Power tool including a shaftless motor

A method of controlling a motor, the motor including a rotor having a Halbach magnet array and a stator in electromagnetic communication with the rotor, the method comprising:

• sensing, via a position sensor, a position of the rotor;
• generating, via the position sensor, rotor position data;
• determining, via an electronic processor, a commutation angle for each of a plurality of phases of the stator based on the rotor position data;
• dynamically controlling, via the electronic processor, the commutation angle of the motor by selectively advancing or delaying conduction intervals of each phase;
• dynamically controlling, via the electronic processor, a phase advance angle of the motor by modulating the phase advance angle of a motor current relative to a rotor magnetic field;
• receiving, via the electronic processor, an operating parameter;
• and
• applying, to the motor and via the electronic processor, a combined field weakening by implementing the dynamically controlled commutation angle and the dynamically controlled phase advance angle in response to the operating parameter.

A motor comprising:

• a stationary support structure configured to be coupled to a housing;
• a stator mounted to the stationary support structure, the stator including a plurality of stator teeth and a plurality of stator windings wound around the plurality of stator teeth;
• an outer rotor configured to rotate relative to the stator, the outer rotor having at least one bearing positioned between the stationary support structure and the outer rotor to rotatably support the outer rotor;
• and
• a Halbach magnet array coupled to an inner surface of the outer rotor, the Halbach magnet array including:
• a first magnet configured to generate a first magnetic field, and
• a second magnet arranged adjacent the first magnet, the second magnet being magnetically perpendicular to the first magnet;
• wherein the Halbach magnet array is configured to concentrate a magnetic flux radially toward the plurality of stator windings and substantially cancel the magnetic flux radially away from the stator.