Interleaving PWM waveforms is a proven method to reduce ripple in dc-dc converters. The present work explores interleaving for three-phase motor drives. Fourier analysis shows that interleaving the carriers in conventional uniform PWM significantly reduces the common-mode voltage. New DSP hardware supports interleaving directly with changes to just two registers at setup time, so no additional computation time is needed during operation. The common-mode voltage reduction ranges from 36% at full modulation to 67% when idling with zero modulation. Third harmonic injection slightly reduces the advantage (to 26% at full modulation). However, the maximum RMS common-mode voltage is still less than 20% of the bus voltage under all conditions. Low-voltage experimental results support the findings.

Meeting Name

25th Annual IEEE Applied Power Electronics Conference and Exposition (2010: Feb. 21-25, Palm Springs, CA)


Electrical and Computer Engineering


ITW Military GSE
National Science Foundation (U.S.). Industry/University Cooperative Research Centers Program


This work was supported by ITW Military GSE and the National Science Foundation I/UCRC on Intelligent Maintenance Systems.

Keywords and Phrases

DC-DC Power Convertors; PWM Power Convertors; Digital Signal Processing Chips; Fourier Analysis; Additional Computation Time; Bus Voltage; Common Mode Voltage; DSP Hardware; Low-Voltage; Set-Up Time; Third Harmonic; Three Phase Motor; Uniform PWM; Wave Forms; Zero Modulation; Electric Drives; Pulse Modulation; Pulse Width Modulation; Power Electronics

International Standard Book Number (ISBN)


International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version

Final Version

File Type





© 2010 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Feb 2010