| 摘要 |
PURPOSE:To prevent a starting shock from occurring even at time of starting immediately after opening a contact for power interruption by operating the extent of secondary magnetic flux in an electric motor even in an interval opening the contact being closed at starting, and using a secondary magnetic flux operated value at time of contact closing as the initial value, through which operating an exciting constituent current command value. CONSTITUTION:A voltage frequency controller 41 divides a primary current of an electric motor into two parts, one is an exciting constituent current and the other a torque constituent current, performing vector control, and if a contact 1b is closed, a three-phase voltage command value V1 is operated and outputted to a pulse width modulator 41H. When this contact 1b is opened, a secondary magnetic flux phi is calculated by a secondary flux computing element 43, and when the contact 1b is closed, the operated result is set as the initial value of the secondary flux phi and outputted for operation of an exciting constituent current command value id*. Thus, an increase of the secondary magnetic flux at time of starting is controlled, and thereby a starting shock can be prevented. |
