User's Manual

PMAC User Manual
88 Setting Up PMAC Commutation
16
THUMBWHEELS
RS422
8 (16)
POSITION AND
HANDWHEEL
ENCODER
EXPANSION I/O
AND iSBX
PMAC
EXTENSION
HOST
COMPUTER
BUS
DISPLAYS
CONTROL PANEL
PMAC
OUT 3
OUT 8
OUT 9
OUT 16
OUT 1
[2 OF 8(16)]
AVAILABLE
OUTPUTS
OUT 2
-10 V.
D. C.
NO COMMUTATION WITH COMMUTATION
8 (16)
ANALOG INPUTS
TWO AXIS ONE AXIS
TWO OUTPUTS BECOME
3 PH.
4 PH.
90
120
D.C. +/- 10V.
TWO AXIS
VELOCITY OR
TORQUE COMM.
16 BIT RESOLUTION
SINUSOIDAL, +/-10V.
THREE OR FOUR PHASE
6KHz MAX. FREQ.
V
EL. & TORQUE COMM.
16 BIT RESOLUTION
+10 V.
-10 V.
D. C.
+10 V.
CONTROLS ANY
TYPE OF MOTOR
WHEN AMPLIFIER
PROVIDES
COMMUTAT ION
1) AMPLITUDE = TORQUE, FREQUENCY = VELOCITY
2)THE THIRD PHASE MAY BE GENERATED BY EITHER
ALGEBRAICALLY SUMMING OUT 1 & OUT 2, OR BY
DERIVING A CURRENT BALANCE LOOP IN THE AMP.
3) D.C. BRUSHLESS(SYNCHRONOUS), A.C. INDUCTION
(ASYNCHRONOUS), STEPPER & SR MOTORS
Figure 15 PMAC Commutation
Basic Parameter Specification
Regardless of the type of motor PMAC is commutating, several parameters need to be specified for the
commutation. Commutation parameters for motor x begin at Ix70. The commutation parameters are only
used if Ix01=1.
Counts per Commutation Cycle
First to be specified is the number of counts per commutation cycle (or electrical cycle, or pole-pair),
using motor I-variables Ix70 and Ix71, where Ix71/Ix70 is the number of counts per cycle. Ix71 and Ix70
must both be integers. These are encoder counts after the decoding, so if x4 decode is used, there are four
counts per encoder cycle. Usually Ix70 is 1, except for a few special cases like 6-pole motors, where there
is likely not to be an integer number of counts per single pole pair.
Angle Between Phases
The proper angular offset between phases, which is different for three- and four-phase motors, is set by
Ix72. This parameter also permits reversal of the phasing, so that motor leads do not have to be flipped if
the phasing was wrong in assembly. The units of Ix72 are 1/256 of a commutation cycle, so for a three-
phase motor, the possible values are 85 (1/3 of 256) or 171 (2/3 of 256). For a four-phase motor, the
possible values are 64 (1/4 of 256) or 192 (3/4 of 256). Changing Ix72 between the two values for a
given number of phases has the same effect as exchanging two of the motor leads. Tests for the proper
setting within each pair of values are given below.