Datasheet

TMC2130 DATASHEET (Rev. 1.09 / 2017-MAY-15) 73
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18 dcStep
dcStep is an automatic commutation mode for the stepper motor. It allows the stepper to run with
its target velocity as commanded by the step pulses as long as it can cope with the load. In case the
motor becomes overloaded, it slows down to a velocity, where the motor can still drive the load. This
way, the stepper motor never stalls and can drive heavy loads as fast as possible. Its higher torque
available at lower velocity, plus dynamic torque from its flywheel mass allow compensating for
mechanical torque peaks. In case the motor becomes completely blocked, the stall flag becomes set.
18.1 User Benefits
18.2 Designing-In dcStep
In a classical application, the operation area is limited by the maximum torque required at maximum
application velocity. A safety margin of up to 50% torque is required, in order to compensate for
unforeseen load peaks, torque loss due to resonance and aging of mechanical components. dcStep
allows using up to the full available motor torque. Even higher short time dynamic loads can be
overcome using motor and application flywheel mass without the danger of a motor stall. With
dcStep the nominal application load can be extended to a higher torque only limited by the safety
margin near the holding torque area (which is the highest torque the motor can provide).
Additionally, maximum application velocity can be increased up to the actually reachable motor
velocity.
Classic operation area
with safety margin
torque
velocity [RPM]
dcStep operation - no step loss can occur
additional flywheel mass torque reserve
microstep
operation
0
M
NOM1
M
MAX
VDCMIN
VMAX
M
NOM
: Nominal torque required by application
M
MAX
: Motor pull-out torque at v=0
application area
max
.
motor torque
safety margin
dcStep extended
Safety margin:
Classical application operation area is limited by a certain
percentage of motor pull-out torque
M
NOM2
Figure 18.1 dcStep extended application operation area
Quick Start
For detail configuration procedure see Application Note AN003 - dcStep
Motor
–
never loses steps
Application
–
works as fast as possible
Acceleration
–
automatically as high as possible
Energy efficiency
–
highest at speed limit
Cheaper motor
–
does the job!