Patent ID: 8350503
Filing Date: 2013-01-08
Classification: G01D,H02K,H02P

Abstract:
1. An n-phase brushless motor device (n is a positive integer) comprising: a stator placed at a fixed position; a rotor which rotates when said stator is excited sequentially according to a plurality of excitation patterns, said rotor having a predetermined number of poles; a magnet for magnetic pole position detection fixed to a face perpendicular to a rotation axis of said rotor, said magnet having a number of poles which is twice as many as that of said rotor; n main Hall elements arranged opposite to said magnet for magnetic pole position detection, for detecting a magnetic pole position of said rotor; n sub Hall elements arranged opposite to said magnet for magnetic pole position detection in such a way as to have a predetermined offset in a direction of a periphery with respect to said main Hall elements, for detecting the magnetic pole position of said rotor; a main counting unit that calculates an actual position “A” of the rotor; and a sub counting unit that counts a value of “2” in response to a detected change in an output pattern of said main Hall elements as compared to an output pattern of said sub Hall elements, where counting a value of “2” is accomplished by setting the actual rotor position to 2A; where the sub counting unit further counts a value of “1” in response to a detection of the output pattern of said main Hall elements being the same as the output pattern of said sub Hall elements at a predetermined timing, where counting a value of “1” is accomplished, by setting the actual rotor position to 2A+1; and a control unit for controlling a rotation of said rotor according to the value counted by said sub counting unit.