Fundamental Frequency Switching Strategies of a Seven-Level Hybrid Cascaded H-Bridge Multilevel Inverter

Abstract

Abstract-This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require n dc sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the remaining n − 1 dc sources being capacitors, which is referred to as hybrid cascaded H-bridge multilevel inverter (HCMLI) in this paper. It is shown that the inverter can simultaneously maintain the dc voltage level of the capacitors and choose a fundamental frequency switching pattern to produce a nearly sinusoidal output. HCMLI using only a single dc source for each phase is promising for high-power motor drive applications as it significantly decreases the number of required dc power supplies, provides high-quality output power due to its high number of output levels, and results in high conversion efficiency and low thermal stress as it uses a fundamental frequency switching scheme. This paper mainly discusses control of seven-level HCMLI with fundamental frequency switching control and how its modulation index range can be extended using triplen harmonic compensation.Index Terms-Fundamental frequency modulation control, hybrid cascaded H-bridge multilevel inverter (HCMLI), triplen harmonic compensation.

Seven-level cascaded ANPC-based multilevel converter

“…In the second case, the four switching angles per quarter period are obtained by solving (1)- (2) where one additional harmonics is controlled or by using triplen harmonic voltage injection method [14], where the number of harmonics eliminated from the output voltage spectrum remains similar to the three-angle case. The triplen harmonic injected to the output waveform is given by:…”

Bootstrap cascaded multilevel converter

“…1), the main advantages of the proposed topology is that higher output voltage is achievable (2 Vdc instead of 3/2 Vdc) since the second H-bridge can provide real power to the load, this is not possible in the topology in Fig. 1 where the second bridge has no connection to the DC-source and it works similar to a filter smoothing the output voltage, another advantage is that it is not necessary to measure the output current for maintaining the voltage in the floating capacitor (which is necessary in [4]). …”

“…There is a special kind of cascaded multilevel converter is which only one DCsource is used [4], in this case the DC-source is used to feed an H-bridge and a floating capacitor feed a second bridge, see Fig. 1.…”

Improving power quality with reducing output harmonics for electric vehicle applications by using bacteria foraging algorithm

“…The aim of a multilevel converter is creating a sinusoidal voltage of different levels of DC voltage. These converters have been introduced as a solution for working with higher levels of voltage that include an arrangement of electronic semiconductors of power and capacitor voltage sources (Du et al, 2009).…”