User manual

TMCM-6110 TMCL Firmware V1.19 Manual (Rev. 1.03 / 2012-JUL-31) 72
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6.1 stallGuard2 Related Parameters
The module is equipped with TMC260 motor driver chip. The TMC260 features load measurement that can
be used for stall detection. stallGuard2™ delivers a sensorless load measurement of the motor as well as a
stall detection signal. The measured value changes linear with the load on the motor in a wide range of
load, velocity and current settings. At maximum motor load the stallGuard2™ value goes to zero. This
corresponds to a load angle of 90° between the magnetic field of the stator and magnets in the rotor. This
also is the most energy efficient point of operation for the motor.
Figure 6.1: Principle function of stallGuard2
Stall detection means that the motor will be stopped when the load gets too high. This level is set using
axis parameter #174 (stallGuard2™ threshold). In order to exclude e.g. resonances during motor
acceleration and deceleration phases it is also possible to set a minimum speed for motor being stopped
due to stall detection using axis parameter #181. Stall detection can also be used for finding the reference
point. Do not use RFS in this case.
PARAMETERS NEEDED FOR ADJUSTING THE STALLGUARD2™ FEATURE
Number
Axis Parameter
Description
6
absolute max.
current
(CS / Current
Scale)
The maximum value is 255. This value means 100% of the maximum current of
the module. The current adjustment is within the range 0… 255 and can be
adjusted in 32 steps.
The most important motor
setting, since too high values
might cause motor damage!
0… 7
79…87
160… 167
240… 247
8… 15
88… 95
168… 175
248… 255
16… 23
96… 103
176… 183
24… 31
104… 111
184… 191
32… 39
112… 119
192… 199
40… 47
120… 127
200… 207
48… 55
128… 135
208… 215
56… 63
136… 143
216… 223
64… 71
144… 151
224… 231
72… 79
152… 159
232… 239
173
stallGuard2™
filter enable
Enables the stallGuard2™ filter for more precision of the measurement. If set,
reduces the measurement frequency to one measurement per four fullsteps.
In most cases it is expedient to set the filtered mode before using coolStep™.
Use the standard mode for step loss detection.
0 – standard mode
1 – filtered mode
motor load
(% max. torque)
stallGuard2
reading
100
200
300
400
500
600
700
800
900
1000
0 10 20 30 40 50 60 70 80 90 100
Start value depends
on motor and
operating conditions
Motor stalls above this point.
Load angle exceeds 90° and
available torque sinks.
stallGuard value reaches zero
and indicates danger of stall.
This point is set by stallGuard
threshold value SGT.