A Novel Multilevel DC-Link Three-Phase T-Type Inverter

Abstract

This research proposes a four-level T-type inverter that is suitable for low-power applications. The presented topology outranks other types of inverters in terms of a smaller number of semiconductor devices, absence of passive components such as clamping diodes and flying capacitors, low switching and conduction losses, and high efficiency. The proposed topology is free from voltage deviation and unbalanced voltage occurrences that are present in other multilevel converters having clamping diodes or flying capacitors. The proposed inverter can extend to N levels using unequal dc-link voltage sources for medium-voltage application. The inverter employs the simple fundamental frequency staircase modulation technique. Moreover, this paper presents a current commutation strategy to prevent the occurrences of short circuit and minimizing the number of required switching devices and switching transitions, resulting in improving the efficiency of the inverter. This paper also analyses the theoretical converter losses showing lower switching and conduction losses when compared to existing four-level inverters. The experimental validation of the proposed inverter shows its operating feasibility and a low output voltage THD.

Detailed Power Loss Analysis of T-Type Neutral Point Clamped Converter for Reactive Power Compensation

“…After substituting Equations ( 2)-(6) into Equation (1), each device's conduction losses are given as Equation (7). In Figure 3, one can see that the normalised function i T1 /I n for T T1 = 125 • C with n T1 (125 • C) = 1.65 matches the data for a normalised voltage in the range between 0 and 1.…”

“…Thanks to these converters, it was possible to efficiently convert electrical energy without using expensive and large transformers [3,4]. Over the years, it has become clear that many multilevel converter topologies often have better performance parameters than the classic two-level converter, even at low voltage levels [5][6][7][8][9]. One of the most important features of these converters is high efficiency, which was not always an obvious fact with the greater number of semiconductor devices used in converters with a very high number of voltage levels [10][11][12].…”

“…After substituting Equations ( 2)-( 6) into Equation (1), each device's conduction losses are given as Equation (7).…”

A New Control for Improving the Power Quality Generated by a Three-Level T-Type Inverter

“…The T-type-inverter-based SAPF is a versatile solution for energy quality improvement in various applications [20]. It operates with high efficiency, reducing its energy consumption and operating costs.…”