Resonance type electric power conversion apparatus and method

A resonance type electric power conversion apparatus which includes a main circuit including a main reactor (L1), a main switching device (S1), an inverse-parallel (D4) diode and an output power diode (D3), and an auxiliary circuit (4) including an auxiliary reactor (L2), an auxiliary switch (S2), and an auxiliary capacitor (C1) connected in parallel to the main switching device (S1) for forming a recovery current elimination circuit and a partial resonance circuit, includes period calculation means for calculating a recovery current elimination period after the present point of time until the current flowing through the output power diode becomes zero and the charge of the output power diode disappears based on a voltage value across the auxiliary reactor, a current value of the main reactor (L1) and an inductance value of the auxiliary reactor, and control means for controlling the auxiliary switching device to turn on based on the recovery current elimination period.