Patent ID: 8203322

Claim:
A DC-DC converter comprising: a main switching element storing energy from a direct-current power source in a main inductor; a diode connected in inverse parallel with the main switching element; a main diode discharging energy stored in the main inductor to the output side; and an auxiliary circuit discharging the electric charges of a capacitance between ends of the main switching element during a short period including when the main switching element is turned on, wherein the auxiliary circuit includes: an auxiliary inductor magnetically coupled with the main inductor; an auxiliary switching element storing energy in the auxiliary inductor; and an auxiliary diode discharging energy stored in the auxiliary inductor to the direct-current power source or the output side, wherein the auxiliary inductor is coupled with the main inductor in a direction in which backward voltage is applied to the auxiliary diode when the main inductor discharges energy.