Patent ID: 8892296

Claim:
A power state diagnosis apparatus that diagnoses a power state of a vehicle which comprises an electrical control system supplied from a power supply and a motor controlled by a vector control method, comprising: a d-axis current generating section that gradually increases a d-axis current to a current value that a steering behavior does not occur and applies said d-axis current; a q-axis current generating section that gradually increases a q-axis current that is a rectangular-wave with positive and negative directions to said current value and applies said q-axis current; a power supply voltage determining section that determines whether a voltage value of said power supply is equal to or less than a power supply threshold or not; a time determining section that determines elapse of the time; and a diagnosis determining section that determines degradation of said power supply when said power supply voltage determining section determines that said voltage value is equal to or less than said power supply threshold, and said time determining section determines that a period of time T 1 elapses after said voltage value becomes equal to or less than said power supply threshold.