| 摘要 |
<p>PURPOSE:To improve astringency of steering wheel as a clutch is eliminated by reducing the PWM duty ratio of a first or a second FET to zero according to a detecting signal from a current detector when a sheering wheel is returned during high speed running of a vehicle. CONSTITUTION:A current flows in the direction, in order, of a first FET 11, an electric motor M, and a fourth FET 14 and the electric motor M is run forward. When, in this state, a steering wheel 1 is released from a hold, the wheel 1 is reversed through the action of the caster of a wheel and the electric motor M is reversed, whereby a PWM value is reduced to a minus. When it is decided that a car speed in a high speed area, a duty ratio is set to zero. Since, when the duty ratio is decreased to zero, the first FET 11 is substantially brought into an OFF-state, a generative current flows to a short-circuit through which a third FET 13, the electric motor M, and the fourth FET 14, and the regenerative brake is applied on the electric motor M. Thereby, overshoot is prevented from occurring during return of the wheel 1 and astringency is improved.</p> |
