| 摘要 |
PROBLEM TO BE SOLVED: To achieve execution of soft switching even in an operation condition that polarity of a current is frequently switched due to an extremely light load.SOLUTION: When a current of a main reactor is less than a predetermined value and is directed to a positive direction or when the current of the main reactor is less than the predetermined value and directed to a negative direction, a voltage reducing switch 14 is continuously held at ON during a period from ON of a first auxiliary switch 18a up to storage of energy for supplying electric charge equivalent or larger to/than electric charge accumulated in a first snubber capacitor 19 to a second snubber capacitor 20 in an auxiliary rector 16 on the ON side of a boost switch 13, and the boost switch 13 is continuously held at ON during a period from ON of a second auxiliary switch 18b up to storage of energy for supplying electric charge equivalent or larger to/than electric charge accumulated in the second snubber capacitor 20 to the fist snubber capacitor 19 in the auxiliary reactor 16 on the OFF side of the boost switch 13. |
