Families of Forward Converters Suitable for Wide Input Voltage Range Applications

A topology approach is proposed to derive forward converters suitable for wide voltage range applications. A unified forward switching cell concept from the core principle of forward conversion is proposed with three cells given, named as forward positive cell, forward negative cell, and forward composite cell. All cells consist of active switch, diode, transformer, and comprehensive demagnetizing voltage source. By utilizing different subcircuit to balance the voltage of the comprehensive demagnetizing voltage source, various types of forward switching cells, including RCD type, active-clamping type, LCDD type, flyback-integrated type, and independent-circuit type, are deduced from the traditional forward converters with topology derivation rules given. Families of forward converters, including existing ones and novel ones, are constructed as examples. The forward converters built in such a way illustrates features such as recycle of leakage and magnetizing energy, low voltage stress on devices, etc. The proposed method is extended to flyback converter family to further justify the feasibility. An input-series interleaved RCD forward converter and an active-clamping forward converter are analyzed in detail and verified with experimental results.