Hitachi SJ100 Instruction Manual page 86

3–14
"A" Group: Standard Functions
parameters A_42 and A_43. The manual boost is calculated as an addition to the
standard straight V/f line (constant torque curve).
NOTE: Manual torque boost is not operational when sensorless vector control is in use.
Be aware that running the motor at a low speed for a long time can cause motor
overheating. This is particularly true when manual torque boost is ON, or if the motor
relies on a built-in fan for cooling.
NOTE: Manual torque boost applies only to constant torque (A_44=00) and variable
torque (A_44=01) V/f control.
Voltage Gain – Using parameter A_45 you
Voltage Gain
V
can modify the voltage gain of the inverter (see
100%
graph at right). This is specified as a percent-
age of the full scale setting (Automatic Voltage
A 45
Regulation) AVR level in parameter F_03. The
50%
gain can be set from 50% to 100%. It should be
adjusted in accordance with the motor specifi-
0
cations.
Hz
Sensorless Vector Control (SLV) – This advanced torque control algorithm improves
torque performance at very low speeds—down to 0.5 Hz. Set parameter A_44=02 to
select SLV operation. The SLV algorithm must be tuned to match the characteristics of
the particular motor connected to your inverter. Simply using the default motor parame-
ters in the inverter will not work satisfactorily for these control methods. Chapter 4
discusses motor/inverter size selection and how to set the motor parameters either
manually or by using the built-in auto-tuning. Before using the sensorless vector control
methods, please refer to "Auto-tuning for Sensorless Vector Control" on page 4–35.
NOTE: When the inverter is in SLV (sensorless vector) mode, use B_83 to set the carrier
frequency greater than 2.1 kHz for proper operation.
NOTE: You must disable sensorless vector operation when two or more motors are
connected (parallel operation) to the inverter.