98 Program features
Bit 4 of 06.21 Drive status word 3 indicates if the rotor position has already been
determined.
Autophasing modes
Several autophasing modes are available (see parameter 21.13 Autophasing mode).
The turning mode (Turning) is recommended especially with case 1 (see the list
above) as it is the most robust and accurate method. In turning mode, the motor shaft
is turned back and forward (±360/polepairs)° in order to determine the rotor position.
In case 3 (open-loop control), the shaft is turned only in one direction and the angle is
smaller.
Another turning mode, Turning with Z-pulse, can be used if there is difficulty using the
normal turning mode, for example, because of significant friction. With this mode, the
rotor is turned slowly until a zero pulse is detected from the encoder. When the zero
pulse is detected for the first time, its position is stored into parameter 98.15 Position
offset user, which can be edited for fine-tuning. Note that it is not mandatory to use
this mode with a zero pulse encoder. In open-loop control, the two turning modes are
identical.
The standstill modes (Standstill 1, Standstill 2) can be used if the motor cannot be
turned (for example, when the load is connected). As the characteristics of motors
and loads differ, testing must be done to find out the most suitable standstill mode.
The drive is capable of determining the rotor position when started into a running
motor in open-loop or closed-loop control. In this situation, the setting of 21.13
Autophasing mode has no effect.
The autophasing routine can fail and therefore it is recommended to perform the
routine several times and check the value of parameter 98.15 Position offset user.
An autophasing fault (3385 Autophasing) can occur with a running motor if the
estimated angle of the motor differs too much from the measured angle. This could
be caused by, for example, the following:
• The encoder is slipping on the motor shaft
• An incorrect value has been entered into 98.15 Position offset user
• The motor is already turning before the autophasing routine is started
• Turning mode is selected in 21.13 Autophasing mode but the motor shaft is
locked
• Turning with Z-pulse mode is selected in 21.13 Autophasing mode but no zero
pulse is detected within a revolution of the motor
• The wrong motor type is selected in 99.03 Motor type
• Motor ID run has failed.
Settings and diagnostics
Parameters 06.21 Drive status word 3 (page 171), 21.13 Autophasing mode (page
247), 98.15 Position offset user (page 495) and 99.13 ID run requested
(page 497).
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