A double T‐type H‐bridge reduced switch multilevel inverter for a wide range of DC voltage variations

Abstract

Renewable energy sources are subject to input source uncertainties, which can negatively impact output voltage THD. Having a high number of voltage levels in multilevel inverters (MLIs) with minimum components is cost‐effective. This paper proposes a new structure, Double T‐type H‐bridge (DTH) module, that can produce 9, 13, 17, 19, 21, and 25 levels using reduced components. Switching patterns in MLIs refer to the way in which the power switches are controlled to generate the desired output voltage waveform. As a result, having more switching patterns make the converter flexible to produce voltage levels in the face of input source uncertainties. The DTH structure provides new switching patterns, making it possible to produce levels when the difference of capacitor voltage is negative in a positive cycle or vice versa. This paper presents a new algorithm based on nearest level control to order voltage levels in ascending order, which improves output THD significantly. This topology brings a lower switching state that is linked to switching losses directly compared to the topologies with the same number of power switches. The DTH module's performance is evaluated through graphical analysis, simulations, and experimental results in symmetrical, asymmetrical, and load change conditions.