Reference Manual

PMAC 2 Software Reference
PMAC I-Variable Specification 101
• PMAC’s maximum output of 32,768, or 10 volts, corresponds to 20 amps.
• The motor has the lower instantaneous current rating, so we use its limit of 15
amps.
• I369 is set to 32,768 * 15/20 = 24,576.
3. Motor 5 is driving a self-commutating brushless-motor amplifier in current (torque)
mode with a single analog output. The amplifier has a gain of 5 amps(RMS)/volt and
an instantaneous current limit of 50 amps (RMS). The motor has an instantaneous
current limit of 60 amps (RMS).
• PMAC’s maximum output of 32,768, or 10 volts, corresponds to 50 amps (RMS).
• The amplifier has the lower instantaneous current rating, so we use its limit of 50
amps (RMS).
• I569 is set to 32,768 * 50/50 = 32,767 (note that the maximum value is 32,767).
4. Motor 7 is driving a “sine-wave” amplifier for a brushless servo motor with two analog
outputs. The Ix77 magnetization current limit is set to 0. The amplifier has a gain on
each phase of 4 amps/volt. The amplifier has an instantaneous current limit of 25 amps
(RMS). The motor has an instantaneous current limit of 30 amps (RMS).
• PMAC’s maximum output of 32,768, or 10 volts, corresponds to 40 amps peak in
the phase.
• The amplifier has the lower instantaneous current rating, so we use its limit of 25
amps (RMS).
• 25 amps (RMS) corresponds to peak phase currents of 25*1.414 = 35.35 amps.
• I769 is set to 32,768 * 35.35/40 = 28,958.
5. Motor 8 is driving a direct-PWM “power-block” amplifier and an AC induction motor.
The Ix77 magnetization current parameter is set to 3000. The A/D converters in the
amplifier are scaled so that a maximum reading corresponds to 100 amps of current in
the phase. The amplifier has an instantaneous current limit of 60 amps (RMS), and the
motor has an instantaneous current limit of 75 amps (RMS).
• PMAC’s maximum ADC phase reading of 32,768 corresponds to 100 amps in the
phase.
• The amplifier has the lower instantaneous current rating, so we use its limit of 60
amps (RMS).
• 60 amps (RMS) correspond to peak phase currents of 60*1.414 = 84.84 amps.
• 84.84 amps correspond to an ADC reading of 32,768 * 84.84/100 = 27,800.
• The vector sum of Ix69 and Ix77 should equal 27,800 * 0.866 = 24,075.
• I869 should be set to sqrt(24,075
2
-3,000
2
) = 23,887.