AUXILIARY CIRCUIT OF DC-DC CONVERTER, AND BIDIRECTIONAL STEP-UP/DOWN DC-DC CONVERTER ARRANGED BY USE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide step-up type, step-down type, step-up/down type DC-DC converters capable of performing ZCS action over a wide range by addition of a relatively simple auxiliary circuit.SOLUTION: An auxiliary circuit 1 comprises: a series resonance type switched capacitor 2; and a ZCS facilitating inductor 3. In the case of a step-up type, the ZCS facilitating inductor 3 is connected in series on a positive electrode side of a switching element for step-up, thereby forming a series connection structure; and the series resonance type switched capacitor 2 is connected in parallel with the series connection structure at two ends thereof. In the case of a step-down type, the ZCS facilitating inductor 3 is series-connected in series with a reflux diode on a positive electrode side thereof, thereby forming a series connection structure; and the series resonance type switched capacitor 2 is connected in parallel with the series connection structure at the two ends thereof. In the case of a step-up/down type, the ZCS facilitating inductor 3 is series-connected in series with a switch including a switching element for step-up and a diode connected in inverse-parallel with the switching element on a positive electrode side of the switch, thereby forming a series connection structure; and the series resonance type switched capacitor 2 is connected in parallel with the series connection structure at the two ends thereof.SELECTED DRAWING: Figure 3