A Dynamic Gain Modulation Scheme for Differential Inverters With Enhanced Harmonic Performance

To adapt to the application scenarios of low-voltage DC sources, the traditional voltage source inverter requires additional pre-boost circuits for their utilization in low voltage applications. This led to inception of differential inverters which constitute a topology capable of integrating both boost and inversion functions within a single stage, making them a promising alternative to two-stage inverters. However, the existing static gain modulation scheme (SGMS) for differential inverters overlooks the nonlinear phenomena induced by the dynamic variation of converter gain, causing inevitable harmonic distortion in the output voltage. This paper discusses the nonlinear harmonic distortion and proposes a dynamic gain modulation scheme (DGMS) for differential inverters. This scheme models both Boost-type and Buck-Boost-type differential inverters using a unified mathematical model. A more accurate modulation function is adopted by employing approximate solutions to the state equations, effectively reducing harmonic components in load voltage compared to SGMS. The experiment results validate that DGMS significantly lowers Total Harmonic Distortion (THD) and effectively enhances the quality of the output voltage waveform, demonstrating its considerable potential for practical applications.