| 摘要 |
PROBLEM TO BE SOLVED: To perform a synchronous rectifying operation even when a current smoothing reactor current is cut off and to reduce a loss generated in a DC-DC conversion device which is constituted by using a unipolar transistor as a main switching element. SOLUTION: The rise voltage of the parasitic diode of the unipolar transistor which constitutes the DC-DC conversion device (a chopper) is made larger than an ON-voltage at a time when a current is made to flow to the unipolar transistor. The operating frequency of the parasitic diode is made high which is nearly the same as the switching frequency of a unipolar semiconductor element. As a result, a bidirectional unipolar characteristic is obtained. A current smoothing reactor is formed as a DC reactor and a saturable reactor. The cutoff of the current smoothing reactor current is detected. |
