Abnormality detection apparatus for resolver

An abnormality detection apparatus for resolver comprising:

• a resolver that is provided with a first system excitation winding, first system two output windings, a second system excitation winding, and second system two output windings, in which magnetic interference occurs between a first system and a second system;
• a first system exciter that applies AC voltage of a first period to the first system excitation winding;
• a second system exciter that applies the AC voltage of a second period different from the first period, to the second system excitation winding;
• a first system output signal detector that detects periodically output signals of the first system two output windings at preliminarily set detection timing;
• a first system reduction processor that performs a second period component reduction processing which reduces component of the second period, to detection values of the output signals of the first system two output windings;
• a first system square sum calculator that calculates a first system square sum which is a sum of square values of the detection values of output signals of first system two output windings after the second period component reduction processing;
• and
• a first system abnormality detector that determines abnormality of first system, based on whether or not the first system square sum is within a preliminarily set normal range of first system.