Importance

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Abstract

A single excitation phase pulse brushless DC motor (10) including a rotor portion (12) mounted upon a shaft subassembly (14) and rotating therewith with respect to a stator portion (16). The rotor portion (12) includes a first zone of steady state magnetization in the form of a main field magnet (24) divided into radially polarized sectors (26). The stator portion (16) includes the main stator stack (34) upon which the stator windings (38) are placed and a second zone of steady state magnetization in the form of a permanent disk magnet (46). The disk magnet (46) is divided into radially polarized sectors (48) similarly to those of the field magnet (24). A hall effect senior (40) is also provided to act as a commutator triggering element. The motor (10) is characterized in that the opposition of the first and second steady state zones of magnetization provides a steady state torque curve which urges the rotor (12) to rotate with respect to the stator (16 ) when it is in certain rotational positions. A current through the stator winding (38) overcomes the steady state torques at other positions and causes, upon properly timed activation, continuous rotation of the rotor (12). The primary usage of the motor (10) is in high speed, low cost fans and in magnetic media disk drives.

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First Claim