Patent ID: 7786636

Claim:
A magnetic bearing device, comprising: a rotor; three or more electromagnets for controlling a radial position and/or an axial position of the rotor; a power source for supplying power to the electromagnets; a common node commonly connected to each one end of the electromagnets; switch means for switching a voltage of the common node; and excitation control means for controlling excitation of each of the electromagnets by a supply current that is supplied from the other end of one of the electromagnets to a negative electrode of the power source and that flows through the electromagnets in one direction, or by a regenerated current that is regenerated from the other end of one of the electromagnets to a positive electrode of the power source and that flows through the electromagnets in one direction; wherein the switch means includes: a first switch element for connecting and disconnecting between the positive electrode and the common node; and a first rectifier element for causing a current to flow from the negative electrode to the common node; and wherein the excitation control means includes: a second switch element for connecting and disconnecting between the other end of one of the electromagnets and the negative electrode without being connected in parallel with a rectifier element; and a second rectifier element for causing a current to flow from the other end of one of the electromagnets to the positive electrode without being connected in parallel with a switch element.