For example, as shown in FIG. 6C, in the case where an input current Vdcb input to the unfolding inverter 540 crosses zero at Tr1 rather than T0, T1, and T2 at which a grid voltage Vacr crosses zero, the controller 550 or the power factor correction unit may control a current Vdcm to flow from the inverter 540 to the converter 530 in a first period Pam between T0 and Tr1, and control the current Vdcm to flow from the converter 530 to the inverter 540 in a second period Pbm subsequent to the first period Pam, as shown in FIG. 8A.

That is, as shown in FIG. 8A, the controller 550 or the power factor correction unit may control the current Vdcm, which is input to the inverter 540, to be negative in polarity in the first period Pam between T0 and Tr1, and may control the current Vdcm to maintain positive in polarity in the second period Pbm subsequent to the first period Pma.

Specifically, in a normal section such as the second period Pbm, a current flows to an output terminal of the bidirectional converter 530, and therefore, the current Vdcm flows from the converter 530 to the inverter 540. In a section such as the first period Pam where current correction is performed, a current flows from the inverter 540 to the converter 530, and therefore, the current flows to the input terminal of the bidirectional converter 530.