| 摘要 |
PURPOSE:To ensure the conditions of the vector control of an induction motor extending over the wide range of a rotor temperature by estimating a secondary resistor by the change of the response characteristics of a current ripple by the variation of the secondary resistor and correcting slip frequency. CONSTITUTION:A bypass filter 1 extracts a carrier ripple component in detecting currents of one phase. A peak holding circuit 3 holds an amplitude maximum value Im. A mean value lm' is obtained through integration in consideration of the thermal time constant of a motor rotor by an integrating circuit 4. The temperature change of a rotor secondary resistor is estimated from a mean value acquired regarding the time of an initial state and the time of actual use by a CPU 6, a torque constant K0' under the initial state is corrected from the temperature change of the secondary resistor, and a secondary current command i2 and the constant K0' are multiplied, thus obtaining slip frequency omegas after correction. |
