A Two-Level Parallel Similar-Interleaved Integrated Space Vector Modulation Strategy with Optimized Comprehensive
Du Yan1, Liang Jing1, Cai Zhicheng1, Yang Xiangzhen2, Su Jianhui2
1. School of Electrical Engineering and Automation Hefei University of Technology Hefei 230009 China; 2. Research Center for Photovoltaic System Engineering of Ministry of Education Hefei 230009 China
Abstract：Paralleling two three-phase inverters is a straightforward approach to expanding system capacity in high-power power electronics. Interleaved paralleling with carrier phase shift can cancel output current ripples of two inverters, significantly reducing the total harmonic distortion (THD) of grid-connected current and optimizing power quality. However, conventional interleaved systems typically adopt two-level space vector modulation (SVM), which is limited by insufficient vector degrees of freedom and struggles to meet multiple objectives such as common-mode voltage suppression, zero-sequence circulating current optimization, and switching loss reduction. Practical implementations often face issues, including common-mode voltage peaks reaching 1/2 of the DC bus voltage and zero-sequence circulating current Root Mean Square value exceeding the rated current, severely degrading system efficiency and reliability. This paper proposes a similarly interleaved integrated space vector modulation (SISVM) strategy. By leveraging the advantages of vector degrees of freedom, a selection method for three-level vector sequences was established. The method incorporates three key innovations: (1) A multi-objective constrained vector selection framework is established with constraints including the feasibility of interleaved pulse generation, zero-sequence circulating current suppression, common-mode voltage reduction, and efficiency improvement. (2) The first large sector is re-divided into six sub-sectors, and the equivalent three-level vector sequences are accurately screened out with small zero-sequence circulation and low switching losses within each sub-sector. (3) A carrier- phase-shifted equivalent three-level space vector modulation technique is adopted to break through the vector degree-of-freedom limitation of two-level space vector modulation, expanding the degrees of freedom of interleaved paralleling. First, an equivalent three-level system model of paralleled inverters was constructed. This model was used to investigate the effects of different vector sequences on common-mode voltage, zero-sequence circulating current, output current ripple, and switching losses. Accordingly, appropriate vector sequences were selected to optimize performance in each sub-sector. Then, quantitative calculation methods for output current ripple and zero-sequence circulating current in the two-phase stationary coordinate system were presented. The SISVM strategy can reduce zero-sequence circulating current and switching losses more effectively than the conventional TLSVM strategy, particularly under medium-to-high modulation indices. Finally, a parallel system of two 3 kW inverters was built using a DSP+Starsim platform. Comparative experiments were carried out on four modulation strategies: ISVM, AZVPWM, TLSVM, and SISVM. Under different modulation ratios, performance metrics such as common-mode voltage, zero-sequence circulating current, output current THD, system efficiency, and program resource utilization were compared. Results showed that the common-mode voltage can be suppressed within Vdc/6 by the SISVM strategy. Without an additional increase in output current harmonics and hardware resources, the zero-sequence circulating current and switching losses in interleaved parallel modulation can be further reduced by the SISVM strategy. The effectiveness of the SISVM modulation strategy in terms of zero-sequence circulating current and switching losses is further demonstrated. The system's comprehensive performance can be optimized.
杜燕, 梁晶, 蔡志成, 杨向真, 苏建徽. 一种综合性能优化的两电平并联类交错一体化空间矢量调制策略[J]. 电工技术学报, 2026, 41(2): 622-634.
Du Yan, Liang Jing, Cai Zhicheng, Yang Xiangzhen, Su Jianhui. A Two-Level Parallel Similar-Interleaved Integrated Space Vector Modulation Strategy with Optimized Comprehensive. Transactions of China Electrotechnical Society, 2026, 41(2): 622-634.
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