1 Scope and Purpose

This document serves as a user guide for the new 4kW Phase-Shifted Full-Bridge (PSFB) with Current Doubler Rectifier (CDR), DC-DC converter demonstrator application board utilizing the dsPIC33C DSP digital signal microcontroller. The PSFB-CDR board is a 800V to 12V DC-DC converter intended to support power conversion applications from HV 800 VDC battery to 12 VDC Electric Vehicle bus. The DC-DC converter uses a highly efficient and wide input voltage range, Phase-shifted-full-bridge topology which demonstrates partial to full ZVS (Zero Volts Switching) at the primary HV SiC full bridge. The option to add an external shim inductance is available to tune peak efficiency operating point. The secondary side uses robust current doubler topology which reduces the current requirements for system magnetics. Smart reverse current detection is implemented in firmware to safely operate the current doubler stage and automatically enable synchronous rectification to increase efficiency. In light load conditions, switching losses at primary side full bridge are quite significant; therefore, Burst mode is implemented to increase system efficiency.

The user guide provides an in-depth review of the hardware, converter theory of operation and an overview of the digital control implementation. Test results and measurements for this design are covered in the corresponding operational manual document. The converter is designed as a dual-rail solution, offering redundancy and maximizing light load efficiency. Each rail can transfer 1700W continuous and 2700W peak power for short durations (> 10s with 20s breaks) outputting a total power of over 4000W to the 12 VDC bus.