Vonsch Quatrofrem Series, Конфигурация и диагностика

Страница: 141 / 180

UNIFREM v.3.41x
10 May 2017 Page 141 from 180
Importance of function coefficients „Resonance damping“
Resonance damping can reduce or completely suppress undesired motor vibration, especially if
there is a small load operation.
8.6 Voltage controller (VC) - Dynamic deceleration (DD) a Kinetic backup
(KB).
DC-link voltage (V
DC
) is the one of the most important parameters of frequency converter.
Its value is equal to the peak value of the rectified AC phase to phase voltage (U
DC
= 1.414 * U
UV
)
under normal conditions. For 400V power supply network this value is around 565V. DC link
voltage can therefore vary with the grid voltage. If motor is under load at large voltage drop of
power supply network, motor will not get enough voltage, which causes its deexcitation, slip and
load current increasing. It is necessary to reduce the frequency to a value when there is sufficient
voltage on motor at lower grid voltage, if we want to prevent overheating of the motor and
converter or unwanted fault "Overcurrent". Block
"Voltage controller" and its part kinetic backup
controller (KBC) are made for these cases in UNIFREM 400 XXX frequency converters. Among
other things, it also serves to bypass short-term supply network outages, when the required
minimum voltage U
DC
is maintained with controlled setpoint frequency reduction and by mass
inertia braking.
V
DC
voltage rises due to spillover of the energy from the motor back to the converter during motor
braking, thus at ramp-down or under the influence of external forces to the motor. In this case the
converter has sufficient voltage to correct motor control, but the voltage stress of the power
components increases and there is risk of "overvoltage" fault. Braking resistors and modules that
convert the excess energy into the heat are generally used to limit the V
DC
at drives, where motor
works mainly in the regenerative operation mode (strokes of cranes, lifts, rapid ramp-up / ramp-
down of inertia). It is possible to use the second part of the section
"Voltage controller" -
Dynamic deceleration controller (DDC ), where it is not strictly prescribed the stopping time of the
drive. Dynamic deceleration controller will stop growth of the DC voltage with the setpoint
frequency increasing. Controller will stop to correct it at the frequency maximum and will allow
voltage increasing to the fault level (the same is true even in current limit - MCC).
Each part of the
Voltage controller can be independently turned on / off by parameters:
Parameter ID: 748
SETTINGS
– > CONTROL AND REGULATION – > VOLTAGE CONTROLLER (VC) -> Kinetic
backup (KB)
ID 515
Σ Σ
Setpoint frequency
F
out
dV
DC
dt
ID 516
ID 514
d ω
Is
dt
Σ
V
out
Setpoint voltage
dI
S
dt