Abstract: A resolver output correction device receives sine output signal and cosine output signal from a resolver. Each of the sine output signal and the cosine output signal has an offset error and a gain differential error due to a secular variation. The correction device detects maximal and minimal values with respect to both the sine output signal and the cosine output signal. It calculates average values between the maximal values and the minimal values. Then, it corrects the offsets of the signals based on the average values. It also calculates gain differentials between the maximal value and the minimal value with respect to both the sine and cosine signals. Then, it corrects the gain differentials of the signals based on the calculated gain differentials. As a result, both the offset and gain errors of the signals are corrected with accuracy.

Abstract: A monitoring system monitors a microcomputer in which an angle calculator calculates the electrical angle of a motor using output signals from a rotation angle sensor. In the microcomputer, a control signal generator generates a coded control signal that indicates the range to which the calculated electrical angle belongs. In the monitoring system, the electrical angle detected by the rotation angle sensor is multiplied by an excitation signal provided for the rotation angle sensor, and an angle detector detects the resultant signals. Based on the detected signals, a supervisory signal generator outputs a coded supervisory signal that indicates the range to which the electrical angle detected by the rotation angle sensor belongs. Then a fault detector determines that a failure occurs in the microcomputer, if a comparator determines that the coded control signal disagrees with the coded supervisory signal.