A Simple PWM Strategy for Three-Level NPC Converters in Aircraft Electric Starter/Generator System With Improved DC-Link Voltage Utilization and Reduced Common-Mode Voltage

• Main Authors: Guo, Feng, Yang, Tao, Yeoh, Seang Shen, Bozhko, Serhiy, Wheeler, Patrick, Diab, Ahmed M.
• Format: Conference Proceeding
• Language: English
• Subjects: Aircraft electric starter/generator; common-mode voltage; DC-link voltage utilization; Energy conversion; Insulation; Insulation life; neutral-point potential balance; Pulse width modulation; Reactive power; Simulation; three-level topology; Voltage
• ISSN: 2329-3748
• DOI: 10.1109/ECCE47101.2021.9595933

Due to the employment of three-level neutral-point-clamped (3L-NPC) converters in the aircraft electric starter/generator (ESG) systems, the pulse-width-modulation (PWM) strategy plays a significant role in the converter-fed PMSM drives. However, the studied ESG system operates under a high modulation index and low power factor conditions during generation mode. It means the neutral-point (NP) voltage imbalance issue will become aggravated. Regarding the reliability and efficiency of high-speed motors, reduced common-mode voltage (CMV) is favorable for the lifetime of bearing insulation. Also, a definite aircraft DC-bus voltage of 270VDC causes deep flux-weakening currents when the machine operates at a high-speed. Additionally, the applied modulation scheme desires short execution-time for the purpose of algorithmic-efficiency. In this paper, a high-performance PWM strategy is proposed to achieve a higher DC-link voltage utilization, CMV reduction, capacitor voltage balance and simple implementation at the same time.