PURPOSE: To increase an acceleration torque in an acceleration-deceleration mode by a method wherein a phase regulation amount of a current command value is increased gradually to a limit value when a speed and a speed deviation amount exceed the respective set values thereof, and the phase regulation amount is returned gradually to a proper phase value corresponding to the speed when either the speed or the speed deviation amount turns smaller than the set value.
CONSTITUTION: In a judgment circuit 23, a speed feedback value 3 and a speed deviation value 4 are compared with the respective set values thereof and determined and a judgment flag 22 thereof is outputted. According to this judgment flag 22, in a phase regulation circuit 21, a magnetic pole position and a phase of a current command value are increased or decreased in stages and a phase regulation amount 79 obtained consequently is outputted. In a limiter circuit 20, a phase regulation amount 78 obtained by limiting the maximum and minimum values of the phase regulation amount 79 is outputted. In a three-phase conversion circuit 7 of a sine wave current, three phases of a since wave current command value are determined on the basis of the phase regulation amount 78 and a magnetic pole position signal 24, current command values 8, 9 and 10 of the discrete phases are generated in an amplitude corresponding to a torque command value 6 and they are outputted to a current control circuit 11.
KINOSHITA HISASHI
KAKE SHINOBU
OOTO MASAHIRO
