Elmomc SimplIQ Digital Servo Drives-Bell Command Referenc Manual de usuario descargar pdf (Pagina 223)

Command Description

S[20]

tator field angle, in 1024 counts/revolution units.

tator field angle (degrees) = WS[20] x (360/1024).

S[21] Commutation counter. WS[21] counts the main high-resolution

osition sensor, modulo CA[18].

For analog encoders, WS[21] counts the position with maximum interpolation,

regardless of the user selected interpolation factor CA[31]

The process of initializing the commutation counter WS[21] is called commutation

finding, or pole identification.

Commutation finding is made when the motor is first set to ON. The process of

commutation finding may involve extra motions, according to the method you select –

refer to the next sections of this chapter. The PN[6] parameter determines if commutation

search is made every motor ON or just the first time.

4.2. Commutation Sensors

Vector commutation requires rotor position sensors. Commutation sensors are divided

into two main groups:

 Direct field sensors that sense the magnetic field of the motor

 Shaft position sensors

Commutation with position sensor is always made with the main sensor, even if

the auxiliary sensor is the position feedback (UM=4).

4.2.1 Hall Sensors

The Hall sensors report the rotor electrical position directly. However, digital Hall

sensors provide only rough information with six counts per electrical cycle.

SimplIQ can use Hall sensors as the only information for commutation. Many applications

achieve smoother commutation by using digital Hall sensors for initial pole identification

and for backup; most of the time the commutation is made by a higher-resolution

position sensor.

The following table describes the most common digital Hall sensor arrangement.

Hall A

Hall B

Hall C

Electrical Rotor

Position (Degrees)

Transformation angle

for best torque

(Degrees)

0 0 0 Illegal

1 0 0 330 – 30 90

1 1 0 30 – 90 150

SimplIQ for Steppers Application Note Commutation and Pole Identification

MAN-STECR (Ver. 1.1)

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Elmomc SimplIQ Digital Servo Drives-Bell Command Referenc Manual de usuario Pagina 223