Line rotation speed estimation device and line rotation speed estimation method

摘要

PPROBLEM TO BE SOLVED: To more precisely estimate the coasting rotation speed of a PMSM for driving an electric vehicle even when a control computation period is long. PSOLUTION: A short circuit control unit 12 short-circuits the terminals of the respective phases of a motor M for a short-circuiting time T. Based on a current detected by a current sensor 50 during the first round of short-circuiting, a short circuit current vector computation unit 14 determines the angle of a short circuit current vector. When a short-circuiting time interval predetermined as a time shorter than a time in which the rotor of the motor M is rotated half at maximum rotational speed has passed after the first round of short-circuiting, the short circuit control unit 12 short-circuits the terminals of the respective phases of the motor M for the same short-circuiting time T as the first round of short-circuiting. Based on a current detected by the current sensor 50 during the second round of short-circuiting, the short circuit current vector computation unit 14 determines the angle of the second short circuit current vector. A speed estimation unit 16 estimates the rotational speed of the motor M based on the phase difference SBI2/SB-SBI1/SBbetween the first short circuit current vector and the second short circuit current vector, the short-circuiting time T, and the short-circuiting time interval . PCOPYRIGHT: (C)2007,JPO&INPIT