial windings and the windings of all phases are interconnected with one another in a Y circuit.A parallel connection of the first partial windings and the second partial windings, on the other hand, can also be referred to as a YY circuit, since, in the case of a parallel connection of the first partial windings and the second partial windings in the electric machine, two independent complete winding systems are produced, which are arranged electrically in parallel.An electric machine which is designed such that the first partial windings and the second partial windings can be connected both in parallel and in series can also be referred to as voltage-switchable.A bridge circuit is understood within the scope of this patent application to mean any circuit which can connect an output of the bridge circuit selectively to a positive or a negative DC voltage.Within the scope of this patent application, a changeover switch is understood to mean a switching element which has three connections, wherein one of the connections can optionally be electrically coupled to one of the two further connections.A switch is understood to mean a switching element which can electrically connect or disconnect two nodes to one another.A control device is understood to mean any type of circuit which can generate control signals for the bridge circuit or for the switching device. The control device can be constructed from discrete analog components. However, the control device can also be designed, for example, as a digital logic circuit or can be executed as a program in a processor or microcontroller.DESCRIPTION OF EMBODIMENTSFIG. 1 shows a block diagram of an embodiment of a control device 1 according to the invention.The control device 1 of FIG. 1 is designed to control an electric machine 2 which has a first partial winding TW 1, TW 1 u, TW 1 v, TW 1 wand a second partial winding TW 2, TW 2 u, TW 2 v, TW 2 win each phase P 1-PN (see FIG. 2 ).For this purpose, the control device 1 has an inverter device 5 which has a bridge circuit 6- 1- 6- nfor each phase P 1- Pnof an electric machine 2 to be controlled. Only two bridge circuits 6- 1, 6- nare shown in FIG. 1. However, further bridge circuits 6- 1, 6- nare indicated by three points.The individual bridge circuits 6- 1- 6- nare each coupled to a changeover switch US 1, USnof a switching device 7.The changeover switches US 1- USncan electrically couple the first partial winding TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial winding TW 2, TW 2 u, TW 2 v, TW 2 wof the corresponding phase P 1- Pnof the electric machine 2 in series with the respective bridge circuit 6- 1- 6- nof the inverter device 5 in a first switch position.In a second switch position, the changeover switches US 1- USn can electrically couple the first partial winding TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial winding TW 2, TW 2 u, TW 2 v, TW 2 wof the corresponding phase P 1- Pn in parallel with the respective bridge circuit 6- 1- 6- nof the inverter device 5.For the sake of clarity, an electrical energy source is not shown, which can be coupled to the inverter device 5 and which can supply the individual bridge circuits 6- 1- 6- nwith electrical energy, which convert the bridge circuits 6- 1- 6- ninto a suitable control voltage for the individual phases P 1- Pnof the electric machine 2.The changeover switches US1-USn and the switching elements of the bridge circuits 6- 1- 6- nmay be designed, for example, as contactors, relays, anti-parallel connected thyristors T 1-T 6 or the like. In particular, the changeover switches US1-USn and the switching elements of the bridge circuits 6- 1- 6- ncan also have a combination of a contactor or a relay with a circuit of anti-parallel connected thyristors T1-T6. This makes it possible to carry out a rapid changeover with the aid of the thyristors T1-T6 and, after the rapid changeover with the aid of the contactors or relays, to bypass the current requirement caused by the thyristors T1-T6. This combination of a contactor or a relay and a circuit of anti-parallel connected thyristors T1-T6 can also be used for all further switches, changeover switches or the like which are mentioned in this patent application.In the switching between a series connection and a parallel connection of the first partial windings TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2, TW 2 u, TW 2 v, TW 2 w, the time of the switching may depend on different factors.For example, the series connection or Y-connection can be maintained until the inverter device 5 can no longer provide the voltage required for a predefined power. In order to reduce the required voltage, the parallel connection of the first partial windings TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2, TW 2 u, TW 2 v, TW 2 wmay then be selected. This increases the current that the inverter device 5 must provide to the first partial windings TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2, TW 2 u, TW 2 v, TW 2 w.FIG. 2 shows a block diagram of an embodiment of an electric machine 2 according to the invention.The electric machine 2 of FIG. 2 has a control device 1 according to FIG. 1. However, in the control device 1 of FIG. 2, a control device 9 is also provided, which is coupled to the inverter device 5 and to the switching device 7 in order to control the latter.The electric machine 2 further comprises a housing 10 in which a plurality of phases P1-Pn are arranged. In one embodiment, the electric machine 2 may have, for example, three phases P 1-P 3.Each of the phases P1 - Pn comprises a first subwinding TW1 and a second subwinding TW2. Furthermore, each of the phases P1-Pn is respectively coupled to a changeover switch US1-USn of the switching device 7, which is designed to control the connection of the individual partial windings TW1, TW2 in such a way that they are coupled to the respective bridge circuit 6- 1- 6- 2 either in a series connection or in a parallel connection.The electric machine 2 can be designed, for example, as an asynchronous machine 2. Alternatively, the electric machine 2 can also be designed as a synchronous machine 2. Further embodiments of the electric machine 2 are likewise possible.In one specific embodiment, electric machine 2 may be designed, for example, as a drive motor of a motor vehicle. In this case, the electric machine 2 can be used, for example, as one of two drive motors in a hybrid vehicle. Alternatively, the electric machine 2 can also be used as the sole drive motor in an electric vehicle.In this case, the electric machine 2 can have a low power of a few kW, for example, if the electric machine 2 is used in a passenger car. However, the electric machine 2 can also have a high power of several hundred or thousand kW if the electric machine 2 is used, for example, as a drive motor for a rail vehicle or in an industrial plant.In one embodiment, the control device 1 is arranged in a housing which allows the control device 1 to be coupled directly to the housing 10 of the electric machine 2. This allows, for example, simple joint cooling of both the electric machine 2 and the control device 1. Furthermore, the cable lengths for contacting the individual phases P1-Pn of the electric machine are minimized.The control device 9 illustrated in FIG. 2 can generate PWM signals, for example, which serve to actuate the bridge circuits 6- 1- 6- nof the inverter device 5, so that the desired voltages and currents result in the phases P 1- Pnof the electric machine 2. In one embodiment, the control device 9, as shown in FIG. 2, is arranged in the drive apparatus 1. In a further embodiment, however, the control device 9 can also be arranged outside the control device 9. For example, the function of the control device 9 can be integrated in a control unit. This control device can be, for example, an engine control device in a passenger car or a system control device of an industrial system.FIG. 3 shows a flow diagram of an embodiment of a method according to the invention.The method provides for driving the bridge circuits 6- 1- 6- nin S 1. In this case, the bridge circuits 6- 1- 6- nare controlled in such a way that predefined operating currents are produced in the phases P 1- Pnof the electric machine 2.Finally, the method provides for switching S 2 the respective interconnection of the first partial windings TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2, TW 2 u, TW 2 v, TW 2 wbetween a parallel connection and a series connection as a function of the instantaneous power of the electric machine 2.Prior to the switchover S 2, the bridge circuits 6- 1- 6- ncan be controlled in such a way that the operating currents in the phases P 1- PNof the electric machine 2 during the switchover amount to zero. This enables low-loss, electroless switching of the interconnection of the first partial windings TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2, TW 2 u, TW 2 v, TW 2 w.In one embodiment of the method, the switching can comprise the generation of control signals for the individual changeover switches US1-USn of the switching device 7. Depending on the embodiment of the changeover switches, the control signals can be embodied, for example, as individual discrete control signals, as a plurality of discrete control signals or else as digital control signals.The method according to the invention can be carried out, for example, in the control device 9. In this case, the method according to the invention can be embodied in the control device 9 in hardware, for example in a programmable logic module or as a discrete structure of logic elements. Alternatively, the method according to the invention can also be designed as a program, which is executed, for example, by a processor, microcontroller or the like in the control device 9.FIG. 4 shows a block diagram of an embodiment of partial windings TW 1 u, TW 1 vand TW 1 wand TW 2 U, TW 2 Vand TW 2 Win series connection according to the invention.Three phases P1-P3 are shown in FIG. 4. The first phase P 1 or else U phase has a first partial winding TW 1 uand a second partial winding TW 2U. The second phase P 2 or also V phase has a first partial winding TW 1 vand a second partial winding TW 2V. Finally, the third phase P 3 or also W phase has a first partial winding TW 1 wand a second partial winding TW 2W.The outputs U 22, V 22, and W 22 of the second sub-windings TW 2U, TW 2V, and TW 2W are electrically connected to each other. Electrical connections are respectively drawn between the outputs U 12, V 12, W 12 of the first partial windings TW 1 u, TW 1 vand TW 1 wand the inputs U 21, V 21, W 21 of the second partial windings TW 2 U, TW 2V and TW 2W, which electrically couple these to one another.These connections are designed to be switchable according to the invention and can be implemented, for example, by the changeover switches US1-USn.In conjunction with the following FIG. 5, it becomes clear how a changeover can be made between a series connection and a parallel connection of the first partial windings TW 1 u, TW 1 vand TW 1 wof the second partial windings TW 2 U, TW 2 Vand TW 2 W.FIG. 5 shows the subwindings TW1u, TW1v and TW1w and TW2U, TW2V and TW2W of FIG. 4 connected in parallel.In order to interconnect the partial windings TW 1 u, TW 1 vand TW 1 wand TW 2 U, TW 2 Vand TW 2 Win a parallel connection, the electrical connections between the outputs U 12, V 12, W 12 of the first partial windings TW 1 u, TW 1 vand TW 1 wand the inputs U 21, V 21, W 21 of the second partial windings TW 2 U, TW 2 Vand TW 2 W have been disconnected. Instead, an electrical connection was established between the outputs U12, V12, W12 of the first subwindings TW1u, TW1v and TW1w, and the inputs U21, V21, W21 of the second subwindings TW2U, TW2V and TW2W were electrically connected to the respective inputs U11, V11, W11 of the corresponding first subwindings TW1u, TW1v and TW1w.For the sake of clarity, the connection of the inputs U 11, V 11, W 11 of the first partial windings TW 1 u, TW 1 vand TW 1 wto a power source is not illustrated in FIG. 4 or FIG. 5.It can be clearly seen in FIG. 5 that the first partial windings TW 1 u, TW 1 vand TW 1 wof the three phases P 1-P 3 are arranged in a star connection or else a Y circuit by the electrical connection of the outputs U 12, V 12, W 12 thereof. The same applies to the second sub-windings TW 2U, TW 2V, and TW 2W of the three phases P 1-P 3. The first partial windings TW 1 u, TW 1 vand TW 1 ware thus arranged in a parallel connection with the second partial windings TW 2 U, TW 2Vand TW 2W.The switching between a parallel circuit and a series circuit of the first partial windings TW 1 u, TW 1 vand TW 1 wand the second partial windings TW 2 U, TW 2 Vand TW 2W takes place with an arrangement according to FIG. 7.FIG. 6 shows a block diagram of a comparative example of a control device 1 for a three-phase electric machine 2, which can have, for example, three phases P 1-P 3 according to FIGS. 4 and 5.The control device 1 has a switching device 7 which has a changeover switch USu, USv, USw for each phase P1-P3. Each of the changeover switches USu, USv, USw is coupled to the input U 21, V 21, W 21 of the corresponding second partial winding TW 2 u, TW 2 v, TW 2 wof the corresponding phases P 1-P 3.The changeover switches can selectively couple the inputs U 21, V 21, W 21 of the second partial windings TW 2 u, TW 2 v, TW 2 wto the input U 11, V 11, W 11 or the output U 12, V 12, W 12 of the respective first partial winding TW 1 u, TW 1 v, TW 1 wof the corresponding phase P 1-P 3.The switching device 7 further comprises three first switches S1u, S1v, S1w for the three phases P1-P3, which are respectively coupled to the output U12, V12, W12 of the corresponding first partial winding TW1u, TW1v, TW1w. At the second outputs of the first switches S 1 u, S 1 v, S 1 w, the first switches S 1 u, S 1 v, S 1 win the star node Ks are electrically coupled to one another.Finally, the drive apparatus 1 of FIG. 6 further comprises an inverter device 5 which comprises a bridge circuit 6- 1- 6- 3 for each of three phases P 1- P 3. Each of the bridge circuits 6- 1- 6- 3 includes a second switch S 2 u, S 2 v, and S 2 wcoupled to a positive supply line DC+ carrying a positive supply voltage. Further, each of the bridge circuits 6- 1- 6- 3 includes a third switch S 3 u, S 3 v, and S 3 wcoupled to a negative supply line DC- carrying a negative supply voltage. The second switches S 2 u, S 2 vand S 2 wand the third switches S 3 u, S 3 vand S 3 ware each coupled to one another in a common first node K 1 u, K 1 vand K 1 w. The first nodes K1u, K1v and K1w are further coupled to the input U11, V11, W11 of the corresponding first partial winding TW1u, TW1v and TW1w of the corresponding phase P1-P3, respectively.In order to arrange the respective first partial windings TW 1 u, TW 1 v, TW 1 win series with the respective second partial windings TW 2 u, TW 2 v, TW 2 w, the changeover switches USu, USv, USw are driven in such a way that they couple the inputs U 21, V 21, W 21 of the second partial windings TW 2 u, TW 2 v, TW 2 wto the output U 12, V 12, W 12 of the corresponding first partial windings TW 1 u, TW 1 v, TW 1 wof the corresponding phase P 1-P 3. Further, the first switches S 1 u, S 1 v, S 1 ware opened. This switch position results in the interconnection of the first partial windings TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2 u, TW 2 v, TW 2 w, as is illustrated in FIG. 4.To arrange the respective first partial windings TW 1 u, TW 1 v, TW 1 win a parallel connection to the respective second partial windings TW 2 u, TW 2 v, TW 2 w, the changeover switches USu, USv, USw are driven in such a way that they couple the inputs U 21, V 21, W 21 of the second partial windings TW 2 u, TW 2 v, TW 2 wwith the inputs U 11, V 11, W 11 of the corresponding first partial windings TW 1 u, TW 1 v, TW 1 wof the corresponding phase P 1-P 3. Further, the first switches S 1 u, S 1 v, S 1 ware closed. This switch position results in the interconnection of the first partial windings TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2 u, TW 2 v, TW 2 w, as is illustrated in FIG. 5.FIG. 7 shows a block diagram of an embodiment of a control device 1 according to the invention.The drive device 1 of FIG. 7 differs from the drive device 1 of FIG. 6 in that the bridge circuits 6- 1- 6- 3 each have a further pair of switches, the fourth switches S 4 u, S 4 v, S 4 wand the fifth switches S 5 u, S 5 v, S 5 w. The fourth switches S 4 u, S 4 v, S 4 ware each likewise coupled to the positive supply line DC+, which conducts a positive supply voltage. Furthermore, the fifth switches S 5 u, S 5 v, S 5 ware each likewise coupled to the negative supply line DC- which conducts a negative supply voltage. The fourth switches S 4 u, S 4 v, S 4 wand the fifth switches S 5 u, S 5 v, S 5 win each bridge circuit 6- 1, 6- 2, 6- 3 are respectively coupled to each other at a second node K 2 u, K 2 v, K 2 w.Finally, the changeover switches USu, USv, USw are designed to not selectively couple the inputs U 21, V 21, W 21 of the second partial windings TW 2 u, TW 2 v, TW 2 wto the input U 11, V 11, W 11 or the output U 12, V 12, W 12 of the first partial winding TW 1 u, TW 1 v, TW 1 wof the corresponding phase P 1-P 3.Rather, the changeover switches USu, USv, USw are designed to couple the inputs U21, V21, W21 of the second partial windings TW2u, TW2v, TW2w selectively to the corresponding second node K2u, K2v, K2w or the output U12, V12, W12 of the first partial winding TW1u, TW1v, TW1w of the corresponding phase P1-P3.In order to arrange the respective first partial windings TW 1 u, TW 1 v, TW 1 win series with the respective second partial windings TW 2 u, TW 2 v, TW 2 w, the changeover switches USu, USv, USw are driven in such a way that they couple the inputs U 21, V 21, W 21 of the second partial windings TW 2 u, TW 2 v, TW 2 wwith the outputs U 12, V 12, W 12 of the corresponding first partial windings TW 1 u, TW 1 v, TW 1 wof the corresponding phase P 1-P 3. Further, the first switches S 1 u, S 1 v, S 1 ware opened. This switch position results in the interconnection of the first partial windings TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2 u, TW 2 v, TW 2 w, as is illustrated in FIG. 4. This procedure corresponds to the procedure in the control device 1 of FIG. 6.To arrange the respective first partial windings TW 1 u, TW 1 v, TW 1 win a parallel connection to the respective second partial windings TW 2 u, TW 2 v, TW 2 w, the changeover switches USu, USv, USw are driven in such a way that they couple the inputs U 21, V 21, W 21 of the second partial windings TW 2 u, TW 2 v, TW 2 wto the corresponding second node points K 2 u, K 2 v, K 2 w. Further, the first switches S 1 u, S 1 v, S 1 ware closed. This switch position results in the interconnection of the first partial windings TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2 u, TW 2 v, TW 2 w, as is illustrated in FIG. 5.An advantage of this embodiment is that the fourth switches S 4 u, S 4 v, S 4 wand the fifth switches S 5 u, S 5 v, S 5 wdo not have to be clocked in a series connection, and the current load of the first switches S 1 u, S 1 v, S 1 win the parallel connection is halved.FIG. 8 shows a section of a block diagram of an embodiment of a control device 1 according to the invention.FIG. 8 shows in particular the switching device 7 for a phase P 1 or also the U phase of the electric machine 2, as can be used in combination with FIG. 6. In this case, the changeover switch USu and the first switch S1u are designed as switching elements based on anti-parallel connected thyristors T1-T6.An input U of the arrangement of Fig. 8 is coupled to the first node K1u (not shown). Furthermore, the input U is coupled to the input U 11 of the first partial winding TW 1 u. The input U is further coupled to the changeover switch USu, which has in each case two anti-parallel thyristors T 1, T 2 and T 3, T 4, which are connected in series. Between the series-connected anti-parallel thyristors T 1, T 2 and T 3, T 4, the changeover switch is coupled to the input U 21 of the second partial winding TW 2 u. The second pair of anti-parallel connected thyristors T3, T4 is coupled at its other end to the output U12 of the first partial winding TW1u and to the first switch S1u. The first switch S1u also comprises a pair of anti-parallel connected thyristors T5 and T6 and is coupled at its output Y to the star node Ks (not shown).The embodiment with thyristor-based switching elements shown in FIG. 8 enables a very rapid switching between a parallel connection and a series connection of the first partial windings TW 1, TW 1 u, TW 1 v, TW 1 wand the second partial windings TW 2, TW 2 u, TW 2 v, TW 2 w.In one embodiment, the thyristor-based switching elements can also be supplemented by contactors or relays. Thus, power consumption after the switching is reduced.

Claims

Control device (1) for an electric machine (2) having a first partial winding (TW1, TW1u, TW1v, TW1w) and a second partial winding (TW2, TW2u, TW2v, TW2w) in each phase (P1 - Pn) which is independent of the first partial winding (TW1, TW1u, TW1v, TW2w), having an inverter device (5) which has at least one bridge circuit (6-1 - 6-n) for each phase (P1 - Pn) of the electric machine (2); and having a switching device (7) which has at least one changeover switch (US1 - USn, USu, USv, for each phase (P1 - Pn) of the electric machine (2), USw) which is configured to electrically couple in series the first partial winding (TW 1, TW 1 u, TW 1 v, TW 1 w) and the second partial winding (TW 2, TW 2 u, TW 2 v, TW 2 w) of the corresponding phase (P 1 - Pn) in each case to the respective bridge circuit (6- 1 - 6- n) of the inverter device (5) or to electrically couple the first partial winding (TW 1, TW 1 u, TW 1 v, TW 1 w) and the second partial winding (TW 2, TW 2 u, TW 2 v, TW 2 w) of the corresponding phase (P 1 - Pn) in parallel to the respective bridge circuit (6- 1 - 6- n) of the inverter device (5); wherein the switching device (7) has, for each phase (P1-Pn) of the electric machine (2), a first switch (S1u, S1v, S1w), which is coupled in each case to an output (U12, V12, W12) of the first partial winding (TW1, TW1u, TW1v, TW1w) of the respective phase (P1-Pn) and to a star node (Ks); wherein each bridge circuit (6-1-6-n) comprises a second switch (S2u, S2v, S2w) coupled to a positive supply line (DC+) and to a first node (K1u, K1v, K1w), and a third switch (S3u, S3v, S3w) coupled to the first node (K1u, K1v, K1w) and to a negative supply line (DC-); wherein the first node (K1u, K1v, K1w) is coupled to an input (U11, V11, W11) of the first subwinding (TW1, TW1u, TW1v, respectively, TW1w) of the respective phase (P1-Pn), each bridge circuit (6-1-6-n) having a fourth switch (S4u, S4v, S4w) coupled to the positive supply line (DC+) and to a second node (K2u, K2v, K2w), and a fifth switch (S5u, S5v, S5w) coupled to the second node (K2u, K2v, K2w) and to the negative supply line (DC-), each of the changeover switches (US1-USn, USu, USv, USw) being coupled to the input (U21, V21, respectively, W21) of the second subwinding (TW2, TW2u, TW2v, TW2w) of the respective phase (P1-Pn) is coupled and is designed to controllably couple the respective input (U21, V21, W21) of the second subwinding (TW2, TW2u, TW2v, TW2w) to the output (U12, V12, W12) of the corresponding first subwinding (TW1, TW1u, TW1v, TW1w) of the respective phase (P1-Pn) or to the respective second node (K2u, K2v, K2w).The drive device according to claim 1, wherein at least one of the changeover switches (US1 - USn, USu, USv, USw) and / or the first switches (S1u, S1v, S1w) and / or the second switches (S2u, S2v, S2w) and / or the third switches (S3u, S3v, S3w) and / or the fourth switches (S4u, S4v, S4w) and / or the fifth switches (S5u, S5v, S5w) comprises contactors and / or relays and / or anti-parallel connected thyristors (T1 - T6).The drive device according to claim 2, wherein at least one of the changeover switches (US1 - USn, USu, USv, USw) and / or the first switches (S1u, S1v, S1w) and / or the second switches (S2u, S2v, S2w) and / or the third switches (S3u, S3v, S3w) and / or the fourth switches (S4u, S4v, S4w) and / or the fifth switches (S5u, S5v, S5w) comprises a combination of at least one contactor or relay and anti-parallel connected thyristors (T1 - T6).Drive device according to one of the preceding claims, having a control device (9) which is designed to drive the changeover switches (US1 - USn, USu, USv, USw) and / or the first switches (S1u, S1v, S1w) and / or the second switches (S2u, S2v, S2w) and / or the third switches (S3u, S3v, S3w) and / or the fourth switches (S4u, S4v, S4w) and / or the fifth switches (S5u, S5v, S5w) in such a way that the first partial windings (TW1, TW1u, TW1v, TW 1 w) and the second subwindings (TW 2, TW 2 u, TW 2 v, TW 2 w) are each electrically connected in series when the power of the electric machine (2) is below a first threshold value and that the first subwindings (TW 1, TW 1 u, TW 1 v, TW 1 w) and the second subwindings (TW 2, TW 2 u, TW 2 v, TW 2 w) are each electrically connected in parallel when the power of the electric machine (2) is equal to or above the first threshold value.Control device according to one of the preceding claims, wherein the control device (9) is designed to control the second switches (S2u, S2v, S2w) and / or the third switches (S3u, S3v, S3w) and / or the fourth switches (S4u, S4v, S4w) and / or the fifth switches (S5u, S5v, S5w) in such a way that phase currents in the electric machine (2) are zero before the control device (9) controls the changeover switches (US1 - USn, USu, USv, USw) and / or the first switches (S1u, S1v, S1w).Electric machine (2) having at least two phases (P1 - Pn), each phase (P1 - Pn) having a first partial winding (TW1, TW1u, TW1v, TW1w) and a second partial winding (TW2, TW2u, TW2v, TW2w) which is independent of the first partial winding (TW1, TW1u, TW1v, TW1w); and having a drive device (1) according to one of the preceding claims, which is coupled to the phases (P1 - Pn) of the electric machine (2).Electric machine according to Claim 6, wherein the activation device (1) is mechanically coupled to a housing (10) of the electric machine (2).Electric machine according to Claim 6 or 7, wherein the outputs (U22, V22, W22) of the second partial windings (TW2, TW2u, TW2v, TW2w) are electrically coupled to one another.Electric machine according to one of Claims 6 to 8, wherein the electric machine (2) is designed as an asynchronous machine or a synchronous machine.Method for driving an electric machine (2) according to one of Claims 6 to 9, having the steps: driving (S1) the bridge circuits (6-1 - 6-n) in such a way that predefined operating currents are produced in the phases (P1 - Pn) of the electric machine (2); and switching over (S2) the respective interconnection of the first subwindings (TW1, TW1u, TW1v, TW1w) and of the second subwindings (TW2, TW2u, TW2v, TW2w) between a parallel circuit and a series circuit as a function of the instantaneous power of the electric machine (2), wherein each changeover switch (US1 - USn, USu, USv, USw) is driven, the respective input (U21, V21, W21) of the second subwinding (TW2, TW2u, TW2v, TW2w) can be coupled to the output (U12, V12, W12) of the corresponding first subwinding (TW1, TW1u, TW1v, TW1w) of the respective phase (P1-Pn) or to the respective second node (K2u, K2v, K2w).Method according to Claim 10, wherein, before the switching (S2), the bridge circuits (6-1-6-n) are driven in such a way that the operating currents during the switching are zero.

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