Power supplying apparatus, design method of the same, and power generation apparatus

Although increasing the switching frequency is effective to downsize a power supplying apparatus, the switching loss of a switching element increases if the switching frequency is increased. In a power supplying apparatus including a transformer having a very high boosting ratio, and a plurality of switching elements for supplying AC power to the primary side of the transformer, the frequency of the AC power is set to 0.25 to 2 times the self-resonance frequency of the transformer.