Abstract: A system and method for heating ferrite permanent magnets in an electrical machine is disclosed. The permanent magnet machine includes a stator assembly and a rotor assembly, with a plurality of ferrite permanent magnets disposed within the stator assembly or the rotor assembly to generate a magnetic field that interacts with a stator magnetic field to produce a torque. A controller of the electrical machine is programmed to cause a primary field current to be applied to the stator windings to generate the stator magnetic field, so as to cause the rotor assembly to rotate relative to the stator assembly. The controller is further programmed to cause a secondary current to be applied to the stator windings to selectively generate a secondary magnetic field, the secondary magnetic field inducing eddy currents in at least one of the stator assembly and the rotor assembly to heat the ferrite permanent magnets.

Abstract: An electric drive system includes an induction machine and a power converter electrically coupled to the induction machine to drive the induction machine. The power converter comprising a plurality of silicon carbide (SiC) switching devices. The electric drive system further includes a controller that is electrically coupled to the power converter and that is programmed to transmit switching signals to the plurality of SiC switching devices at a given switching frequency such that a peak-to-peak current ripple is less than approximately five percent.

Abstract: A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing step that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.

Abstract: A magnet management method of controlling a ferrite-type permanent magnet electrical machine includes receiving and/or estimating the temperature permanent magnets; determining if that temperature is below a predetermined temperature; and if so, then: selectively heating the magnets in order to prevent demagnetization and/or derating the machine. A similar method provides for controlling magnetization level by analyzing flux or magnetization level. Controllers that employ various methods are disclosed. The present invention has been described in terms of specific embodiment(s), and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.

Abstract: A control sub-system for controlling an electric machine is presented. The control sub-system includes a phase shift control unit to receive an electric signal indicative of an angular position of a rotor. The phase shift control unit generates a phase shifted electric signal by applying a phase shift to the electric signal. The magnitude of the phase shift is determined based on a speed control signal. The phase shift control unit is configured to generate a phase command signal based on the phase shifted electric signal. The control sub-system also includes a switching unit to control a supply of a phase current to one or more phase windings the electric machine based on the phase command signal such that the rotor is operated at a predetermined rotational speed. Related method of controlling the electric machine is also presented.

Abstract: An electric drive system includes an induction machine and a power converter electrically coupled to the induction machine to drive the induction machine. The power converter comprising a plurality of silicon carbide (SiC) switching devices. The electric drive system further includes a controller that is electrically coupled to the power converter and that is programmed to transmit switching signals to the plurality of SiC switching devices at a given switching frequency such that a peak-to-peak current ripple is less than approximately five percent.

Abstract: An electrical machine exhibiting reduced friction and windage losses is disclosed. The electrical machine includes a stator and a rotor assembly configured to rotate relative to the stator, wherein the rotor assembly comprises a rotor core including a plurality of salient rotor poles that are spaced apart from one another around an inner hub such that an interpolar gap is formed between each adjacent pair of salient rotor poles, with an opening being defined by the rotor core in each interpolar gap. Electrically non-conductive and non-magnetic inserts are positioned in the gaps formed between the salient rotor poles, with each of the inserts including a mating feature formed an axially inner edge thereof that is configured to mate with a respective opening being defined by the rotor core, so as to secure the insert to the rotor core against centrifugal force experienced during rotation of the rotor assembly.

Abstract: A stator assembly that includes a graphite sheet-like element that has fold(s) so as to define at least two planar sections. The face of one of the planar section abuts a surface of a heat generating location(s) of the stator assembly and a face of another planar section abuts one the tooth or the slot bottom of the stator assembly. Also, a subassembly that includes an electrical machine stator assembly that includes a sheet-like element of a material having high thermal conductivity, wherein a portion of the element abuts the end winding(s) such that the sheet-like element conducts heat to the magnetic core, the stator housing, and/or a winding heat conduction element.

Abstract: A method, system, and apparatus including an electric machine having a plurality of rotor bars and a first coupling component configured to electrically couple the plurality of rotor bars together. Each rotor bar of the plurality of rotor bars includes a first metallic material having a first electrical resistivity and a second metallic material cast about the first material, where the second metallic material has a second electrical resistivity greater than the first electrical resistivity. The first metallic material has a first end and a second end opposite the first end and the first coupling component is coupled to the first end of the first metallic material.

Abstract: A magnetic component including at least one region is disclosed. The at least one region includes nitrogen and a concentration of the nitrogen in the at least one region is graded across a dimension of the at least one region. Further, a saturation magnetization in the at least one region is graded across the dimension of the at least one region. Further, a method of varying the magnetization values in at least one region of the magnetic component is disclosed.

Abstract: A magnetic component including first and second regions, and a method of varying the magnetization values in different regions of the magnetic component are disclosed. The first and the second regions are characterized by a nitrogen content that is different from each other. At least one of the first region and the second region is partially-magnetic and has a nitrogen content in a range from about 0.1 weight % to about 0.4 weight % of that region. A concentration of carbon, if present, of both the first and second regions is less than about 0.05 weight % of the respective regions.

Abstract: An apparatus, such as an electrical machine, is provided. The apparatus can include a rotor defining a rotor bore and a conduit disposed in and extending axially along the rotor bore. The conduit can have an annular conduit body defining a plurality of orifices disposed axially along the conduit and extending through the conduit body. The rotor can have an inner wall that at least partially defines the rotor bore. The orifices can extend through the conduit body along respective orifice directions, and the rotor and conduit can be configured to provide a line of sight along the orifice direction from the respective orifices to the inner wall.

Abstract: A permanent magnet machine includes a stator configured to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity, a rotor disposed inside said cavity and configured to rotate about the longitudinal axis, and a plurality of permanent magnets for generating a magnetic field, which interacts with the stator magnetic field to produce a torque. At least one of the plurality of permanent magnets has a light rare earth material including neodymium and praseodymium, and less than about 5 weight percent of a heavy rare earth material, wherein the weight percentage of neodymium is larger than the weight percentage of praseodymium but smaller than three times of the weight percentage of praseodymium.

Abstract: A rotor component that comprises a rotor circuit configured for use with either an interior permanent magnet (IPM) machine or a synchronous reluctance machine (SRM) that includes a pole circuit made of a conductive, non-magnetic material and has a midpoint that substantially aligns with a d-axis of the IPM or SRM. An electric machine with a similar rotor component therein or having a loop or ring of a conductive, non-magnetic material that is substantially concentric about a d-axis of the electric machine.

Abstract: A stator lamination for an electric machine has a circular lamination with an annular bore therethrough; winding slots therethrough; and, slot closures disposed adjacent to the winding slots. The stator lamination is formed of a dual magnetic phase material, such that the magnetic property of the lamination can have a first state and a magnetic property in a second state, wherein the second state is different than the first state. The slot closures regions are treated so as to transition to the second state. A method of manufacturing an electric machine component is also disclosed.

Abstract: An internal permanent magnet machine includes a rotor assembly having a shaft comprising a plurality of protrusions extending radially outward from a main shaft body and being formed circumferentially about the main shaft body and along an axial length of the main shaft body. A plurality of stacks of laminations are arranged circumferentially about the shaft to receive the plurality of protrusions therein, with each stack of laminations including a plurality of lamination groups arranged axially along a length of the shaft and with permanent magnets being disposed between the stacks of laminations. Each of the laminations includes a shaft protrusion cut formed therein to receive a respective shaft protrusion and, for each of the stacks of laminations, the shaft protrusion cuts formed in the laminations of a respective lamination group are angularly offset from the shaft protrusion cuts formed in the laminations in an adjacent lamination group.

Abstract: A magnet management method of controlling a ferrite-type permanent magnet electrical machine includes receiving and/or estimating the temperature permanent magnets; determining if that temperature is below a predetermined temperature; and if so, then: selectively heating the magnets in order to prevent demagnetization and/or derating the machine. A similar method provides for controlling magnetization level by analyzing flux or magnetization level. Controllers that employ various methods are disclosed. The present invention has been described in terms of specific embodiment(s), and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.

Abstract: A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing step that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.

Abstract: A rotor lamination that is made of a circular laminar element that has multiple rotor bar openings displaced circumferentially around the element and is made of a magnetic material, such as a dual-phase or bi-state magnetic material. A region of the element has received a treatment, thereby rendering the region so that the relative magnetic permeability of the treated region is less than that of the magnetic material. A rotor core assembly and induction machine that incorporates the rotor lamination and method of manufacture of the rotor lamination are also disclosed.

Abstract: An electrical generator includes a stator having fractional-slot concentrated windings and a rotor having field windings. A drive is provided having a circuit to control current flow to the field windings and a controller to input an initial DC field current demand to the circuit to cause the circuit to output an initial DC field current representative of a DC field current demand that would cause an electrical generator having sinusoidal stator windings to output a desired AC power. The controller receives feedback on the magnetic field generated by the initial DC field current, isolates an ideal fundamental component of the magnetic field based on the feedback and to generate a modified DC field current demand, and inputs the modified DC field current demand to the circuit, thereby causing the circuit to output an instantaneous non-sinusoidal current to the field windings to generate a sinusoidal rotating air gap magnetic field.