Novel voltage spectra investigation of space vector modulation technique

Abstract

Absiraciqn the inverter-fed ac drives the space vector modulation technique is the most popular and wide spread one since it produces a high quality inverter-fed ac drive especially for low and middle amplitudes of motor voltages. For realization of the space vector PWM usually two different PWM methods can be applied. This paper deals with the analysis and comparison of voltage spectra of these methods and the derivation of the analytical equations of motor voltage harmonics for these PWM methods. It is shown that for the infinite value of the sampling frequency all realization methods produce the same voltage spectrum which is characterized by the relatively simple equation. This expression also ensures an accurate computation of voltage, current and torque harmonics for the relatively low value of the sampling frequency.Index Term-space vector PWM, naiural and regular PWMs, harmonic amplitudes.

DC components and subharmonics of carrier-based PWM

“…Thus e.g. if m=8.02 then subharmonics with the order This result follows from expressions derived in[7] and naturally from direct computations of switching points. A similar result is obtained for third harmonic injection where for m between 7 is better for the regular PWM.…”

“…Therefore only the direct computation of intersections of the reference and triangular waves is possible with the following Fourier decomposition. The reference is [7]: It should be noted that in case of SV PWM for m <2.72 one triangular side can intersect the reference wave two times therefore the further computation is given for m ≥3. The results for 0 = ϕ are drawn in Fig.…”

Space Vector Modulation techniques applied in Voltage Source Converters of ultrahigh speed induction machines

“…In [4]- [6] it was shown that the SVM can be realized as a carrier-based modulation (or in other words Naturally Sampled, see next chapter) with a three phase reference signal and a common triangular carrier signal according to Fig.2, where m f = 8.…”

“…The theory of SVM is well covered in the literature [4]- [6]. Here only a short summary is presented to lay the foundation for the next sections.…”

Comparison of Naturally Sampled PWM techniques in ultrahigh speed drives

“…In this paper two most widely applied carrier-based PWM techniques using sinusoidal signal (SPWM) and sinusoidal plus third-harmonic reference signal (THI-PWM) as reference waveform are compared with the widely used Space Vector Modulation (SVM) technique [3], [7], which can be also realized as a carrier-based PWM [8]. The paper compares the three different techniques by assuming natural sampling and low frequency ratios.…”