To provide a failure diagnosis device of a current detecting circuit being provided in a system for controlling a motor without using a pole position sensor by detecting the motor current and diagnosing the failure of a filter circuit for extracting the high frequency component of motor current, and to provide a motor control system comprising that failure diagnosis device.
Difference of currents iu, iv and iw of a synchronous motor 1 sampled every half period of a carrier at a failure diagnosis section 16 is compared with difference of high frequency components iuf, ivf and iwf of the iu, iv and iw extracted at a filter section 15 and sampled every half period of a carrier, and a decision is made whether filtering at the filter section 15 is normal or not for three phases uvw. When a decision is made that filtering of two or more phases is abnormal, pole position θ of the motor 1 is calculated from the sampling values iu, iv and iw of a motor current not subjected to filtering.
MASAKI RYOZO
KANEKO SATORU
SAWADA TAKEFUMI
HITACHI LTD
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