Packed U Cell Seven Level and Five Level Inverter Topologies for Renewable Energy Applications

Abstract

The multilevel inverter (MLI) is a power electronic circuit applied for power and voltage applications. It has the advantages of minimum total harmonic distortion (THD), less voltage stress on the switching devices, fewer switching losses, and a smaller size of passive filters. These high-level inverters are applied in applications like AC drives, FACTS, and in the field of renewable energy. There are various inverters for such applications. A PUC multilevel inverter contains fewer components, fewer switching losses, and easy-to-balance voltage on capacitor sides. In this paper, the performance of the transformer less seven-level inverter and the five-level inverter is analyzed. The sinusoidal pulse width modulation (PWM) has been used with this PUC-based structure. The new control strategy is designed to reduce harmonic contents and low filter ratings. A relative analysis is carried out to focus on the superiority of the recently developed packed U-cell topology. The performance of packed U-cell, seven-level, and five-level inverters has been compared. These types of inverters consist of two power switches and a single capacitor to make this inverter effective. The PUC 7 inverter contains a lot of sensors and other control components to balance the voltage on the capacitor side by one-third of the input voltage, so the structure becomes complex. While PUC 5 is sensor less technology, there is no voltage balancing issue and no complexity found in this inverter. In PUC5, the only level is low, but it is very easy to interface with grids and other devices. So it is the most preferable as compared to PUC7. The performance analyses of these inverters have been verified through simulation.

Keywords

• multilevel inverter
• packed u-cell
• sensor-less controller
• renewable energy