A step‐up switched‐capacitor multilevel inverter based on 5‐level T‐type modules

Abstract

The paper presents a new transformer-less step-up multilevel inverter structure with a single DC source. The concept was based on cascaded connection of bipolar T-type 5-level modules. Proper charging and discharging of capacitors across the load in prearranged time durations would make a nearly sinusoidal staircase voltage. The output voltage amplitude was several times greater than the DC input depending on the number of modules and charging mode of the capacitors. Multiplying the input voltage, self-balancing, generating bipolar voltage waveform, easy circuit expansion and considerably low THD (Total Harmonic Distortion) were found to be the advantages of the proposed topology. The paper also adds operating principle, simulation and experimental results of a 29-level prototype based on the presented inverter structure.

Review on Single-DC-Source Multilevel Inverters: Topologies, Challenges, Industrial Applications, and Recommendations

“…In addition, the number of the switched capacitors corresponds to the maximum boost ratio. Similarly, a transformer-less step-up MLI was proposed in [76] based on cascaded connection of bipolar T-type 5-level modules. Nevertheless, the NPC-based topologies have been suffering from the requirement of capacitive divider bridge to deal with the midpoint balancing (large voltage ripples).…”

Recent trends and review onswitched‐capacitor‐basedsingle‐stageboost multilevel inverter

“…In this section, five‐level switched‐capacitor MLIs are discussed, to get the higher voltage, two or more stages are used, and later stage switches have to suffer a drawback of high‐voltage stress across them. Therefore, the desirable property is to get the inherent voltage boosting capability, inherent capacitor voltage balancing with a minimum number of devices so that transformers, inductors, and other auxiliary devices are not needed to step‐up the voltage 15‐19 . Comparison of different topologies for five‐level output voltage is made based on number of switches (N SW ), number of drivers(N driver ), number of capacitors(N capacitors ), number of diodes (N diodes ), number of sources (N sources ), the peak inverse voltage (PIV in pu), and so on.…”

“…Voltage boosting capability will be essential when converters are designed for renewable energy generated systems because the voltage generated by PV panels and fuel cells are not high enough and needed to be boosted to be able to integrate with the grid‐connected systems. For instance, some topologies can provide voltage boosting 15‐19 . Similarly, seven‐level MLIs could give a voltage gain of 1.5 20‐25 and 3 26‐32 .…”

Single DC source diode‐assisted hybrid multilevel inverter using a reduced number of active and passive components

“…The topology in [11], discusses a circuit that uses a combination of battery cells to achieve multilevel output with the aim to reduce the number of passive devices, but the number of active devices required makes it uneconomical. The ability to generate multilevel output using single source is significantly advantageous: consequently, several single‐source topologies [12–25] have been recently proposed. In [12–15] single source‐based MLIs were proposed, but total standing voltage (TSV) and peak inverse voltage (PIV) increase drastically with the increase in the number of voltage levels.…”

“…The ability to generate multilevel output using single source is significantly advantageous: consequently, several single‐source topologies [12–25] have been recently proposed. In [12–15] single source‐based MLIs were proposed, but total standing voltage (TSV) and peak inverse voltage (PIV) increase drastically with the increase in the number of voltage levels. In [17, 19, 21], topologies with low PIV were presented, but these require a considerably large number of switching devices.…”