IEEE Access (Jan 2019)
Generalized Circuit Topology of Qn-Hybrid-NPC Multilevel Converter With Novel Decomposed Sensor-Less Modulation Method
Abstract
In this paper, a novel generalized circuit topology of the n-time quadrupled-hybrid-neutral-point-clamped (Qn-HNPC) converter and a new decomposed sensor-less modulation method are proposed to multiply the number of output voltage levels of the 5L-HNPC converter with a less number of components. The Qn-HNPC converter is realized by applying $n$ number of the proposed voltage-level multiplier modules (VLMMs) to the 5L-HNPC converter. Hence, the number of output voltage levels is n-time quadrupled in the attained Qn-HNPC converter, whereas a less number of components, as well as, low cost and size, are added to the main 5L-HNPC converter. Moreover, a novel generalized decomposed sensor-less modulation method is introduced to decompose the main 5L-HNPC and the proposed VLMMs reference signals in the attained Qn-HNPC converter. Consequently, only four low-voltage and low-power switches operate at switching frequency, whereas the remaining devices commutate at the low or fundamental frequency. Furthermore, employing the proposed modulation method in the attained Qn-HNPC converter causes self-balancing of all the capacitors voltage, doubling the first switching harmonic cluster frequency of the output voltage, as well as a remarkable decrease in the control complexity, the stored energy, and the size of the VLMMs capacitor. The presented simulation and experimental results verify the performance and viability of the proposed Qn-HNPC converter topology, as well as, the suggested decomposed modulation method.
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