| 摘要 |
PROBLEM TO BE SOLVED: To enable reliable and stable actuation and reduce the time required until the normal rotation is realized from the start of rotation by forming non- magnetic material layers at the predetermined angle section on the external surface of the rotor. SOLUTION: A rotor 3 is formed in a four poles system comprising a couple of permanent magnets having the mechanical positional deviation of 90 degrees with each other and a non-magnetic material layer 6 is formed, by adhering, for example, a thinner conductive non-magnetic material such as a thinner layer of aluminum or copper foil to the external cicumferential surface of the rotor 3, using a bonding agent, for the predetermined angle section (for example, the range of electrical angle of 80 to 100 deg.) toward the normal rotating direction from the intermediate part of the N and S poles of the rotator 3 itself and for the same angle section as that of the normal rotating direction toward the reverse rotating direction of the rotor 3. A high frequency current is applied to a stator coil to generate an eddy current to the non-magnetic material layer and the magnetic pole position of the rotor is assumed on the basis of this information. Thereby, if the rotor stops, position of the rotor can be detected. |
