A Generalized Multilevel Inverter Based on T-Type Switched Capacitor Module with Reduced Devices

Yaoqiang Wang,Yisen Yuan,Kewen Wang,Jun Liang,Gen Li,Tianjin Chen

doi:10.3390/en13174406

Abstract

Conventional multilevel inverters have problems in terms of their complicated expansion and large number of devices. This paper proposes a modular expanded multilevel inverter, which can effectively simplify the expansion and reduce the number of devices. The proposed inverter can ensure the voltage balancing of the voltage-dividing capacitors. The cascading of the T-type switched capacitor module and the step-by-step charging method of the switched capacitors enable the inverter to achieve high output voltage levels and voltage gain. In addition, the inversion can be achieved without the H-bridge, which greatly reduces the total standing voltage of the switches. The nine-level inverter of the proposed topology can be realized with only ten switches, obtaining a voltage gain that is two times larger. The above merits were validated through theoretical analysis and experiments. The proposed inverter has good application prospects in medium- and low-voltage photovoltaic power generation.

Highlights

The development of solar energy has attracted more and more industry attention in recent years, such as photovoltaic power generation
Conventional Multilevel inverters (MLIs) can be predominantly divided into the following types: neutral-point-clamped (NPC), flying capacitor (FC) and cascade H-bridge (CHB)
In order to reduce the use of devices and control the complexity, this paper proposes an expandable MLI based on the T-type switched capacitor module (TSCM)

Summary

Introduction

The development of solar energy has attracted more and more industry attention in recent years, such as photovoltaic power generation. Multilevel inverters (MLIs) have been extensively studied and used because of their advantages of improved power quality, reduced device voltage stress, and reduced filter requirement, etc. Conventional MLIs can be predominantly divided into the following types: neutral-point-clamped (NPC), flying capacitor (FC) and cascade H-bridge (CHB). These inverters have been widely used due to their advantages such as low device voltage stress and low switching frequency [3,4,5]. In order to obtain higher voltage levels than conventional topologies, a new NPC inverter was proposed in [7]. The critical problem of voltage balance still exists even if the control algorithm is simplified [10]. The mentioned inverters have a common disadvantage in that the expansion is complex and does not have a voltage-boosting ability

Methods

Results

Conclusion