Abstract: An electrical sub-assembly comprises a stator having a plurality of coils and cooling means attached to the stator. The electrical sub-assembly further comprises a plurality of pairs of diodes attached to the cooling means, each pair of diodes being in antiparallel configuration and having three electrical terminals. One of the three electrical terminals is a common terminal shared by both diodes in each pair of diodes in each pair of diodes. A plurality of busbars electrically connect each of the diodes to at least one of the plurality of coils via one or more of the electrical terminals. In use, the cooling means is configured to simultaneously cool the stator and the plurality of diodes. The electrical sub-assembly may have particular application as a part of a switched reluctance machine.

Abstract: A surface mounted permanent magnet motor includes a stator having poles and windings. A rotor includes magnets fixed to an outer surface of a support assembly. The stator poles face the outer surface of the rotor. The support assembly has magnetically conductive magnet carriers spaced from each other and supporting two magnets of opposing polarity. The magnet carriers have a central region of low permeability that blocks q-axis flux flowing from the stator radially towards the rotor axis surrounded by regions of high permeability. A first high permeability region defines a continuous flux path on the side of the barrier region closest to the rotor axis and links central regions of the two magnets carried by the magnet carriers. A second high permeability region is located on the side of the barrier nearest the stator that defines a flux path linking the end regions of the magnets.

Abstract: An electrical sub-assembly comprises a stator having a plurality of coils and cooling means attached to the stator. The electrical sub-assembly further comprises a plurality of pairs of diodes attached to the cooling means, each pair of diodes being in antiparallel configuration and having three electrical terminals. One of the three electrical terminals is a common terminal shared by both diodes in each pair of diodes in each pair of diodes. A plurality of busbars electrically connect each of the diodes to at least one of the plurality of coils via one or more of the electrical terminals. In use, the cooling means is configured to simultaneously cool the stator and the plurality of diodes. The electrical sub-assembly may have particular application as a part of a switched reluctance machine.

Abstract: An electrical sub-assembly comprises a stator having a plurality of coils and a cooling means attached to the stator. The electrical sub-assembly further comprises a plurality of pairs of diodes attached to the cooling means, each pair of diodes being in antiparallel configuration and having three electrical terminals. One of the three electrical terminals is a common terminal shared by both diodes in each pair of diodes. A plurality of busbars electrically connect each of the diodes to at least one of the plurality of coils via one or more of the electrical terminals. In use, the cooling means is configured to simultaneously cool the stator and the plurality of diodes. The electrical sub-assembly may have particular application as a part of a switched reluctance machine.

Abstract: A radial portion of a rotor is rotatably mounted to a stator and a cylindrical portion axially extends over radial teeth formed on the stator. A first surface of the first soft ferromagnetic material element is mounted to an inner surface of the cylindrical portion and a second surface of the first soft ferromagnetic material element has mounted on it a first magnet such that a surface of a pole of the first magnet is oriented substantially non perpendicular to a line from the centre of the rotor to the first magnet. A first surface of a second soft ferromagnetic material element is mounted to the first magnet such that the first magnet is sandwiched between the first and second soft ferromagnetic material elements. A second surface of the second soft ferromagnetic material element is substantially perpendicular to the line from the centre of the rotor to the first magnet.

Abstract: An electrical sub-assembly comprises a stator having a plurality of coils and a cooling means attached to the stator. The electrical sub-assembly further comprises a plurality of pairs of diodes attached to the cooling means, each pair of diodes being in antiparallel configuration and having three electrical terminals. One of the three electrical terminals is a common terminal shared by both diodes in each pair of diodes. A plurality of busbars electrically connect each of the diodes to at least one of the plurality of coils via one or more of the electrical terminals. In use, the cooling means is configured to simultaneously cool the stator and the plurality of diodes. The electrical sub-assembly may have particular application as a part of a switched reluctance machine.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes generating a first signal having a voltage that is proportional to a voltage across a winding of the motor, and generating a second signal having a voltage that is proportional to a current in the winding. The second signal is then differentiated to generate a third signal, and the voltages of the first signal and the third signal are compared. An output signal is generated in response to the comparison, the output signal having an edge whenever the voltages of the first signal and the third signal correspond. The winding is then commutated at times relative to the edges in the output signal. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: A rotor for an electric motor or generator, the rotor comprising a radial portion, a cylindrical portion, a first soft ferromagnetic material element, and a second soft ferromagnetic material element, wherein the radial portion is arranged to be rotatably mounted to a stator and the cylindrical portion is arranged to axially extend over radial teeth formed on the stator when the rotor is rotatably mounted to the stator, wherein a first surface of the first soft ferromagnetic material element is mounted to an inner surface of the cylindrical portion and a second surface of the first soft ferromagnetic material element is arranged to have mounted on it a first magnet such that a surface of a pole of the first magnet is oriented substantially non perpendicular to a line from the centre of the rotor to the first magnet, wherein a first surface of the second soft ferromagnetic material element is arranged to be mounted to the first magnet such that the first magnet is sandwiched between the first soft ferromagneti

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes generating a first signal having a voltage that is proportional to a voltage across a winding of the motor, and generating a second signal having a voltage that is proportional to a current in the winding. The second signal is then differentiated to generate a third signal, and the voltages of the first signal and the third signal are compared. An output signal is generated in response to the comparison, the output signal having an edge whenever the voltages of the first signal and the third signal correspond. The winding is then commutated at times relative to the edges in the output signal. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: A stator (50) for an electrical machine. A core of the stator (50) is made up of a series of connected segments (42), that are rotatable relative to one another during an assembly operation. Each segment (42) includes a radially outermost base portion (44) from which a respective integral pole piece (46) projects substantially inwardly to a pole piece tip. The tip includes a surface (49) that is arcuate and concentric with an axis of rotation of the machine. Each pole piece (46) projects in a non-radial direction and such that a semi-closed slot (48) arranged to locate part of a least one coil (30) therein is provided between each pair of juxtaposed pole pieces (46). A coil (30) is fittable to a respective one of the pole pieces (46) during the assembly operation without deformation of the pole piece (46).

Abstract: A switched reluctance machine has a stator which has an array of alternate wide and narrow poles around its inner circumference. Coils are wound around the wide poles only. The rotor includes segments of soft magnetic material carried on a non-magnetic core. The segments are so proportioned at the air gap that the flux produced by one stator coil passes through two or more segments and returns through the adjacent narrow poles. The machine is capable of producing a high output.

Abstract: A power tool comprising a body (20), a motor and a roller (38), characterized in that the motor acts as the roller (38).

Abstract: (57) A stator (50) for an electrical machine. A core of the stator (50) is made up of a series of connected segments (42), that are rotatable relative to one another during an assembly operation. Each segment (42) includes a radially outermost base portion (44) from which a respective integral pole piece (46) projects substantially inwardly to a pole piece tip. The tip includes a surface (49) that is arcuate and concentric with an axis of rotation of the machine. Each pole piece (46) projects in a non-radial direction and such that a semi-closed slot (48) arranged to locate part of a least one coil (30) therein is provided between each pair of juxtaposed pole pieces (46). A coil (30) is fittable to a respective one of the pole pieces (46) during the assembly operation without deformation of the pole piece (46).

Abstract: A switched reluctance machine has a stator which has an array of alternate wide and narrow poles around its inner circumference. Coils are wound around the wide poles only. The rotor includes segments of soft magnetic material carried on a non-magnetic core. The segments are so proportioned at the air gap that the flux produced by one stator coil passes through two or more segments and returns through the adjacent narrow poles. The machine is capable of producing a high output.

Abstract: A power tool comprising a body (20), a motor and a roller (38), characterized in that the motor acts as the roller (38).