4.1 Test Run
4-6
Vector control with speed sensor
The inverter is equipped with an optional PG (Pulse Generator) interface card and receives the feedback
signals from the PG to detect the motor rotational position and speed for speed control. In addition, it
decomposes the motor drive current into the exciting and torque current components, and controls each of
those components in vector.
It is possible to obtain the desired response by adjusting the control constants (PI constants) using the
speed regulator (PI controller).
This enables quicker-response control of the motor speed with higher accuracy than vector control without
speed sensor.
(It is recommended to use Fuji motors (VG motors) exclusively designed for vector control.)
Since slip compensation and dynamic torque vector control use motor parameters, the following
conditions should be satisfied; otherwise, full control performance may not be obtained.
• A single motor should be controlled per inverter.
• Motor parameters P02
*
, P03
*
, and P06
*
to P23
*
, P55
*
, and P56
*
should be properly configured or
auto-tuning should be performed. (When using a VG motor under vector control with speed sensor,
just selecting the VG motor (setting the function code P99
*
＝2) is enough and auto-tuning is not
required.)
• The capacity of the motor to be controlled should be two or more ranks lower than that of the inverte
under the dynamic torque vector control and should be the same capacity as the inverter under
vector control with/without speed sensor. Otherwise, the inverter may not control the motor due to
decrease of the current detection resolution.
• The wiring distance between the inverter and motor should be 50 m or less. If it is longer, the inverte
may not control the motor due to leakage current flowing through stray capacitance to the ground or
between wires. Especially, small capacity inverters whose rated current is also small may be unable
to control the motor correctly even when the wiring is less than 50 m. In that case, make the wiring
length as short as possible or use a wire with small stray capacitance (e.g., loosely-bundled cable) to
minimize the stray capacitance.
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