JPS5728562A - Commutatorless motor - Google Patents

Abstract

PURPOSE:To contrive to reduce the cost of a commutatorless motor by a method wherein the first and the second tracks for detection of position are formed in a rotor of the commutatorless motor using two magnetic conditions, and detected positional signals sent from two position detecting elements are processed logically to obtain three phase positional signals. CONSTITUTION:The first track 2 for detection of position is so magnetized for four poles as the magnetized angles of an N pole and an S pole to have the ratio of 1:2 during one electric period, and the second track 3 for detection of position is so magnetized for four poles as the relative magnetized position thereof to the magnetized poles of the first track 2 for detection of position to change magnetic pole detecting condition of a position detecting element 5 from the N pole to the S pole when thetam is the positions of nearly pi/3 and 4pi/3, and to change from the S pole to the N pole when it is in the positions of 2pi/3<thetam<pi and 5pi/3<thetam<2pi. The detected positional signals sent from the position detecting elements 4, 5 are processed in a logical processing means 11, and accordingly the three phase positional signals having phase difference of 120 deg. electric angles with each other can be obtained.