The present disclosure relates to electrical machines (100, 200) configured to be fed by pulse width modulation from a power converter (170) and comprising a stator (110), a rotor (120), a rotor shaft (130) and one or more bearings (140, 141) arranged between the rotor (120) and the stator (110). The electrical machine (100, 200) further comprising an electrical shunt (160, 161) arranged between the rotor shaft (130) and the stator (110). The present disclosure also relates to methods (500) to mitigate electrical discharge machining bearing currents in electrical machines (100, 200).

The present disclosure relates to electrical machines (100, 200) configured to be fed by pulse width modulation from a power converter (170) and comprising a stator (110), a rotor (120), a rotor shaft (130) and one or more bearings (140, 141) arranged between the rotor (120) and the stator (110). The electrical machine (100, 200) further comprising an electrical shunt (160, 161) arranged between the rotor shaft (130) and the stator (110). The present disclosure also relates to methods (500) to mitigate electrical discharge machining bearing currents in electrical machines (100, 200).

A method of electrically grounding a rotor shaft of an electric motor includes removing a first lockplate fastener from a motor endshield and an internal bearing lockplate. A second lockplate fastener remains coupled to the motor endshield and internal bearing lockplate such that the internal bearing lockplate stays secured along an interior side of the motor endshield. A mounting plate of a shaft ground assembly is positioned along an exterior side of the motor endshield. The mounting plate supports a shaft ground that includes a conductive element configured to electrically couple to the rotor shaft. The first lockplate fastener is replaced with a first mounting plate fastener coupled to the mounting plate, motor endshield, and bearing lockplate to secure the mounting plate to the endshield and to secure the bearing lockplate along the interior side of the motor endshield.

A method of electrically grounding a rotor shaft of an electric motor includes removing a first lockplate fastener from a motor endshield and an internal bearing lockplate. A second lockplate fastener remains coupled to the motor endshield and internal bearing lockplate such that the internal bearing lockplate stays secured along an interior side of the motor endshield. A mounting plate of a shaft ground assembly is positioned along an exterior side of the motor endshield. The mounting plate supports a shaft ground that includes a conductive element configured to electrically couple to the rotor shaft. The first lockplate fastener is replaced with a first mounting plate fastener coupled to the mounting plate, motor endshield, and bearing lockplate to secure the mounting plate to the endshield and to secure the bearing lockplate along the interior side of the motor endshield.

A cooling apparatus includes a cold plate made of a metal, a casing, a pump, a ground wire, and a conductive component. The pump includes a motor to drive an impeller, and a circuit board to control the motor. The circuit board is connected to the ground wire. The conductive component electrically connects the cold plate to the ground wire.

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 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.

An electric motor and a vehicle are provided. The electric motor includes a metal member, a rotor core, a shaft, a conductive bearing, and an elastic conductive member. The metal member is grounded. The rotor core is disposed on one side of the metal member, and includes a shaft hole. The shaft is connected to the rotor core, and penetrates through the shaft hole. The conductive bearing is disposed on the shaft in a sleeving manner. At least a portion of the elastic conductive member is disposed between the conductive bearing and the metal member. The elastic conductive member generates compression force through elastic deformation thereof, to be in tight contact with the conductive bearing.

An electric motor and a vehicle are provided. The electric motor includes a metal member, a rotor core, a shaft, a conductive bearing, and an elastic conductive member. The metal member is grounded. The rotor core is disposed on one side of the metal member, and includes a shaft hole. The shaft is connected to the rotor core, and penetrates through the shaft hole. The conductive bearing is disposed on the shaft in a sleeving manner. At least a portion of the elastic conductive member is disposed between the conductive bearing and the metal member. The elastic conductive member generates compression force through elastic deformation thereof, to be in tight contact with the conductive bearing.

An electric tool, a blower and a method of discharging electrostatic charge in an electric tool. The tool may include a housing, a motor supported by the housing and powered by a power source, the motor including a rotor, a fan supported by the housing and driven by the motor to cause an air flow, and a wire electrically connected between the rotor and a terminal of the power source and operable to dissipate electrostatic discharge in the tool.