A Comparative Study Between AI-HM and SPD-HM for Railway Auxiliary Inverter With Pulsating DC Link

High frequency isolated dc-ac converters are becoming popular in on-board auxiliary inverters for railway applications. Compared to conventional fixed dc-link inverter (FDCLI), pulse dc-link inverter (PDCLI) has simpler circuit topology and higher power density, but greatly different control algorithm. This paper is going to study the application possibility of PDCLI for railway auxiliary inverter, and will be concerned with algorithm and their performance comparison between approximately independent hybrid modulation (AI-HM) and six-pulse demodulation hybrid modulation for PDCLIs, including fundamental principle and harmonic performance of output voltage under zero portion effect. Then a piecewise compensation of modulation wave and a carrier phase-shift strategy are proposed to improve the output voltage quality of AI-HM under zero portion effect. The simulation and experimental results, as well as the output filter parameter comparison are provided to verify the theoretical analysis and the feasibility of the proposed strategies.