Aerotech UNIDEX 600 Series, Руководство пользователя

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U600 User’s Guide Parameters
Version 1.4
Aerotech, Inc.
C-25
the range of +10 volts through –10 volts. This voltage is applied to the command input of
the servo amplifier, knowing the G
m
(transconductance) value of the servo amplifier
allows the current (Amperes) output to be calculated. Aerotech’s amplifiers typically
(model dependant) have a peak output current of 20 or 30 amperes. Simply meaning, a +/-
10 volts in to the amplifier will be equal to +/- x amperes, where x is the peak output
current of the servo amplifier. This current produces a torque generated by the motor,
equal to the current multiplied by the K
T
of the motor. For example, if the peak output
command (or instantaneous output command) from the DAC was 16,384 (+5 volts), the
amplifier produced 30 amperes for an input of 10 volts and the motor had a K
T
of 16
oz.in. (Ounce-inches) per ampere, then:
(5 volt command / 10 volt, max. amps, input command) * 30 Amperes (max. I. Output) *
16 oz.in K
T
= 240
or
(5/10) * 30 * 16 = 240
Therefore, the applied torque is 240 oz.in.
To calculate this value for an Aerotech brushless motor, from the motor data, use the
"continuous stall current max" (A peak) specified for the motor, or use the "continuous
stall current" (A RMS) specified after converting it to Peak by multiplying it by 1.414
To calculate this value for an Aerotech DC brush motor, from the motor data, use the
RMS current specified for the motor, or divide the continuous toque (Tc) by the motor
torque constant (Kt); i.e.,
Tcont / Kt = RMS value
Be sure to set the RMS Current Limit bit in the FAULTMASK axis parameter to enable
the detection of this fault, then set the bit in the appropriate mask parameter
(DISABLEMASK, HALTMASK, AUXMASK, ABORTMASK, INTMASK and
BRAKEMASK) for the action to occur on this fault.
C.2.50. IAVGTIME
This axis parameter defines the time period over which the system will average the
instantaneous commanded current. However, this parameter is only used to next lowest 10
milliseconds interval. For example, a value of 12 or 19 is equivalent to a value of 10. The
IAVGLIMIT parameter is dependent on the setting of this parameter to detect an over-
current condition.
C.2.51. ICMD
The ICMD axis parameter returns the instantaneous current command, where
±
32767
represents
±
10 volts. This voltage is the command applied to the drive module.
C.2.52. ICMDPOLARITY
The ICMDPOLARITY axis parameter is used for two purposes. The first is to vary the
polarity of the current command output by the servo loop, which inverts the current
command polarity that is output from the DAC to the drive. On a UNIDEX 600/650, a
positive current command should generate negative axis motion. This parameter is
normally set to 0 for no inversion, it may be set to 1 to correct for reversed servo loop
phasing, not to reverse the direction of the motor on a properly phased servo loop. Also, if