Output voltage of multi-phase inverter with sine-wave approximation of switching cells generation algorithm

Аuthors

Schetinin V. E.^1*, Averin S. V.^2**

1. MobTechOnline, 4, str. 1, office 66M, proyezd 4806, Moscow, 124498, Russia
2. ,

*e-mail: shetininve@gmail.com
**e-mail: acb@mai.ru

Abstract

Operation algorithm of traditional multi-phase inverter structuresfor multi-level output voltage formation assumes consecutive summing of voltages from individual cells along the period of the function. According to the proposed algorithm, sinusoidal reference signal is divided into equal voltage levels in accordance with the number of inverter cells so that the output voltage approaches sinusoidal waveform.Then we determine the intersection points of voltage levels with the sinusoidal signal and time intervals for each level.The increment valueof voltage levels is the same. It depends upon the number of cells, and only the durations of each level vary. As aresult we obtain approximated sinusoidal signal. By increasing the number of cells, the output voltage approaches the form of the reference sinusoidal signal.

Each time interval of a voltage level operation is divided into equal intervals, according to the number of inverter cells.Then, using the proposed algorithm of power switches commutation, we obtain the total voltage of each level by summing voltages of all cells both in serial and in parallel.

This algorithm allows uniform distribution of the loads of all cells, which, in its turn, allows using similar cells for multilevel inverter.Other well-known schemes for formation of an approximate sinusoidal output signal does not provide an equal cells load.

The proposed algorithm of operation of power switches of cells is clearly structured, and allows commutation scheme scalingfor any number of cells.Theoretically, the maximum number of cells of a multi-phase inverter depends on the minimum switching time of a single power switch, comprising a cell of an inverter.

The study of simulation results show that there are practically no low-order harmonics when the number of cells equals to six.

Keywords:

secondary power supply, inverter, switching algorithm, multi-channel conversion, voltage spectral analysis

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