ElmoMC SimplIQ Software Manual - Manual (Page 198)

SimplIQ Software Manual Limits, Protections, Faults and Diagnosis
MAN-SIMSW (Ver. 1.4)
13-3
The maximum time for which the peak current can be maintained after the current
demand has been zero for a long time is:
τ ⋅
⎥
⎦
⎤
⎢
⎣
⎡
−
] 1 [
] 1 [
1 log
PL
CL
seconds.
If PL[1] = MC, the maximum time allowed for peak current is PL[2]. Otherwise, the servo
drive can provide the peak current for a longer time.
Generally, if a current demand of PL[1] has been placed after the current command is
stable at I1 < CL[1] for a long time, peak current PL[1] will be available for:
τ ⋅
⎥
⎦
⎤
⎢
⎣
⎡ −
− −
] 1 [
1 ] 1 [
1 log
PL
I CL
seconds.
The resolution of PL[1] is approximately MC/1000, and the resolution of PL[2] is
approximately 0.1 second.
Example:
The following graph depicts the signals related to the current command limiting process
for MC=6, PL[1]=6, PL[2]=3 and CL[1]=3.
0 1 2 3 4 5 6 7 8 9
0
1
2
3
4
5
6
A pplication current dem and
m otor current
com m and
F ilter state
LC current lim it
Indication
The application motor current command increases from 0 to 6 amperes at the time of 0
seconds, and then decreases to 0 at the time of 5 seconds.
The state of the filter increases until it reaches the continuous current limit of 3 at the time of
3 seconds. At that time, the LC flag is raised and the motor current command decreases to
CL[1] -= amperes.
After the motor current command is set to zero, the state of the filter begins to drop.
When it drops to 2.7 amperes = 90% of 3 amperes, the LC flag is reset and the torque
command limiting returns to 6 amperes.