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A Bridgeless, Quasi-Resonant ZVS-Switching, Buck-Boost
Power Factor Correction Stage (PFC)
ABSTRACT:
This paper presents a new bridgeless, quasi-resonant zero voltage switching
(ZVS), buck boost power factor correction stage (PFC). The elimination of the
input rectifier leads to a higher level of efficiency, especially at low input voltages.
Several bridgeless PFC circuits already exist, but the proposed new converter also
achieves ZVS in a wide operating range with significant reduced switching losses
and some other benefits.
EXISTING SYSTEM:
 Due to the elimination of the full-bridge input rectifier, the components in the
current path are reduced and this results in fewer conduction losses.
 There are several bridgeless PFC topologies already published, for example the
“Basic Bridgeless Boost PFC”, “Dual Boost Bridgeless PFC”, “Totem-Pole
Bridgeless Boost PFC” or “True Bridgeless PFC Converter”.
 In a power supply, these PFC stages are often followed by an isolated DC-DC
converter with a transformer to achieve an isolated output with a lower output
voltage.
 The “True Bridgeless PFC Converter” is different.
 This converter could be extended to an isolated converter without adding an
additional DC-DC stage.
DISADVANTAGE:
 A converter soft start with completely discharged output capacitor.
 Overvoltage across the switch during turn off.
CIRCUIT DIAGRAM:
(“True Bridgeless PFC Converter”)
PROPSED SYSTEM:
 This circuit always offers a low impedance commutation path for the input
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inductor current, meaning there is no overvoltage across the switch during the
turn-off transition.
This PFC is a special buck-boost converter.
A startup without additional component stress is possible.
It should be noted that the converter voltage gain has no similarities with a
conventional buck-boost converter.
Compared to the known bridgeless topologies, the proposed topology has a
negligible inrush current.
The circuit makes zero voltage switching possible.
ADVANTAGE:
 Inrush current limitation is not necessary.
 The switching losses are reduced significantly.
CIRCUIT DIAGRAM:
(the bridgeless, quasi-resonant ZVS switching, buck-boost
power factor correction stage (PFC))
References:
[1] D. Miller, R. Kennel, M. Reddig, “New methods for digitally controlled
bridgeless PFC converters”, Proceedings of the Intellec 2013, Hamburg, Germany,
13-17 Oct. 2013.
[2] S. Cuk, “True bridgeless PFC converter achieves over 98% efficiency, 0.999
power factor”, Power Electronics Technology Magazine, July 2010.
[3] S. Nigsch, S. Cuk, K. Schenk, “Analysis, Modeling and Design of a True
Bridgeless Single Stage PFC with Galvanic Isolation”, Proceedings of the APEC
2015, Charlotte, NC, 15-19 March 2015.