Delta Tau GEO BRICK LV Benutzerhandbuch
Turbo PMAC User Manual
Motor Compensation Tables and Constants
151
1. It can be used as regular feedback to the Turbo PMAC, just as on a servo motor. In this method, the
key issue is the resolution and phasing of the encoder edges relative to the steps or microsteps
produced by the drive – some deadband may have to be created with Ixx64 and Ixx65 to prevent
hunting at rest.
produced by the drive – some deadband may have to be created with Ixx64 and Ixx65 to prevent
hunting at rest.
2. The encoder can just be used for position confirmation at the end of moves. However, this technique
requires the use of two encoder channels on the Turbo PMAC: one for the simulated feedback of the
pulse train, and one for the confirmation encoder.
pulse train, and one for the confirmation encoder.
Stepper-Replacement Servo Amplifiers
These take position feedback from the servo motor and close all the loops inside the drive. Do not use the
encoder signal from the drive for feedback into Turbo PMAC’s servo loop, because the position loops in
the drive and the controller will conflict with each other. With these drives, use the commanded pulse
train from the Turbo PMAC as simulated feedback.
When using simulated feedback, it is possible to set up the Turbo PMAC servo gains solely with analytic
methods. See the Setting up Turbo PMAC2 for Pulse-and-Direction Control section for details. When
using real encoder feedback, tune the servo loop just as for an analog velocity-mode drive.
These take position feedback from the servo motor and close all the loops inside the drive. Do not use the
encoder signal from the drive for feedback into Turbo PMAC’s servo loop, because the position loops in
the drive and the controller will conflict with each other. With these drives, use the commanded pulse
train from the Turbo PMAC as simulated feedback.
When using simulated feedback, it is possible to set up the Turbo PMAC servo gains solely with analytic
methods. See the Setting up Turbo PMAC2 for Pulse-and-Direction Control section for details. When
using real encoder feedback, tune the servo loop just as for an analog velocity-mode drive.
Hydraulic-Valve Amplifiers
Hydraulic-valve amplifiers, whether for servo valves or proportional valves, control a fluid-volume flow
proportional to their command input. Since fluid flow into or out of a hydraulic cylinder is proportional
to the velocity of the moving member of the cylinder, the command into the valve’s amplifier is
effectively a velocity command.
proportional to their command input. Since fluid flow into or out of a hydraulic cylinder is proportional
to the velocity of the moving member of the cylinder, the command into the valve’s amplifier is
effectively a velocity command.
Amplifiers for Which Servo Produces Torque/Force Command
Several types of amplifiers require the Turbo PMAC servo loop to close the velocity loop as well, making
the output of this servo loop a torque or force command. If Turbo PMAC is not doing commutation for
this motor, the torque/force command is output to the amplifier; if Turbo PMAC is doing the
commutation, this command is an input to the commutation algorithm. The main types of amplifiers that
require the controller to close the velocity loop are:
the output of this servo loop a torque or force command. If Turbo PMAC is not doing commutation for
this motor, the torque/force command is output to the amplifier; if Turbo PMAC is doing the
commutation, this command is an input to the commutation algorithm. The main types of amplifiers that
require the controller to close the velocity loop are:
•
Analog-input torque-mode amplifiers
•
Sinusoidal-input amplifiers
•
Direct-PWM power-block amplifiers
If the command value from the Turbo PMAC servo loop, regardless of signal type, is a torque or force
command, the Turbo PMAC servo must close the velocity loop for the motor. With the standard PID loop,
this means that the derivative (D) term Ixx31 must be set to a non-zero value. This derivative action is
required to get the damping action needed for stability. Because motors produce a torque or force
proportional to motor current, the torque/force command out of the servo can also be considered a current
command.
There is no need to tune anything in the amplifier with the load attached to the motor, because no
velocity-loop closure is done in these types of amplifiers. Any tuning that may be required is dependent
only on motor properties, so potentially this can even be done by the amplifier manufacturer.
command, the Turbo PMAC servo must close the velocity loop for the motor. With the standard PID loop,
this means that the derivative (D) term Ixx31 must be set to a non-zero value. This derivative action is
required to get the damping action needed for stability. Because motors produce a torque or force
proportional to motor current, the torque/force command out of the servo can also be considered a current
command.
There is no need to tune anything in the amplifier with the load attached to the motor, because no
velocity-loop closure is done in these types of amplifiers. Any tuning that may be required is dependent
only on motor properties, so potentially this can even be done by the amplifier manufacturer.
Analog-Input Torque-Mode Amplifiers
Analog-input “torque-mode” amplifiers accept an analog voltage that represents a torque/force, and hence
current, command. These amplifiers close a current loop inside, and if for brushless motors, perform the
motor phase commutation as well. Another name occasionally used for these types of amplifiers is the
transconductance amplifier, signifying that a voltage input results in a proportional current output.
current, command. These amplifiers close a current loop inside, and if for brushless motors, perform the
motor phase commutation as well. Another name occasionally used for these types of amplifiers is the
transconductance amplifier, signifying that a voltage input results in a proportional current output.
Sinusoidal-Input Amplifiers
A sinusoidal-input amplifier accepts two phase-current commands that are sinusoidal functions of time in
the steady state. This type of amplifier expects the controller to calculate the commutation, using the
torque/force command from the position/velocity-loop servo as the current-magnitude command into the
commutation. The amplifier performs the current-loop closure in this style.
the steady state. This type of amplifier expects the controller to calculate the commutation, using the
torque/force command from the position/velocity-loop servo as the current-magnitude command into the
commutation. The amplifier performs the current-loop closure in this style.