A synchronous machine having a hybrid rotor excitation. The synchronous machine includes a rotor having a plurality of permanent magnets and electromagnets embedded within a rotor body. The permanent magnets produces a constant magnet field having a magnetic axis along a direct axis (D-axis). The electromagnets produces a variable magnetic field along a magnetic axis offset from the D-axis, preferable substantially orthogonal to the D-axis. The plurality of permanent magnets are separated from the electromagnets by a rotor air-gap. The plurality of permanent magnets includes inner pairs and outer pairs of permanent magnets nested in a V-shaped configuration. In another embodiment, the outer pairs of permanent magnets are replaced with outer radius electromagnets.

Various implementations include an electric motor including an annular radial stator, an annular axial stator, and a rotor. The annular radial stator has an opening with an inner surface and distributed windings disposed along at least the inner surface of the opening. The annular axial stator has concentrated windings disposed along at least a first side of the axial stator. The rotor includes two or more magnets. Flux from the two or more magnets interacts with one or both of a magnetic field created by the radial stator windings or axial rotor windings. The rotor is disposed within the radial stator opening and the axes of the axial stator and radial stator are coincident with the rotor axis. The flux interacting with one or both of the radial stator magnetic field or the axial stator magnetic field turns the rotor about the rotor axis.

A single stack transverse flux machine includes a rotor assembly having an internal rotor disc with a rotor shaft extending from and rotating with the internal rotor disc, and a rotor ring having a plurality of stator poles interleaved with a plurality of interpoles. The plurality of stator poles and the plurality of interpoles are radially disposed around the internal rotor disc. Each stator pole has a plurality of core components spaced apart from one another. Primary magnets are interposed between the plurality of core components. The machine also includes a stator assembly with a plurality of shaped cores, each shaped core having a base with a plurality of legs with a corresponding gap therebetween. Each leg has a winding, and the shaped cores are positioned so that each leg is juxtaposed with a corresponding one of the plurality of core components and has an air gap therebetween.

A synchronous machine having a hybrid rotor excitation. The synchronous machine includes a rotor having a plurality of permanent magnets and electromagnets embedded within a rotor body. The permanent magnets produces a constant magnet field having a magnetic axis along a direct axis (D-axis). The electromagnets produces a variable magnetic field along a magnetic axis offset from the D-axis, preferable substantially orthogonal to the D-axis. The plurality of permanent magnets are separated from the electromagnets by a rotor air-gap. The plurality of permanent magnets includes inner pairs and outer pairs of permanent magnets nested in a V-shaped configuration. In another embodiment, the outer pairs of permanent magnets are replaced with outer radius electromagnets.

A transverse flux reciprocating motor and a linear compressor including the same are described. The transverse flux reciprocating motor includes an outer stator including a stator core, a teeth portion extended from the stator core to an inside, and a teeth shoe extended from an inner end of the teeth portion in a circumferential direction; a coil disposed on the teeth portion; an inner stator disposed in the outer stator and configured to reciprocate in an axial direction due to an electromagnetic interaction with the coil; and a magnet disposed on the teeth shoe and facing the inner stator. The stator core includes a plurality of core plates stacked in the axial direction. The magnet includes first and second magnets that are spaced from each other in the axial direction.

A power tool with a combined printed circuit board (PCB) that reduces internal wiring of the power tool and provides a large amount of air flow to internal components. In some instances, the combined PCB has a surfboard shape and includes a motor control unit and power switching elements (Field Effect Transistors or FETs). The combined surfboard PCB is located above the trigger, but below the motor and drive mechanism. In other instances, the combined PCB has a doughnut shape and is located coaxially with a motor shaft. The combined PCB may be positioned between a doughnut-shaped control PCB and the motor.

A rotor for an electric machine having posts extending partially or completely between end irons. Each end iron is formed of a single piece of magnetic material with the posts extending from it, including the other end iron where the posts extend completely between them. Magnets are arranged between the posts with poles facing the posts to concentrate flux. In order to prevent too much of the flux from being drawn into flux paths through the end irons, the total magnetic flux is made to exceed a saturation flux of at least a portion of the flux path. This may be achieved by using interdigitated posts extending only partially between the end irons to provide gaps in the flux path, by providing flux resistors in the end irons to reduce a saturation flux below the total flux, or by using high aspect ratio magnets or posts so that the magnetic flux exceeds a saturation flux of the posts or end irons.

Disclosed is a motor rotor structure including a rotor core. A plurality of radial slots each are in the rotor core along a circumferential direction, and a first flux barrier slot is provided between every two adjacent radial slots. Two kinds of permanent magnets having different coercivities mounted in each radial slot. The two kinds of permanent magnets having different coercivities are distributed along a radial direction of the rotor core. The two kinds of permanent magnets having different coercivities are both magnetized along a tangential direction of the rotor core. A second flux barrier slot is provided between the two kinds of permanent magnets having different coercivities.

A rotor for an electric machine having posts extending partially or completely between end irons. Each end iron is formed of a single piece of magnetic material with the posts extending from it, including the other end iron where the posts extend completely between them. Magnets are arranged between the posts with poles facing the posts to concentrate flux. In order to prevent too much of the flux from being drawn into flux paths through the end irons, the total magnetic flux is made to exceed a saturation flux of at least a portion of the flux path. This may be achieved by using interdigitated posts extending only partially between the end irons to provide gaps in the flux path, by providing flux resistors in the end irons to reduce a saturation flux below the total flux, or by using high aspect ratio magnets or posts so that the magnetic flux exceeds a saturation flux of the posts or end irons.

A power tool with a combined printed circuit board (PCB) that reduces internal wiring of the power tool and provides a large amount of air flow to internal components. In some instances, the combined PCB has a surfboard shape and includes a motor control unit and power switching elements (Field Effect Transistors or FETs). The combined surfboard PCB is located above the trigger, but below the motor and drive mechanism. In other instances, the combined PCB has a doughnut shape and is located coaxially with a motor shaft. The combined PCB may be positioned between a doughnut-shaped control PCB and the motor.