Recently, due to the growing concern about the harmonic pollution of power distribution systems and the adoption of standards such as IEEE 519 and IEC 1000-3-2, there is a need to reduce the harmonic contests of the AC line currents of power supplies. To meet this requirement, a power supply is generally composed of a power factor correction (PFC) stage and a DC/DC power conversion stage. To obtain power factor correction, the topology generally used is the boost converter, which presents an output voltage greater than the input voltage. Thus, the input voltage of the DC/DC power conversion stage is also very high. The conventional converters applicable to these high power applications operating from the high input voltage has been proposed such as the full-bridge converter, the series connection of switches, and the neutral point clamped (NPC) converter. However, these converters still have some serious problems.
To overcome these drawbacks, a novel three-level DC/DC converter is proposed. Its switch voltage stress is only one-half of the input voltage. Nevertheless, all input voltage is applied to the transformer primary side. Therefore it features a low voltage stress, small current stress and high efficiency compared with the conventional circuits. It is especially well suited for high power converters operating from high input voltage.
Experimental results from a 100kHz, 200W/600Vdc-48Vdc prototype, applicable to the power supply for a telecommunication system, are presented and tested to validate the proposed converter
