| 摘要 |
PROBLEM TO BE SOLVED: To perform proper vector control of an induction moor, without having to continuously change over control structure, from a low-speed range to a high-speed one in which the number of pulses of PWM becomes one pulse. SOLUTION: The induction motor 2 is controlled by an inverter 1, that converts a DC voltage into alternating currents of a variable voltage and a variable frequency, and of a constant voltage and a variable frequency; the output voltage of the inverter is controlled by modulation rate (an output voltage command) Vc, obtained by voltage constant commands Vd*, Vq* that correspond to each constituent computed based on the excitation current component command Id* and torque current component command Iq* in the primary current of the electric motor; slip angular frequency ωs* of the electric motor is computed from the commands Id*, Iq*. Based on this frequency, the output frequency of the inverter is controlled; in this method of controlling the induction motor, the modulation rate is limited to a given value after the control of the variable voltage and variable frequency is shifted to the control range of the constant voltage and variable frequency; and at the same time, the command Id* is held to a predetermined value and corrected by a torque current component Iq that has detected only the command Iq*. |
