| US 7,586,277 B2 | ||
| Electric power steering device | ||
| Hideyuki Kobayashi, Maebashi (Japan); Toru Sakaguchi, Maebashi (Japan); Takeshi Hara, Maebashi (Japan); and Sakae Nejo, Maebashi (Japan) | ||
| Assigned to NSK Ltd., Tokyo (Japan) | ||
| Appl. No. 10/582,931 PCT Filed Dec. 03, 2004, PCT No. PCT/JP2004/018425 § 371(c)(1), (2), (4) Date Jun. 14, 2006, PCT Pub. No. WO2005/058672, PCT Pub. Date Jun. 30, 2005. |
||
| Claims priority of application No. 2003-417689 (JP), filed on Dec. 16, 2003. | ||
| Prior Publication US 2007/0120511 A1, May 31, 2007 | ||
| Int. Cl. H02P 7/00 (2006.01) | ||
| U.S. Cl. 318—432 [318/434; 318/599; 318/811] | 8 Claims |
| 1. An electric power steering device for controlling the output of a motor that applies an auxiliary steering force to a steering
mechanism from a current reference value calculated based on at least a steering torque signal generated in a steering shaft,
said device comprising:
a duty ratio calculator for calculating a duty ratio D1 and a duty ratio D2 determined by a motor terminal voltage based on said current reference value; and
a motor drive circuit including a motor connected across the output terminals and a power supply connected across the input
terminals of an H bridge circuit made up of a first arm and a second arm each containing a pair of semiconductor devices connected
in series, a PWM signal for a duty ratio D1 driving said semiconductor device in the upper stage of said first arm, and a PWM signal for a duty ratio D2 driving said semiconductor device in the lower stage of said second arm of said H bridge circuit,
wherein said duty ratio calculator calculates said duty ratio D1 and said duty ratio D2 having a continuous characteristics between the motor current and a duty ratio D from said current reference value based
on a specified calculation formula.
|