4-265
■
Motor no-load voltage (17-08)
a) Motor no-load voltage is mainly used in SV or SLV mode, set to value 10~50V lower than the input
voltage to ensure good torque performance at the motor rated frequency.
b) Set to 85 ~ 95% of the motor rated voltage. In general, the no-load voltage can be closer to the motor
rated voltage for larger motors, but cannot exceed the motor rated voltage.
c) The motor no-load voltage can be set to a value greater than the actual input voltage. In this case, the
motor can only operates under relatively low frequency. If the motor operates at the rated frequency an
over voltage condition may occur.
d) The higher the motor power is, the higher the no-load voltage is.
e) A smaller no-load voltage will reduce the no-load current.
f) When load is applied the magnetic flux is weakened and the motor current increases.
g) A higher no-load voltage results in a higher the no-load current.
h) When load is applied the magnetic flux weakens and the motor current increases. Increasing the
magnetic flux generates back EMF and results in poor torque control.
■
Motor excitation current (17-09)
a) Motor excitation current is used for rotational auto-tune.
b) Set motor excitation current to 33% of the motor rated current. Refer to parameter 02-09 for test running.
c) Only the static-type or stator resistance measurement auto-tune (17-00=1 or 1700=2) can be set.
d) It is required to refer to the monitoring parameter 12-76 for adjusting the motor excitation current (17-09).
When the excitation current change, parameter 12-76 is also affected so it should be adjusted to the
setting no-load voltage (17-08).
■
Automatic tuning start (17-10)
Set parameter 17-10 to 1 and press ENTER
the inverter will display “Atrdy” for Auto-tune ready. Next press
RUN to start the auto-tune procedure. During auto-tune the keypad will display
“Atune “for Auto-tune in
progress. When the motor is successfully tuned, the keypad shows "AtEnd".
■
Error history of automatic tuning (17-11)
If auto-tuning fails the keypad will display the AtErr" message and the auto-tune cause is shown in parameter
17-11. Refer to section 5 for troubleshooting and possible automatic tuning error causes.
Note:
The motor tuning error history (17-11) shows the tuning result of the last auto-tune. No error is displayed
when auto-tune is aborted or when the last auto-tune was successful.
Perform the “Stator resistance measurement” (17-00=2) auto-tune if the inverter/motor leads are longer than
167ft (50m).
For the best performance in vector control perform the rotary-type automatic tune (17-00 = 0) first (using short
motor leads between the inverter and motor) and
a “Stator resistance measurement” (17-00=2) next.
If a rotary auto-tune (17-00=0) cannot be performed, manually enter the mutual induction (02-18), excitation
current (02-09), core saturation compensation factor 1-3 (02-11 - 02-13).
Perform the “Stator resistance measurement” (17-00=2) in V/F control when inverter/motor leads are longer
than 167ft (50m).