31-05-2012, 02:18 PM
Design of a 28 V-to-300 V/12 kW Multicell Interleaved Flyback Converter Using Intercell Transformers
Design of a 28 V-to-300 V12 kW Multicell Interleaved Flyback.pdf (Size: 1.01 MB / Downloads: 63)
Abstract
A low-input voltage high-power realization is presented
with the aim to demonstrate the feasibility and the interest of
topologies using intercell transformer. They constitute a promising
option to interleave converter stages, and therefore, can answer to
the specifications considered in this paper. These specifications require
a galvanic insulation and the chosen topology is the Intercell
Transformer (ICT) flyback converter, previously proposed by the
authors. In a first part, the operating principle of the ICT flyback
converter is recalled. The second part presents briefly themain features
of the intercell transformer design, more precisely described
in a previous paper. This part includes a discussion about the choice
of the cell number.
INTRODUCTION
INTERLEAVED multicell converters are now widely used,
especially for low-voltage/high-current applications. Among
which voltage regulator module (VRM) is probably the most
prominent example. Other emerging applications fields of these
topologies are provided by systems connected to low-voltage energy
sources and storage elements as photovoltaic (PV) arrays,
fuel cells, batteries, ultracapacitors [1]–[5], especially when
these systems are onboard and weight and space savings are
required.
GENERAL FEATURES OF THE DESIGN
ICT
The design of ICT is somewhat specific especially because of
the shape and the distribution of the currents among the different
windings, as explained in [10]. This is summarized in Fig. 5
related to transformer TR2 . Since planar transformers are to be
used, the four windings should be stacked vertically with an
interval of height ha separating the windings of one phase from
the windings of the other phase. The interval allows choosing
the coupling between phases and thus the ICT common-mode
inductance (the storage inductance).
Number of Cells
The choice of the number of cells is another crucial point of
the design. Using the method described in [10], several designs
have been made for different number of cells and switching
frequencies. This preliminary study has been made with the
specifications of the application described in the last section
of the present paper, namely Vin = 28 V, Vout = 300 V and a
power of 12 kW. Planar cores are a priori chosen, because they
are compatible with the high power density specification.
CONCLUSION
The topology and the operating mode of the ICT flyback converter
have been first recalled. This structure is an attractive
solution for answering to specifications requiring the interleaving
of insulated power stages. The ICT flyback converter needs
only one magnetic component per cell, and avoids the drawbacks
of the single-cell flyback converter. To confirm its interest, the
design and the realization of a 28 V–12 kW demonstrator is
proposed. The design and the experimental tests of one cell
are first made. Then, an advanced packaging of the complete
eight-cell converter is defined and realized. The experimental
results show the need of some technological improvements, but,
above all, show the real viability of the proposed topology.