Voltage balance evaluation strategy for DC-port faults in centralized aircraft ground power unit based on three-level neutral point clamped cascaded converter

An aircraft ground power unit (GPU) can replace the auxiliary power unit (APU) in an aircraft while the aircraft is parked at an airport. Therefore, the problems associated with the oil consumption and air pollution of the APU are solved. However, the GPU is faced with challenges in terms of utilization, power quality, and fault tolerance. Thus, a novel centralized aircraft GPU based on a three-level neutral point clamped cascaded converter (3LNPC-CC) is introduced in this paper to improve utilization and power quality. Furthermore, an evaluation voltage balance strategy is proposed for the DC-port fault tolerance of the 3LNPC-CC. In addition, both the modulation of the phase shift pulse width modulation (PSPWM) and the control of the double closed loop are used in the 3LNPC-CC. A simulation platform including the control, modulation, and fault tolerance of the system is established to verify the feasibility and performance of the proposed GPU. In particular, it is used to evaluate the voltage balance strategy for DC-port faults. Moreover, a prototype of the GPU and relevant experiments are completed to verify the correctness and feasibility of the system and the strategy.