Axpert MKS-4000/KS-5000 Service manual
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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 Axpert
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.
