test, integral period is set to 5OO[ps]. Therefore, the rotor
direction is estimated every 500[p] (1 O[cycles]).
When d-axis is oriented to u-axis as shown in Fig.16
(a), output of Walsh harmonic detector circuit (second
order harmonics) becomes positive. On the other hand
when -d-axis is oriented to u-axis as shown in Fig. 16 (b),
it becomes negative. Therefore, it is possible to identify
the magnetic pole whether is N-pole or S-pole. Same
result is obtained in the case of B=?30" as shown in
Fig.17. Therefore, magnetic pole can be identified in all
positions.