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TABLE OF CONTENTS
TECHNICAL REFERENCE
SERVICE
MANUAL
VF-SERIES
4.9 SERVO CHARACTERISTICS (BRUSHLESS)
Servo characterstics are explained in detail in the previous chapter. The following is an example of how to achieve 130
inches/minute.
The exponential accel/decel time constant is set by Parameters 113, 114, 115, 116 and 168. It has units of 0.0001 seconds.
The speed limit at which exponential accel/decel is not available is defined by the relationship between Parameters 7 and
113 (for the X-axis). Thus if Parameter 7 is 8000000 steps/sec/sec and Parameter 113 is 375 (0.0375 seconds); the
maximum velocity for accurate interpolation should be:
8000000 x 0.0375 = 300000 steps/second
For a 8192 line encoder and 6 mm screw, this would be:
60 x300000 / 138718 = 130 inches/minute
4.10 SERVO AMPLIFIERS (BRUSHLESS)
NOTE: REFER TO PCB AND CABLE LOCATION SECTION FOR BOARD DIAGRAMS.
The brushless servo amplifier is a PWM based current source. The PWM outputs control the current to a three phase
brushless motor. The PWM frequency is 16 KHz. The amplifiers are current limited to 30 amps peak. However there are
fuse limits both in hardware and software to protect the amplifiers and motors from over current. The nominal voltage for
these amplifiers is 320 volts. Therefore the peak power is about 9600 watts or 13 H.P. The amplifiers also have short circuit
and over temperature and over heat protection.
There is a 10 amp supply fuse for failure protection. This fuse is relatively slow, therefore it can handle the 30 amp peak.
Actual continues current limit to the motor is controlled by software.
Commands to the amplifier are +/-5 volts current in two legs of the motor and a digital enable signal. A signal from the
amplifier indicates drive fault or sustained high current in stalled motor.
The connectors on the amplifiers are:
+H.V. + 320 volts DC
-H.V. 320 volts return
A motor lead phase A
B motor lead phase B
C motor lead phase C
J1 Three pin Molex connector used for +/-12 and GND.
J2 Eight pin Molex connector used for input signals.
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