Abstract: A brushless DC motor utilizing a single pole double throw reed switch as a rotor position sensor. In one embodiment, the motor has a four-pole internal stator with bifilar windings providing alternating polarization for each subsequent pole, and a hollow outer rotor with radially magnetized ring-shaped permanent magnet. The rotor magnet has magnetically uninterrupted four-pole torque generating surface and incorporates features to interact with the reed switch. A non-uniform air gap between the stator poles and an inner surface of the rotor magnet allows generating a complementary reluctance torque between the energization pulses. The motor includes means to limit the electric current through the reed switch.

Abstract: A brushless DC motor utilizing a single pole double throw reed switch as a rotor position sensor. In one embodiment, the motor has a four-pole internal stator with bifilar windings providing alternating polarization for each subsequent pole, and a hollow outer rotor with radially magnetized ring-shaped permanent magnet. The rotor magnet has magnetically uninterrupted four-pole torque generating surface and incorporates features to interact with the reed switch. A non-uniform air gap between the stator poles and an inner surface of the rotor magnet allows generating a complementary reluctance torque between the energization pulses. The motor includes means to limit the electric current through the reed switch.