Setting
up Compax3
C3I20T11 / C3I32T11
172
192-120103 N13 C3I20T11 / C3I32T11 December 2010
Explanation:
The motor is controlled by the servo drive with control voltage U. During motion of
the motor, an internal back e.m.f. U
EMC
is induced. This antagonizes the control
voltage and is therefore deduced in the motor model. The difference is available for
the acceleration of the motor.
The first order delay component represents the delaying property of the motor
winding with the time constant T=L/R. According to Ohm's Law, a current I=U/R
results.
The drive torque of the motor is calculated by multiplying the current with the motor
torque constant K
T
. This is antagonized by the load torque of the machine.
The remaining acceleration torque accelerates the motor.
The resulting acceleration depends on the total mass moment of inertia (= motor +
load moment of inertia).
The integration of the acceleration (sum of the acceleration over time) results in the
velocity of the motor, which influences the amplitude of the induced EMC voltage.
Motor parameters relevant for the control
All motor parameters relevant for the control quality will be explained below.
Wizard guided entry of the motor parameters in the MotorManager.
Electromotoric countercheck EMC
A non-energized synchronous motor induces an induction voltage, the so-called
EMC voltage during an armature movement.
The EMC constant (motor EMC) states the value of the induced voltage subject to
velocity.
The EMC constant corresponds to the motor torque constant K
T
, which represents
the correlation between the torque-producing current and the drive torque, however
in a different unit.
The EMC voltage antagonizes the control voltage of the servo drive.
As the control voltage of the drive is not unlimited, it must be taken into
consideration that the drive may approach the voltage limit at high velocities and
therefore high EMC voltages.
The EMC constant is important with respect to the velocity control design.
The motor EMC is entered in the "motor characteristics" wizard window of the
MotorManager. You may choose between different units. Please note the
information on the motor type specification plate.
Mass inertia
The mass moment of inertia (moment of inertia) is also an important motor
parameter for the design of the velocity control loop. For the velocity control design,
this parameter is effective in correlation with the external mass moment of inertia of
the load. The external load is entered in the C3 ServoManager. With the "load
identification" function of the C3 ServoManager, the mass inertia can be
determined, if it is not yet known.
