AztecFEC is the first team of electrical engineering undergraduates from San Diego State University to undertake the challenge of designing and constructing a high power density AC-DC converter. Under the guidance of graduate expertise, AztecFEC is near completion of a PFC (Power Factor Correction) boost converter capable of outputting 350 W at 390 VDC in response to an input voltage range of 85-265 VAC. For assurance of system reliability and output consistency, the team is working to meet a handful of performance aspects including high power output efficiency at various loads, inrush current limitations, reduced system harmonics, minimized output voltage ripple, electromagnetic interference filtering, environmental insensitivity, thermal discipline, regulated output current, system safety and shutdown, as well as size economical PCB layout. Our team is working to achieve each of these structured assets by using components of high caliber such as a Vitec boost inductor, a low RDS switching MOSFET, a fast-recovery flyback schottky diode, a high rated output capacitor, a Texas Instruments PFC feedback controller, and a heavy-duty heat sink. In consideration of budget regulations, we work to attain our system's performance traits through improved design iterations, as well as increased attentiveness during the testing and verification process. AztecFEC works continuously on this advanced PFC boost design and plans for it to soon be implemented in real-life applications such as hybrid-electric vehicles, lighting systems, and in industrial machines.
Boost PFC Topology
There are several options for circuit topology when designing an AC to DC power supply. We used the boost converter topology for our design. A boost converter steps up the voltage but it steps down the current. Some boost power supplies incorporate a multiphase boost converter to achieve higher efficiencies, however such a design requires complex circuitry to maintain exact currents which could be very slightly due to mismatches and inconsistencies in real life component values, greatly affecting the performance of the entire system. A multiphase design would also require more expensive lower tolerance components on a larger PCB to achieve desired performance. For these reasons we have chosen to incorporate a single boost phase design which will depend heavily on an advanced microcontroller to maintain high efficiency and consistent operation.The microcontroller senses currents from the bridge rectifier stage and voltages from the boost PFC stage and uses internal feedback topology to control the mosfet in the boost PFC via a gate driver to maintain optimal operation.