Brushless DC motor with permanent magnet rotor - has electromagnetic commutator switched by coupling and decoupling transformer windings

摘要

The commutator includes a stationary transformer including a primary winding and secondary windings equal in number to the number of stator windings. The primary and secondary windings may be in the form of conductive patterns on printed circuit boards. An oscillator supplies an RF signal to the primary. An apertured shield located between the primary and secondary windings rotates with the rotor and causes the secondary windings to be energized in sequence. Switches, which may be transistors associated with the stator windings, are closed and opened in sequence, in response to energization and deenergization of the secondary windings, in order to energize and deenergize the stator windings in sequence. The position of the secondary windings may be adjusted, or an auxiliary set of secondary windings may be used, to reverse the rotor.