| 摘要 |
<p>PROBLEM TO BE SOLVED: To appropriately protect a motor driving circuit from the continuous drive at a rated value or less and the excessive load drive by computing the energy storage quantity to a motor driving circuit, and reducing the driving current to be input to the motor driving circuit in response to the computed energy storage quantity. SOLUTION: Detecting signals from a torque sensor 21, which is fitted to a steering shaft 11 and which detects largeness of the input torque, a position sensor 23 for detecting the position of a stepping motor 15, and a car speed sensor are input to an ECU 30, and the ECU 30 computes the assist torque command value on the basis of these detecting signals, and supplies the driving power from a battery 27 to the stepping motor 15 on the basis of this command value. At this stage, energy storage quantity to a stepping motor 15 driving circuit is computed on the basis of the assist torque command value, and the driving current to be input to the stepping motor 15 driving circuit is reduced in response to the computed energy storage quantity. Consequently, the motor driving circuit can be appropriately protected from the continuous drive at a rated value or less.</p> |
