WEG MVW3000 A0040 V023, User Manual

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3-8 | MVW3000
3
Product Characteristics
3.4 CONTROL
The MVW3000 has protections against overload, short circuit, current limit, under and overvoltage,
overtemperature, ground fault and monitoring of the individual faults of each power cell. The control type can be
selected by the user between: scalar control (constant V/f ratio) or vector control (sensorless or with feedback by
speed sensor).
The MVW3000 inverter uses the PWM modulation technique (Pulse Width Modulation); from the direct voltage
of each independent DC links, it synthesizes an alternate voltage with variable frequency and amplitude at the
output terminals. The medium voltage level is obtained at the converter output terminals from the association of
“n” low voltage cells in series. For further information on the central control, refer to
Section 4.3 CONTROL RACK
on page 4-6 .
HMI
MVC4 PIC
PS24
24 V 0 V
MVC3
F.O.
F.O.
U1
U2
Wn
FOI3.02
Input BT (220 V 1~ or 3~)
Figure 3.8: Central control simplified diagram
The output currents of the three phases (motor currents) are measured using the Hall-effect CTs (current
transformers). Those current signals are sent to the central control board. The measurement is done for indication
on the HMI and for implanting the converter control and protection functions.
The pre-charge is done by means of an auxiliary winding of the input transformer, which is driven by the inverter
auxiliary supply circuit via current limiter elements. In order to prevent high starting current levels on the inverter,
activation of protection systems or even damages to its own components, the cell capacitor pre-charge must be
done through and auxiliary winding of the input transformer. The auxiliary supply is also responsible for feeding
the control circuit and fans for the panel cooling.