| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable combined use of sensorless drive system and flux-weakening control without impeding smooth drive of a motor. <P>SOLUTION: A current command value generating section 11 generates a current command value I<SB>dq</SB><SP>*</SP>(d-axis current command value and q-axis current command value). A position estimator 20 estimates the induced voltage of a motor 3, and determines the estimated rotational position θ^ of the rotor in the motor 3 based on the induced voltage thus estimated. The estimated rotational position θ^ is used in coordinate converters 14 and 18 which perform coordinate transformation between a rotary coordinate system and a fixed coordinate system. In order to increase torque output from the motor 3 in a high-speed rotation range, the current command value generation section 11 performs flux-weakening control using a d-axis current command value of a negative significant value. The d-axis current command value is limited so that an induced voltage required for maintaining precision at the position estimator 20 for estimating rotational position of the rotor can be ensured. <P>COPYRIGHT: (C)2010,JPO&INPIT |
