Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Setting Up Turbo PMAC-Based Commutation and/or Current Loop
119
Make sure the motor is completely at rest. Now multiply the sensor position value read by I170, and
subtract this from the phase position read by M171. (If the motor is moved manually so that M171=0, the
product can be negated). Enter this value into I175 using a statement such as:
subtract this from the phase position read by M171. (If the motor is moved manually so that M171=0, the
product can be negated). Enter this value into I175 using a statement such as:
I175=M171-(M175*I170)
Finally, set up I181 to read the absolute sensor on subsequent Turbo PMAC resets and store these values
with the SAVE command. Perform another phase reference on this motor.
Using the Test Results for Incremental Index Pulse
For the incremental encoder index pulse, we will use the position capture feature to note where the index
is. Set variable I7mn2 (MS{node},MI912 for a MACRO Station) to 1 if there is a high-true index
pulse, or to 9 if there is a low-true index pulse. (To see which it is, define Mxx19 to its suggested
definition and put it in the Watch window. Generally, if it is 0 there is a high-true pulse.) With a
PMAC2-style Servo IC, to make sure the effective index pulse is only 1 count wide, set I7mn4
(MS{node},MI912 for a MACRO Station) to 1, and I7mn5 (MS{node},MI912 for a MACRO
Station) to the appropriate value for the encoder.
Now assign an M-variable to the encoder flag capture register:
with the SAVE command. Perform another phase reference on this motor.
Using the Test Results for Incremental Index Pulse
For the incremental encoder index pulse, we will use the position capture feature to note where the index
is. Set variable I7mn2 (MS{node},MI912 for a MACRO Station) to 1 if there is a high-true index
pulse, or to 9 if there is a low-true index pulse. (To see which it is, define Mxx19 to its suggested
definition and put it in the Watch window. Generally, if it is 0 there is a high-true pulse.) With a
PMAC2-style Servo IC, to make sure the effective index pulse is only 1 count wide, set I7mn4
(MS{node},MI912 for a MACRO Station) to 1, and I7mn5 (MS{node},MI912 for a MACRO
Station) to the appropriate value for the encoder.
Now assign an M-variable to the encoder flag capture register:
M103->X:$078003,0,24,S
; Encoder 1 flag capture register
Add this to the Watch window. With the motor at rest, note the phase position value in M171 and the
encoder position register in M101. Write these values down. Now turn/push the motor manually in the
direction to home to the machine until M103 changes. The new value is the value of the encoder register
captured at the index pulse.
Subtract your starting M101 value from this new M103 value. Multiply the difference by I170 and add
this to the starting M171 value. The result is the value we will write to the phase position register when
we are settled at the index to refine our initial rough phasing. Mathematically speaking:
encoder position register in M101. Write these values down. Now turn/push the motor manually in the
direction to home to the machine until M103 changes. The new value is the value of the encoder register
captured at the index pulse.
Subtract your starting M101 value from this new M103 value. Multiply the difference by I170 and add
this to the starting M171 value. The result is the value we will write to the phase position register when
we are settled at the index to refine our initial rough phasing. Mathematically speaking:
(
)
171
StartM
101
StartM
103
IndexM
*
170
I
Pos
IndexPhase
+
−
=
Alternately, in a technique that is easier mathematically but harder physically, put M119 in the Watch
window (or the index signal on an oscilloscope) and turn the motor shaft until it stops on the index pulse.
Read the M171 phase position register value. This is the value we will write to the phase position register
when we are settled at the index to refine our initial rough phasing.
window (or the index signal on an oscilloscope) and turn the motor shaft until it stops on the index pulse.
Read the M171 phase position register value. This is the value we will write to the phase position register
when we are settled at the index to refine our initial rough phasing.
Using Hall-Effect Sensors for Phase Reference
Hall-effect sensors or their optical equivalents on a commutation encoder, for a 3-phase motor can be
used for rough phasing on power-up without the need for a phasing search move. This initial phasing
provides reasonable torque, but it will need to be corrected for top operation. Usually the correction is
done when the index pulse is reached, in the same technique that is described above for the correction
after a power-on phasing search move.
used for rough phasing on power-up without the need for a phasing search move. This initial phasing
provides reasonable torque, but it will need to be corrected for top operation. Usually the correction is
done when the index pulse is reached, in the same technique that is described above for the correction
after a power-on phasing search move.
Hall-effect sensors usually map out 6 zones of 60
o
elec. each. In terms of Turbo PMAC’s commutation
cycle, the boundaries should be at 180
o
, -120
o
, -60
o
, 0
o
, 60
o
, and 120
o
. Typically a motor manufacturer
will align the sensors to within a few degrees of this, because these are the proper boundary points if all
commutation is done from the commutation sensors. If mounting the hall-effect sensors, take care to
align the boundaries at these points. The simplest way is to force the motor to the zero degree point with
a current offset (as shown above) and adjust the sensor while watching its outputs to get a boundary as
close as possible to this point.
commutation is done from the commutation sensors. If mounting the hall-effect sensors, take care to
align the boundaries at these points. The simplest way is to force the motor to the zero degree point with
a current offset (as shown above) and adjust the sensor while watching its outputs to get a boundary as
close as possible to this point.