LAUSR

Regular sampled space vector pulsewidth modulation is a widely implemented technique in permanent magnet synchronous machine (PMSM) drives with the voltage-source inverter. The modulation technique would generate the sideband harmonics and increase electromagnetic loss, vibration, and acoustic noise. Therefore, a fast and accurate evaluation of sideband harmonics is particularly important. However, the carrier frequency ratio could be relatively low in some applications, which means it would cause sampling delay and influence the sideband harmonics. This article analyzes the sampling delay effect in PMSM drives, and proposes a modified sideband harmonic model using Lagrange expansion and complex coordinate transformation for both symmetric and asymmetric regular sampling methods. Furthermore, the amplitudes and phases of whole sideband harmonic components are derived. Experimental results are carried out to validate the accuracy improvement of the modified model, which reveals that it could give a superior estimation of the sideband harmonics in the PMSM drives under the low carrier frequency ratio.