Sensorless commutation circuit for brushless DC motor, continuously compares voltages of star center points of motor star and virtual star in all phases, and outputs commutation signal to control commutation of DC motor

摘要

A virtual star circuit (2) analogous to a motor star circuit (1), is formed of resistors (R1-R3). An evaluation circuit (4) continuously compares the voltages of the star center points of motor star and virtual star in all phases, and outputs a comparison value which is used to generate a commutation signal for controlling the commutation of DC motor.