| 摘要 |
PROBLEM TO BE SOLVED: To surely turn of a DC/DC converter by preventing the self-exciting oscillation of the converter when its main circuit is stopped, by connecting a fifth switching element in parallel with a fixed-width switching element and sequentially controlling each switching element. SOLUTION: A fifth switching element Q5 and a control means 30 are provided in parallel with one of two fixed-width transistors Q3 and Q4. When the main circuit 10 of a DC/DC converter is stopped, the control means 30 turns off variable-width transistors Q1 and Q2, makes the fixed-width transistors Q3 and Q4 to continuously oscillate for a fixed period of time, and sets the fifth switching element in a continuous turned-on state synchronously to the turning-on of the transistor Q4. The current of an inductor L2 is reset and becomes '0 (zero)' the voltage drops at a diode D3 connected in antiparallel with the transistor Q3 and at the fifth switching element Q5. Thereafter, the converter is surely stopped by preventing the self-exciting oscillation of the converter by giving turning-off signals to the transistors Q3, Q4, and Q5. |
