To estimate the position of a magnetic pole and to detect the magnetic pole simply by superposing a high frequency to a voltage according to the difference in conductivity even without using any position sensor, by composing one pole of the permanent magnets of a motor with a permanent magnet with high conductivity and the other pole with a permanent magnet with low conductivity.
When a high-frequency voltage is applied to a U-phase coil when the center of U-phase teeth coincides with that of an N-pole magnet 11, the N pole has high conductivity since it is an NdFeB magnet and an eddy current is generated in the magnet. As a result, secondary resistance becomes smaller equivalently and a high-frequency current that flows to the coil becomes larger. On the other hand, when an S-pole magnet 12 faces the U phase, the S pole does not have almost any conductivity since it is a ferrite magnet and an eddy current is also nearly zero, so that equivalent impedance becomes larger and the high-frequency current becomes smaller. In this manner, the N and S-pole magnets 11 and 12 are composed of magnets with different conductivity, the magnetic pole can be detected according to the difference in conductivity even if a sensor for detecting the magnetic pole is not used.
NAKADA TAKANORI
HINO TOKUAKI
TANAE SHUNICHI
ARAHORI NOBORU
NAGASE HIROSHI
