Comparison of characteristics using two Hall-ICs and one Hall-IC for 3 phase slotless PM brushless DC motor

Slotless permanent magnet brushless DC motor (slotless PM BLDC motor) with the characteristics of high speed and high power density has been more widely used in industrial and automatic machine. Generally, because the position sensor represents the important factor in PM BLDC motor drives, slotless PM BLDC motor is necessary that the three Hall-ICs evenly be distributed around the stator circumference in case of the 3 phase motor. The Hall-ICs are set up in this motor to detect the main flux from the rotor. So the output signal from Hall-ICs is used to drive a power transistor to control the stator winding current. However, instead of using three Hall-ICs, though we used two Hall-ICs or one Hall-IC, we estimate information of the others phase in sequence through a revolving rotor. This paper compared the characteristics and performance by using three, two Hall-ICs and one Hall-IC for the 3 phase PM BLDC whose six stator and two rotor designed.