Lenze MC1000 Series - Manual (Page 56)

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20 AC BOOST (ACCELERATION BOOST)
AC BOOST is similar to FX BOOST, but is only active when the drive is accelerating.
During acceleration, the output voltage is increased according to the setting of AC
BOOST, which increases motor torque. Refer to the diagram below. AC BOOST,
like FX BOOST, is used in applications with high-inertia loads.
The diagram below illustrates how FX BOOST and AC BOOST alter the V/Hz ratio
to increase motor torque.
FX BOOST sets the boost at 0 Hz (approximately 15% in the example above), and
as the output frequency approaches 30 Hz, the boost decreases to zero.
OUTPUT FREQUENCY (Hz)
OUTPUT VOL
TA
GE
(%) FX BOOST
CONSTANT V/Hz
10 20 30 40 50 60
10
20
30
40
50
60
70
80
90
100
AC BOOST
AC BOOST only functions during acceleration. In the diagram above, the drive
is operating at 35 Hz and is then commanded to 50 Hz. The output voltage is
increased by the AC BOOST setting (approximately 15% in the example above)
during acceleration to the new speed set point. Once the new set point is reached,
the output voltage returns to normal.
21
SLIP CMP (SLIP COMPENSATION)
SLIP COMPENSATION is used to compensate for changes in motor speed (“slip”)
which occur due to changes in load. In a standard AC induction motor, as the load
on the motor increases, the motor current increases and the motor shaft speed
decreases. By increasing the output frequency in response to the increased motor
current, SLIP COMPENSATION is able to counteract the reduction in motor speed
due to increased load. This parameter is useful in applications where precise
speed regulation is needed, even under changing load conditions. The use of SLIP
COMPENSATION can result in speed regulation of less than 1% of base speed in
most applications. SLIP COMPENSATION is often set to 3%, which is the standard
slip rating of most AC induction motors.