Comparative Evaluation of SVPWM Duty-Cycle Calculation Methods for Two-Level and Quasi-Two-Level Flying-Capacitor Inverters

This paper presents a controlled and reproducible comparison between two duty-cycle computation routes for space vector pulse width modulation (SVPWM) applied to three-phase two-level inverters: the classical trigonometric formulation and the algebraic g , h approach. Both methods were implemented in MATLAB/Simulink under identical operating conditions, including the same reference signals, switching sequence, sampling configuration, and spectral evaluation window, enabling isolation of the computational stage effects. The results show that both approaches produce identical duty ratios within numerical precision and exhibit equivalent spectral performance, with individual harmonic distortion indices at the post-filter measurement point remaining practically unchanged, typically around 3.10% (5th), 3.21% (7th), 2.95% (11th), and 2.75% (13th). A significant difference was observed in computational cost, with the mean execution time reduced from 78.7 ms for the trigonometric formulation to 60.6 ms for the g , h approach, corresponding to a reduction of approximately 23% without measurable degradation in waveform quality. Additionally, evaluation of a flying-capacitor leg operating in quasi-two-level (Q2L) mode demonstrated that resolving zero-state redundancy for capacitor clamping does not alter active-vector dwell times or spectral indicators (post-filter THD ≈ ≈ 14.16%). These findings indicate that the g , h formulation provides a computationally efficient alternative while preserving the spectral behavior of conventional two-level SVPWM and that the flying-capacitor arrangement can be incorporated without compromising waveform quality.