ElmoMC SimplIQ Software Manual - Manual (Page 115)

SimplIQ Software Manual Commutation
MAN-SIMSW (Ver. 1.4)
8-5
8.3.3 Combining Sensor Types
8.3.3.1 Initializing Encoder-based Commutation
When starting a motor, the electrical angle can be roughly estimated from the digital Hall
sensors, which usually read the electrical angle to +30 electrical degrees. The exception is
that instant at which the Hall sensor reading switches; at this point, the Hall sensors read
the electrical angle accurately. After the first Hall sensor switch, accurate commutation is
maintained by updating the commutation counter incrementally using the shaft position
sensor.
8.3.3.2 Detecting Commutation Errors (Loss of Feedback)
After encoder commutation begins, two sources of electrical angle measurement are
available: the high-resolution measurement by the encoder, and the low-resolution — but
reliable — digital Hall sensor readout.
The digital Hall sensor readout defines a range in which the high-resolution calculated angle
should reside. Deviating from this range by more than a few degrees results in a
commutation error and automatic motor shutdown.
The allowed deviation is increased at higher speeds, because then the sensor and the
calculation delays contribute a significant matching error.
The most common causes for commutation loss are:
ƒ
A slit in the encoder disk is clogged with direct. When this happens, an encoder of 4000
counts/revolution may count, for example, 3999 counts/revolution. After a number of
revolutions, the cumulative error grows to a large number.
ƒ Too fast a speed relative to the defined encoder filter (EF[1] and EF[2] commands), and
encoder pulses are lost.
ƒ An interpolator derives the encoder A/B pulses. Certain interpolators intermittently
send pulse batches of much higher frequency than the motor speed. Encoder filters
should not be used with interpolators, even if the motor speed is supposed to be slow.
8.3.4 Parameterization of Commutation and
Commutation Errors
8.3.4.1 Winding Order
The SimplIQ drive has three motor connection pins: A, B and C. The pin names are not
rigidly assigned an actual role: The SimplIQ drive can internally define which motor phase is
connected to which output pin. The CA[25] parameter controls this connection, as follows:
CA[25] Phase A
Connected to Pin: Phase B
Connected to Pin: Phase C
Connected to Pin:
0 A B C
1 A C B
Table 8-1: Motor Connection Pin Parameters