3.2.1 Logic Section
The control card contains most of the logic section (see
). The primary logic element of the control card is
a microprocessor, which supervises and controls all
functions of adjustable frequency drive operation. In
addition, separate PROMs contain the parameters to
provide programmable options. These parameters are
programmed to enable the adjustable frequency drive to
meet specific application requirements. This data is then
stored in an EEPROM which provides security during
power-down and allows for changing the operational
characteristics of the adjustable frequency drive.
A custom-integrated circuit generates a pulse width
modulation (PWM) waveform which is then sent to the
interface circuitry on the power card.
Figure 3.2 Logic Section
The PWM waveform is created using an improved control
scheme called VVC
plus
, a further development of the earlier
VVC (Voltage Vector Control) system. VVC
plus
provides a
variable frequency and voltage to the motor which
matches the requirements of the motor.
Another part of the logic section is the local control panel
(LCP). The LCP is a removable keypad/display mounted on
the front of the adjustable frequency drive. The LCP
provides the interface between the internal digital logic
and the operator.
All the programmable parameter settings can be uploaded
into the EEPROM of the LCP. This function is useful for
maintaining a backup adjustable frequency drive profile
and parameter set. It can also be used, through its
download function, in programming other adjustable
frequency drives or to restore a program to a repaired unit.
The LCP is removable during operation to prevent
undesired program changes. With the addition of a remote
mounting kit, the LCP can be mounted in a remote
location of up to 3 m (10 ft.) away.
Control terminals, with programmable functions, are
provided for input commands such as run, stop, forward,
reverse and speed reference. Additional output terminals
are provided to supply signals to run peripheral devices or
for monitoring and reporting status.
The control card logic can communicate via serial link with
outside devices such as personal computers or
programmable logic controllers (PLC).
The control card also provides two voltage supplies for use
from the control terminals. The 24 V DC is used for
switching functions such as start, stop, and forward/
reverse. The 24 V DC supply can supply 200 mA of power,
part of which may be used to power external encoders or
other devices. A 10 V DC supply on terminal 50 is rated at
17 mA is also available for use with speed reference
circuitry.
The analog and digital output signals are powered through
an internal adjustable frequency drive supply.
Two relays for monitoring the status of the adjustable
frequency drive are on the power card. These are
programmable through parameter group
5–4* Relays
. The
relays have different ratings. See the corresponding
Instruction Manual or Design Guide for more information
on ratings.
Internal Adjustable Frequen...
Service Manual
34
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
MG94A222
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Summary of Contents for VLT FC 103
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