SEW-Eurodrive MOVIDRIVE compact MCH41A, System Manual

Page: 196 / 436

196
System Manual – MOVIDRIVE® compact Drive Inverters
4
Motor selection for asynchronous servomotors (CFC)
Project Planning
CFC operation
with torque con-
trol (CFC & M-
CONTROL) This operating mode permits direct torque control of the asynchronous motor in the ba-
sic speed range (n
≤
n
trans
). The setpoint sources of the speed-controlled CFC mode
can also be used for torque control. All speed setpoint sources (except for bus setpoints)
are interpreted as current setpoint sources. Assign "Current" to a process data word for
fieldbus control. The settings for evaluating the analog input (
→
P11_, parameter de-
scription) also remain in effect. The fixed setpoints (P16_, P17_) can be entered in the
units [1/min] or [%I
N_inverter
] as required (
→
MOVITOOLS
®
).
The following relationship exists between the units:
3000 1/min = 150 % rated inverter current
The torque on the output shaft of the motor can be calculated for the basic speed range
(n
≤
n
trans
) using the following formulae:
Specification of a setpoint for the motor torque in %I
N_inverter
:
Specification of a setpoint for the motor torque in 1/min:
In addition to the current I
q
for creating the torque, the inverter also needs to supply the
magnetizing current I
d
. The actual inverter output current I
tot
can be calculated using the
following formulae:
Specification of a setpoint for the motor torque in %I
N_inverter
:
Specification of a setpoint for the motor torque in 1/min:
04972AEN
04973AEN
I
N_inverter
= Rated output current of the inverter
k
T
= Torque constant = M
n
/ I
q_n
M
n
and I
q_n
are motor-specific values. For the values of the torque constants k
T
and the motor-specific values M
n
and I
q_n
, refer to the motor tables (DT/DV
→
page 203, CT/CV
→
page 197).
04974AEN
04975AEN
I
q_n
= Nominal value of the torque-generating current according to the motor table
I
d_n
= Nominal value of the magnetizing current according to the motor table
M = k
T
x I
n_inverter
x Setpoint
M = k
T
x 1.5 x I
n_inverter
x
3000 rpm
Setpoint
I Setpo I I
tot n inverter d N
= × +
int
_ _
d i
2
2
I Setpo I
rpm
I
tot n inverter d N
= × × ×
F
HG
I
KJ
+
int .
_ _
1 5
1
3000
2
2