Patent ID: 6307337
Filing Date: 2001-10-23
Classification: H02K

Abstract:
A brushless dc motor comprising:a stator assembly having a stator winding thereon and a rotor opening formed therein;a rotor assembly having a rotor shaft, a rotor core fixed to said rotor shaft, and first and second bearings secured to said rotor shaft on opposite sides of said rotor core, said rotor core being disposed at least partially within said rotor opening with said first and second bearings positioned on opposite sides of said stator assembly; anda control board having control electronics connected thereto for receiving an electrical input and establishing current in said stator winding for generating a rotating magnetic field in said stator assembly;wherein said control electronics include first and second hall effect devices for sensing a rotational position of said rotor and providing first and second feedback signals, respectively, to said control board representative of said rotational position,and wherein said control electronics are connected to said stator winding to form an H-bridge circuit for establishing said current in said stator winding in dependence of said electrical input and a user-controlled enable input to said control board,said H-bridge circuit comprising first and second pairs of driving elements having conducting and non-conducting states, said first pair of driving elements being in a conducting state to conduct a first current through said winding when said first feedback signal and said enable signal are high, and said second pair of driving elements being in a conducting state to conduct a second current through said winding when said second feedback signal and said enable signal are high, said first current being in a direction through said winding which is opposite from the direction of said second current.