Generalised sinusoidal PWM with harmonic injection for multi-phase VSIs

Abstract

Application of power electronics in electric drives enables utilisation of ac machines with a phase number higher than three. Such multi-phase motor drives are nowadays considered for various applications. Multi-phase drives are invariably supplied from multi-phase voltage source inverters (VSIs) and adequate methods for VSI pulse width modulation (PWM) are therefore required. This paper deals with carrierbased PWM, where harmonic injection enables an improvement in the dc bus utilisation without moving into the over-modulation region, while still providing sinusoidal output phase voltages. A generalised concept of n th harmonic injection for n-phase inverters is presented. The viability of the proposed concept is proved by simulation taking five-phase VSI as an example. The method of fifth-harmonic injection in five-phase VSIs enables operation with pure sinusoidal voltages up to a certain reference voltage value which is smaller than the maximum achievable with the given dc link voltage. Sinusoidal PWM is further modified, by injecting other harmonics, in order to enable full utilisation of the dc bus voltage. The correlation of this PWM scheme with space vector PWM, based on utilisation of large vectors only, is established in this way. Some experimental results, illustrating application of the sinusoidal PWM in series-connected five-phase two-motor drives, are included.

Novel insight into the output current ripple for multilevel and multiphase converter topologies

“…, n ph }. M ∈ [0, 1] without extended DC bus utilization, or M ∈ [0, 1 cos π 2n ph ] when the common mode signal m CM (t) is used to extend the linear modulation range [5]. The common mode signal is generated either by (i) n ph -th harmonic injection, (ii) min/max or (iii) generalized flat-topped modulation (extension for multi-phase systems of the proposal in [6]).…”

New Multi Phase Quasi Static Fundamental Wave Electric Machine Models for High Performance Simulations

“…The two different machine models can be combined with either a quasi static and transient converter models. Both the quasi static and the transient machine and converter can be operated by one control algorithm [5][6][7][8][9][10]. This way, the level of modularity of electric drives can be increased by means of the new quasi static fundamental wave machine models.…”

Five-Phase Inverters with Synchronized PWM

“…1 [7]. In particular, in the case of a five-phase motor as a load, the five stator phases a, b, c, d and e are distributed with a spacing of 72 0 .…”

“…And during overmodulation control is based on the using of only ten large vectors and two zero vectors [7]. …”