OMD91046 rev D
9
The block diagram in picture 1 shows the UPS subsystems that will be analysed in
the following chapters:
Rectifier/Battery Charger (R)
Inverter
(I)
Battery
(B)
Static Switch: Static Inverter Switch (SSI) and Static Bypass Switch (SB)
Manual Bypass (MB)
NOTE
The description and the diagrams in the various sections always refer to the single
conversion module.
1.1
RECTIFIER / BATTERY CHARGER
The Rectifier/Battery charger converts the AC input voltage to DC voltage, feeding
the inverter and keeping the battery charged.
Picture 4 – Rectifier
The rectifier is based on a full-digital control of the IGBT bridge, which allows to
minimize the harmonics re-injected into the mains and reduces the harmonic distortion
of the current to less than 3%. The trend of the power absorbed by the mains is almost
sinusoidal with a power factor higher than 0,99, thanks to the PFC (Power Factor
Correction) technology.
Each IGBT of the rectifier bridge operates on a battery polarity, and the neutral
conductor of the input line represents the central point.
Current transducer TA1 provides the feedback for the input current waveform, that is
used by the microprocessor to vary the modulation (PWM) of the IGBT’s.
The battery recharging current is automatically limited by the control software, using
the feedback signals provided by the transducers TA3-TA4.
Inductors L3-L4, installed as an OPTION, reduce the current ripple to optimize the
expected battery life.