| 摘要 |
PURPOSE:To prevent overcurrent by reversely rotating a magnetic flux vector on the same circumference at the time of switching between normal and reverse rotations to eliminate the danger of a magnetic flux saturation. CONSTITUTION:A magnetic flux phase calculator 8 calculates the magnetic flux phase command 9 of a motor on the basis of an operation frequency command 1 and a normal/reverse rotation command 7. A PWM pattern generator 5 generates a PWM voltage pattern corresponding to a magnetic flux phase advanced by pi from the magnetic flux phase immediately before at the time of reverse rotation on the bases of the command 9 and a voltage command 2. Thus, when a normal rotation is switched to a reverse rotation, a magnetic flux vector is reversely rotated on the same circumference. This prevents overcurrent from being generated due to a magnetic flux saturation. |
