is127-overview-and-comparison-board-chargers-topologies-semiconductors-choices-and-synchronous-recti

Conclusions
› Several solutions are existing in the market for On Board Chargers, PFC and
DC/DC stages use many different topologies;
› New topologies are enabled and give a significant benefit by using Wide Bandgap
switches, SiC and GaN;
› Input and output diodes represent a large portion of total losses, due to their
high forward dropout, in both PFC and DC/DC stages:
– In a standard boost PFC, around 33% of total power losses are in the input
bridge diodes;
– In a HV-DC/DC converter, around 45-50% power losses are in the output
Ultrafast Diodes rectification;
› Synchronous rectification may allow good reduction of diodes’ losses in both
stages and boost efficiency of standard topologies:
– This will also greatly reduce the size of heat sinks and save money on
hardware, to compensate higher cost of Mosfet+SR_IC;
› Slow body diodes of most very low RDS-on MOSFETs may reduce the Synch-
Rect advantage, use of SiC or GaN switches can avoid this drawback.
› For input bridges the advantage of using synchronous rectification is much more
evident since the lower operating frequency.
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