ElmoMC SimplIQ Software Manual - Manual (Page 113)

SimplIQ Software Manual Commutation
MAN-SIMSW (Ver. 1.4)
8-3
You can read the electrical and mechanical angle of the motor using the following
commands:
Command Description
WS[20] Stator field angle, in 1024 counts/revolution units.
Stator field angle (degrees) = WS[20] x (360/1024).
WS[21] Commutation counter. WS[21] counts the main high-resolution
position sensor, modulo CA[18].
8.3 Commutation Sensors
For BLDC commutation, rotor position sensors are required. Commutation sensors can be
categorized into two main groups:
ƒ
Direct field sensors that sense the magnetic field of the motor
ƒ Shaft position sensors
8.3.1 Rotor Magnetic Field Sensors
This first group of sensors consists mainly of digital Hall sensors, which may be used for
commutation with minimum calculation, because they reflect the direction of the rotor with
direct respect to the windings. However, digital Hall sensors provide only rough
information. Standard digital Hall sensors divide the electrical period of the motor into six
units, as illustrated in the following figure.
Hall A
Hall B
HallC
270
deg 330
deg 30
deg
90
deg
150
deg 210
deg 270
deg
Figure 8-1: Digital Hall Sensor Readout