Mixed bar and wire conductor combinations for stators of high-speed electric motors
Presented are electric machines with both bar and wire conductors, methods for making/using such machines, and vehicles equipped with such machines. An electric machine, such as a traction motor or electric generator, includes an outer housing, a stator fixedly mounted to the housing, and a rotor movably mounted to the housing and spaced across an airgap from the stator. Multiple magnets, such as permanent magnet blocks, are mounted on or in slots of the rotor (or the stator). A set of electromagnetic conductors extends through each radially elongated slot of the stator (or the rotor). Each conductor set includes a group of solid-wire or multistrand-wire conductors that is located adjacent the airgap. A group of hairpin or I-pin bar conductors is radially spaced from the airgap and located adjacent the wire conductors. The bar conductors have a cross-sectional area/shape that is distinct from a cross-sectional area/shape of the wire conductors.
1 . An electric machine, comprising:
a housing;
a stator attached to the housing;
a rotor movable with respect to and spaced across an airgap from the stator;
a plurality of magnets attached to one of the rotor or the stator; and
a plurality of electromagnetic conductors attached to the other of the rotor or the stator, the electromagnetic conductors including a plurality of wire conductors and a plurality of bar conductors, the wire conductors located adjacent the airgap and each having a first cross-sectional area, and the bar conductors radially spaced from the airgap, located adjacent the wire conductors, and each having a second cross-sectional area larger than the first cross-sectional area,
wherein the bar conductors are grouped into a single rectilinear line and spaced from each other, and wherein the wire conductors are grouped into multiple rectilinear lines and spaced from each other.
2 . The electric machine of claim 1 , wherein a ratio of the wire conductors to the bar conductors is at least about 3:1.
3 . The electric machine of claim 1 , wherein the second cross-sectional area is at least five-times larger than the first cross-sectional area.
4 . The electric machine of claim 1 , further comprising a first power inverter module (PIM) electrically coupled with and configured to control a feed of electric current to the wire conductors and not the bar conductors, and a second PIM electrically coupled with and configured to control a feed of electric current to the bar conductors and not the wire conductors.
5 . The electric machine of claim 1 , further comprising a plurality of relay switches and a shared power inverter module (PIM) both electrically coupled with and configured to control a feed of electric current to both the wire conductors and the bar conductors.
6 . The electric machine of claim 1 , wherein the wire conductors include solid-wire conductors and/or multistrand-wire conductors, and the bar conductors include I-pin conductors, D-pin conductors, flat-bar conductors, and/or hairpin conductors.
7 . The electric machine of claim 1 , wherein each of the wire conductors has a first cross-sectional geometry and the bar conductors each has a second cross-sectional geometry distinct from the first cross-sectional geometry.
8 . The electric machine of claim 7 , wherein the first cross-sectional geometry is a simple closed curve, and the second cross-sectional geometry is a rectilinear, beveled, or rounded polygon.
9 . The electric machine of claim 1 , wherein the rotor includes a rotor core bearing the magnets, and the stator includes a stator core coaxial with and circumscribing the rotor core, the stator core defining a radially elongated stator slot containing the electromagnetic conductors with the wire conductors located at a radially inner end of the stator slot and the bar conductors located at a radially outer end of the stator slot.
10 . The electric machine of claim 9 , wherein a slot fill factor of the electromagnetic conductors and the stator slot is at least about 0.4.
11 . The electric machine of claim 9 , wherein the wire conductors extend across about 30% to about 60% of a radial length of the stator slot.
12 . A method of assembling an electric machine, the method comprising:
receiving a housing of the electric machine;
attaching a stator to the housing;
attaching a rotor to the housing such that the rotor is movable with respect to and spaced across an airgap from the stator;
attaching a plurality of magnets to one of the rotor or the stator; and
attaching a plurality of electromagnetic conductors to the other of the rotor or the stator, the electromagnetic conductors including a plurality of wire conductors and a plurality of bar conductors, the wire conductors located adjacent the airgap and each having a first cross-sectional area, and the bar conductors located adjacent the wire conductors, radially spaced from the airgap, and each having a second cross-sectional area larger than the first cross-sectional area,
wherein the bar conductors are grouped into a single rectilinear line and spaced from each other, and wherein the wire conductors are grouped into multiple rectilinear lines and spaced from each other.
13 . The method of claim 12 , wherein the wire conductors have a first cross-sectional geometry and the bar conductors have a second cross-sectional geometry distinct from the first cross-sectional geometry.
14 . The method of claim 12 , wherein a ratio of the wire conductors to the bar conductors is at least about 3:1.
15 . The method of claim 12 , wherein the second cross-sectional area is at least five-times larger than the first cross-sectional area.
16 . The method of claim 12 , further comprising:
connecting a first power inverter module (PIM) to the wire conductors and not the bar conductors, the first PIM configured to control a first feed of electric current to the wire conductors; and
connecting a second PIM to the bar conductors and not the wire conductors, the second PIM configured to control a second feed of electric current to the bar conductors.
17 . The method of claim 12 , wherein the wire conductors include solid-wire conductors and/or multistrand-wire conductors, and the bar conductors include I-pin conductors, D-pin conductors, flat-bar conductors, and/or hairpin conductors.
18 . The method of claim 12 , wherein the rotor includes a rotor core bearing the magnets, and the stator includes a stator core coaxial with and circumscribing the rotor core, the stator core defining a radially elongated stator slot containing the electromagnetic conductors with the wire conductors located at a radially inner end of the stator slot and the bar conductors located at a radially outer end of the stator slot.
19 . The method of claim 18 , wherein a slot fill factor of the electromagnetic conductors and the stator slot is at least about 0.4, and wherein the wire conductors extend across about 30% to about 60% of a radial length of the stator slot.
20 . An electric machine, comprising:
a housing;
a stator attached to the housing;
a rotor movable with respect to and spaced across an airgap from the stator;
a plurality of magnets attached to one of the rotor or the stator;
a plurality of electromagnetic conductors attached to the other of the rotor or the stator, the electromagnetic conductors including a plurality of wire conductors and a plurality of bar conductors, the wire conductors located adjacent the airgap and each having a first cross-sectional area, and the bar conductors located adjacent the wire conductors, radially spaced from the airgap, and each having a second cross-sectional area larger than the first cross-sectional area;
a first power inverter module (PIM) electrically coupled with and configured to control a feed of electric current to the wire conductors and not the bar conductors; and
a second PIM electrically coupled with and configured to control a feed of electric current to the bar conductors and not the wire conductors.