TMC2041 DATASHEET (Rev. 1.02 / 2017-MAY-16)
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11 coolStep Operation
coolStep is an automatic smart energy optimization for stepper motors based on the motor
mechanical load, making them “green”.
11.1 User Benefits
Energy efficiency
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consumption decreased up to 75%
improved mechanical precision
for motor and driver
Motor generates less heat
Less cooling infrastructure
Cheaper motor
does the job!
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 in the power supply and cooling components.
Reducing motor current by half results in reducing power by a factor of four.
11.2 Setting up for coolStep
coolStep is controlled by several parameters, but two are critical for understanding how it works:
Parameter
Description
Range
Comment
SEMIN
4-bit unsigned integer that sets a lower threshold. 0
disable coolStep
threshold is SEMIN*32
If SG goes below this threshold, coolStep
increases the current to both coils. The 4-bit
SEMIN value is scaled by 32 to cover the lower
half of the range of the 10-bit SG value. (The
name of this parameter is derived from
smartEnergy, which is an earlier name for
coolStep.)
1…15
SEMAX
4-bit unsigned integer that controls an upper 0…15
threshold. If SG is sampled equal to or above this
threshold enough times, coolStep decreases the
current to both coils. The upper threshold is
(SEMIN + SEMAX + 1)*32.
threshold is
(SEMIN+SEMAX+1)*32
Figure 11.1 shows the operating regions of coolStep:
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The black line represents the SG measurement value.
The blue line represents the mechanical load applied to the motor.
The red line represents the current into the motor coils.
When the load increases, SG falls below SEMIN, and coolStep increases the current. When the load
decreases, SG rises above (SEMIN + SEMAX + 1) * 32, and the current is reduced.
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TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
