Electric motor

Abstract

The invention relates to an electric motor (10) comprising a stator (11) having a plurality of field conductors (12) designed as rods, a plurality of power electronic components for controlling the field conductors (12), the power electronic components being arranged on one or more printed circuit boards (15), the at least one printed circuit board (15) being arranged on at least one cooling plate (16), the cooling plate (16) being arranged in such a way that the field conductors (12) are electrically connected to the stator (11). The field conductor (12) is mechanically operatively connected to the cooling plate by means of a current conductor (18) electrically connected to the field conductor (12),-wherein at least one groove-like recess (20) is recessed in the cooling plate (16), in which recess at least one bus bar (22) is arranged in an electrically insulated manner with respect to the cooling plate (16),-and is at least partially covered by a circuit board (15), and-the printed circuit board (15) is in electrical contact with the at least one bus bar (22).

Description

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

[0002] The electric motor can have a rod winding on the stator side. Here, the stator has a series of rods instead of wound wires as field conductors. The rods have a low inductance compared to conventional windings. Therefore, a relatively high current is required to generate a predetermined magnetic field. This type of motor is described in patent document EP19167289A1.

[0003] However, due to the low resistance of the rod, only a relatively low voltage of, for example, 12 V is required for such a high current. The low voltage makes it possible to arrange the components of the inverter for controlling the rod at a short distance from one another. Thus, the components of the power electronics can be arranged, for example, on one or more circuit boards (printed circuit boards) arranged close to the electric motor. The rod can be used here directly or via an electrically conductive rod-shaped connecting element as a mechanical support for the circuit board.

[0004] The circuit boards are mounted on the cooling plate and contacted individually via electrical busbars. The busbars are located on the circuit boards and contacted with them via screw connections. However, the screw connections are also fixed in the cooling plate (mechanically separated from the cooling plate) to produce reliable contact. This results in the problem of insulation between the screw connection and the cooling plate, which must be solved for each individual screw connection by means of a corresponding sleeve. In particular, if a circuit board must be replaced due to a single component failure, the two busbars that hold up to 150 circuit boards and supply them with electricity usually have to be unscrewed, then completely insulated and screwed on again.

[0005] The object of the present invention is to provide an electric motor with a stator-side bar winding and integrated power electronics which requires less maintenance effort than in the prior art when replacing printed circuit boards of the power electronics.

[0006] The solution to the above-mentioned technical problem is an electric motor having the features of claim 1 .

[0007] The motor includes

[0008] a stator with a plurality of field conductors designed as rods,

[0009] - a plurality of power electronic components for controlling the field conductors, wherein

[0010] - the power electronic components are arranged on one or more circuit boards,

[0011] at least one circuit board arranged on at least one cooling plate,

[0012] - wherein the cooling plate is arranged such that the field conductor is in mechanical operative connection with the cooling plate via a current conductor which is electrically connected to the field conductor. The current conductor thus forms an electrically conductive connecting element between the field conductor and the circuit board and ultimately to the power electronic component (even the semiconductor switch). Due to the mechanical operative connection, it also has load-bearing properties for the cooling plate, wherein it is electrically insulated relative to the cooling plate.

[0013] wherein at least one groove-shaped recess is hollowed out in the cooling plate, in which recess at least one busbar is arranged electrically insulated relative to the cooling plate,

[0014] - and is hereby at least partially covered by a printed circuit board, and

[0015] The circuit board is in electrical contact with at least one busbar.

[0016] The motor differs from conventional motors in that the stator has a series of rods instead of wound wires as field conductors. The rods have a low inductance compared to conventional windings. Therefore, a relatively high current is required to generate a predetermined magnetic field.

[0017] The design of the rod winding constitutes a fundamental advantage in the operation of the machine: Due to the segmented controllability of the magnetic flux between each two field conductors, a much more flexible magnetic field form can be introduced into the machine than can be achieved with distributed windings and their inherent superposition effects. This results in many (control technology) advantages in terms of the operating characteristics of the machine. In addition, the failure of one phase (control of one field conductor) has much less consequences than in the case of, for example, a two-phase three-phase or even a normal three-phase machine. In addition, since this effect can be well compensated by the adjacent phases, in the case of corresponding control, the drive power only drops by a small amount with each phase failure, without significantly affecting the remaining characteristics.

[0018] In this electric motor, an advantage over the prior art of electric motors of this type is that the busbars are not arranged on the circuit board, but are located recessed in the cooling plate. In this way, each circuit board can be removed and replaced individually without much effort by loosening the screw connections, which usually also represent the contact with the busbars. Therefore, it is not necessary to dismantle a large part or even the entire structure from all circuit boards for maintenance, which means that work expenditure is greatly saved in maintenance work on power electronics and thus represents a cost advantage. The maintenance costs are significantly reduced.

[0019] Furthermore, this design allows the insulation between the cooling plate and the busbar to be technically simple to construct, since the contact is only made between the printed circuit board and the busbar. The busbar itself can be insulated from the cooling plate by conventional insulating materials. If necessary, the previously customary screw connection to the cooling plate can be omitted, which means a further reduction in installation effort.

[0020] It is expedient here to arrange the two busbars in the recess. This is advantageous because the surface of the groove-shaped recess which is not structurally available for heat dissipation from the printed circuit board can be reduced in this way. The two busbars can be arranged radially side by side in the recess relative to the motor axis. This makes it possible to guide the two busbars in a recess with little effort for insulation between the cooling plate and the busbars.

[0021] In another embodiment, the two busbars are arranged one above the other in the recess along the motor axis, which requires greater effort in contacting but is suitable for keeping the width of the recess small and thus providing a larger surface for heat dissipation.

[0022] On the other hand, it is expedient to provide at least two recesses, in which at least one busbar extends in each case. In this way, specific areas of the printed circuit board can be contacted in a targeted manner.

[0023] It is also expedient if the cooling plate is designed as a busbar. This means that the recess takes up as small a portion of the surface of the cooling plate as possible and at least one busbar runs therein. If the cooling plate is designed as metal, it can take over the function of a second busbar. This again reduces the assembly and disassembly effort.

[0024] It should be taken into account that in general, it is not necessary to use exactly two busbars for the electric machine. It is advantageous to use duplicate potentials or, for example, three potentials with an intermediate circuit center or a double (redundant) intermediate circuit, in which more than two busbars are required. Thus, by using the cooling plate as a busbar, one busbar is eliminated.

[0025] In an advantageous embodiment of the invention, the cooling plate is designed to be annular. In this way, it can be integrated into the electric motor in a space-saving manner. In this respect, it is suitable that the busbar is designed to be annular or in the form of a ring segment. It then extends along the contour of the cooling plate and the circuit board matched thereto.

[0026] It is also expedient to clamp the busbar in the recess by means of an insulating flexible material. Such a flexible and insulating material can be, for example, a profiled silicone ring or a heat-resistant and electrically insulating glass fiber fabric.

[0027] Furthermore, it is expedient if the printed circuit board is electrically contacted with the at least one busbar via a screw connection.

[0028] The circuit board can be designed in a circular or ring segment shape. Circuit boards with such a shape can be assembled into a circle or ring and can therefore be arranged on the axial end of the machine in the best adaptation to the shape of the motor, wherein high modularity is simultaneously achieved.

[0029] The terms "axial", "radial" and "tangential" are here based on the axis of the rotor and therefore also on the corresponding axis of symmetry of the stator. "Axial" here describes a direction parallel to the axis, "radial" describes a direction orthogonal to, towards or away from the axis, and "tangential" is a direction oriented circularly around the axis at a constant radial distance from the axis and a constant axial position. The expression "circumferentially" is equivalent to "tangential".

[0030] When the terms "axial", "radial" and "tangential" are used with respect to a surface, such as a cross section, these terms describe the orientation of the normal vector to that surface, ie, the vector perpendicular to the relevant surface.

[0031] Further embodiments and features of the present invention will be described in detail with reference to the following drawings, which are purely schematic and do not limit the scope of protection.

[0032] in:

[0033] Figure 1 An electric motor having a cooling plate for dissipating heat from a circuit board is shown in a side view;

[0034] Figure 2 The electric motor is shown in a front view;

[0035] Figure 3 A side view showing a portion of the cooling plate Figure 1 together with the busbars according to the prior art,

[0036] Figure 4 Shown with Figure 3 The same parts together with the modified arrangement of the busbars;

[0037] Figure 5 shows a cross section through the cooling plate, together with the circuit board and the busbars sunk into two groove-like recesses;

[0038] Figure 6 Shown with Figure 5 The same cross section in the figure, together with the busbars arranged one above the other in a recess,

[0039] Figure 7 Shown with Figure 5 and Figure 6 The same cross section as in FIG. 1 , with a single recess and two generatrixes arranged therein;

[0040] Figure 8 A partial cross section through a cooling plate is shown, schematically illustrating the screw connection between busbars and a circuit board.

[0041] Figure 1An 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 is rotated about the axis 9 by the electromagnetic interaction between the rotor and the energized stator. The rotor is separated from the stator 11 by an air gap.

[0042] In other embodiments, the motor 10 may also be an outer rotor motor or a bell armature motor.

[0043] The stator 11 comprises a plurality of rigid and straight conductor rods 12 as field conductors. Figure 1 The conductor bars 12 are connected to each other on the back side 13 of the motor 10 by short-circuit rings. On the back side 14 of the motor 10, the conductor bars 12 are each powered individually by the corresponding inverter module. Due to the conductor bars 12, the motor 10 is operated at a low voltage, and the inverter module can be arranged relatively closely on the circuit board 15 together with other components of the electronic device (DC voltage converter, rectifier). The circuit board 15 is in the form of a ring segment in this example and many individual circuit boards 15 together form an annular circuit board structure. The rigidly constructed conductor bars can be composed of metal bars, such as copper bars, or of fixed multifilament conductors.

[0044] In the example, the circuit board 15 is considered to carry an inverter module, but a part of the circuit board 15 may also carry a rectifier and a DC / DC converter.

[0045] 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 electric motor 10, in particular the number of conductor bars 12. Each circuit board 15 comprises a plurality of power electronic components, in particular semiconductor switches 26.

[0046] In addition, a part of the circuit board 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 switch 26 is a power semiconductor, such as IGBTs, MOSFETs or JFETs, and may also include a diode not shown depending on the circuit. The semiconductor switch 26 is 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 switch 26 of the circuit board 15 can be assigned to a single phase or multiple phases here.

[0047] The circuit board 15 also comprises contact locations 24 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.

[0048] Since in the electric motor 10 relatively high currents are required in the conductor bars compared to conventional electric motors with windings, preferably a plurality of inverters 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 boards 15 at the contact point, or at least make contact in the case of the outermost cooling plate 16.

[0049] 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 a shoe 17. The inverters 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.

[0050] Figure 3 1 also shows a busbar 22' in a design according to the prior art. The busbar is screwed to the circuit board 15 and is thus fixed to the cooling plate 16. If the circuit board 15 fails and has to be replaced, the busbar 22 together with all the individual screw connections to the circuit board 15 must be removed. This means that, for example, in the case of one hundred circuit boards 15 each having three screw connections 28, three hundred screw connections 28 must be loosened. Figure 4 and in Figures 5 to 8 The design shown schematically and enlarged in the figure reduces this expenditure.

[0051] exist Figure 4 In, with Figure 3 The same arrangement of busbars 22 is designed in such a way that they are arranged below the circuit board 15 in the recess 20 of the cooling plate 16. Figure 4 The overview view shows the basic position of the busbar 22, although Figure 5-8 An enlarged view is schematically shown in FIG.

[0052] Figure 5 A cross section through a cooling plate 16 is schematically shown, on which a circuit board 15 and a recess 20 in which a busbar 22 is arranged are mounted. Figure 5 is represented by point 24. Figure 5Two recesses 20 are provided in the circuit board 15, wherein the busbars extend separately from each other. The recess 20 is arranged in the radially outer region of the cooling plate 16, and the second busbar 22 is arranged in the radially inner region of the cooling plate 16. The busbars 22 extend relatively far from each other, and the contact is made at the respective outer ends of the circuit board 15.

[0053] exist Figure 5 In the embodiment of the invention, the busbars are each completely covered by the circuit board 15. However, in some embodiments of the invention not shown here, the busbars 22 can protrude beyond the cooling plate 16 at the edge and be only partially covered by the circuit board 15. In this case, the recess opens at the outer edge of the cooling plate and is only laterally located on one side in the cooling plate. However, it is important that, as in Figure 4-Figure 8 As in all cases under consideration, the busbars 22 are located in the recesses 20 between the circuit boards 15 and the cooling plate 16 and can therefore be removed and replaced by loosening the screw connections 28 of only one circuit board 15. If only one circuit board 15 is to be replaced, it is not necessary to unscrew the entire ring of busbars 22 from all circuit boards 15. It should be noted here that a screw connection 28 can be understood as any detachable connection with electrical contact. Correspondingly designed screws can also be included in the term screw connection here. However, a technically particularly advantageous embodiment for such a contact is the introduction of metal screws.

[0054] On the contrary, according to Figure 6 , only one recess 20 is provided in the cooling plate 16, in which two busbars 22 are mounted one above the other but electrically insulated from one another. Contact via contact points 24 is also provided here, wherein the contacts here are insulated from one another and contact one of the busbars 22 respectively. Figure 5 The structure, according to Figure 6 The advantage of the structure is that only one recess 20 is provided, and therefore there is a larger bearing surface for heat dissipation between the surface of the circuit board 15 and the cooling plate 16. Figure 6 In this structure, greater effort must be made to insulate the contacts and the two busbars 22 from each other. Figure 5-Figure 7 It is only indicated very schematically by dashed lines.

[0055] In accordance with Figure 7 In another alternative embodiment, only one recess 20 is provided, which extends radially around the center of the cooling plate 16. However, in this case, two busbars 22 are arranged side by side. Only one recess 20 is required here, but the recess is smaller than the one in order to position the two busbars 22 side by side. Figure 6 The similar recess 20 in is designed to be wider.

[0056] Figure 82 also shows very schematically the contact between the busbar 22 and the printed circuit board 15. Here, a screw connection 28 is guided through the at least partially electrically conductive contact point 24, wherein the screw connection 28 is screwed into the busbar 22 so that current can flow from the busbar 22 to the contact point 24 via the screw connection 28. Figure 8 Also shown is an insulator 30 that electrically insulates the busbar 22 from the cooling plate 16. This can be a flexible material, such as a silicone pad, which can also help to confine the busbar 22 in the recess 20 and fix it there. Figure 8 The design can also be used to use only one busbar 22 and use the conductive cooling plate 16 as the conductive second unit. The cooling plate 16 thus assumes the task of the second busbar 22. This simplifies the contacting and saves one busbar 22.

[0057] Reference numerals list

[0058] 8 stator / rotor blocks

[0059] 9 Motor shaft

[0060] 10 Electric Motor

[0061] 11 Stator

[0062] 12 conductor rods

[0063] 13. End side

[0064] 14 Dorsal

[0065] 15 Circuit Board

[0066] 16 Cooling Plate

[0067] 17 Boots

[0068] 18 Connecting elements

[0069] 20 concavities

[0070] 22 busbar

[0071] 24 contact positions

[0072] 26Semiconductor switch

[0073] 28 threaded connection

[0074] 30 Insulator

Claims

1. An electric motor (10) having: a stator (11) having a plurality of field conductors (12) designed as rods, - a plurality of power electronic components for controlling the field conductor (12), in - the power electronic components are arranged on one or more circuit boards (15), - at least one circuit board (15) is arranged on at least one cooling plate (16), the cooling plate (16) is arranged in such a way that the field conductor (12) is in mechanical operative connection with the cooling plate via a current conductor (18) which is electrically connected to the field conductor, -in, At least one groove-shaped recess (20) is hollowed out in the cooling plate (16), in which recess at least one busbar (22) is arranged in an electrically insulated manner relative to the cooling plate (16). - and is at least partially covered by a circuit board (15), and The circuit board (15) is in electrical contact with at least one busbar (22).

2. The electric motor according to claim 1, characterized in that At least two busbars (22) are arranged in the recess (20).

3. The electric motor according to claim 1 or 2, characterized in that The two busbars (22) are arranged side by side in the recess in a radial direction relative to the motor axis (9).

4. The electric motor according to claim 1 or 2, characterized in that: Two busbars (22) are arranged one above the other in the recess along the motor axis (9).

5. The electric motor according to claim 1, characterized in that At least two recesses are provided, in each of which at least one generatrix extends.

6. The electric motor according to claim 1, characterized in that The cooling plate is designed as a second busbar.

7. The electric motor according to any one of the preceding claims, characterized in that The cooling plate is designed in a ring shape.

8. The electric motor according to any one of the preceding claims, characterized in that The busbar is constructed in a ring shape.

9. The electric motor according to any one of the preceding claims, characterized in that The busbar is clamped in the recess by the insulating flexible material.

10. The electric motor according to claim 1, characterized in that The circuit board (15) is in electrical contact with at least one busbar (22) via a threaded connection.

11. The electric motor (10) according to claim 1, wherein: The circuit board (15) is designed to be circular or ring segment shaped.

12. The electric motor (10) according to claim 1, wherein: The cooling plate (16) is arranged perpendicular to the axis (9) of the electric motor (10).

13. The electric motor (10) as claimed in claim 1, which is designed to control each of the field conductors (12) via its own phase.

14. The electric motor (10) according to claim 1, wherein: The inverter is designed to generate an AC voltage with an amplitude of 200 V or less, in particular 150 V or less, in particular 50 V or less.

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