Neutral point potential balance algorithm for three‐level NPC inverter based on SHEPWM

Abstract

In order to obtain the capability of neutral point potential balancing with low switching frequency, a novel balance control algorithm for neutralpoint-clamped (NPC) three-level inverter based on Selective harmonic elimination pulse-width modulation (SHEPWM) are proposed. On the basis of the switch sequences and voltage vector action angle corresponding to the three-phase SHEPWM waveform at different modulation index, the three kinds of redundant vector adjustment schemes are designed. Then, load current and neutral point potential feedback to the controller, and the three-phase pulse-width modulation signal adjusted directly by the hysteresis controller to realise neutral point potential balance. Experimental results show that different redundant vector adjustment schemes have different neutral point potential balancing speed and average switching frequency, but do not affect the harmonic elimination ability of the line voltage.

Neutral-Point Potential Balancing Control Strategy for Three-Level ANPC Converter Using SHEPWM Scheme

“…Figures 12 and 13 show the experimental results of the two strategies under the same experimental environment. Harmonic order It can be seen from Figures 12a,b and 13a,b, the proposed control strategy takes about 30 ms for capacitor voltage balance, while the control strategy in [25] takes about 90 ms for balance. The proposed control strategy uses a shorter balance time, and the midpoint voltage fluctuation of the proposed control strategy is also smaller.…”

“…The purpose of this experiment is to compare the proposed control strategy with the control strategy in [25]. The experimental platform was implemented with a Texas Instruments TMS320F28335 DSP (Digital Signal Processing) chip, an Altera Cyclone III EP3C55F484C6 FPGA (Field-Programmable Gate Array) chip, and an RT_LAB.…”

“…The purpose of this experiment is to compare the proposed control strategy with the control strategy in [25] shows the line voltage waveform. Figure 10c shows the spectrum of line voltages, where the 5th, 7th, and 11th order harmonics are eliminated.…”

“…Figure 12 and Figure 13 show the experimental results of the two strategies under the same experimental environment. In order to further verify the effectiveness and superiority of the proposed method, the contrast experiment was made to compare with the neutral point voltage balancing strategy reported in [25]. Figures 12 and 13 show the experimental results of the two strategies under the same experimental environment.…”

Research on hybrid SHEPWM based on different switching patterns

“…It determines not only whether the target of power conversion can be realized, but also the final output quality of the voltage and current. Hence, the performance characteristics of a power converter (e.g., voltage quality and power factor) greatly depend on the selection of the appropriate modulation strategy and modification of its operating parameters [5][6][7][8].…”