| 摘要 |
PROBLEM TO BE SOLVED: To provide a small and inexpensive EPS(electric power steering) control unit for remarkably improving applicability and mountability to a large vehicle increasing in a motor current. SOLUTION: A driving circuit 32 is mounted on a metallic base board 60, and a control circuit 33 is mounted on an insulating substrate 70. The metallic base board 60 and the insulating substrate 70 are formed as a structure (the inside is a two-piece structure) of being installed in a heat radiating case 50 in a layered state. The first current limiting function of forcedly reducing the motor current so as to become a current limiting value ImaxA or less on the basis of a detecting temperature TA by a thermistor 42 mounted on the metallic base board 60 and the second current limiting function of forcedly reducing the motor current so as to become a current limiting value ImaxB or less on the basis of an estimative temperature TB of the insulating substrate 70 estimated from a detecting current Im are arranged as the control function of the control circuit 33 to surely prevent overheat of the unit. |
