Electric motor

Abstract

The invention relates to an electric motor having a rod winding on the stator side, comprising a plurality of inverters for controlling rod bars, the power components of the inverters being arranged on one or more circuit boards which form at least one circular or annular structure, the circuit boards being electrically connected by means of a connecting plate, and the connecting plate is annular and is inserted on the circuit board.

Description

[0001] The invention relates to an electric motor with a stator-side bar winding.

[0002] The electric motor can have a bar winding on the stator side. Here, the stator has a series of bars instead of wound wires as field conductors. The bars have a low inductance compared to conventional windings. Therefore, a relatively high current is required to generate a predetermined magnetic field.

[0003] However, due to the low inductance of the rod, such a high current only requires a relatively low voltage of, for example, 12 V. The low voltage allows the components of the inverter for controlling the rod to be arranged at a small distance from each other. Thus, the components of the power electronics can be arranged, for example, on one or more boards arranged close to the electric motor.

[0004] It is particularly advantageous that such an electric motor can be designed in a compact manner so that each field conductor is controlled by its own power section and thus each field conductor can be controlled by its own phase. Thus, electric motors with 48, 72 or even 120 field conductors and phases can be compactly constructed.

[0005] The problem here is that a large number of power components must be connected to the central control device. The cable connection between the central control device and the plurality of power components disadvantageously leads to a very complex structure.

[0006] The object of the present invention is to provide an electric motor which eliminates the disadvantages mentioned at the outset and in particular has an efficient connection between the control device and the power section.

[0007] This object is achieved by an electric motor having the features specified in claim 1 .

[0008] The electric motor according to the invention comprises a stator with a plurality of field conductors designed as bars. In addition, the electric motor comprises an inverter with one or more parallel-connected power components for each field conductor for controlling the same, wherein the inverter comprises a control device for generating control signals for the power components.

[0009] In this case, the output stages of the inverter are arranged on a plurality of printed circuit boards, which are in turn arranged in such a way that they form at least one circular or ring-shaped structure.

[0010] One or more plug connector devices are arranged on each circuit board for contacting the output stage. A connection plate is plugged onto the plug connector devices of at least two circuit boards in one of the circuit boards in a round or annular configuration.

[0011] Since the circular or annular structure is formed from a plurality of circuit boards, it should be understood that it is not geometrically accurate and the circular or annular surface does not have to be completely filled. Rather, gaps are left between the circuit boards.

[0012] The plug connector device can be, for example, a spring contact or a direct board-plug connector device. This can be a socket or a (embedded) plug or a threaded contact, wherein the corresponding opposite side is arranged on the connecting plate.

[0013] The final stage is understood in the context of this document to be a power semiconductor switch that is associated with the AC voltage output. Since the gate drive circuit associated with the power semiconductor switch is partially separated from the power semiconductor switch in some embodiments of the invention, it is not included in the final stage. The power component is understood to be a power semiconductor switch together with its corresponding gate drive circuit. The entirety of the power component and the control device is called an inverter.

[0014] The invention advantageously enables particularly simple contacting of electronic components on the circuit board, wherein the multiple cables between the control device and the circuit board are replaced by a single connection plate for each circular or ring-shaped structure. If such an electric motor has, for example, 72 phases, i.e., 72 field conductors, and three of these field conductors are each controlled by a circuit board, then each circular or ring-shaped structure comprises 24 circuit boards. The 24 cables for the control are then replaced by a connection plate, which is conveniently connected to the plug connector arrangement of all circuit boards. This can be connected to the control device via a single cable.

[0015] Expediently, there is one web, in particular exactly one web, for each circular or annular structure.

[0016] The connecting plate advantageously establishes an indirect connection between the control device and the end stage on the circuit board, ie the power semiconductor switch. Indirectly means that the gate driver circuit for the power semiconductor switch is located in the connection. The gate driver circuit can be arranged in various ways.

[0017] Advantageous designs of the electric motor according to the invention are derived from the dependent claims. Here, the embodiments of the independent claim can be combined with the features of one of the dependent claims or the features of several dependent claims. For this purpose, the following features can also be provided in addition:

[0018] The connecting plate is preferably circular or annular. As in the case of the annular structure, in the case of the connecting plate, the annular shape leaves a recess in the center through which air cooling can be achieved.

[0019] The connecting plate is preferably plugged into the plug connector devices of all circuit boards of the corresponding circular or annular structure. It then connects all circuit boards of the circular or annular structure to the control device and reduces the quantity of required cable connections as much as possible.

[0020] In the alternative design, the connecting plate is annular sector-shaped. In other words, the connecting plate only forms an annular cutout. In this case, it is also only plugged into a part of the circuit board of the circular or annular structure. It is preferably designed here so that a plurality of connecting plates of the same type cover the entire ring, so that all circuit boards are plugged into one of the connecting plates. When the motor is small, the center angle can be appropriately about 180°, 120° or 90°, so 2, 3 or 4 connecting plates are required for the connection of all circuit boards of the circular or annular structure. In the case of a larger motor with many phases, the diameter of the circular or annular structure can be within the range of meters. In this case, it is appropriate to use a much smaller center angle, because otherwise the connecting plate will be too large. In this case, the connecting plate can be designed so that it, for example, contacts two, three or four circuit boards. In a motor with 120 phases, where the connecting plate contacts three circuit boards, the center angle is only about 9°. In this connecting plate, the curvature of the circumference is very small and a rectangular plate (German: Platine) can be used instead of the connecting plate of the annular sector. Since the printed circuit boards are advantageously all designed in the same manner, it is expedient if the positioning of the plug connector arrangements also corresponds to the annular arrangement.

[0021] Of course, the data for the center angle do not necessarily have to be exact. The actual center angle can be slightly smaller, since this leaves some space between the connection plates and all circuit boards can still be contacted. Although such a connection plate leads to a greater number of cables for the control than an annular connection plate, it is easier to install and remove, especially when the electric motor comprises a plurality of cooling plates covered with circuit boards on both sides.

[0022] The number of connecting plates is preferably equivalent to the number of circular or annular structures. If the circuit board forms two or more circular or annular structures, then preferably for each circular or annular structure, the connecting plate is plugged into the plug connector devices of at least two circuit boards of each circular or annular structure.

[0023] In a certain embodiment, the connecting plate is connected to a plurality of circuit boards of two different circular or annular structures, wherein these structures are then suitably arranged on two adjacent cooling plates on the sides facing each other. Here, the connecting plate is plugged into the circuit board of one of the two circular or annular structures by a plug connector device. In addition, the connecting plate can also be plugged into the circuit board of another circular or annular structure by a plug connector device. But alternatively, the connection can also be realized by cable connection here, so as to keep a more flexible distance and simplify installation with one of the two circular or annular structures. This design can be combined with other embodiments. For example, two concentric and coplanar connecting plates can be present, and can be plugged into the circuit boards of two circular or annular structures facing each other, so as to have redundancy during control. The connecting plate can also be a complete ring or a ring sector-shaped connecting plate, or a connecting plate with different shapes.

[0024] Even if the connecting plate is completely annular, the electric motor can also include two or more connecting plates for each circular or annular structure. They can, for example, have different radii and can therefore be inserted concentrically and coplanarly on the circular or annular structure.

[0025] When the connecting plate only had the ring sector, similar design was also feasible.In this case, the connecting plates with different radiuses can also be inserted concentrically and coplanarly on the circle or the annular structure and form two rings with gap thus.

[0026] In both cases, the connection plates and the printed circuit boards can be designed so that each printed circuit board is plugged into exactly one of the connection plates. In this case, for example, the inner ring can connect every second printed circuit board or every second phase, and the outer ring can connect the remaining printed circuit boards or phases. In this case, the connection plate covers all printed circuit boards, but only connects every second one in each case.

[0027] It can also be designed so that each circuit board is plugged into two or more connecting plates. Wherein, the connecting plate just connects all the covered circuit boards. This can achieve redundancy and avoid the failure of the entire motor or most of the motor when the connecting plate fails.

[0028] The central axis of one or more circular or annular structures may correspond to the motor axis. In other words, this means that the center of each circular or annular structure is located on the motor axis, and each circular or annular structure is arranged perpendicular to the motor axis.

[0029] If the electric motor has a plurality of circular or annular structures, these are preferably arranged parallel to one another and axially offset relative to one another, so that their centers of circle lie on a common central axis.

[0030] The connecting plate is preferably arranged parallel to the inserted circular or annular structure, ie perpendicular to the central axis, in particular perpendicular to the motor axis.

[0031] In this arrangement of a circular or annular structure, the field conductor or the current conductor extending the field conductor runs through the circular or annular structure in a rotationally symmetrical manner in the case of a straight line. This results in a highly modular construction, in which the same type of plates can be used and in which the connection of the corresponding field conductors is particularly simple.

[0032] Furthermore, the field conductor or the current conductor extending the field conductor can even serve as a mechanical support for the plate, thereby further simplifying the design.

[0033] The connection board can include a gate drive circuit for the power components. This allows the gate drive circuit to no longer occupy its own space on the board. As a result, there is more space on the circuit board for the power components, which simplifies the design of the board. In addition, the waste heat generated by the gate drive circuit is also removed from the board, thereby simplifying heat dissipation.

[0034] Furthermore, the connection board may also include one or more local control chips, which perform control tasks, such as current measurement for the corresponding output stage. The local control chips are respectively associated with and connected to one or more gate driver circuits.

[0035] Alternatively, the gate drive circuit can be arranged on the board itself together with the corresponding power semiconductor switch. The connection board thus becomes simpler in structure, since it only needs to establish a connection between the control device and the board and thus the gate drive circuit. For this purpose, the connection board can advantageously include a multiplexer.

[0036] In another alternative design, the gate driver circuit can also be arranged on its own driver board. It is preferably plugged onto the board with the power semiconductor switch, wherein the arrangement of the boards is sandwich-shaped in this case, i.e. the driver board at least partially covers the board. In this case, the connection board can be plugged onto the driver board or the circuit board, i.e. have a connection to one of the types of boards, via which the signals are transmitted.

[0037] Each phase controlled on the board has a half-bridge constructed from two logic switches for this purpose. The logic switch can here comprise exactly one single power semiconductor switch. However, in order to allow the switching of higher currents, the logic switch can also comprise a plurality of power semiconductor switches, for example two, three, five or even more power semiconductor switches connected in parallel.

[0038] The gate driver circuit is preferably designed to control control terminals (eg gate terminals) of two logic switches of the half bridge, i.e. to provide current / voltage in such a way that the switching action required by the control device is performed and the switches are turned on and off in the manner required by the control device.

[0039] If the logic switches of the half-bridge each include more than one power semiconductor switch connected in parallel, the gate drive circuit can be designed to drive all power semiconductor switches. However, it is also possible to provide more than one gate drive circuit for the control. For example, the number of gate drive circuits can correspond exactly to the number of parallel power semiconductor switches. Thus, if the half-bridge includes five high-side MOSFETs and five low-side MOSFETs, there can be up to ten gate drive circuits. In this case, it is advantageous for space reasons if the gate drive circuit is arranged on a driver board or a connection board.

[0040] The connecting board may include a multiplexer and other additional circuits, such as monitoring, control, amplification / buffering circuits or communication interfaces, and may be designed such that a control signal for a first power component having a multiplexer input from a control device on a first signal line is transmitted to one of a plurality of second signal lines, which is connected to the first power component via, for example, a spring contact.

[0041] The multiplexer on the connection board makes it possible to connect the control device to the connection board via only a single signal line, which simplifies the design. It is particularly advantageous if the connection board connects a plurality of power components on a single board and a plurality of power components connected in parallel to the control device, since in this case, without a multiplexer, a large number of parallel control lines from the control device to the connection board would be required. The single signal line can be a direct electrical line or also a connection that operates according to a communication standard, such as a USB connection, a LAN connection, an optical connection or a screw connection.

[0042] The connecting plate may include one or more spiral connections with one or more circular or annular structures. The screw connection prevents the connecting plate from loosening due to vibration and other external factors.

[0043] The connecting plate can be a flexible printed circuit board. A flexible printed circuit board can deform under mechanical load. The conductor tracks and other electronic components on such a printed circuit board retain their electrical function.

[0044] The current conductor can be designed as an axially extended field conductor. The current conductor is designed similarly to the field conductor of the electric motor, but can have different cross-sectional shapes, for example. For example, the current conductor can have a circular cross section, while the field conductor can have an elongated rectangular cross section. It is expedient for the current conductor to be able to carry at least the same current as the field conductor. The current conductor and the field conductor can be connected by a shoe designed for this purpose, which ensures a mechanical and electrical connection.

[0045] The circuit board can be arranged on at least one cooling plate. The cooling plate can be covered with plates on both sides to achieve a high density of electrical components. The cooling plate is preferably a metal, essentially circular or annular plate. The cooling plate can have heat pipes for heat dissipation or cooling channels for air to flow through. The cooling plate can also be composed of two annular, parallel plates that are screwed to each other so that a distance is maintained between them. Active ventilation can then be arranged so that air is sucked in between the plates.

[0046] The cooling plate can be arranged in such a way that the field conductor or the current conductor electrically connected to the field conductor is in mechanical operative connection with the cooling plate. For example, the current conductor or the field conductor can be designed as a mechanical support for the cooling plate. For this purpose, the cooling plate is preferably arranged perpendicular to the axis of the electric machine. In this way, the cooling plate with the circuit board can be arranged at the axial end of the electric machine in a space-saving manner.

[0047] The circuit board can be in the form of a circle or an annular sector. A circuit board with such a shape can be assembled particularly well into a circle or an annular shape and can therefore be arranged on the axial end of the machine in an optimal manner adapted to the shape of the electric machine, wherein a high degree of modularity is simultaneously achieved.

[0048] The power component is preferably designed to generate an AC voltage with an amplitude of 200 V or less, in particular 100 V or less, in particular 50 V or less. This makes it possible to arrange components of the power electronics, in particular power semiconductor switches, at short distances from one another in the millimeter range and thus to arrange a very large number of power semiconductor switches in a relatively small space. This makes it possible to provide high currents and to generate a plurality of phases, for example 6, 12, 24, 48, 72 or even 120 phases, simultaneously without requiring much space.

[0049] Field conductors designed as rods can be solid rods, for example made of copper, but in other designs of the electric motor can also have subdivisions in the longitudinal direction or can be designed as conductor bundles, wherein the general structure remains as a rod (rather than a winding).

[0050] The present invention will be further described and illustrated below based on the embodiments shown in the accompanying drawings. In the schematic diagram:

[0051] Figure 1 An electric motor having power components arranged on a circuit board carried by a cooling plate is shown;

[0052] Figure 2 The plate arranged on the cooling plate is shown in a front view;

[0053] Figure 3 A detail of an electric motor having a cooling plate with a circuit board is shown in an oblique view;

[0054] Figure 4 A detail of an electric motor is shown in a side view, with a cooling plate with said plate and a connecting plate plugged in via spring contacts;

[0055] Figures 5 to 7 A front view of the electric motor is shown with a cooling plate together with a circuit board and a connection plate;

[0056] Figure 8 A cross-sectional view of a cooling plate with a circuit board, a driver board and a connection board is shown.

[0057] Figure 1 An isometric view of an electric motor 10 according to an embodiment of the present invention is shown. The electric motor 10 includes a stator 11 and a rotor substantially arranged in the stator 11. Figure 1 The rotor is fixed to the Figure 1 The rotor is connected to a shaft (not shown in the figure). The rotor rotates around the axis 9 by electromagnetic interaction with the energized stator. The rotor is separated from the stator 11 by an air gap. In other embodiments, the motor 10 can also be an external rotor motor or a bell-shaped armature motor.

[0058] The stator 11 comprises a plurality of rigid and straight conductor bars 12 as field conductors. Figure 1 The two ends 13 facing each other are connected to each other via short-circuit rings. On the back side 14 of the electric motor 10, the conductor bars 12 are each powered individually by a corresponding inverter module. Due to the conductor bars 12, the electric motor 10 is operated at a low voltage, and the inverter module can be arranged relatively closely together with other components of the electronic device (DC converter, rectifier) ​​on the circuit board 15. The circuit board 15 is in the form of a ring segment in this example, and a plurality of individual circuit boards 15 together form a ring circuit board structure.

[0059] In the example, it is assumed that the circuit board 15 carries at least the power components of the inverter, but a part of the circuit board 15 may also carry a rectifier and a DC / DC converter.

[0060] Figure 2 A top view of such a circuit board structure is shown. Figure 2 The number of circuit boards shown in FIG. 1 is not shown here for the sake of clarity. Figure 1 The specific number of such circuit boards 15 depends on the specific design of the motor 10, in particular the number of conductor bars 12. Each circuit board 15 includes a plurality of semiconductor switches 422. The semiconductor switches 422 together form the power part of the inverter, which provides the conductor bars 12 with an AC voltage.

[0061] In addition, a portion of the circuit boards 15 or all of the circuit boards 15 may include driver circuits and other electronic components not shown in the figure, such as capacitors. The semiconductor switches 422 are power semiconductors, such as IGBTs, MOSFETs or JFETs, and may also include diodes not shown, depending on the circuit. The semiconductor switches 422 are connected to form a half bridge, for example. The capacitor not shown may be, for example, an intermediate circuit capacitor of a half bridge. The semiconductor switches 422 of the circuit board 15 can be assigned to a single phase here. In the case of an electric motor 10 having a large number of field conductors 12 and a corresponding number of phases, it is advantageous that the circuit board 15 carries power components for multiple phases.

[0062] The circuit board 15 also comprises contact locations 421 to which the conductor bars 12 are connected. The circuit board 15 is carried by a disk-shaped cooling plate 16, wherein the cooling plate 16 can be provided with the circuit board 15 on both sides for better utilization of space.

[0063] Since relatively high currents are required in the conductor bars in the electric motor 10, preferably a plurality of power components are connected in parallel for supplying it. This can be achieved, for example, by: Figure 1 The six circuit board structures shown in the figure on three cooling plates 16 are all connected in the same way to the conductor bars 12 and are therefore electrically connected in parallel. It is utilized here that the conductor bars 12 or the connecting elements 18 to the conductor bars 12 also pass through the cooling plates 16 and also through the circuit board 15 at the contact point, or at least make a contact in the case of the outermost cooling plate 16.

[0064] Figure 3 The cross-sectional view of the electric motor 10 is shown in an oblique view. It can be seen here that the connecting element 18 is mechanically supported and passes through three cooling plates 16. The connecting element 18 is connected to the conductor bar 12 via the shoe 17. The output stages on the circuit board 15, which are located in the area where one of the connecting elements 18 passes through the cooling plate 16, are connected in parallel and jointly supply the conductor bar 12 with current. Figure 3 In the illustrated configuration, two connecting elements 18 each pass through the circuit board 15. Thus, each board carries the final stages for two phases of the motor 10. In other variants of the motor 10, a single circuit board 15 can also carry only one phase or three or more phases, wherein the same number of connecting elements 18 pass through the circuit board 15.

[0065] Figure 4 A side view of a detail of the electric motor 10 is shown. Figure 4 Eight circuit boards 15 are shown which are arranged on two cooling plates 16 . Figure 4 Four connecting plates 32 are also shown, which are respectively connected to two of the circuit boards 15. The connecting plates 32 are connected to the sockets 34 of the corresponding circuit boards 15 via spring contacts 33 in parallel with the circuit boards. Each connecting plate 32 also has a socket 35.

[0066] The socket 35 is provided for a cable connection 36 connected to a control device. It can lead out signal lines in parallel, for example as a socket strip for a direct board plug connector device or as a socket for parallel interface cables. Another possibility is that the socket 35 is a USB or LAN (RJ45) socket. Other connection types, such as optical connections, are also possible. The connecting board 32, 61 can also have electronic components, not shown, for example for the control of the socket 35 or for other signal preparation, signal processing or communication.

[0067] Figure 4 The layout in corresponds to Figures 1 to 3 Therefore Figure 4 The cross-sectional view of FIG. 1 includes eight circuit boards 15 in a ring structure formed by the circuit boards 15 . Figure 4 The connecting plate 32 shown in FIG. 1 is annular and is also plugged onto the printed circuit board 15 (not shown).

[0068] Figure 5 The same structure is shown in the previous figure. Figure 5 As can be seen in FIG. 1 , the circuit board 15 forms a ring structure and the connecting plate 32 is ring-shaped. Figure 5 , 12 circuit boards 15 are arranged on the front side of the cooling plate 16, and the cooling plate 16 is arranged on both sides and as Figure 4 When two cooling plates are used, the electric motor 10 therefore comprises 48 circuit boards 15, which are connected to the control board via four connecting plates 32. Only four cable connections 36 are required for this connection. Figure 5 Only the front side of the cooling plate 16 and only one connecting plate 32 are shown in the front view of FIG. 3 , all other elements being covered.

[0069] The accompanying drawings show a single spring contact 33 and a socket 34 in a simplified manner. However, in each case, multiple actual signal lines can also be referred to. The socket 34 can therefore actually be a socket strip and the spring contact 33 can be a corresponding plug strip. It is not important which element carries the socket 34 or the spring contact, which can be replaced.

[0070] Therefore, according to Figure 4 and Figure 5 In the example of a ring-shaped connecting plate 32, all circuit boards 15 of the ring structure are connected to the corresponding connecting plate 32 and connected to the control device via it. The connecting plate 32 has a gate drive circuit 72 and a local control chip 73 for each connected circuit board 15 in this example. This is provided by a multiplexer 93 with the signal received via the cable connection 36. In addition, the connecting plate 32 has electrical connections between the elements, but for the sake of clarity, this is not shown.

[0071] Figure 6 A front view of an alternative embodiment is shown. Figure 5 As shown, the circuit board 15 also forms a ring structure. Figure 5On the contrary, the connection board is divided into three ring-sector connection boards 61. Each ring-sector connection board 61 includes a socket 35 for the cable connection part 36 of the control device and a multiplexer 93 for dividing the input signal. In other aspects, the ring-sector connection board 61 includes a gate drive circuit 72 and a local control chip 73 associated with the circuit board 15 connected respectively. The ring-sector connection boards 61 each have a center angle slightly less than 120°, that is, they each form about one-third of a circle. Therefore, by combining three ring-sector connection boards 61, all circuit boards 15 of the ring structure are connected to the control device again. In addition to the examples shown, the ring-sector connection board 61 can also be designed with a center angle of 180° or 90°, whereby the circuit board 15 is connected through two or four connection boards 61.

[0072] By means of three annular segment-shaped connecting plates 61 , each with its own cable connection 36 and two cooling plates arranged on both sides, a total of twelve cable connections 36 are produced between the connecting plate 61 and the control device.

[0073] Another possible design is Figure 7 . The connection board 75 is annular, but in contrast to the previous example, does not contain the gate drive circuit 72 and the local control chip 73, but only contains the socket 35, the multiplexer 93 and the spring contacts 33 to the circuit board 15. In addition, the connection board 75 may also have other electronic components for signal preparation, signal processing and communication. The spring contacts 33 are connected to the multiplexer 93 via signal lines 82. For clarity, the signal lines are shown as simple lines, but each single line can include multiple separate electrical connections. The connection board 75 therefore acts as a signal distributor. The gate drive circuit 72 and the local control chip 73 are arranged on the circuit board 15 in this embodiment ( Figure 7 not shown).

[0074] In addition to being able to plug the connecting plate 75 directly onto the circuit board 15 carrying the final stage, there is also Figure 8 Another embodiment is shown in a cross-sectional view in FIG. The circuit board 15 arranged on the cooling plate 16 carries the final stage of the inverter, which is simplified as a power semiconductor switch 71. The driver board 70 carries the gate drive circuit 72 and the local control chip 73. The plug connector device 74 transmits signals between the circuit board 15 and the driver board 70. The spring contact 33 is arranged on the driver board 70 in this embodiment. Therefore, in this embodiment, the connecting plate 75 is plugged into the driver board 70, as shown in the figure.

[0075] Reference numerals list

[0076] 9 Motor axis

[0077] 10. Electric Motor

[0078] 11. Stator

[0079] 12 Conductor rods

[0080] 13 End side

[0081] 14 Dorsal

[0082] 15 Plate

[0083] 16 Cooling Plate

[0084] 17 Boots

[0085] 18 Connecting elements

[0086] 32, 61, 75 connecting plate

[0087] 33 Spring contacts

[0088] 34, 35 sockets

[0089] 36 Cable connection

[0090] 61 Ring fan-shaped connecting plate

[0091] 70 Driver board

[0092] 71 Power semiconductor chips

[0093] 72 Gate drive circuit

[0094] 73 Local control chip

[0095] 82 signal line

[0096] 93 Multiplexer

[0097] 421 Contact Position

[0098] 422 Semiconductor Switches

Claims

1. An electric motor (10) having: a stator (11) having a plurality of field conductors (12) designed as rods, - an inverter with one or more parallel-connected power components for each field conductor (12) for controlling the same, wherein: The inverter comprises a control device for generating control signals for the power components, wherein: - the inverter's final stage is arranged on a plurality of circuit boards (15), - the circuit boards (15) are arranged so that they form one or more circular or annular structures, - one or more plug-in connector devices (33) are arranged on each printed circuit board (15) for contacting the end stage, The connecting plate (32, 61, 75) is plugged onto the plug connector arrangement (33) of at least two circuit boards in one of the circuit boards (15) of a circular or annular structure.

2. The electric motor (10) according to claim 1, wherein The connecting plates (32, 61, 75) are plugged into the plug connector devices (33) of all the circuit boards (15) in a circular or ring-shaped structure.

3. The electric motor (10) according to claim 1 or 2, wherein: The connecting plate (32, 61, 75) is annular or ring sector shaped.

4. The electric motor (10) according to claim 1, wherein: The circuit boards (15) form two or more circular or annular structures, and for each circular or annular structure, a connecting plate (32, 61, 75) is plugged into the plug connector devices (33) of at least two circuit boards (15) of each circular or annular structure.

5. The electric motor (10) according to claim 4, wherein: The circular or annular structures are arranged parallel to one another and axially offset from one another, so that their centers of circle lie on a common central axis.

6. The electric motor (10) according to claim 5, wherein: The axis of the circular or annular structure corresponds to the motor axis (9).

7. The electric motor (10) according to any one of claims 4 to 6, wherein: The circular or annular structures have the same diameter.

8. The electric motor (10) according to claim 1, wherein: The connecting plates (32, 61, 75) are arranged parallel to the plug-in circular or annular structure.

9. The electric motor (10) according to claim 1, wherein: The connecting plate (32, 61, 75) includes a gate drive circuit (72) for the final stage of a plug-in circular or ring-shaped structure.

10. The electric motor (10) according to claim 1, wherein: The connecting board (32, 61, 75) includes a multiplexer (93) and is designed to transmit a control signal input from the control device to one of a plurality of signal lines so as to input the control signal to a power component to which the control signal is applicable.

11. The electric motor (10) according to claim 1, wherein: The connection plate (32, 61, 75) includes one or more spiral connections to a circular or annular structure.

12. The electric motor (10) according to claim 1, wherein: The circuit board (15) is arranged on at least one cooling plate (16), wherein the cooling plate (16) is arranged such that the field conductor (12) or a current conductor (18) electrically connected to the field conductor (12) is in mechanical operative connection with the cooling plate, in particular in the form of a mechanical support for the cooling plate (16).

13. The electric motor (10) according to claim 1, wherein: The circuit board (15) is designed to be a circular sector or an annular sector.

14. The electric motor (10) as claimed in claim 1, which is designed to control a field conductor (12) having at least six phases.

15. The electric motor (10) according to claim 1, wherein: The inverter is designed to generate an AC voltage with an amplitude of 100 V or less, in particular 50 V or less, in particular 20 V or less.

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