| 摘要 |
PROBLEM TO BE SOLVED: To reduce the capacity of a switching element by increasing the efficiency of a PWM converter that is connected to an AC power supply with a large internal impedance. SOLUTION: A capacitive impedance Cc is connected in series with each phase of the AC input terminal of a PWM converter part 100, and an AC input terminal is subjected to PWM modulation, so that the equivalent circuit of the PWM converter when viewed from terminals 27-29 becomes a series circuit of the capacitive impedance Cc and a resistive impedance. Since the capacitive impedance Cc is connected in series with the AC input side of the PWM converter part 100 in this manner, a voltage which applied to the switching elements 16-21 of the PWM converter can be reduced, thus reducing the conductive loss and the switching loss of the switching elements 16-21. |
