Motor Stator Insulation Stress Due to Multilevel Inverter Voltage Output Levels and Power Quality

Arshiah Yusuf Mirza, Ali Bazzi, Hiep Hoang Nguyen and Yang Cao
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Arshiah Yusuf Mirza: Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269, USA
Ali Bazzi: Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269, USA
Hiep Hoang Nguyen: Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269, USA
Yang Cao: Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269, USA

Energies, 2022, vol. 15, issue 11, 1-18

Abstract: Multilevel Inverters (MLIs) are widely sought after in medium-voltage applications like electric ships, electric aircraft, and renewable energy integration due to excellent advantages like lower device stress, better power quality, and modularity. However, non-sinusoidal excitations from MLIs pose a serious problem to motor-insulation and lead to their premature breakdown. This paper investigates stress in medium-voltage motor insulation when the stator winding is excited by 3-, 5-, and 7-level multilevel inverter output waveforms. The effect of firing angle on insulation stress is also studied for each of the multilevel inverters. Results show that in addition to the number of output voltage levels, PWM wave shape is a critical factor which affects the insulation stress. Both these factors work together to impact the insulation health. A strong correlation is shown between the increase in the voltage root mean square (RMS) value and increase in dielectric stress when ignoring the dv / dt impact for a fixed DC input voltage and operating frequency of the inverter. Similarly, the dielectric stress in the stator insulation increased with an increase in firing angle for each of the MLIs. This paper shows a potential that both the RMSs can be optimized to reduce the insulation stress and improve the power quality of MLIs in medium voltage drives.

Keywords: multilevel inverters; 3-level; 5-level; 7-level; voltage; dv / dt; frequency; stress; motor stator ground-wall insulation; cable insulation; insulation stress; dielectric stress; leakage current; RMS; THD (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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