Power conversion device, motor drive unit, and electric power steering device

A power conversion device that converts power from a power supply to power supplied to a motor having n-phase windings where n is an integer of 3 or more, the power conversion device comprising:

• a first inverter connected to first ends of the windings of each phase of the motor;
• a second inverter connected to second ends of the windings of each phase;
• a first phase separation relay circuit to switch between connection and disconnection between the first ends of the windings of each phase and the first inverter;
• a second phase separation relay circuit to switch between connection and disconnection between the second ends of the windings of each phase and the second inverter;
• a sub-inverter circuit connectable to the first ends and the second ends of the windings of each phase;
• a third phase separation relay circuit to switch between connection and disconnection between the first ends of the windings of each phase and the sub-inverter circuit;
• and
• a fourth phase separation relay circuit to switch between connection and disconnection between the second ends of the windings of each phase and the sub-inverter circuit.