Control apparatus for AC motor

摘要

A control apparatus for conducting a variable speed control of an AC motor by controlling an M-axis component and a T-axis component of a current flowing through the AC motor. The control apparatus comprises: M-axis current regulator for executing proportional plus integral computation on a difference between an actual value of the M-axis component and an M-axis current reference value to obtain an M-axis proportional value and an M-axis integration value, and for determining an M-axis voltage reference value by adding the M-axis proportional value to the M-axis integration value; T-axis current regulator for executing proportional plus integral computation on a difference between an actual value of the T-axis component and a T-axis current reference value to obtain a T-axis proportional value and a T-axis integration value, and for determining a T-axis voltage reference value by adding the T-axis proportional value to the T-axis integration value; and a renewal coefficient computing device for computing a vector sum of the M-axis voltage reference value and the T-axis voltage reference value, and determining a renewal coefficient for renewing the M-axis integration value and the T-axis integration value based on the relation between the vector sum and a predetermined output voltage limit value.