A power conversion apparatus is provided with a transformer, a primary circuit, and a secondary circuit. The primary circuit is connected to a primary winding of the transformer, has a primary positive bus and a primary negative bus, and includes at least one switching element. The secondary circuit is connected to a secondary winding of the transformer, has a secondary positive bus and a secondary negative bus, and includes at least one switching element. The power conversion apparatus is further provided with a coupling circuit including at least a first capacitor. The power conversion apparatus is configured such that the primary circuit is an unbalanced circuit and the secondary circuit is a balanced circuit, and having the coupling circuit connected between a center tap of the secondary winding of the transformer, and one of the primary positive bus and the primary negative bus.