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Brushless Core
OPEN DRIVE
4.8. IPP Initial Pole position detection
This function is useful when the drive has to control a brushless motor with incremental sensor.
Setting C78 ≠ 0, at the first run command a fixed angle current is injected on the motor, with a
linear ramp (1,6 seconds with PWM=5KHz) up to value set on P114 ; at this point the motor starts
to move to align with the current.
The control test the motor velocity and if it becomes greater than 0,4% of maximum motor velocity
(P65) the current is reduced to decrease the velocity itself.
The alignment is executed with the velocity controlled and it’s possible to choose the
movement direction with the connection C78:
C78
1
2
3
Description
Random
Positive sense
Negative sense
Setting C78 = 1 or 2 if the alignment movement starts in the wrong sense, after one mechanical
degree the current sense is inverted, so the test continues with the motor runs in the opposite
direction.
When the motor is aligned with the magnet, there is a wait of 6 seconds (with PWM=5KHz), after
that the function is finished and it goes at high level the logical function o18 “IPP executed”.
At this point it is necessary to switch off the run command and automatically is stored in parameter
P75 the initial angle.
After that, the drive is able to control the motor as long as the regulation card is switched on.
Obviously this IPP function must be repeat every time the regulation card is switched on.
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08.06.09