Comparison of Motor Neutral Point Overvoltage Oscillations in SiC-Based Adjustable Speed Drives using Two-Level and Three-Level Inverters

Wenzhi Zhou, Mohamed Diab, Xibo Yuan

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

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Abstract

In SiC-based adjustable speed drives, power cables have similar behaviour to transmission lines due to the steep voltage pulses (high dv/dt) which experience back and forth voltage reflections while travelling across the cables, known as the reflected wave phenomenon, resulting in serious motor overvoltage oscillations. Besides the widely known overvoltage at the motor terminals, the motor neutral point experiences overvoltage oscillations that can be more detrimental than the terminal overvoltage. This paper investigates the motor neutral point overvoltage oscillations due to the reflected wave phenomenon in SiC-based adjustable speed drives using the two-level (2L) and three-level (3L) power inverters under the conventional PWM scheme. In fact, the overvoltage at the motor neutral point arises from the propagation of the inverter common mode (CM) voltage pulses through the motor winding itself, which emulates the same effect of long cables. The analysis and experimental results show that the motor neutral point overvoltage oscillations are characterized by the first anti-resonance point of the motor drive system, while the amplitude of the neutral point overvoltage is affected by the inverter CM voltage waveform. The results show that the motor neutral point experiences a higher overvoltage when the inverter is operated at high switching frequency and low modulation index. Moreover, when the switching frequency coincides with the first anti-resonance frequency of the motor drive system, the motor neutral point experiences the highest overvoltage. Specifically, the maximum motor neutral point voltage is 3 times the dc-link voltage for the 2L inverter. In contrast, the maximum motor neutral point voltage is 1.5 times the dc-link voltage when the 3L inverter is used.
Original languageEnglish
Title of host publication2022 IEEE Energy Conversion Congress and Exposition
Subtitle of host publication(ECCE)
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
ISBN (Electronic)978-1-7281-9387-8
ISBN (Print)978-1-7281-9388-5
DOIs
Publication statusPublished - 1 Dec 2022
Event2022 IEEE Energy Conversion Congress and Exposition (ECCE) -
Duration: 9 Oct 202213 Oct 2022

Publication series

NameIEEE Energy Conversion Congress and Exposition
PublisherIEEE
ISSN (Print)2329-3721
ISSN (Electronic)2329-3748

Conference

Conference2022 IEEE Energy Conversion Congress and Exposition (ECCE)
Period9/10/2213/10/22

Bibliographical note

Funding Information:
ACKNOWLEDGMENT This work was supported in part by the UK EPSRC under grant EP/S00081X/1.

Publisher Copyright:
© 2022 IEEE.

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