Patent ID: 9278708
Filing Date: 2016-03-08
CPC Classification: B62D,H02P

Claim Text:
1. An electric power steering apparatus for calculating a steering assist command value based on a steering torque and a velocity, generating a pulse-width modulation (PWM) signal based on said steering assist command value, PWM-controlling a three-phase brushless DC motor via a motor drive circuit comprised of switching elements, and assist-controlling a steering system that an electromagnetic type motor relay is inserted between said motor drive circuit and said three-phase brushless DC motor, comprising: a temperature estimating section that estimates a temperature of a relay spring portion or a relay coil portion of said electromagnetic type motor relay, a comparing section that compares an estimated temperature value that is estimated by said temperature estimating section with a given temperature, and a motor current control section that controls a motor current flowing in said electromagnetic type motor relay in accordance with a comparison result of said comparing section; and a substrate temperature sensor that detects a temperature of a substrate that is equipped with said electromagnetic type motor relay; wherein said substrate temperature is inputted into said temperature estimating section, wherein said temperature estimating section is a relay-spring-portion-temperature estimating section, said relay-spring-portion-temperature estimating section comprises: