COOLING WATER STATE-DETERMINING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a cooling water state-determining method capable of determining whether or not cooling water is in a state of shortage and whether or not cooling water circulation is abnormal.SOLUTION: A cooling water state-determining method includes following steps of: operating a pump driving motor for circulating cooling water at a fixed current, a fixed torque, or a fixed output; calculating an average rotational speed for a predetermined time period of the motor during the operation; and determining normal circulation of the cooling water on the basis of an error between the calculated average rotational speed and a predetermined reference rotational speed.