| 摘要 |
PROBLEM TO BE SOLVED: To perform stable compensation in the total area of an inverter without using extra hardware for dead-time compensation by setting the dead-time compensation value to 0 for the preset frequency of the inverter and setting the value closer to 0 for the maximum value as much as possible. SOLUTION: R, S and T are three-phase AC power supplies. The AC power supplies are converted to DC by a forward rectifier 20. The DC is converted to the AC with a smoothing capacitor 21 and a reverse inverter 22 by PWM control. An induction motor load 23 and a one-chip CPU 24 having a PWM generating means 25 and a dead-time correcting means 26 are provided. A frequency command device 27 is provided. An inverter, which controls the speed of the induction motor 23, is constituted of these parts. In the vicinity, where the output voltage of the inverter is 0, it is possible that the output voltage becomes unstable by the excessive correction. In the vicinity, where the output voltage V has the maximum value, the compensation at the dead-time compensation value cannot be performed. Then, the coefficient is set so that the PWM compensation value is 0 at the output voltage and becomes small in the vicinity of the maximum value. The PWM compensation value is made to be the value obtained by multiplying the coefficient on the dead-time compensation value. |
