Switching period randomisation for multilevel converter modulation

Walker, Geoffrey R. & Ledwich, Gerard F. (2015) Switching period randomisation for multilevel converter modulation. In 2015 IEEE 11th International Conference on Power Electronics and Drive Systems (PEDS), IEEE, Sydney, NSW, pp. 975-980.

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The spectral energy associated with the carrier and sidebands of naturally sampled carrier based PWM can be spread by randomising the carrier (switch) half-period Tc = 1/2fc. So long as the switch duty cycle each period still correctly reflects the value of the modulating fundamental waveform as sampled during that switch period, then the fundamental component will remain undistorted. Natural sampling will ensure this occurs. Carrier based PWM can be extended to (m+1) level multilevel converter waveform generation by creating m triangular carriers, each with an equal 2*pi/m phase displacement. Alternatively the carrier disposition strategy calls for m amplitude displaced triangular carriers, each of amplitude 1/m and frequency mfc. Randomising these carrier sub-periods T0> = 1/2mfc is shown to generate (m+ 1) level PWM waveforms where the first (m-1) carrier groups are cancelled, while the remaining carrier and sidebands at multiples of mfc are spectrally spread. Numerous five level simulation and experimentally gathered randomised PWM waveforms are presented, showing the effects of the variation of the degree of randomisation, modulation depth and pulse number.

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ID Code: 92800
Item Type: Conference Paper
Refereed: Yes
Additional URLs:
DOI: 10.1109/PEDS.2015.7203508
ISBN: 9781479944026
Divisions: Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2015 Crown
Deposited On: 11 Feb 2016 02:14
Last Modified: 27 Jun 2017 01:03

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