Servosila-Device-Reference-0xA020192

initiating a motion of the rotor in a way that does not require any
knowledge of the rotor's position. Once the rotor starts moving under
Kickstart Control, then the physics behind the "Sensorless Observer" kicks
in, and the controller switches into the efficient Field Oriented Control
(FOC) method to proceed with acceleration of the rotor. It typically takes a
fraction of a second for the Kickstart Control to do its thing, and hand over
the control to Field Oriented Control (FOC) function. A side effect is that
the "Kickstart" procedure might create ripples of torque while accelerating
the motor. As those start-up ripples are not a problem for many
applications, the sensorless motors are popular due to simplicity and low
cost, albeit at the expense of complexity of the controller.
The parameter "Kickstart: Speed Limit" defines a speed which the
Kickstart procedure accelerates the rotor to, before attempting to hand over
control to Field Oriented Control (FOC). An implied assumption is that the
magic behind the "Sensorless Observer" method starts producing reliable
estimates of the rotor's position at that speed, so that it becomes possible
for Field Oriented Control (FOC) to take over.
NOTE: The value for this limit is automatically computed by the
"Spreadsheet" tool or by an auto-configuration procedure of the controller.
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Kickstart: T sec The parameter "Kickstart: T" defines a timeframe within which the
"Kickstart" procedure accelerates a motor towards a pre-configured
"Kickstart: Speed Limit". If the kickstart procedure does not succeed
within the given timeframe, the controller makes another attempt, and
keeps making attempts until it successfully hands over control of the motor
to Field Oriented Control (FOC).
Tuning intuition:
• INCREASE the "Kickstart: T" parameter if the kickstart procedure
does not reliably start the sensorless motor each time. This might
happen, for example, if a payload attached to the motor has a
moment of inertia too large to be accelerated to "Kickstart: Speed
Limit" within the specified time.
• DECREASE the "Kickstart: T" parameter if a torque ripple caused
by the "Kickstart" procedure becomes a problem in a given
application. Shorter kickstart times makes the torque ripples shorter
in time too.
NOTE: The value for this parameter is automatically computed by the
"Spreadsheet" tool or by an auto-configuration procedure of the controller.
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11 Sensorless Observer:
EMF Zero Speed
Voltage (high
watermark)
V The "Sensorless Observer" method works by measuring voltages generated
by the motor. Whenever the rotor is moving, permanent magnets of the
rotor happen to interact with coils of the stator in such a way that
measurable voltages are generated on phase lines (just like in an electric
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