ABSTRACT
Asymmetric Cascaded Multilevel Inverter (ACMLI) was widelystudied. Various control strategies have been investigated.However, most of the reported control strategies not discussedhow to determinate voltage levels, firing angle, switching-stateand other parameters control design. This work was developed auniversal algorithm to overcome the problems in the variousnumber of H-Bridges and various DC voltages of ACMLI. Theproposed algorithm based on combination theorem and matrixoperation. The MATLAB computer program and simulation usingMATLAB SIMULINK in the binary, trinary, equal interval, sinequantization and random DC voltage are the methods for verifythe proposed algorithm. The results program execution andsimulation in the single phase of ACMLI show that the proposedalgorithm produces ACMLI control more accurate and faster ifcompared with previous control strategies.
General Terms Algorithms, Control, Power Electronics
Keywords universal algorithm, asymmetric multilevel inverter, voltagelevels, firing angle, switching-state.
1. INTRODUCTION
Recently the multilevel inverter (MLI) is the most popular dc toac converters topology for high voltage and high power in thepower industry. The MLI synthesize a sinusoidal voltage fromseveral levels of voltages [1],[4-5].[8],[11]. There are three wellknowntopologies; diode-clamps, flying capacitor, and cascadedmultilevel inverter (CMLI) [2],[5],[7],[9-10]. CMLI had manyadvantages than others, especially in reduced component, reducedpower loss, reduced power stress, reduced frequency switching,reduced electromagnetic interference, increase voltage and powercapability and increase power quality [1],[4],[5].[8],[10-11].In the early development, all of H-Bridge inverters of CMLI havesame voltage, and called equal or symmetric CMLI (SCMLI). Butin order to improve power quality with provides a large number ofoutput levels without increasing the number of inverters, unequalDC voltages or asymmetric cascaded multilevel inverters(ACMLI) built, where each H-Bridge inverters have differentvoltages [10]. These voltages can be followed a certain function[4]. The most popular asymmetric CMLI that follow functions arebinary (orde-2) and trinary (orde-3) progressions of DC voltages.Others DC progression are equal interval [6] and sinequantization [3]. To implement ACMLI in the various DC voltageprogressions and various numbers of H-Bridges, the mainproblem is control design that consist some control parameters,especially voltage levels, firing angle and switching-state, becausenothing researches reported how to determine these parameters..S21 S11S41 S31Vo,1Vdc,1+-+-S22 S12S42 S32Vo,2Vdc,2+-+-S1NS2NS4N S3NVo,NVdc,N+-+-VoFig. 1. A Single Phase Asymmetric Cascaded Multilevel Inverter.This paper proposes an algorithm to determine voltage levels,firing angle and switching-states in the ACMLI to overcome theproblem. This algorithm based on effective combination andmatrix operations that implemented in the m-file MATLABprogram. Result this program then fill in the look up table ofsingle phase ACMLI MATLAB SIMULINK circuit.


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