Rotor angle detection apparatus for brushless DC motor, determines sine and cosine reference value from current values detected by current detectors connected to three phase armature, for calculating rotor angle

摘要

The apparatus has current detector for detecting current flow through primary and secondary phases of the three-phase armature. Sine and cosine reference values are determined from detected current values when a high frequency voltage is imposed on the drive. The rotor angle is calculated from sine and cosine reference values which are twice the rotor angle of the DC brushless motor.