INVERTER AND A MOTOR COMPRISING THE INVERTER

Abstract

An inverter for an electric motor may include a capacitor board and at least one electrically conductive contacting unit. The capacitor board may include at least one capacitor and at least one transistor board. The capacitor board and the at least one transistor board may be aligned transversely to a longitudinal direction. The capacitor board and the at least one transistor board may be electrically interconnected. The at least one electrically conductive contacting unit may be configured to contact at least one electrically conductive phase terminal of the motor. The at least one contacting unit may be connected to the at least one transistor board in an electrically conductive manner. The at least one contacting unit may be resilient in the longitudinal direction.

Claims

1. An inverter for an electric motor, comprising: a capacitor board including at least one capacitor and at least one transistor board; the capacitor board and the at least one transistor board aligned transversely to a longitudinal directions; the capacitor board and the at least one transistor board electrically interconnected; at least one electrically conductive contacting unit for contacting at least one electrically conductive phase terminal of the motor; the at least contacting unit connected to the at least one transistor board in an electrically conductive manner; and wherein the at least one contacting unit is resilient in the longitudinal direction.

2. The inverter according to claim 1, further comprising a cooling element, wherein: the cooling element is aligned transversely to the longitudinal direction at least in some regions; and in response to an axial pressing force, the at least one contacting unit presses the at least one transistor board against the cooling element axially to facilitate a transfer of heat.

3. The inverter according to claim 1, wherein: the at least one contacting unit includes a plate-like electrically conductive contact plate and a spring element; the contact plate is aligned transversely to the longitudinal direction; and the spring element is arranged axially between the contact plate and the at least one transistor board, and resiliently connects the at least one transistor board and the contact plate to one another.

4. The inverter according to claim 3, wherein at least one of: spring element is material bonded to the contact plate; the contact plate is connected in an electrically conductive and material bonded manner to the at least one transistor board; and the at least one transistor board and the capacitor board are material bonded to one another at a contact point.

5. The inverter according to claim 3, wherein: the spring element includes (i) a plate-like plate element aligned transversely to the longitudinal direction and (ii) at least two feet integrally connected to the plate element; and the spring element rests with the plate element against the contact plate and resiliently with the at least two feet against the at least one transistor board.

6. The inverter according to claim 3, wherein the contact plate includes: a central contact opening configured to receive and engage the at least one phase terminal in an electrically conductive manner; and at least two contact pins disposed at the contact opening, the at least two contact pins aligned towards a center of the contact opening and axially to the spring element.

7. The inverter according to claim 6, wherein: the at least two contact pins each have a contact surface aligned parallel to the longitudinal direction and facing towards the center of the contact opening; and the contact surface of each of the at least two contact pins includes a groove structure.

8. An electric motor, comprising: an inverter; a motor body, and at least one electrically conductive phase terminal extending axially towards the inverter at least in some regions; the inverter including: a capacitor board including at least one capacitor and at least one transistor board, the capacitor board and the at least one transistor board electrically interconnected and aligned transversely to a longitudinal direction; and at least one electrically conductive contacting unit connected to the at least one transistor board in an electrically conductive manner, the at least one contacting unit resilient in the longitudinal direction; wherein a longitudinal end of the inverter, which faces the motor body, is axially attached to the motor body; and wherein the at least one contacting unit is contacted in an electrically conductive manner with the at least one phase terminal.

9. The motor according to claim 8, wherein: the inverter further includes a cooling element; the at least one phase terminal provides an axial pressing force on the at least one contacting unit; and via the axial pressing force, the at least one contacting unit presses the at least one transistor board against the cooling element axially to facilitate a transfer of heat.

10. The motor according to claim 8, further comprising an axis of rotation, wherein: the at least one phase terminal includes six phase terminals arranged around the axis of rotation; and the at least one transistor board includes six transistor boards for the six phase terminals, the six transistor boards arranged around the at least one capacitor.

11. The motor according to claim 8, wherein the at least one contacting unit includes: a plate-like electrically conductive contact plate extending transversely to the longitudinal direction; and a spring element arranged axially between the contact plate and the at least one transistor board, the spring element resiliently connecting the at least one transistor board and the contact plate to one another.

12. The motor according to claim 11, wherein: the contact plate includes a central contact opening and a plurality of contact pins projecting radially into the contact opening, the plurality of contact pins angled axially away from the spring element; and the at least one phase terminal is arranged in the contact opening and contacts the plurality of contact pins in an electrically conductive manner

13. The motor according to claim 12, wherein: the plurality of contact pins each have a radially inward facing contact surface; and the contact surface of each of the plurality of contact pins includes a groove structure contacting the at least one phase terminal.

14. The inverter according to claim 1, wherein the at least one contacting unit includes: a plate-like electrically conductive contact plate extending transversely to the longitudinal direction; and a spring element arranged axially between the contact plate and the at least one transistor board, the spring element resiliently connecting the at least one transistor board and the contact plate to one another; the contact plate including: a central contact opening configured to receive and engage the at least one phase terminal in an electrically conductive manner; and a plurality of contact pins projecting radially into the contact opening, the plurality of contact pins angled axially away from the spring element.

15. The inverter according to claim 14, wherein: the plurality of contact pins each have a radially inward facing contact surface; and the contact surface of each of the plurality of contact pins defines a conical surface segment.

16. The inverter according to claim 14, wherein: the plurality of contact pins each have a radially inward facing contact surface; and the contact surface of each of the plurality of contact pins includes a plurality of grooves.

17. The inverter according to claim 16, wherein at least a portion of the contact surface of each of the plurality of contact pins has a wave-shaped profile that defines the plurality of grooves.

18. The inverter according to claim 3, wherein: the spring element is welded to the contact plate; the contact plate is welded to the at least one transistor board in an electrically conductive manner; and the at least one transistor board and the capacitor board are welded to one another at a contact point.

19. The inverter according to claim 3, wherein: the spring element includes (i) a plate-like plate element aligned transversely to the longitudinal direction and (ii) at least two resilient feet extending transversely to the plate element; the at least two feet each include a curved portion and are each integrally connected to the plate element by the curved portion; the plate element directly contacts and rests against the contact plate; and the at least two feet directly contact and resiliently rest against the at least one transistor board.

20. An inverter for an electric motor, comprising: a capacitor board; a plurality of capacitors arranged symmetrically in a circle on the capacitor board; and a plurality of transistor boards electrically connected to the capacitor board, the plurality of transistor boards arranged radially outside the plurality of capacitors and distributed evenly around the plurality of capacitors in a circumferential direction; a plurality of electrically conductive contacting units each configured to contact an associated electrically conductive phase terminal of the motor, the plurality of contacting units each connected to an associated transistor board of the plurality of transistor boards in an electrically conductive manner; and wherein the plurality of contacting units are resilient in an axial direction and are configured to press against the associated transistor board when subjected to an axial pressing force.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In each case schematically,

[0027] FIGS. 1 and 2 show views of an EMI filter according to the invention, which is illustrated without a housing;

[0028] FIG. 3 shows an exploded view of the EMI filter according to the invention, which is illustrated without a housing;

[0029] FIG. 4 shows a view of the EMI filter according to the invention, which is illustrated with a housing;

[0030] FIG. 5 shows a view of a choke in the EMI filter according to the invention;

[0031] FIG. 6 shows an equivalent circuit diagram of the choke illustrated in FIG. 5 of the EMI filter according to the invention;

[0032] FIG. 7 shows a view of the choke illustrated in FIG. 5 with the modeled course of the magnetic flux;

[0033] FIGS. 8 to 11 show diagrams for characterizing the choke illustrated in FIG. 5 and FIG. 7.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a lateral view of an EMI filter 1 according to the invention, which is illustrated without a housing here. FIG. 2 shows a view of the EMI filter 1 according to the invention, which is illustrated without a housing from the bottom here. FIG. 3 shows an exploded view of individual components of the EMI filter 1 according to the invention. The EMI filter thereby has a choke 2, several X-capacitors 3, several Y-capacitors 4, an E-choke 5, an electrically conductive ground plate 6, an electrically conductive positive pole battery terminal 7a, and an electrically conductive negative pole battery terminal 7b. The choke 2 thereby comprises a magnetic inner core 9, a magnetic outer core 10, and three conductor pairs 11, which each have an electrically conductive positive conductor 12a and an electrically conductive negative conductor 12b.

[0035] The respective positive conductors 12a and the respective positive pole battery terminal 7a are thereby realized by means of a positive pole element 13a, and the respective negative conductor 12b and the respective negative pole battery terminal 7b are thereby realized by means of a negative pole element 13b. The positive pole element 13a and the negative pole element 13b are thereby formed to be electrically conductive, and integrally, and plate-shaped, and folded. The respective positive conductors 12a and the positive pole battery terminal 7a are thus electrically conductive and are connected to one another in an electrically conductive manner. The respective negative conductors 12b and the negative pole battery terminal 7b are thus electrically conductive and are connected to one another in an electrically conductive manner. The positive conductors 12a and the negative conductors 12b are thereby formed to be flat or plate-like, respectively, or as plate-like busbars, respectively.

[0036] In the choke 2, the inner core 9, the outer core 10, the respective positive conductors 12a, and the respective negative conductors 12b extend along a longitudinal central axis LA of the choke 2. The conductors 12a and 12b, the inner core 9 and the outer core 10 are electrically insulated from each other. The electrical insulation can be realized by the air. Alternatively, the conductors 12a,12b, the inner core 9 and the outer core 10a can be molded in a plastic housing to provide electrical insulation. The respective positive conductors 12a and the respective negative conductors 12b are thereby arranged between the inner core 9 and the outer core 10 in a radial direction, which is aligned radially to the longitudinal central axis LA. In addition, the respective positive conductors 12a and the respective negative conductors 12b are arranged so as to alternate and so as to be distributed evenly in a circumferential direction, which revolves around the longitudinal central axis LA. In addition, the respective adjacent conductors 12a and 12b are arranged spaced apart from one another in the circumferential direction, so that a gap 14 is in each case formed between the inner core 9, the outer core 10, and the respective conductors 12a and 12b, which are adjacent in the circumferential direction. The advantageous properties of the choke 2 will be described in more detail below on the basis of FIG. 7-11.

[0037] The choke 2, the X-capacitors 3, and the Y-capacitors 4 are electrically interconnected to form a filter circuit 8. In addition, the ground plate 6, the positive pole battery terminal 7a, and the negative pole battery terminal 7b are electrically interconnected with the filter circuit 8. The X-capacitors 3 are each interconnected with the respective conductors 12a, 12b of the respective conductor pair 11 of the choke 2 and the Y-capacitors 4 are connected each between the respective conductor 12a, 12b of the at respective conductor pair 11 and the chassis—here a metal casing—of the inverter 1 through the ground plate 6. As can be seen particularly well in FIG. 3, the E-choke 5 has two E-shaped magnetic cores 15, which are arranged around the positive pole element 13a and the negative pole element 13b. The E-choke 5 or the cores 15, respectively, are thereby arranged between the choke 2 or the positive conductors 12a, respectively, as well as negative conductors 12b and the positive pole battery terminal 7a as well as the negative pole battery terminal 7b.

[0038] FIG. 4 shows a view of the EMI filter 1 according to the invention. FIG. 4 shows the EMI filter 1 with a housing 16, which encloses or surrounds, respectively, the components of the EMI filter 1 at least in some regions. The housing 16 is dielectric and can be formed of a plastic. The housing 16 can in particular be formed in a casting process, wherein the components of the EMI filter 1 can then be cast in.

[0039] With reference to FIG. 1-4, the EMI filter 1 is provided for an inverter for an electric motor. If the EMI filter is interconnected with the inverter, the respective conductors 12a and 12b are connected in an electrically conductive manner to a capacitor board of the inverter. The positive pole battery terminal 7a and the negative pole battery terminal 7b then form direct current battery terminals of the inverter.

[0040] FIG. 5 shows a view of the choke 2 in the EMI filter 1 according to the invention. As can be seen particularly well here, the positive conductors 12a and the negative conductors 12b are arranged so as to alternate and so as to be distributed evenly in the circumferential direction. The inner core 9 and the outer core 10 are in each case shown by a hollow straight prism with a regular hexagonal base surface. The respective one of the six conductors 12a or 12b, respectively, is in each case assigned to one of the six edges/sides of the respective prism. The respective conductor 12a or 12b, respectively, is thereby in each case arranged in an outer recess 17 of the outer core 10.

[0041] In the choke 2, the respective conductors 12a and 12b are encased or are surrounded on the outside, respectively, by the outer core 10 in the circumferential direction, whereby the choke 2 is suitable to filter the electromagnetic interferences in the common mode. In addition, the inner core 9 is encased or surrounded on the outside, respectively, by the respective conductors 12a and 12b in the circumferential direction, so that the choke 2 is suitable to filter the electromagnetic interference in the differential mode. In addition, the choke 2 has a high symmetry, and the current can be distributed symmetrically in the choke 2. The electromagnetic interferences can thus be filtered out particularly efficiently.

[0042] The properties of the choke 2 will be described in more detail below on the basis of FIG. 6-11. For this purpose, the choke 2 is shown in a model. In the model, the positive conductors 12a and the negative conductors 12b are numbered consecutively one after the other with numbers 1 to 6 in the circumferential direction. The respective three positive conductors 12a of the choke 2 are thereby identified with numbers 1, 3, and 5. The respective three negative conductors 12b of the choke 2 are thereby identified with numbers 2, 4, and 6.

[0043] A magnetic coupling between the individual conductors 12a and 12b is created in the choke 2 by means of the outer core 10, which encases or surrounds the conductors 12a and 12b on the outer side, respectively. Inductances are thus created between the individual conductors 12a and 12b.

[0044] The created common mode inductances can be combined as follows in a matrix:

[00001]$\left[L_{\mathrm{CM}}\right]=\left[\begin{array}{cccccc}{L}_{\mathrm{CM}11}& L_{\mathrm{CM}12}& L_{\mathrm{CM}13}& L_{\mathrm{CM}14}& L_{\mathrm{CM}15}& L_{\mathrm{CM}16}\\ L_{\mathrm{CM}21}& L_{\mathrm{CM}22}& L_{\mathrm{CM}23}& L_{\mathrm{CM}24}& L_{\mathrm{CM}25}& L_{\mathrm{CM}26}\\ L_{\mathrm{CM}31}& L_{\mathrm{CM}32}& L_{\mathrm{CM}33}& L_{\mathrm{CM}34}& L_{\mathrm{CM}35}& L_{\mathrm{CM}36}\\ L_{\mathrm{CM}41}& L_{\mathrm{CM}42}& L_{\mathrm{CM}43}& L_{\mathrm{CM}44}& L_{\mathrm{CM}45}& L_{\mathrm{CM}46}\\ L_{\mathrm{CM}51}& L_{\mathrm{CM}52}& L_{\mathrm{CM}53}& L_{\mathrm{CM}54}& L_{\mathrm{CM}55}& L_{\mathrm{CM}56}\\ L_{\mathrm{CM}61}& L_{\mathrm{CM}62}& L_{\mathrm{CM}63}& L_{\mathrm{CM}64}& L_{\mathrm{CM}65}& L_{\mathrm{CM}66}\end{array}\right]$

[0045] The created differential mode inductances can be combined as follows in a matrix:

[00002]$\left[L_{\mathrm{DM}}\right]=\left[\begin{array}{cccccc}{L}_{\mathrm{DM}11}& L_{\mathrm{DM}12}& L_{\mathrm{DM}13}& L_{\mathrm{DM}14}& L_{\mathrm{DM}15}& L_{\mathrm{DM}16}\\ L_{\mathrm{DM}21}& L_{\mathrm{DM}22}& L_{\mathrm{DM}23}& L_{\mathrm{DM}24}& L_{\mathrm{DM}25}& L_{\mathrm{DM}26}\\ L_{\mathrm{DM}31}& L_{\mathrm{DM}32}& L_{\mathrm{DM}33}& L_{\mathrm{DM}34}& L_{\mathrm{DM}35}& L_{\mathrm{DM}36}\\ L_{\mathrm{DM}41}& L_{\mathrm{DM}42}& L_{\mathrm{DM}43}& L_{\mathrm{DM}44}& L_{\mathrm{DM}45}& L_{\mathrm{DM}46}\\ L_{\mathrm{DM}51}& L_{\mathrm{DM}52}& L_{\mathrm{DM}53}& L_{\mathrm{DM}54}& L_{\mathrm{DM}55}& L_{\mathrm{DM}56}\\ L_{\mathrm{DM}61}& L_{\mathrm{DM}62}& L_{\mathrm{DM}63}& L_{\mathrm{DM}64}& L_{\mathrm{DM}65}& L_{\mathrm{DM}66}\end{array}\right]$

[0046] In both cases, L_CM/DM_xx thereby represents a self-inductance of the respective conductor 12a or 12b, respectively, and L_CM/DM_yx represents a mutually generated inductance between the respective conductors 12a or 12b, respectively. If x does not equal y, then L_CM/DM_xy=L_CM/DM_yx. If the electrical resistances R_xx of the respective conductors 12a and 12b are considered as well, the equivalent circuit diagram shown in FIG. 6 results.

[0047] FIG. 6 thus shows the equivalent circuit diagram of the choke 2 according to the above-described model. Three upper branches thereby represent the respective positive conductors 12a of the choke 2. Three lower branches thereby represent the respective negative conductors 12b of the choke 2.

[0048] In the case of the respective positive conductors 12a of the choke 2, which are numbered with 1, 3, and 5: [0049] I_DC—identifies the direct current in the choke 2; [0050] I_DC/3—identifies the partial direct current in the respective positive conductor 12a; [0051] i_DM11, i_DM33, i_DM55—identifies the differential mode partial direct current in the respective positive conductor 12a; [0052] i_CM11, i_CM33, i_CM55—identifies the common mode partial direct current in the respective positive conductor 12a; [0053] R_11, R_33, R_55—identifies the electrical resistance of the respective positive conductor 12a; [0054] L_DM11, L_DM33, L_DM55—identifies the differential mode self-inductance of the respective positive conductor 12a; [0055] L_CM11, L_CM33, L_CM55—identifies the common mode self-inductance of the respective positive conductor 12a in equivalent circuit diagram.

[0056] In the case of the respective negative conductors 12b of the choke 2, which are numbered with 2, 4, and 6: [0057] I_DC—identifies the direct current in the choke 2; [0058] I_DC/3—identifies the partial direct current in the respective negative conductor 12b; [0059] i_DM22, i_DM44, i_DM66—identifies the differential mode partial direct current in the respective negative conductor 12b; [0060] i_CM22, i_CM44, i_CM66—identifies the differential mode partial direct current in the respective negative conductor 12b; [0061] R_22, R_44, R_66—identifies the electrical resistance of the respective negative conductor 12b; [0062] L_DM22, L_DM44, L_DM66—identifies the differential mode self-inductance of the respective negative conductor 12b; [0063] L_CM22, L_CM44, L_CM66—identifies the common mode self-inductance of the respective negative conductor 12b
in the equivalent circuit diagram.

[0064] The electrical resistances R11, R33, R55, R22, R44, R66 are combined to form a block RES block. The differential mode self-inductances L_DM11, L_DM33, L_DM55, L_DM22, L_DM44, L_DM66 are combined to form a block LDM_block. What applies for this block LDM_block is: (L M)/2. Here, the L refers to self-inductance of each conductor 12a, 12b or diagonal elements in the matrix [L_DM]—elements L_DM11, L_DM33, L_DM55, L_DM22, L_DM44, L_DM66—and the M refers to the mutual inductance between two conductors 12a, 12b or out-diagonal elements in the matrix [L_DM] L_xy, where x does not equal y. The common mode self-inductances L_CM11, L_CM33, L_CM55, L_CM22, L_CM44, L_CM66 are combined to form a block LCM_block. What applies for this block LCM_block is: (L+M)/2. Here, the L refers to self-inductance of each conductor 12a, 12b or diagonal elements in matrix [L_CM]—elements L_CM11, L_CM33, L_CM55, L_CM22, L_CM44, L_CM66—and the M refers to the mutual inductance between two conductors 12a, 12b or out-diagonal elements in matrix [L_CM]—elements Lxy, where x does not equal y.

[0065] FIG. 7 shows a view of the choke 2 with the modelled course of magnetic flux within the choke 2. It can be seen in FIG. 7 that the magnetic flux of the common mode in the inner core 9 and in the outer core 10 in each case tends to flow in the same direction. The magnetic flux of the differential mode tends to bridge the gap 14.

[0066] FIG. 8 shows a diagram for characterizing the choke 2. The diagram shows the differential mode inductance L_DM14, L_DM12, LDM_16 between one of the positive conductors 12a and each of the three negative conductors 12b. The differential mode inductance is defined as the inductance between two conductors 12a, 12b carrying the opposite way current. Thus only the inductances L_DM14, L_DM12, LDM_16 are relevant for differential mode filtering. The differential mode inductance is thereby plotted in nH against the width of the gap in mm at a direct current I_DC equal to 1100 A. The maximum differential mode inductance L_DM14 is thereby generated between the conductors 12a and 12b, which are located opposite one another and at a maximum distance.

[0067] FIG. 9 shows a further diagram for characterizing the choke 2. The diagram shows the common mode inductance L_CM12, L_CM16 between one of the positive conductors 12a and the adjacent negative conductors 12b. Because of the choke symmetry, the follow equalities apply: [0068] L_DM14=L_DM25=L_DM36 [0069] L_DM41=L_DM14 [0070] L_DM52=L_DM25 [0071] L_DM63=L_DM36.

[0072] The common mode inductance is thereby plotted in pH against the width of the gap 14 in mm at a direct current I_DC equal to 1100 A. The common mode inductance L_CM12, L_CM16 is thereby identical in the case of both pairs of the conductors 12a and 12b.

[0073] FIG. 10 shows a further diagram for characterizing the choke 2. The diagram shows the differential mode inductance L_DM12, L_DM14, L_DM16 between one of the positive conductors 12a and each of the three negative conductors 12b. The common mode inductance is thereby plotted in nH against the direct current I_DC in A with the width of the gap 14 equal to 1050 μm. The differential mode inductance L_DM12, L_DM14, L_DM16 thereby shows a constant connection with the direct current I_DC until the saturation of the inner core 9 and of the outer core 10.

[0074] FIG. 11 shows a further diagram for characterizing the choke 2. The diagram shows the common mode inductance L_CM14 between one of the positive conductors 12a and the negative conductor 12b, which is located opposite at a maximum distance. The common mode inductance is thereby plotted in pH against the direct current I_DC in A with the width of the gap 14 equal to 1050 μm. The common mode inductance L_CM14 decreases with the increasing direct current I_DC. This is due to the fact that the magnetic material of the inner core 9 and of the outer core 10 approach the magnetic saturation, and the permeability of the material decreases.