Learning Advanced Features
Speed Search Operation Setting Details
Sets the speed search current based on the motor’s rated current. This
parameter is only displayed when dr.09 (Control Mode) is set to 6 (PM
Sensorless).
Select a speed search type.
The speed search is carried out as it controls
the inverter output current during idling below
the Cn.72 (SS Sup-Current) parameter setting.
If the direction of the idling motor and the
direction of operation command at restart are
the same, a stable speed search function can
be performed at about 10 Hz or lower. However,
if the direction of the idling motor and the
direction of operation command at restart are
different, the speed search does not produce a
satisfactory result because the direction of idling
cannot be established.
The speed search is carried out as it PI controls
the ripple current which is generated by the
counter electromotive force during no-load
rotation. Because this mode establishes the
direction of the idling motor (forward/reverse),
the speed search function is stable regardless
of the direction of the idling motor and direction
of operation command. However because the
ripple current is used which is generated by the
counter electromotive force at idle (the counter
electromotive force is proportional to the idle
speed), the idle frequency is not determined
accurately and re-acceleration may start from
zero speed when the speed search is
performed for the idling motor at low speed
(about 10 - 15 Hz, though it depends on motor
characteristics).
This speed search is available when operating
a PM synchronous motor. It is used when dr.09
(Control Mode) is set to 6 (PM Sensorless).
Speed search can be selected from the following 4 options. If the top
display segment is on it is enabled (On), and if the bottom segment is on
it is disabled (Off).
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