Abstract: An interior permanent magnet machine includes a stator including a plurality of electrical conductors. The interior permanent magnet machine further includes a rotor concentrically disposed in relation to the stator. The rotor is configured to rotate relative to the stator about a rotational axis and includes a plurality of polar pieces arranged annularly about the rotational axis. At least one of the polar pieces includes a magnetic layer configured to magnetically interact with the electrical conductors. The magnetic layer has a substantially conic section shape.

Abstract: An interior permanent magnet machine includes a rotor having a plurality of slots. First and second slots are disposed in a first pole and the third and fourth slots are disposed in a second pole. A first angle is defined between respective centerlines of the first and second slots. A second angle is defined between respective centerlines of the third and fourth slots. The first angle is configured to be sufficiently different from the second angle so that torque ripple is reduced. Thus the rotor is configured such that the angular configuration of slots in a first pole is different from the angular configuration of slots in a second pole of the rotor.

Abstract: An electric machine is provided with a rotor configured to be rotatable within a stator. A first and second tooth are disposed circumferentially along an outer perimeter of the rotor and at least partially define a first slot. The first and the second tooth define a respective first and second outer edge extending between a respective tooth base and a respective tooth tip. An arc radius from the origin to the outer perimeter of the rotor varies along the first outer edge of the first tooth, thereby creating a first non-uniform gap between the rotor and the stator. The arc radius from the origin to the outer perimeter of the rotor varies along the second outer edge of the second tooth, thereby creating a second non-uniform gap between the rotor and the stator. The rotor geometry is configured to reduce torque ripple without skewing either the rotor or the stator.

Abstract: A stator assembly includes a plurality of stator slots defining multiple slot layers. The assembly includes a plurality of hairpins each having a respective first leg positioned in one of the multiple slot layers and a respective second leg positioned in another of the multiple slot layers. Each hairpin is configured to allow a current to flow from the respective first leg to the respective second leg. The plurality of hairpins is divided into multiple hairpin layers. The hairpins form multiple winding sets, such as first, second, third and fourth winding sets. Each of the winding sets at least partially includes the hairpins from at least two of the multiple hairpin layers. The multiple slot layers may include six slot layers. The multiple hairpin layers may include six hairpin layers. Thus, at least one of the hairpin layers may be “shared” by two winding sets.

Abstract: A controller-implemented method for monitoring a permanent magnet electric machine includes determining a threshold direct-axis (d-axis) current corresponding to inception of irreversible demagnetization of the permanent magnet based upon material properties of a permanent magnet mounted in a rotor of the PM electric machine and a temperature of the permanent magnet. A d-axis current associated with controlling the PM electric machine is determined, and a state of health of the PM electric machine is determined based upon the threshold d-axis current and the monitored d-axis current.

Abstract: An interior permanent magnet machine includes a rotor having a plurality of slots. First and second slots are disposed in a first pole and the third and fourth slots are disposed in a second pole. A first barrier is defined by the first, second, third and fourth slots. The slots are configured to be symmetric relative to their respective pole axes. A first angle is defined between the first and second slots. A second angle is defined between the third and fourth slots. The first angle is configured to be sufficiently different from the second angle so that torque ripple is minimized. Thus the rotor is configured such that the angular configuration of slots in a first pole is different from the angular configuration of slots in a second pole of the rotor.

Abstract: An interior permanent magnet machine includes a rotor formed with a plurality of slots that are substantially arc-shaped and referred to herein as arc segments. A first layer of arc segments are disposed in a first pole. The first layer defines a first configuration relative to a first arc center. A second layer of arc segments are disposed in a second pole. The second layer defines a second configuration relative to a second arc center. The rotor is configured such that the first configuration is different from the second configuration, thereby exhibiting pole-to-pole asymmetry. The first configuration is sufficiently different from the second configuration such that torque ripple may be minimized. In one embodiment, the first layer includes first, second and third arc segments. The rotor may be configured such that the second arc segment is radially offset relative to the first and third arc segments.

Abstract: A rotor core for an Internal Permanent Magnet (IPM) machine includes a cavity having a magnet disposed therein. The cavity defines an air slot adjacent a radially outermost edge of the magnet disposed therein. A leakage flux path extends across the air slot and connects opposing sides of the cavity. The leakage flux path is oriented in an approximate tangential relationship relative to an axis of rotation of the rotor core, and is angled relative to the radially outermost edge of the magnet disposed within the cavity to direct flux away from the magnet. The cavity further includes an air pocket disposed along a radial inner surface of the magnet relative to the axis of rotation, adjacent the air slot of the cavity.

Abstract: A permanent magnet machine is provided with a rotor positioned at least partially within a stator. The rotor includes first and second ring segments oriented axially around a central axis. The rotor defines first and second configurations in the first and second ring segments, respectively. The first configuration is sufficiently different from the second configuration such that torque ripple may be minimized. A first layer of slots, defining a slot outer edge, may be formed in the rotor. In one embodiment, a stator-to-slot gap varies between the first and second ring segments. In another embodiment, a stator-rotor gap varies between the first and second ring segments. In another embodiment, a bridge thickness varies between the first and second ring segments. Thus the rotor exhibits axial asymmetry.

Abstract: A bar wound stator includes a stator core defining a plurality of slots. Bar-type conductors are disposed within each slot. Each slot includes a slot liner and an insulator cap. Each slot liner includes an end portion disposed against an inner wall surface, and side portions disposed against a first wall surface and a second wall surface respectively. Each insulator cap includes a base portion disposed against an outer wall surface, and side portions disposed against the first wall surface and the second wall surface respectively. The side portions of the insulator cap in each slot overlap the side portions of the slot liner in each slot along the first wall surface and the second wall surface respectively. Each slot includes a recessed feature in each of the first wall surface and the second wall surface to accommodate the overlapping side portions of the insulator cap and the slot liner.

Abstract: A stator assembly includes a plurality of stator slots defining a plurality of slot layers. The assembly includes a plurality of hairpins each having respective first and second legs positioned in respective ones of the slot layers. Each of the hairpins is one of a short-pitched coil, a long-pitched coil and a full-pitched coil. The short-pitched, long-pitched and full-pitched coils are configured to extend over a first, second and third number of the stator slots, respectively. The hairpins may be divided into first, second, third, fourth, fifth and sixth hairpin layers. One of the hairpin layers includes at least one short-pitched coil, and another of the hairpin layers includes at least one long-pitched coil. The first, third and fifth hairpin layers each may include at least two short-pitched coils while the second, fourth and sixth hairpin layers each may include at least two long-pitched coils.

Abstract: A rotor core for an Internal Permanent Magnet (IPM) machine includes a cavity having a magnet disposed therein. The cavity defines an air slot adjacent a radially outermost edge of the magnet disposed therein. A leakage flux path extends across the air slot and connects opposing sides of the cavity. The leakage flux path is oriented in an approximate tangential relationship relative to an axis of rotation of the rotor core, and is angled relative to the radially outermost edge of the magnet disposed within the cavity to direct flux away from the magnet. The cavity further includes an air pocket disposed along a radial inner surface of the magnet relative to the axis of rotation, adjacent the air slot of the cavity.

Abstract: An interior permanent magnet machine includes a rotor configured to magnetically interact with a stator. First and second dividers are integrally formed within the rotor and configured to create a first layer of three respective first segments. Each of the respective first segments may be substantially arc-shaped. A plurality of first magnets may be positioned in the first layer. The first magnets may be substantially arc-shaped and defined around an arc center. A third and a fourth divider may be integrally formed within the rotor and configured to create a second layer of three respective second segments. The placement of dividers or structural webs provides for increased rotational speed and reduced rotational stress compared to an undivided arc-shaped magnet configuration.

Abstract: A permanent magnet motor includes a permanent magnet rotor, a stator surrounding the rotor having a plurality of teeth radially inwardly oriented toward a longitudinal axis of the stator wherein each tooth has a tooth length and a tooth tip surface geometry. An asymmetric air gap is defined by variations in the tooth lengths and tooth tip surface geometries.

Abstract: A rotor core for an internal permanent magnet machine includes at least one ferrite pole and at least one rare earth pole, arranged radially about an axis in alternating relationship. The ferrite poles define a plurality of first pole cavities, and the rare earth poles define a plurality of second pole cavities. One of a plurality of ferrite magnets is disposed within each of the first pole cavities of the ferrite poles, and one of a plurality of rare earth magnets is disposed within each of the second pole cavities of the rare earth poles.

Abstract: A rotor for a permanent magnet electric machine includes an axis of rotation, an outer surface, and a cross-section orthogonal to the axis of rotation with a non-circular contour of the outer surface defined by a plurality of radii angularly distributed around the axis of rotation.

Abstract: An interior permanent magnet machine includes a stator including a plurality of electrical conductors. The interior permanent magnet machine further includes a rotor concentrically disposed in relation to the stator. The rotor is configured to rotate relative to the stator about a rotational axis and includes a plurality of polar pieces arranged annularly about the rotational axis. At least one of the polar pieces includes a magnetic layer configured to magnetically interact with the electrical conductors. The magnetic layer has a substantially conic section shape.

Abstract: A rotor core defines a plurality of cavities, and includes one magnet disposed within each cavity. Each magnet includes a cross section that defines an arcuate shape having an arc center. The magnets are arranged about a pole axis to define a first group of magnets disposed on a first side of the pole axis, and a second group of magnets disposed on a second side of the pole axis. The arc centers of each of the magnets of the first group of magnets and the second group of magnets are spaced from each other and are spaced from the pole axis. The plurality of magnets is arranged in a plurality of layers. The arc centers of each of the magnets in each of the layers are spaced from each other.

Abstract: An electric machine includes a stator core defining a number of stator slots (Z). A rotor assembly is positioned at least partially within the stator core. The rotor assembly includes at least one permanent magnet and defines a number of poles (M). A plurality of stator windings are positioned in the number of stator slots and define a number of phases (M). The machine defines a non-integer slots per pole per phase value (X), which is expressed as a mixed fraction in the form of A.(B/C), where A, B and C are integers. Optimal configurations for the electric machine are specified that maximize torque while minimizing torque ripple, noise and manufacturing complexity. In one embodiment, the slots per pole per phase value (X) is 2½. In another embodiment, the slots per pole per phase value (X) is 3½.

Abstract: A rotor core defines a plurality of cavities, and includes one magnet disposed within each cavity. Each magnet includes a cross section that defines an arcuate shape having an arc center. The magnets are arranged about a pole axis to define a first group of magnets disposed on a first side of the pole axis, and a second group of magnets disposed on a second side of the pole axis. The arc centers of each of the magnets of the first group of magnets and the second group of magnets are spaced from each other and are spaced from the pole axis. The plurality of magnets is arranged in a plurality of layers. The arc centers of each of the magnets in each of the layers are spaced from each other.