2DoF BTSPWM for Parallel Current Source Converter with Improved CMV and Harmonic Performance

The three-phase current source converter (CSC) can work as a buck-type rectifier or boost-type inverter with a wide voltage regulation range, which is a promising solution for single-stage power conversion. Parallel connection of power converters is a popular choice to increase the power rating and system reliability. Meanwhile, supervisor harmonic performance can be achieved through interleaving operation. Carrier-based sinusoidal pulse width modulation (SPWM) is widely adopted for interleaved converters due to its easy and modular implementation features. In this paper, a 2 degree-of-freedom (2DoF) optimization-based bi-tri logic SPWM (BTSPWM) is proposed for a parallel CSC system, where the harmonic spectrum of output and common-mode voltage (CMV) is analyzed comprehensively. The carrier shift angles are optimized to improve the CMV and harmonic performance for interleaving BTSPWMs. Meanwhile, the optimized zero-state replacement (ZSR) method can be combined with 2DoF modulations to further reduce the CMV. The effectiveness of the proposed method is verified on a 2-CSC parallel system with experiment results.