122 - 23/May/97
The quantity J in Fig. 5 stands for the total motor+load inertia in [kgm2]. The values of the
feedback parameters
p and i are influenced by the numerical values KP and KI, imposed by
the user via serial link. Moreover, particular control routines performing the correlation and
the AWU (Anti Wind Up) are influencing the values of the gains internal to the Digital Signal
Processor. These routines are designed so as to optimize the drive performance in various
operating conditions and to alleviate the problems of noise and imperfection of the current
controller. In the simplified analysis, illustrated in Fig.5, their influence on the gains should be
neglected.
Relation between the gains
p and i in Fig. 5 and the parameters KP and KI imposed by the
user is given by:
p
KP
i
KI
=
∗
=
∗
8 31
1635
.
The range of parameters KP and KI is: 0 to 255. For typical 5-10 Nm motor connected to the
load having 3-5 times the motor inertia, the speed loop bandwidth can up to 60Hz, having at
the same time the torque ripple below 1.5%. Higher bandwidths might be obtained at the
penalty of an increased torque ripple. In a typical application, the torque ripple is originated
by the noise at the drive analog inputs, imperfection of the sensors and finite resolution of
A/D and D/A converters applied within the drive control board.
(7)
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