Hitachi S1 Series - Page 51

S1 series standard inverter
-46-
b
f
b
V
Output voltage
Output frequency
Straight-type
Torque -down V/F curve (1.3
th
order)
Square-type
Torque -down V/F curve (1.7
th
order)
Torque -down V/F curve (2.0
th
order)
S1inverter also provides multi-point V/F curve. Users can alter the V/F curve outputted by inverter
through setting the voltage and frequency of the three points in the middle. The whole curve consists
of five points starting from (0Hz, 0V) and ending in (fundamental motor frequency, rated motor
voltage). During setup, it is required that 0≤f1≤f2≤f3≤fundamental motor frequency, and
0≤V1≤V2≤V3≤rated motor voltage
b
f
Output voltage
f1
f2
f3
V1
V2
V3
b
V%100
Output frequency
Hz
S1inverter provides dedicated function codes for V/F control mode. Users can improve the
performance of V/F through settings.
1. Torque boost
Torque boost function can effectively compensate for the low-speed torque performance during V/F
control. Automatic torque boost has been set by default to enable the inverter to adjust the torque
boost value based on actual load conditions.
Note:
(1) Torque boost is effective only under torque boost cut-off frequency;
(2) If the torque boost is too large, low-frequency vibration or overcurrent may occur to the motor, if
such situation occurs, lower the torque boost value.