Modulation and Power Losses of a Stacked Polyphase Bridge Converter

摘要

This paper presents and analyzes the modulation and power losses of a stacked polyphase bridge (SPB) converter—a modular topology potentially allowing increased compactness and fault tolerance for automotive drive systems. In particular, an analysis of the impact of modulation on the harmonic content of the dc link current of the converter is made. Due to the possibility of using higher switching frequency devices, the current ripple of the SPB converter can be smaller than that of the two-level three-phase converter with the same dc link capacitor. However, higher switching frequency will result in higher switching losses per fundamental period. Therefore, this paper also investigates the reduction in the dc link ripple current achieved by interleaving the modulation among the different converter submodules. The amount of reduction can be predicted using an analytical model whose results are demonstrated to be in good agreement with the results from the corresponding simulations and an experimental setup. Furthermore, based on the experimentally verified analysis, the SPB converter in a typical automotive drive system is discussed and compared with a conventional two-level three-phase converter.