Light Load Efficient Silicon Power Converters Based on Wide Bandgap Circuit Extensions

Abstract

A power electronics converter is generally designed for a specific load condition. However, depending on the applications and its mission profiles, the operating load conditions can be distinctly lower than the specified ones (PV cell under shading conditions, etc.). During this light load condition, the efficiency diminishes considerably, especially if Si–IGBT devices are considered within the power circuit. This study explains a light-load circuit extension based on wide-bandgap (WBG, silicon carbide and gallium nitride) material, which can improve the light-load efficiency and transient response of the conventional IGBT-based active rectifiers and inverter. Such an additional circuit extension is, in general, associated with additional cost. Numerous factors, such as the power electronics application itself, mission profiles, converter power rating and sizing of passive components, etc., can shift the break-even point of the upgraded power electronics system in terms of time. Therefore, a profound investigation of the relevant areas of interest is required in advance to ensure the most efficient amortization of the additional incurred costs of the applied circuitry. A 125 kW 3-phase six-switch inverter is discussed to highlight relevant effects in light-load operation that must be considered for final product design.