Motor drive apparatus and refrigeration cycle apparatus

A motor drive apparatus comprising:

• a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor;
• a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm and to control the power converter;
• and
• a voltage detector provided in the power converter and configured to detect a voltage of the power converter,
• the drive controller being configured to control the power converter by switching
• a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and
• a second mode in which a second correction value smaller than the first correction value is employed to control the power converter,
• the drive controller being further configured to
• enter the first mode,
• set an operational frequency of the electric motor,
• determine whether the operational frequency of the electric motor is lower than a threshold frequency,
• maintain the first mode when the operational frequency of the electric motor is not lower than the threshold frequency, and
• switch from the first mode to the second mode when the operation frequency of the electric motor is lower than the threshold frequency,
• wherein the dead time is a time period during which the upper arm and the lower arm are both turned off.