Modified CBPWM-Controlled Semi-Two-Stage AC-DC Converter for Low-Frequency Pulsed Load

Abstract

Pulsed load poses a significant challenge to the safe operation of the airborne power systems. This article proposes a semi-two-stage ac dc converter with power decoupling function for the airborne power system with pulsed load. The semi-two-stage converter provides two dc ports, in which one dc port with lower voltage is the output port connected to the pulsed load, while the other dc port is the decoupling port and interfaced with the output via a buck converter. A power flow path with single conversion stage from the ac input to the load exists, and the steady-state power can be directly fed to the load. Hence, higher efficiency can be achieved comparing to the conventional two-stage solution. After analyzing the effect of the zero-sequence components in modulation strategy on power flow control, a simple and effective carrier-based pulsewidth modulation (CBPWM) with adjustable zero-sequence injection and variable carriers is proposed to achieve the power regulation of the two dc ports. The detailed operation principle and control scheme of the semi-two-stage ac dc converter are presented, and the effectiveness and feasibility of the proposed solution for pulsed load are validated by simulation and experimental results.