Performance of Nine-Level Transformerless Photovoltaic Powered Inverter (TPVPI) Using Technique of Equal Maximum Phase Delay Time

A simple inverter is constructed by some switching components that connected in half bridge or full bridge circuit. The switching component can be a metal oxide semiconductor field effect transistor (MOSFET), transistor or insulated gate bipolar transistor (IGBT) which is driven by simple technique of pulse wave modulation (PWM). This technique generates a square alternating current (AC) waveform but it is still AC pulse wave with rich harmonic production and it is not good for the long life of electric devices. A multilevel inverter is better than the previous inverter. Some techniques have been developed to generate multilevel inverter for main objective to generated AC waveform toward sinusoidal waveform and reduce the harmonic. Also, an inverter is constructed by a transformer which is big in size and produce losses and it can increase the harmonic. This paper presents a nine-level transformerless photovoltaic powered inverter (TPVPI) system using technique of equal maximum phase delay time. It is constructed by two main elements. The first is photovoltaic (PV) module as a main direct current (DC) voltage source and the second is four full bridge circuits in cascaded connection. The proposed technique is that each two MOSFETs for cross position in the same full bridge have a same pattern of pulse wave for the period of 0.02 s. It has a phase delay time of 0.00111 s for generating the nine-level AC waveform.