| 摘要 |
PURPOSE:To stabilize the current control system in all the speed ranges, by changing the amplitude of carrier waves in correspondence to the speed of an AC motor or to the terminal voltage of an AC motor. CONSTITUTION:The AC power from an AC power source 2 is converted into DC with a rectifier 3 and inputted into a PWM inverter 5 through a smoothing capacitor 4, with the output AC from which an induction motor 6 is put to a variable-speed operation. By comparing the output with the carrier waves from a carrier generator 15 by a comparator 16, the signal to indicate the switching timing to a base drive circuit 1 is outputted. In correspondence to the speed actual value of the motor, a function generator 21 is provided to output a certain value in a specified functional relation to this actual value, and the output of this function generator 21 is introduced to a multiplier 22, by which the amplitude from the carrier generator 15 is changed. |
