Rectifier and motor control apparatus having power regeneration function

A rectifier comprising:

• a main circuit unit configured to perform power conversion between AC power on a side of a three-phase AC power supply and DC power on a DC side by rectifying operation of a rectifying device and ON-OFF operation of a switching device;
• a power calculation unit configured to calculate a value of a power flowing between the side of the three-phase AC power supply and the DC side via the main circuit unit;
• a control unit configured to perform control to execute the ON-OFF operation of the switching device;
• and
• a state determination unit configured to determine, based on the value of the power calculated by the power calculation unit, whether the main circuit unit is in a power running state, in which AC power on the side of the three-phase AC power supply is converted to DC power and outputted to the DC side, or in a regeneration state, in which DC power on the DC side is converted to AC power and outputted to the side of the three-phase AC power supply,
• wherein the control unit changes the length of the ON period per cycle in the ON-OFF operation executed on the switching device according to the value of the power calculated by the power calculation unit when the state determination unit has determined that the main circuit unit is in the regeneration state, and
• wherein the control unit changes the length of the ON period per cycle in the ON-OFF operation executed on the switching device according to the value of the power calculated by the power calculation unit when the state determination unit has determined that the main circuit unit is in the power running state and the value of the power calculated by the power calculation unit is smaller than a first power threshold value.