Rotation angle estimation apparatus for rotating electric machine

A rotation angle estimation apparatus for a rotating electric machine, the rotation angle estimation apparatus being applied to a system which includes the rotating electric machine and an electric power conversion circuit, the rotating electric machine including a stator having a plurality of winding groups wound therein, each of the winding groups being offset from another of the winding groups to have a spatial phase difference therebetween, the electric power conversion circuit being electrically connected with the winding groups to apply voltages to the winding groups,

• the rotation angle estimation apparatus comprising:
• a high-frequency voltage setting unit that sets a plurality of high-frequency voltages which change at an angular velocity higher than an electrical angular velocity of the rotating electric machine;
• a circuit operating unit that operates the electric power conversion circuit to apply each of the high-frequency voltages set by the high-frequency voltage setting unit to a corresponding one of the winding groups;
• and
• a rotation angle estimating unit that estimates a rotation angle of the rotating electric machine based on at least one of high-frequency currents that flow in the winding groups upon application of the high-frequency voltages to the winding groups,
• wherein
• the high-frequency voltage setting unit sets the high-frequency voltages based on the spatial phase difference between the winding groups so that in a fixed coordinate system of the rotating electric machine, the magnitude of a resultant vector of a plurality of high-frequency voltage vectors, which are respectively applied to the winding groups, becomes smaller than the magnitude of each of the high-frequency voltage vectors.