Analysis and Design of a Novel Six-Switch Five-Level Active Boost Neutral Point Clamped Inverter

Abstract

This paper presents an analysis and design of a new boost type six-switch five-level Active Neutral Point Clamped (ANPC) inverter based on switched/flying capacitor technique with self-voltage balancing. Compared to major conventional 5-level inverter topologies, such as, Neutral Point Clamped (NPC), Flying Capacitor (FC), Cascaded Hbridge (CHB) and Active NPC (ANPC) topologies, the new topology reduces the dc-link voltage requirement by 50%. Whilst reducing the dc-link voltage requirement, the number and the size of the active and passive components are also reduced without compromising the reactive power capability. The analysis shows that the proposed topology is suitable for wide range of power conversion applications (for example, rolling mills, fans, pumps, marine appliances, mining, tractions, and most prominently grid-connected renewable energy systems). Experimental results from a 1.2-kVA prototype justifies the concept of the proposed inverter with a conversion efficiency of around 97.5% ± 1% for a wide load range.

Switched-Capacitor-Based Five-Level T-Type Inverter (SC-5TI) With Soft-Charging and Enhanced DC-Link Voltage Utilization

“…The comparison summarized in Table III shows that the 5level NPC type SC-MLI [27] demonstrates the least switch count among all. It requires 6 power transistors with 2 of them are reverse-blocking type, i.e.…”

“…While preserving the 5-level ac voltage generation and full dc-link voltage utilization as in the discussed topologies [27], [32], the salient feature of the proposed SC-5TI is the provision of soft-charging for its SCs that enable excellent current spike mitigation. In order to illustrate the current spike suppression ability of the proposed SC-5TI, a single-phase simulation for all the three topologies are presented in Fig.…”

“…To prevent dc offset while mitigating high frequency CMV, another type of SC-MLI that integrates SC with T-type inverter [26] or neutral-point-clamped (NPC) inverter [27] is recently attempted. In [28], a 4-level topology that uses only four power switches, two diodes and one SC is presented.…”

“…However, this topology is not capable of generating 0 V level. A 7-level topology is presented in [29] by integrating a flying capacitor with the 5-level NPC SC-MLI introduced in [27]. Other variants of 7-level NPC SC-MLI are summarized in [30], [31].…”

Nine-Level Inverter Based on Resonant Switched-Capacitor and NPP/NPC Unit

“…1(s) has a boost factor of 2 and it can be used as a PV micro-inverter. Moreover, a smaller resonant inductor has been successfully used to suppress the inrush charging current of capacitors in [29] and [30]. This technique is further developed in this work to limit the inrush charging current variation speed di/dt at switching instants.…”