SPF 5000 ES Service manual
5
3.2 DC TO DC dual converter (Full bridge converter)
The full bridge topology is a transformer isolated forward-mode regulator. Unlike the Fly-back transformer, the
push-pull transformer does not store any energy and output current is drawn when either power switches (S1-S4
or S2-S3) is conducting. P1 is the battery, P2 is the BUS
This is dual converter, it means that battery can feed power to BUS and also BUS can charge the battery. And it is
an open loop control: the transformer N1:N2 is 1:8, when the battery voltage is transformed through the converter
to more than the BUS voltage, the battery discharge power to the BUS, or the BUS can charge the battery.
Figure 3.2 DC TO DC dual converter
3.3 Inverter (Full bridge)
The Inverter circuit (Figure 3.3) and PWM control are can both active under battery mode and line mode. In line
mode, the inverter can convert power from gird to BUS for charging .The Inverter circuit of SPF 5000 ES series is
based on a full-bridge circuitry and its output is driven by photo-couplers. The photo-couplers are capable to drive
high energy and high speed power of MOSFET and IGBT with independent high and low referenced output
channels.
To construct a high frequency PWM inverter, the drivers receive switching signals from PWM generation circuit
through a pair of photo-couplers to trigger the upper IGBT and the lower IGBT alternately. The output of IGBT's is
filtered by an LC circuit to reduce the o/p voltage harmonics distortion.
Figure 3.3 Full-bridge topology
