Intelligent Approach for Control Techniques Based on Complex Converter Structures Article Swipe
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· 2023
· Open Access
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· DOI: https://doi.org/10.1155/2023/6770322
· OA: W4389606600
Hybrid frequency control strategies are used to eliminate the problem of current inversion in multilevel cascaded asymmetrical H-bridge inverters. Unfortunately, this technique results in unbalanced power at the inverter output. The improved hybrid PWM modulation strategy helps to regulate power balances within a reasonable range at high and low voltages, by adjusting the conduction angle of the cells in high frequencies. However, as the conduction angle of a high-voltage cell increases, the fundamental amplitude of the inverter output voltage decreases, since waveforms with absolute values greater than <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mn>2</a:mn> <a:mi>E</a:mi> </a:math> cannot be perfectly modulated. Based on mathematical models of the conduction time for each level synthesis method, a new modulation strategy is proposed to solve the problems associated with the two strategies mentioned above. This new high-frequency modulation strategy adopts a combination of pulse-width modulation (PWM) and step modulation to combine control of the high-voltage and low-voltage units. At given intervals, the control voltage signals of the low-voltage unit are exchanged. Finally, the power of each unit is balanced and the basic amplitude of the inverter output voltage is not affected. Finally, the MATLAB/Simulink simulation model and experimental platform verify the feasibility of this strategy.
