Patent ID: 7095195

Claim:
A motor comprising: a rotor; windings of a plurality of phases; power supplying means, including a plurality of first drive power transistors and a plurality of second drive power transistors, for supplying electric power to said windings of a plurality of phases; position detecting means for detecting the rotation position of said rotor in response to the terminal voltages of said windings of a plurality of phases; activation controlling means for controlling activation to said windings of a plurality of phases by said power supplying means in response to a position signal output from said position detecting means; commanding means for outputting a speed command signal; and switching operation means for causing at least one of said plurality of first drive power transistors and said plurality of second drive power transistors of said power supplying means to perform high-frequency switching operation in response to said speed command signal; and that said position detecting means is provided with position detection signal switching means that carries out switching between a detection signal for detecting the rotation position of said rotor and an inverted detection signal generated by inverting the logic of said detection signal and outputs the obtained signal in response to voltage comparison signals obtained by a comparison of outputs between each of the terminal voltages of said windings of non-activation phases and the neutral point voltage of the common potential of said windings of a plurality of phases, the output signal of said position detection signal switching means is used as said position signal during the ON operation of said high-frequency switching operation, and said position detection signal switching means outputs said inverted detection signal as said position signal at the beginning of starting.