| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electric power steering device which can perform the assist control of steering force while operating a motor appropriately, according to the charge state of a battery. <P>SOLUTION: A two-axis three-phase conversion means 29 generates three-phase voltage by the D-axis voltage from a D-axis PI control means 28 and the Q-axis voltage orthogonal to the axis D from the Q-axis PI control means 27, and a motor driving means 13 vector-controls a motor 8 via a PWM conversion means 30. At this time, a Q-axis voltage limiting means 32 sets the maximum value of the voltage to be applied to the axis Q, according to the voltage of a battery 19 which supplies the motor 8 with power. The Q-axis voltage limiting means 32 raises the maximum value of the Q-axis voltage when the voltage of the battery 19 is high, and supplies the motor 8 with a large Q-axis current thereby generating high torque. Moreover, when the voltage of the battery 19 is low, it lowers the maximum value of the Q-axis voltage and supplies the motor 8 with a small Q-axis current so that the battery voltage may not drop more. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
