An electric generator has a stator, a rotor and a coil on the stator or the rotor. The coil includes a plurality of turns of one or more high-temperature superconducting conductors shaped as a tape. Each tape conductor includes a substrate having a flat section and a high-temperature superconducting layer, the high-temperature superconducting layer being laid over one of the two major sides of the substrate, the high-temperature superconducting layer having a width in a direction parallel to the major side of the substrate. The turns of the coil are stacked in such a way that the major sides of the substrate are superposed to one another to form a coil section having a first dimension parallel to the width of the high-temperature superconducting layer and a second dimension orthogonal to the first dimension, the ratio between the first dimension and the second dimension being between 2 and 5.

A rotor of a motor includes first and second rotor cores, a field magnet, and a commutator magnet. The first and second rotor cores each include a core base and a plurality of claw poles. The claw poles of the first rotor core and the claw poles of the second rotor core are alternately arranged in a circumferential direction. The field magnet is located between the core bases. The field magnet is magnetized in an axial direction so that the claw poles of the first rotor core and the claw poles of the second rotor core function as different magnetic poles in the circumferential direction. The commutator magnet is located on an outer circumference of the field magnet around the claw poles. The commutator magnet is magnetized so that surfaces having the same polarity face each other between the claw poles and the commutator magnet.

The application is a motor capable of reducing vibration. A motor includes a shaft, a pair of bearings, a sleeve accommodating the pair of bearings, a magnet fixed at one of the shaft and sleeve, a coil fixed at the other of the shaft or the sleeve and opposing the magnet, and an elastic member disposed between the pair of bearings and satisfying Expression 1. D is an outer diameter [m] of the elastic member, d is a wire diameter (p [m] of the elastic member, γ is a unit volume weight [kg/m.sup.3] of a material of the elastic member, S is a no-load rotation number [rotation/min] of the shaft, and g is gravitational acceleration.

[00001]$\begin{array}{cc}S<\frac{20d\sqrt{\frac{\mathrm{gG}}{2\gamma }}}{{\pi D}^2}& \left(1\right)\end{array}$

The application is a motor capable of reducing vibration. A motor includes a shaft, a pair of bearings, a sleeve accommodating the pair of bearings, a magnet fixed at one of the shaft and sleeve, a coil fixed at the other of the shaft or the sleeve and opposing the magnet, and an elastic member disposed between the pair of bearings and satisfying Expression 1. D is an outer diameter [m] of the elastic member, d is a wire diameter (p [m] of the elastic member, γ is a unit volume weight [kg/m.sup.3] of a material of the elastic member, S is a no-load rotation number [rotation/min] of the shaft, and g is gravitational acceleration.

[00001]$\begin{array}{cc}S<\frac{20d\sqrt{\frac{\mathrm{gG}}{2\gamma }}}{{\pi D}^2}& \left(1\right)\end{array}$

A motor includes a stator having a winding, and a rotor. The rotor rotates by receiving a rotational magnetic field generated by drive current supplied to the winding. The winding includes a first winding and a second winding, the first and second windings both being excited at the same timing by the drive current. The first winding and the second winding are connected in series. The rotor includes a first pole section and a second pole section. The second pole section faces the second winding at the rotation position of the rotor at which the first pole section faces the first winding. The magnetic force exerted on the stator by the second pole section is weaker than that exerted by the first pole section.

A motor includes a stator having a winding, and a rotor. The rotor rotates by receiving a rotational magnetic field generated by drive current supplied to the winding. The winding includes a first winding and a second winding, the first and second windings both being excited at the same timing by the drive current. The first winding and the second winding are connected in series. The rotor includes a first pole section and a second pole section. The second pole section faces the second winding at the rotation position of the rotor at which the first pole section faces the first winding. The magnetic force exerted on the stator by the second pole section is weaker than that exerted by the first pole section.

A technique by which the magnetic flux of the magnetic pole facing the stator of the magnet can be further increased in a rotor, is provided. An electric motor according to the present disclosure includes a stator 10; a rotor 20 facing the stator 10 in an axial direction (first direction) and configured to be rotatable in a circumferential direction (second direction) that is orthogonal to the axial direction; and a short-circuit reduction member 25, 26, wherein the rotor 20 includes a main magnet 22 having a first magnetic pole on a surface facing the stator 10; an auxiliary magnet 23, 24 arranged adjacent to the main magnet 22 and having a second magnetic pole and a third magnetic pole that is different in polarity from the second magnetic pole, and configured to increase a magnetic flux of the first magnetic pole, and wherein the auxiliary magnet 23, 24 is arranged adjacent to the main magnet 22 in a radial direction (third direction) that is orthogonal to the axial direction, and the short-circuit reduction member 25, 26 is provided at a portion around the auxiliary magnet 23, 24 facing the auxiliary magnet 23, 24 in parallel with a virtual line connecting the second magnetic pole and the third magnetic pole, to reduce a short-circuit of a magnetic flux between the second magnetic pole and the third magnetic pole.

A power tool is provided including a gear case having a spindle, a motor case connected to a rear end of the gear case along a longitudinal axis; a handle portion extending from a rear end of the motor case along the longitudinal axis; a motor housed inside the motor case; a fan in rotational connection with the motor; at least one air intake arranged at least one of the motor case or the handle portion near the rear end of the motor case; and a power module including power switches for driving the motor and a heat sink. The power module is housed in at least one of the motor case or the handle portion near the rear end of the motor case such that rotation of the fan causes air flow to enter through the air intake and flow near the heat sink and through the motor.

A power tool is provided including a gear case having a spindle, a motor case connected to a rear end of the gear case along a longitudinal axis; a handle portion extending from a rear end of the motor case along the longitudinal axis; a motor housed inside the motor case; a fan in rotational connection with the motor; at least one air intake arranged at least one of the motor case or the handle portion near the rear end of the motor case; and a power module including power switches for driving the motor and a heat sink. The power module is housed in at least one of the motor case or the handle portion near the rear end of the motor case such that rotation of the fan causes air flow to enter through the air intake and flow near the heat sink and through the motor.

An electric motor including a motor rotor and a motor stator including a stator core including a plurality of stator teeth spaced along a circumferential direction of the stator core, a plurality of coil groups, wherein each of the plurality of coil groups includes a plurality of coils wound on a corresponding stator tooth, and an incoming line terminal and an outgoing terminal both comprising a same number of coil ends, and two motor lead groups, wherein a number of the plurality of motor leads of each of the two motor lead groups is equal to a number of the plurality of coil groups, and wherein each of the plurality of motor leads is connected to one incoming line terminal or one outgoing line terminal of one corresponding coil group of the plurality of coil groups.