Abstract: Excitation signals having a phase difference of 120.degree. are generated based on a count of a ring counter and they are supplied to a phase detection type resolver. An output of the resolver is compared with zero level by a comparator to generate uncorrected position data .theta..sub.F which is supplied to a digital delay circuit to delay it in accordance with a position correction value .DELTA..theta. from a position correction ROM to generate corrected position data .theta..sub.B. The corrected position data is supplied to a latch circuit which latches a count of a ring counter and a velocity detection circuit to produce resolver position data .theta..sub.P and velocity data .DELTA.T, which are added and the sum is supplied to the position correction ROM as address data. The velocity data .DELTA.T is converted to a pulse by a pulse generator and it is accumulated by an accumulation counter to detect a position of a moving part.

Abstract: A variable reluctance resolver comprises a rotor core and stator magnetic poles structured to enable reluctance in the space between the rotor core and stator magnetic poles to be changed by the positions of the rotor core and to make the fundamental wave component of the reluctance variation N cycles per revolution of the rotor core, N being an integer of 1 or more; first magnetic poles having a predetermined number 3N phases arranged at equal intervals on the stator magnetic poles; second magnetic poles having a predetermined number of 3N phases formed in the central positions between the first magnetic poles; excitation coils arranged individually between the first and second magnetic poles and connected in series to each other for each phase of the magnetic poles; a current change detecting device for detecting current value change due to the variation of the reluctance when an alternating current is applied to the magnetic coils of each phase of the magnetic poles; 3N difference value calculating devices

Abstract: A resolver system includes a resolver having an annular rotor, and an annular stator arranged around the annular rotor in spaced relationship thereto. The rotor and the stator are arranged such that the reluctance of a space defined between the rotor and the stator varies with a change in the angular position of the rotor in such a fashion that one revolution of the rotor causes one cycle of a fundamental frequency component of variation of the reluctance.The stator has formed thereon a plurality of pole shoes circumferentially arranged at intervals of 120.degree. or 60.degree. to form three of six phases, each of the pole shoes having a single kind of winding wound thereon. A servo driver applies an excitation signal to each of the windings on the pole shoes of the stator to excite same.