Patent ID: 7091686

Claim:
An electric power steering apparatus for applying a steering auxiliary force to a steering mechanism of a vehicle by driving an electric motor in response to an operation to steer the vehicle, the apparatus comprising: first and second temperature calculators that calculate respective estimated temperature values of first and second protection objects which are portions to be protected from overheating due to heat generation caused by driving the electric motor; a temperature detector disposed in the vicinity of the first protection object; an atmosphere temperature calculator that calculates a first temperature variation that is a temperature rise amount in the temperature detector due to the heat generation and calculates an estimated atmosphere temperature value by subtracting the first temperature variation from a detected temperature value by the temperature detector; and a current limiter that limits a current to flow to the electric motor based on the estimated temperature values of the first and second protection objects, wherein the second temperature calculator calculates a second temperature variation that is a temperature rise amount of the second protection object by the heat generation, and calculates an estimated temperature value of the second protection object based on the second temperature variation and the estimated atmosphere temperature value.