ARTronic ARTon Plus series Service Training Manual Download

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1.5.2 PFC3P-R1 IGBT RECTIFIER CONTROLLER BOARD:

This electronic controller board is used to control the 3-Phase IGBT Rectifier at the input stage of the
ARTonPlus Series tansformerless Uninterruptible Power Supplies. By using an IGBT rectifier and this
control board, the nput power factor of the UPS is corrected (to 0.99 at full load) and the input current THD
is improved (less than 5% at full load).

A) Basic functions of PFC3P-R1

It takes the 3-Phase AC nput voltage and current samples coming to the IGBT rectifier and

generates necessary PWM- IGBT driving signals to correct the input pF and to decrease the input
current distortion (THDI). The signals for the control of each phase is generated independently.

It takes the positive and negative DC output voltage samples of the rectifier and adjust the

driving signal pulse widhts to keep these DC voltages constant under normal loading conditions. In case
of overloading of the IGBT rectifier, the rectifier output voltages are decreased to limit the rectifier output
and thus the UPS input current. Different current limiting values for different UPS power ratings can be
set by changing some fixed resistors on PFC3P-R1 board (R63, R124 and R186).

In ARTonPlus Series UPSs, the IGBT rectifier produces a dual polarity DC voltage at its output to

supply the transformerless Inverter stage. The batteries which are the reserve energy supply for the
UPS are directly connected to the rectifier outputs again as two separate battery groups with opposite
polarity. The total number of batteries (12V), in a standard ARTonPlus Series UPS, is 60 (30+30). Thirty
batteries are used for one polarity and the other thirty are used for the opposite polarity. The float
charging voltage value for 2X30 batteries is +/- 405V dc. Therefore the no-load output voltage of the
IGBT rectifier is adjusted to +/- 405V (810V dc total).

During normal operation, IGBT rectifier supplies power to the Inverter and charges the batteries at the

same time. PFC3P-R1 board takes the battery current samples and adjusts the IGBT driving signals to
limit the maximum battery charging current to a pre-adjusted safe value suitable for the VA rating of the
batteries. Therefore the output voltages of the rectifier change in accordance with the battery voltages
during the charging period of the batteries.

PFC3P-R1 board accepts some control signals from UPS Main Controller Board (P3MC-R5)

and performs the following functions:

Boost Charge: During boost charge, the rectifier output voltages are increased to the boost

charging voltage level for the batteries and kept at that level until the end of the boost charging
period. At the end of the boost charging period, the rectifier output voltages are decreased to the
float charge level again. The boost charge voltages for positive and negative battery groups are
adjusted separately on PFC3P-R1 board.

Rectifier Start: When the P3MC-R5 board sends a ‘’Rectifier Start’’ signal to the PFC3P-

R1 board, the input contactor (K1) is energized and the IGBT rectifer starts operating.

Battery Test: When the P3MC-R5 board sends a ‘’Battery Test’’ signal to the PFC3P-R1

board, the rectifier output voltages are both decreased to a preadjusted value and kept at that level
until the end of the battery test procedure.

On the other hand, PFC3P-R1 board sends the following signals to the UPS Main Controller Board:

‘’Rectifier Fault’’

‘’ Positive battery group current sample (either charging or discharging)

‘’ Negative ‘’ ‘’ ‘’ ‘’ ‘’

‘’ Negative battery voltage sample’’