Switching losses and harmonic investigations in multilevel inverters

Abstract

Use of conventional two-level pulse width modulation (PWM) inverters provide less distorted current and voltage but at the cost of higher switching losses due to high switching frequencies. Multilevel inverters are emerging as a viable alternative for high power, medium voltage applications. This paper compares total harmonic distortion and switching losses in conventional two-level inverters with multilevel inverters (three-level and five-level) at different switching frequencies. An optimized switching frequency has been obtained for a lower level of total harmonic distortion and switching losses. Diode-clamped, three-phase topology is considered for study. A sinusoidal PWM technique is used to control the switches of the inverter. Simulation study confirms the reduction in harmonic distortion and switching losses as the number of the levels increases.