POWER REGENERATION DEVICE AND POWER CONVERSION DEVICE

A power regeneration device according to an aspect of embodiments includes a voltage detecting unit, a signal processing unit, a phase detecting unit, and a power conversion unit. The signal processing unit generates, by using self-oscillation when the output of an AC detection signal from the voltage detecting unit is stopped due to a power outage, an AC signal whose frequency is the same as that of and whose phase is continued to that of the AC detection signal just before the stop. The phase detecting unit detects the phase of the AC power supply on the basis of the AC signal from the signal processing unit when power is recovered from the power outage.