| 摘要 |
PURPOSE:To improve the control factor of a cycloconverter and the efficiency of an induction motor by performing a flux weakening control through changing the flux current component of the induction motor according to the rotational speed and load of the motor. CONSTITUTION:The peak value V1 of a motor terminal voltage V1 is operated as V1=(V +V)<1/2> by a peak value arithmetic circuit 13 from a d-axis voltage Vd and q-axis voltage Vq converted by a three phase-two phase converter 11. The pattern change of a secondary flux arithmetic circuit 4 is performed in such manner that the peak value V1 is equal to the maximum output voltage V1* of a cycloconverter 10. Thus, the motor terminal voltage V1 is controlled so as to reach the maximum output voltage or vicinity of the cycloconverter 10. That is, the motor terminal voltage V1, is made higher within a field- weakening control range so that the induction motor 1 can be operated at high efficiency. Also, it is possible to improve the control factor of an apparatus and also the total power factor of a system. |
