TMCM-1141 Hardware Manual (Rev. 1.06 / 2015-JAN-09)
4
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TRINAMIC
S
U
NIQUE
F
EATURES
–
E
ASY TO
U
SE WITH
TMCL
stallGuard2
™
stallGuard2 is a high-precision sensorless load measurement using the back EMF on the coils. It can
be used for stall detection as well as other uses at loads below those which stall the motor. The
stallGuard2 measurement value changes linearly over a wide range of load, velocity, and current
settings. At maximum motor load, the value goes to zero or near to zero. This is the most energy-
efficient point of operation for the motor.
Load
[Nm]
stallGuard2
Initial stallGuard2
(SG) value: 100%
Max. load
stallGuard2 (SG) value: 0
Maximum load reached.
Motor close to stall.
Motor stalls
Figure 1.1 stallGuard2 load measurement SG as a function of load
coolStep
™
coolStep is a load-adaptive automatic current scaling based on the load measurement via
stallGuard2 adapting the required current to the load. Energy consumption can be reduced by as
much as 75%. coolStep allows substantial energy savings, especially for motors which see varying
loads or operate at a high duty cycle. Because a stepper motor application needs to work with a
torque reserve of 30% to 50%, even a constant-load application allows significant energy savings
because coolStep automatically enables torque reserve when required. Reducing power
consumption keeps the system cooler, increases motor life, and allows reducing cost.
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
0
50
100
150
200
250
300
350
Efficiency
Velocity [RPM]
Efficiency with coolStep
Efficiency with 50% torque reserve
Figure 1.2 Energy efficiency example with coolStep