Three-phase, four-wire PWM rectifier applied to variable frequency AC systems in airplane electric grid under fault conditions

This paper analyses the use of PWM rectifier in variable frequency, three-phase, four-wire AC system as present in modern airplanes. The converter is analysed in terms of reliability for maintaining the correct operation of the symmetrical high-voltage DC bus and the power distribution among the phases of the AC source in case of fault. The paper discusses the standards for voltage and current quality and testing in aircraft environment. The PWM three-phase four-wire rectifier with double DC outputs is considered. Based on simulation, the topology is analysed regarding the stress on the circuits and the impact on the AC grid. It is shown the necessity of maintaining balanced DC load during the normal operation and also under fault in order to help preserving the AC power quality.