For this week’s QSPICE schematic capture, we have “PFCanalogControl” by our friend Oğuzhan Öz, a recent graduate of İzmir Katip Çelebi Üniversitesi and an Electrical Department Team Member of IKC Racing. This is his description of the circuit:
As part of my Electrical and Electronics Engineering graduation project and within the IKC Racing Formula Student team, I successfully completed the production and testing of the 3.5 kW Boost PFC converter, which is the AC-DC input layer of the battery charger of our electric racing vehicle.
In this system with 190-250Vrms mains input, 3.5 kW maximum output power, 45 kHz switching frequency and 400 VDC bus voltage; power factor correction in accordance with IEC 61000-3-2 standards was verified with an oscilloscope by ensuring that the current drawn from the mains was in phase with the voltage. The prototype was tested at output powers of 2.1 kW and 3.05 kW with resistive load, achieving a peak efficiency of 92% and a stable output voltage of 398V.
Design and Fit-Out Process:
-Power solid component values and active component requirements to be selected were determined with theoretical calculations.
-Modeling and closed-loop simulations of the entire system were performed on QSPICE.
-In accordance with the requirements of Continuous Transmission Mode (CCM), the UCC28180 integrated was selected as the controller of the system.
-Price, performance and supply situations in Turkey were analyzed and component selection and schematic design were made.
-EMI/EMC filter design was made for compliance with network standards, safety and noise suppression.
-In Altium Designer, clearance-creepage rules were defined in detail and a 2-layer PCB suitable for high voltage/current was designed; The process was carried out in a way that left no room for error.
-Two high-power Si MOSFETs were used in parallel for cost optimization, reducing conduction losses, and dissipating thermal stress.
-Reverse recovery losses were prevented by using SiC Schottky diode at the exit.
In addition to the protections of the -UCC28180, an active inrush current limiter circuit was designed to limit the high current that the 2240 μF output capacitor would initially draw, incorporating NTC, relay, and RC delay.
-The main power elements (Bridge diode, MOSFETs, SiC diode) were placed on the bottom surface of the board, providing effective thermal management with a single large aluminum heatsink and producing a PCB-specific heatsink.
-Due to the fact that the costs of high-power rheostat were out of budget, I modified the household electric heater (UFO) heaters and prepared a special test load with low-cost 2.1 kW and 3.05 kW stages.
-After PCB production, I performed all typesetting, soldering and mechanical assembly processes individually in the laboratory environment.
This project taught me how to design and build a high-powered board from scratch, as well as real-world dynamics: Being able to think things through and make optimal decisions on a very tight budget, develop alternative solutions for components that can’t be supplied or exceed budget, manage component procurement processes, and communicate directly with manufacturers.
Please send any submissions to me at tim.mccune@qorvo.com (Schematic Capture Post #097)
