Highly efficient server and telecom switched-mode power supplies (SMPS) are required to achieve this. Inevitably, the output power levels of the SMPS have to reach higher levels while maintaining the same form factors. This demanding combination explains why power density is gaining importance. Next to performance, system cost down, as well as modularity, and design simplicity are also in focus. To fulfill those requirements and contribute to a greener and safer world through an overall efficiency of 98 percent, it is crucial to achieve super high-efficiency levels in the power factor correction (PFC). In this context, standard PFC topologies do face a limit, and a trend towards bridgeless PFC topologies like the continuous conduction mode (CCM) totem-pole PFC can be observed. The boost converter in the PFC application has been traditionally controlled in CCM. In this operation mode, the half-bridge switches operate mainly in hard-commutation, which avoids the possibility of using silicon (Si) superjunction (SJ) MOSFETs. If keeping the costs low is the primary driver in the design, Si isolated gate bipolar transistors ( IGBT) with antiparallel silicon carbide (SiC) diode are the preferred option. However, for high-end applications, if Si SJ MOSFETs (such as Infineon’s CoolMOS™ transistor products) are implemented in the totem-pole PFC half-bridge, a different control strategy is required. In that case, the triangular current mode (TCM) extends the conduction time to revert the inductor current and obtain zero voltage switching (ZVS) operation. Nevertheless, due to the high inductor current ripple, interleaving of at least two power stages is necessary. TOTEM POLE OUTPUT CONFIGURATION FULLįull ZVS operation leads to increased efficiency however, the rise of part count requires a higher switching frequency to increase the power density. Furthermore, the control complexity (interleaving with variable switching frequency) raises significantly more. When Si SJ MOSFETs are used in a half-bridge configuration in CCM operation, high efficiency cannot be expected.

Totem pole output configuration