TMCM-1310 TMCL Firmware V1.11 Manual (Rev. 1.16 / 2014-MAR-19)
92
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9.9
Field Weakening
For higher velocities a correction of the advance angle is required to compensate for motor Back EMF and
phase shift between electrical and magnetic field. Therefore, axis parameters 108 and 109 are used. These
parameters define corner velocities at which the maximum commutation angle is allowed to go beyond 90
degrees up to a maximum of 180 degrees (= 2 motor fullsteps). The increase is linearly between the field
weakening minimum and the maximum velocity.
Adjusting the field weakening parameters 108 and 109 allows for automatic motor back EMF compensation
in case high velocities are needed. TRINAMIC recommends to start with default values and adjust the field
weakening minimum and maximum velocities carefully. Actual gamma/field weakening values can be read
out on the fly using axis parameter 230.
This mechanism is also applied in positioning and torque mode when exceeding the configured corner
velocities.
gamma
Velocity
0
max. phase
angle correction
of 90°
field weakening
Vmin (SAP 108)
field weakening
Vmax (SAP 109)
Figure 9.8 Principle and parameters for field weakening in velocity mode
A
XIS PARAMETERS RELATED TO FIELD WEAKENING
Number Axis parameter
Description
Units / Default
Acc.
108
CL field
weakening
minimum
velocity
Minimum motor speed at which the speed
dependent Back EMF compensation will be
applied (field weakening).
Based on the velocity measured via encoder
feedback.
0… +327.679.999
[pps]
RW
109
CL field
weakening
maximum
velocity
Maximum motor speed for the speed
dependent Back EMF compensation will be
applied (field weakening).
Based on the velocity measured via encoder
feedback.
0… +327.679.999
[pps]
RW
230
Gamma
Actual field weakening value (field weakening
= speed dependent Back EMF compensation).
This read-out value can be useful to choose
values for axis parameters 108 and 109.
0… 255
R