Section 6: Controlling Motor Current; Current Control Variables - IMS MicroLYNX Quick Manual

Controlling Motor Current
C u r r e n t C o n t r o l V a r i a b l e s
One of the unique and powerful features of the MicroLYNX is the
precision current control available through the instruction set.
Unlike most stepper drives, which only offer the capability
of controlling run current and hold current, the
MicroLYNX also has the capability of setting the accelera-
tion current. By setting the acceleration current to a higher
value, the system designer can deliver more power to the
system at the time when it is needed the most: when
system inertia must be overcome. Afterward, when the
motor has reached peak velocity, the run current may be
set to a lower value, thus reducing motor heating and
improving system power efficiency.
All of these variables may be changed on-the-fly inside a
MicroLYNX Program. The value range of these variables is a
percentage (0 - 100%)
PGM 200
LBL I_SET
MAC=40
MRC=30
MHC=10
ACCL=50000
MOVR 900000
HOLD 2
MAC=75
MRC=75
MHC=50
VI=10000
ACCL=1000000
MOVR -2000000
HOLD 2
END
PGM
M ax V eloc ity
(V M )
In itia l Ve lo c ity (V I)
22
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'start program at address 200
'label program I_SET
'set acceleration current to 40%
'set run current to 30%
'set holding current to 10%
'set acceleration to 50000 munits
'index relative 900000 munits
'suspend program until motion completes
'set acceleration current to 75%
'set run current to 75%
'set holding current to 50%
'set initial velocity to 10000 munits/sec
'set acceleration to 1000000 munits/sec2
'index relative -2000000 munits
'suspend program until motion completes
M R C = 3 5
(I = 35 % )
R U N
M A C = 8 0
(I = 80% )
A C C L
Tim e
Figure 6.1: Motor Current Control Variables
M A C = 8 0
(I = 80% )
A C C L
M H C = 1 5
(I = 15% )
H O LD
M S D T = 3 0 H C D T= 6 0
(M o tor Se ttling
(I D elay Tim e = 60m s)
H O LD
D ela y Tim e = 3 0m s)
6
Acceleration current can be set
higher for higher torque output
during acceleration, allowing the
run current to be set to a lower
value when the torque isn't
needed to overcome inertia. This
keeps me cool and consumes
less power!