Nautel NAB05E, Технические инструкции

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48 VOLT BATTERY CHARGER
NAB05E
Page 2-6
01 September 2004
A1R13/R15 and A1R14/R16 as the output of the
thyristor control circuit. Since the linear ramp
waveforms occur at twice the frequency of the ac
source voltage and their dc reference starting point
coincides with the start of each half cycle of this ac
voltage, the level of the control voltage applied to
A1U3B's non-inverting input will determine when,
during each half cycle of the ac source voltage, the
positive voltage pulses will occur. Any increase in
the control voltage will cause the positive voltage
pulses to occur later, while any decrease will cause
them to occur earlier. Refer to figure 2-1 for timing
information.
2.3.10 FULL-WAVE RECTIFIER: The
switched full-wave rectifier circuit consists of
thyristors Q1/Q2, which are connected as a full- wave
rectifier; free wheeling diode CR1, inductor L1 and
the 150 volt ac, centre tapped secondary winding of
power transformer T1. The centre tap of T1's
secondary winding is connected to TB2-1, thru
inductor L1 as the negative voltage terminal for
voltages developed by the switched full-wave
rectifier. The 75-0-75 RMS ac voltage from T1's
secondary winding is applied to
the anodes of thyristors Q1 and Q2, with the anode of
each 180 degrees out of phase with the other.
Whichever thyristor has a positive voltage on its
anode will turn on when the positive voltage pulse,
from the thyristor turn-on control circuit, is applied to
their control gates. The conducting thyristor will
remain turned on until its anode goes negative.
Current pulses will be applied to the batteries being
charged each time the anode voltage of the conducting
thyristor exceeds the battery terminal voltage.
Inductor L1 and the internal capacitance of the battery
will smooth these current pulses to an average value.
The timing of the positive voltage pulses, applied to
the thyristor control gates, is controlled, as described
in paragraphs 2.3.8 and 2.3.9, to ensure they occur
during the portion of each half cycle that will maintain
the average dc current at the desired charging current
level. Freewheeling diode CR1 prevents oscillation in
inductor L1 during abrupt changes in current flow
thru L1.