Patent ID: 7501733
Filing Date: 2009-03-10
Classification: H02K,H02P

Abstract:
1. An electric machine comprising: a first coil group including a plurality of electrically interconnected coils disposed along a predetermined direction at a predetermined pitch; a second coil group including a plurality of electrically interconnected coils disposed along the predetermined direction at a predetermined pitch, the second coil group having a fixed relative position with the first coil group, the first and second coil groups being disposed at positions that are out of phase with each other by an odd multiple of π/2 in electrical angles; a magnet group including at least one magnet, wherein N poles and S poles are disposed alternately opposite the first and second coil groups and a relative position of the magnet group with the first and second coil groups is changeable along the prescribed direction; a first and a second magnetic sensor associated with the first and the second coil group, respectively, each of the first and second magnetic sensor being configured to detect magnetic flux change due to movement of the magnet group to thereby generate a sinusoidal output signal; and a drive signal generation circuit that executes PWM control based on the sinusoidal ouput signals of the first and second magnetic sensors to thereby generate a first AC drive signal to be supplied to the first coil group and a second AC drive signal to be supplied to the second coil group.