Download zvs-pwm full-bridge converter with reduced conduction losses

ZVS-PWM FULL-BRIDGE CONVERTER WITH REDUCED
CONDUCTION LOSSES
ABSTRACT
The dc–dc zero-voltage-switched (ZVS) pulse-width modulated (PWM) fullbridge (FB) converter is widely used in industry for dc–dc power conversion. With ZVS
operation, it is possible to operate the converter with high switching frequency using
MOSFET so that its size can be reduced without generating excessive switching losses.
Under lighter load conditions, however, the converter switches cannot turn ON with ZVS
as there is insufficient current to discharge their output capacitances. Many researchers,
therefore, have proposed variations on the basic ZVS-PWM-FB topology to extend the
load range of ZVS operation. Some of these topologies use extra passive components to
generate current in the converter’s primary side to discharge the output capacitances of
the switches. This additional current, however, creates conduction losses that offset gains
in efficiency due to ZVS operation so that the net converter efficiency is less than
expected.
The proposed converter is a ZVZCS PWM converter, but has an active auxiliary
circuit connected to the lagging switch leg of the converter to help these switches turn
ON with ZVS. The proposed converter, therefore, has all the benefits of ZVZCS
converters. And also a new soft-switching pulse-width-modulated (PWM) full-bridge
converter is proposed. The proposed converter has zero voltage switching (ZVS) in all its
switches with fewer conduction losses than other ZVS-PWM full-bridge converters, due
to a novel auxiliary circuit scheme.
PROBLEM IDENTIFICATION

High switching stress

High Conduction losses so the power factor and efficiency gets reduced

Switching losses are more

High Leakage current

More components are required

High cost
ADVANTAGE OF PROPOSED SYSTEM

Soft switching are implemented

Less switching stress

Conduction losses is reduced

Duty cycle loss can be minimized

Leakage inductance in the power transformer can be made as low as possible

Components can be implemented with devices that are lower power rated

Fewer components required so the cost will be low.
ZVS
CONVERTER
RECTIFIER
AC input
GATE DRIVER
+12
v
-12v
Power supply
+5
v
MICROCONTROLLER
Load
SIGNAL
CONDITIONI
NG