LEESON Micro Series Compact Inverters User Manual

Page 61

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20 AC BOOST

(AC 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.

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 cur-

rent 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 .

FX AND AC BOOST

FREQUENCY (HERTZ)

OUTPUT

LTA

GE (%

)

AC BOOST

FX BOOST

CONSTANT V/Hz

100

90
80
70
60

50
40

30
20
10

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