par Velaerts, Bruno 
;Mathys, Pierre
Référence E P E Journal, 1, 2, page (133-138)
Publication Publié, 1991-10
;Mathys, Pierre Référence E P E Journal, 1, 2, page (133-138)
Publication Publié, 1991-10
Article révisé par les pairs
| Résumé : | The 3-level voltage inverter is an efficient solution for high power variable speed drives, as it combines high voltage capabilities (due to GTOs in series) and significant reduction of losses and/or switching frequency (due to the intermediate level leading to lower voltage harmonics). This paper shows how the subharmonic and precalculated 3-level pulse-width modulation methods, used to control the inverter, can be implemented by a fully programmed modulator. The subharmonic modulation uses modulating and carrier waves to generate the commutations orders for the inverter. In addition to the classical bipolar 2-level and unipolar 3-level methods, our laboratory has developed a new "dipolar" 3-level subharmonic modulation, which is described in the paper. The precalculated moduylation, also presented, is based on optimized waveforms stored in EPROM, and reproduced in real-time by the modulator. Concerning the implementation of these modulations, a new sampling control method for the subharmonic modulation, and an original way to store the optimal angles of the precalculated modulation are explained. The implementation of the passage from one modulation mode to another is studied, introducing an efficient and simple method of transition. The prototype of the modulator is based on the 8097 micorcontroller from Intel, programmed in C-language. |
