Optimal Low-Switching Frequency Pulsewidth Modulation of Medium Voltage Seven-Level Cascade-5/3H Inverter

Low-switching frequency modulation of multilevel inverters for medium-voltage high-power industrial ac drives is essential to reduce switching losses and, thus, improve the overall energy efficiency of the system. However, minimizing the switching frequency increases the total harmonic distortion (T...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2015-01, Vol.30 (1), p.496-503
Main Authors: Edpuganti, Amarendra, Rathore, Akshay K.
Format: Article
Language:English
Subjects:
Efficiency
Electric currents
Electric potential
Frequencies
Harmonic analysis
Induction motors
Inverters
Modulation
Multilevel
Optimization
Power semiconductor devices
Switches
Switching
Switching frequency
Voltage
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Summary:Low-switching frequency modulation of multilevel inverters for medium-voltage high-power industrial ac drives is essential to reduce switching losses and, thus, improve the overall energy efficiency of the system. However, minimizing the switching frequency increases the total harmonic distortion (THD) of machine currents. Synchronous optimal pulsewidth modulation (SOP) is an emerging technique for controlling multilevel inverters at low-switching frequency without compromising on the THD of machine currents. The goal of our experiment was to implement SOP technique for controlling seven-level cascade inverter for an induction motor drive at an average device switching frequency limited to rated fundamental frequency. First, optimal seven-level waveforms were obtained by ofline optimization assuming steady-state operating conditions. Then, the switching angles for each semiconductor device were obtained that ensure equal distribution of switching losses as well as minimal unbalance in dc-link capacitor voltages. The proposed SOP technique is validated by experimental results obtained from the seven-level cascade inverter feeding a 1.5-kW induction motor.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2014.2313552