Minimum Volume Design of a Forced-Air Cooled Three-Phase Power Factor Correction Stage for Electric Vehicle Chargers

This paper describes a volumetric design study, which evaluates switching loss, thermal management and the physical dimensions of all major passive components, including the electromagnetic interference (EMI) input filter, boost inductors and DC-link capacitors, for a three-phase low-voltage power factor correction (PFC) stage for electric vehicle chargers. The proposed design study considers three popular three-phase pulse width modulated (PWM) active front-end AC-DC topologies: the standard 2-level industry solution, the 3-level neutral point clamped (NPC) converter and the 3-level T-type (T 2 C) converter. For each topology, the pulsating switched phase-leg voltages are computed for both continuous space vector pulse width modulation (SVPWM) and 60° discontinuous pulse width modulation (DPWM). Based on the switched phase-leg voltages, the impact of the modulation technique and switching frequency on switching loss, heatsink and passive components is thoroughly analyzed. For an accurate estimation of the switching loss, the switching energies of state-of-the-art silicon carbide (SiC) MOSFETs have been measured at corresponding operating points. Results are presented for an 11 kW, 800 V active power factor correction (PFC) application.