Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Basic Motor Setup
77
Is Turbo PMAC Commutating or Closing the Current Loop for This
Motor?
Motor?
All motors of significant travel require commutation (reversal of current) in the motor phases in order to
generate consistent torque/force as the motor moves. The only question is where and how this
commutation is done. In a brush DC motor the commutation is performed mechanically inside the motor.
With brushless motors, the commutation is often performed electronically inside the drive. In these cases,
Turbo PMAC is not performing the commutation.
generate consistent torque/force as the motor moves. The only question is where and how this
commutation is done. In a brush DC motor the commutation is performed mechanically inside the motor.
With brushless motors, the commutation is often performed electronically inside the drive. In these cases,
Turbo PMAC is not performing the commutation.
Virtually all modern servomotor control employs current-loop closure for high response, tolerance of
parameter variation, and protection against overcurrent conditions. While this has traditionally performed
in the servo drive, Turbo PMACs with PMAC2-style Servo ICs are capable of closing the current loop
digitally for motors.
parameter variation, and protection against overcurrent conditions. While this has traditionally performed
in the servo drive, Turbo PMACs with PMAC2-style Servo ICs are capable of closing the current loop
digitally for motors.
If Turbo PMAC is either performing the phase commutation, closing the current loop, or both, for the
motor, refer to the Setting Up Turbo PMAC-Based Commutation and/or Current Loop sections for further
instructions. If Turbo PMAC is doing neither task for this motor, continue below in this section.
motor, refer to the Setting Up Turbo PMAC-Based Commutation and/or Current Loop sections for further
instructions. If Turbo PMAC is doing neither task for this motor, continue below in this section.
There are two subsequent sections in this section. The first deals with using the traditional analog
velocity-mode or torque-mode interface, still the most common servo-amplifier interface. The second
deals with the pulse-and-direction interface, the traditional and still most common stepper-amplifier
interface, also used with “stepper-replacement” servo amplifiers.
velocity-mode or torque-mode interface, still the most common servo-amplifier interface. The second
deals with the pulse-and-direction interface, the traditional and still most common stepper-amplifier
interface, also used with “stepper-replacement” servo amplifiers.
Setting up Turbo PMAC for Velocity or Torque Control
If Turbo PMAC is not performing the commutation or current loop for a motor, it provides a single output
command value for the motor. Usually this output represents either a velocity command or a torque
(force, or current magnitude) command, and typically this output is encoded as an analog signal voltage
level. While the servo-loop tuning for velocity and torque commands is different, the setup until that
point is identical for both modes.
command value for the motor. Usually this output represents either a velocity command or a torque
(force, or current magnitude) command, and typically this output is encoded as an analog signal voltage
level. While the servo-loop tuning for velocity and torque commands is different, the setup until that
point is identical for both modes.
When driving a hydraulic cylinder through either a proportional valve or a servo valve, the dynamics
appear to the Turbo PMAC to be those of a velocity command to a motor.
appear to the Turbo PMAC to be those of a velocity command to a motor.
Hardware Setup
Each axis-interface channel on a Turbo PMAC board or axis-expansion board with PMAC-style Servo
ICs (e.g. Acc-24P or Acc-24V) has a single 16-bit analog output. Breakout boards simply direct this
signal to an appropriate connector.
ICs (e.g. Acc-24P or Acc-24V) has a single 16-bit analog output. Breakout boards simply direct this
signal to an appropriate connector.
Board-level Turbo PMAC2 controllers do not have on-board analog outputs for their servo channels; a
breakout board with D/A converters (DACs), such as the Acc-8A or the Acc-8E must be used. With
UMAC systems, the Acc-24E2A analog axis-interface board has DACs for this purpose. With UMAC-
CPCI systems, the Acc-24C2A has DACs for this purpose. With the QMAC box-level controller, if the
analog option is ordered, the DACs are installed inside. In all of these systems, two DACs per channel
are either standard or optional, but only a single DAC is required for velocity or torque-mode control.
The DACs provided by Delta Tau for Turbo PMAC2 systems have 18-bit resolution.
breakout board with D/A converters (DACs), such as the Acc-8A or the Acc-8E must be used. With
UMAC systems, the Acc-24E2A analog axis-interface board has DACs for this purpose. With UMAC-
CPCI systems, the Acc-24C2A has DACs for this purpose. With the QMAC box-level controller, if the
analog option is ordered, the DACs are installed inside. In all of these systems, two DACs per channel
are either standard or optional, but only a single DAC is required for velocity or torque-mode control.
The DACs provided by Delta Tau for Turbo PMAC2 systems have 18-bit resolution.
Consult the appropriate hardware reference or accessory manual for the details of the hardware setup and
connection.
connection.
Turbo PMAC Parameter Setup
Hardware Setup for PMAC2-Style ICs
If the analog output is created through a PMAC2-style Servo IC, which supports other output types as
well, a few parameters in the IC must be set up to achieve the analog output. (This is not necessary if the
analog output is created through a PMAC-style Servo IC.)
well, a few parameters in the IC must be set up to achieve the analog output. (This is not necessary if the
analog output is created through a PMAC-style Servo IC.)