5-12
Torque boost
• Manual torque boost by F09 (Manual adjustment)
• Data setting range: 0.0 to 20.0 (%), (100%/base frequency voltage)
In torque boost using F09, constant voltage is added to the basic V/f pattern, regardless of the load. To secure a
sufficient starting torque, manually adjust the output voltage to optimally match the motor and its load by using F09.
Specify an appropriate level that guarantees smooth startup and yet does not cause over-excitation at no or light
load. Torque boost using F09 ensures high driving stability since the output voltage remains constant regardless of
the load fluctuation. Specify the function code F09 data in percentage to the base frequency voltage. At factory
shipment, boost amount with which approx. 100% of starting torque can be assured, is specified.
• Specifying a high torque boost level will generate a high torque, but may cause overcurrent due to
over-excitation at no load. If you continue to drive the motor, it may overheat. To avoid such a
situation, adjust torque boost to an appropriate level.
• When the non-linear V/f pattern and the torque boost are used together, the torque boost takes effect
below the frequency on the non-linear V/f pat
tern’s point.
•
Auto torque boost
This function automatically optimizes the output voltage to fit the motor with its load. Under light load, auto torque
boost decreases the output voltage to prevent the motor from over-excitation. Under heavy load, it increases the
output voltage to increase the output torque of the motor.
• This function controls in accordance with motor characteristics. Therefore, set the base frequency 1
(F04), rated voltage at base frequency 1 (F05), and other pertinent motor parameters (P01 through
P03 and P06 through P99) in line with the motor capacity and characteristics, or else perform
auto-tuning (P04).
• When a special motor is driven or the load does not have sufficient rigidity, the maximum torque might
decrease or the motor operation might become unstable. In such cases, do not use auto torque boost
but choose manual torque boost using F09 (F37 = 0 or 1).
Output
voltage (V)
Rated voltage at
base frequency 1
Non-linear V/f
pattern 1 (voltage)
Non-linear V/f
pattern 1
(frequency)
V/f pattern of variable
torque V/f pattern
without non-linear V/f
V/f pattern of variable
torque V/f pattern with
non-linear V/f
Base
frequency 1
Output frequency
Rated voltage at
base frequency 1
Non-linear V/f
pattern 1 (voltage)
Increase output
voltage with Torque
boost 1 (F09)
Non-linear V/f
pattern 1
(frequency)
Base
frequency 1
Output frequency
Output voltage (V)
Torque boost 1
Summary of Contents for Frenic-Sce
Page 10: ......
