Investigation of reactive power generation capability of H6-II type transformerless ınverter with different modulation methods

In this study, an investigation of reactive power generation capability of a single phase H6-II type transformerless inverter with modulation techniques, modulation signals (MS), carrier signal (CS) and modulation strategies (MStr) is made. Firstly, performances of sinusoidal pulse width modulation (SPWM) and third harmonic injected pulse width modulation (THI-PWM) technique mods (Mod I-VI) created by conventional modulation strategy and several modulation and carrier signals on standalone H6-II type inverter presented separately and comparative analysis is realized. After that, switching signals generated by the means of the mods (Mod I-XVI) created by several modulation strategies (conventional, conventional-discrete, improved and improved-discrete) based on SPWM and hybrid-PWM (HPWM), modulation and carrier signals are applied into switches of grid connected H6-II type inverter. For each mod, active and reactive power injection capability of the inverter is investigated. Finally, common mode voltage (V_CM) and leakage current (i_cm) characteristics are examined with depending on mods constituted by taking account of power injection (active or reactive), modulation technique (SPWM or HPWM), modulation strategy (MStr- 1-6), modulation signal (MS 1-2), carrier signal (CS 1-6) types. For different parasitic capacitor (C_fv) values, behavior of the leakage currents (i_cm) is observed.