5 Conclusions
This paper proposed the novel position sensorless
drive of PM motor by using ripple-current of PWM
inverter. It is not required to inject voltage for position
estimation. Therefore, audible noise does not exist. In
addition, Walsh harmonic detector circuit is used instead
of BPF, which makes the response of control system fast.
Identification of the magnetic pole was also possible in
the same experiment system without modification.
By using current-ripple with 2O[kHz] carrier, the
rotor position is estimated every 5 O O [ p s ] . Therefore,
the estimation period of the rotor direction becomes
short, and the response of a control system becomes
quick. Step response to speed command change is
about 300[ms], and load step response is about
200[ms].