To suppress an increase in loss due to a discharging and charging current of a capacitor provided in a power converter even when a motor frequently repeats a powering state and a regenerating state.
A power supply apparatus includes a plurality of power supplies Ea and Eb connected to a motor 10 via a power converter 20, a switch circuit including switching means SW1, SW2, and SW3 for switching an electric connection state between the power supplies Ea and Eb between a series connection and a parallel connection, and a controlling means 40 that sets the electric connection state to a series connection when the motor 10 is in a regenerating state and sets the electric connection state to either a series connection or a parallel connection on the basis of the state of the motor 10 when the motor 10 is in a powering state, by controlling the switching means SW1, SW2, and SW3. When the motor changes from the regenerating state to the powering state, the controlling means 40 performs processing to keep the electric connection state fixed at a series connection according to the state of the motor 10.
KOSAKA HIRONORI
Iwa Saki Kokuni
Kawamata Sumio
Masakazu Ito
Shunichi Takahashi
Toshio Takamatsu