A Self‐Boost Bootstrap Methods for Powering Floating Gate Drivers of Long‐Loop Commutation Hybrid Device ANPC Converters

ABSTRACT Conventional three‐phase active neutral‐point clamped (ANPC) gate drive circuits require an excessive number of isolated power supplies, which significantly increases system complexity and overall cost. Although bootstrap circuits have been widely implemented to mitigate power consumption and reduce cost, a critical issue persists: Under prolonged commutation intervals, the charge of the bootstrap capacitor is easily depleted, jeopardizing the reliable turn‐on of the high‐side switch. To address these issues, this study proposes design methodologies for bootstrap circuits tailored to the short‐loop and long‐loop commutation modulation schemes within ANPC gate drive systems. Analytical evaluations reveal that the short‐loop commutation modulation strategy forces switches into noncomplementary operating states, disrupting the bootstrap circuit's energy refresh mechanism. This limitation increases reliance on low‐coupling capacitance isolated power supplies (LCIPS) and leads to additional cost escalation. In contrast, the novel ANPC gate driver power supply topology, based on long‐loop commutation modulation, effectively overcomes this limitation. This strategy innovatively implements a cross‐branch bootstrap supply path to ensure stable power delivery to the high‐side switch of the low‐side half‐bridge, leading to a marked decline in LCIPS usage and a higher degree of integration at the system level. A piecewise linear model of the circuit was established in this paper, and simulation results verify the practical performance of the proposed solution.