Wide CCM region modulation technique with low current ripples for impedance source inverters

Abstract

This study proposes a new pulse‐width modulation (PWM) technique for impedance source inverters, namely non‐tangential maximum boost control (NTMBC) technique at which the voltage gain of inverter in high‐modulation indices is higher than those of three traditional carrier‐based sine wave PWM techniques (simple boost control, maximum boost control (MBC), maximum constant boost control). In the conventional MBC technique, the duration of shoot‐through (ST) states varies from one switching cycle to another. This drawback results in a greater low‐frequency output frequency‐dependent ripple on both inductor current and voltage of the capacitor. Using the proposed NTMBC the ST duty cycle ratio can be kept approximately constant at each switching cycle. Consequently, in comparison with MBC, the peak value of inductor current, as well as its ripple, is noticeably low in the proposed NTMBC. Additionally, the source and ST currents in the proposed NTMBC method are less than those in the conventional MBC method. Using the proposed ST states does not have a considerable effect on total harmonic distortion (THD) of output waveforms and the THD in the NTMBC method is in a reasonable range. The proposed NTMBC method is validated using an experimental set‐up.