Peak Current Control of an Airborne Phase-Shift Full-Bridge High-Frequency-Link Inverter

The phase-shifted full-bridge high-frequency-link (PSFB-HFL) inverter adopts a DC to sinusoidal-half-wave to sinusoidal-wave conversion structure, which uses few passive components with small parameter values, and the switching frequency of the subsequent stage is low, resulting in low losses. This makes it well suited for airborne applications requiring large currents on the low-voltage side and a high step-up ratio, and it has the potential to realize combined three-phase output. To meet the dynamic-performance requirements of this structure, this paper adopts a peak current control strategy. However, this control method suffers from a sub-harmonic oscillation problem, for which a corresponding slope compensation scheme is designed. Furthermore, based on the small-signal model of the Buck converter, an accurate small-signal model of the PSFB peak current inner loop, based on the average value of the filter inductor current, is derived. Accordingly, a voltage-outer-loop PI controller is designed to implement closed-loop control and improve the dynamic performance of the system. An experimental prototype of a PSFB-HFL inverter with a 28 V DC input and a rated power of 4 kW was built. Experimental results show that the proposed control strategy ensures robust large-signal stability, maintaining high-quality sinusoidal waveforms under varying load conditions, thus verifying the effectiveness and engineering feasibility of the PSFB-HFL inverter.