Abstract: A rotor lamination assembly is formed with a central hole wherein a central axis goes through the central hole. The rotor lamination assembly is further formed with an even number of mounting holes arranged between a rim of the central hole and an outer rim of the rotor lamination assembly. The outer rim of the rotor lamination assembly has a projection on a plane substantially perpendicular to the central axis. The projection includes an even number of base curve edges, an even number of protruding curve edges, and connecting curve edges. Each protruding curve edge is arranged between two adjacent base curve edges in a circumferential direction of the central axis. The protruding curve edges and the base curve edges are connected with each other through the connecting curve edges. Every two mounting holes which are arranged symmetrically constitute a mounting hole group.

Abstract: A power tool includes a motor, a first power source access circuit, a first drive circuit, a second power source access circuit and a second drive circuit. The motor includes a rotor, a stator, a plurality of first-type windings and a plurality of second-type windings. The rotor is configured to rotate about a central axis. The stator includes a ring-shaped yoke portion, and a plurality of teeth. The plurality of first-type windings are configured to be wound around part of the plurality of teeth and the plurality of second-type windings are configured to be wound around other part of the plurality of teeth. The first power source access circuit is configured to access a first power source with a first voltage. The first drive circuit includes a plurality of first-type electronic switches connected between the plurality of first-type windings and the first power source access circuit. The second power source access circuit is configured to access a second power source with a second voltage.

Abstract: A rotor lamination assembly is formed with a central hole wherein a central axis goes through the central hole. The rotor lamination assembly is further formed with an even number of mounting holes arranged between a rim of the central hole and an outer rim of the rotor lamination assembly. The outer rim of the rotor lamination assembly has a projection on a plane substantially perpendicular to the central axis. The projection includes an even number of base curve edges, an even number of protruding curve edges, and connecting curve edges. Each protruding curve edge is arranged between two adjacent base curve edges in a circumferential direction of the central axis. The protruding curve edges and the base curve edges are connected with each other through the connecting curve edges. Every two mounting holes which are arranged symmetrically constitute a mounting hole group.

Abstract: A power tool includes a motor, a first power source access circuit, a first drive circuit, a second power source access circuit and a second drive circuit. The motor includes a rotor, a stator, a plurality of first-type windings and a plurality of second-type windings. The rotor is configured to rotate about a central axis. The stator includes a ring-shaped yoke portion, and a plurality of teeth. The plurality of first-type windings are configured to be wound around part of the plurality of teeth and the plurality of second-type windings are configured to be wound around other part of the plurality of teeth. The first power source access circuit is configured to access a first power source with a first voltage. The first drive circuit includes a plurality of first-type electronic switches connected between the plurality of first-type windings and the first power source access circuit. The second power source access circuit is configured to access a second power source with a second voltage.

Abstract: An electric power tool and a method for driving a brushless motor in the electric power tool. The electric power tool includes a driving circuit for driving the brushless motor and position sensors (D1, D2, D3) for detecting positions of the rotor. The rotor of the brushless motor, when rotating in a normal direction, sequentially passes by a commutation position, where a signal of at least one of the position sensors (D1, D2, D3) in the brushless motor changes, and a reference position, where a back electromotive force of the stator winding of at least one phase in the brushless motor is at a midpoint position of the waveform of the back electromotive force. An electrical angle between the commutation position and the reference position ranges from 20° to 40°. The position sensors (D1, D2, D3) are configured such that performance of the brushless motor is improved.

Abstract: An electric power tool and a method for driving a brushless motor in the electric power tool. The electric power tool includes a driving circuit for driving the brushless motor and position sensors (D1, D2, D3) for detecting positions of the rotor. The rotor of the brushless motor, when rotating in a normal direction, sequentially passes by a commutation position, where a signal of at least one of the position sensors (D1, D2, D3) in the brushless motor changes, and a reference position, where a back electromotive force of the stator winding of at least one phase in the brushless motor is at a midpoint position of the waveform of the back electromotive force. An electrical angle between the commutation position and the reference position ranges from 20° to 40°. The position sensors (D1, D2, D3) are configured such that performance of the brushless motor is improved.

Abstract: A cutting machine includes a cutting element for cutting material, a motor for driving the cutting element to rotate and a housing for containing the motor. The motor includes a rotor sleeve being formed with a receiving chamber, a motor shaft being capable of rotating together with the rotor sleeve, a stator core at least partially contained in the receiving chamber, stator coils wound around the stator core, and a stator bracket for fixing the stator core. The stator core is formed with a through hole for the motor shaft to pass there through, the stator coils are located outside the through hole and, the motor shaft is capable of rotating relative to the stator core.

Abstract: A rotor lamination assembly is formed with a central hole wherein a central axis goes through the central hole. The rotor lamination assembly is further formed with an even number of mounting holes arranged between a rim of the central hole and an outer rim of the rotor lamination assembly. The outer rim of the rotor lamination assembly has a projection on a plane substantially perpendicular to the central axis. The projection includes an even number of base curve edges, an even number of protruding curve edges, and connecting curve edges. Each protruding curve edge is arranged between two adjacent base curve edges in a circumferential direction of the central axis. The protruding curve edges and the base curve edges are connected with each other through the connecting curve edges. Every two mounting holes which are arranged symmetrically constitute a mounting hole group.

Abstract: A method is provided for protecting a battery pack. The method includes discharging the battery pack, detecting the temperature T of the battery pack, detecting the discharge current I of the battery pack, detecting the discharge voltage U1 of the battery pack, obtaining an internal resistance R according to the temperature T or the discharge voltage U1, calculating a capacity voltage U2 according to an equation U2=U1+IR, and determining whether the capacity voltage U2 is less than a preset threshold and, if yes, limiting discharging.

Abstract: A cutting machine includes a cutting element for cutting material, a motor for driving the cutting element to rotate and a housing for containing the motor. The motor includes a rotor sleeve being formed with a receiving chamber, a motor shaft being capable of rotating together with the rotor sleeve, a stator core at least partially contained in the receiving chamber, stator coils wound around the stator core, and a stator bracket for fixing the stator core. The stator core is formed with a through hole for the motor shaft to pass there through, the stator coils are located outside the through hole and, the motor shaft is capable of rotating relative to the stator core.