Power conversion device

A power conversion device configured to rotationally drive a drive shaft of a motor and supply power to support coils that support the drive shaft in a non contact manner by an electromagnetic force, the power conversion device comprising:

• a converter circuit configured to
• convert a first alternating current from an AC power source into a direct current and
• output the direct current to a pair of wires;
• an inverter circuit including a switching element, the inverter being configured to
• convert the direct current outputted from the converter circuit to the pair of wires into a second alternating current by a switching operation of the switching element and
• supply the second alternating current to drive coils of the motor so that the drive shaft is rotationally driven;
• a first capacitor connected between the pair of wires;
• a buffer circuit including a second capacitor and a regulator connected in series with the second capacitor, the buffer circuit being connected between the pair of wires;
• and
• a current supply circuit configured to supply a current to the support coils using energy stored in the second capacitor so that a load of the drive shaft is supported in a non contact manner,
• the first capacitor being configured to
• allow pulsation of a voltage outputted from the converter circuit and
• absorb voltage variation between the pair of wires caused by the switching operation, and
• the regulator being configured to regulate a current flowing from the second capacitor to the first capacitor so that
• the current flowing from the second capacitor to the first capacitor when the second capacitor has a higher voltage than the first capacitor by a predetermined voltage difference is smaller than
• a current flowing from the first capacitor to the second capacitor when the first capacitor has a higher voltage than the second capacitor by the predetermined voltage difference.