Harmonic Quantitative Analysis for Dead-Time Effects in SPWM Inverters

Abstract

Dead-time is commonly designed to avoid shoot-through phenomenon within each arm in voltage source converter. The presence of dead-time tends to cause a power quality issue. Quantitative analysis for dead-time effects is important to mitigate power quality issue. This paper presents two harmonic quantitative analysis methods for dead-time effects in SPWM inverters. First, the harmonic analysis method based on double Fourier series is modified to adapt any initial phase angle and calculate additional harmonics from dead-time effects. Then, a calculation method for switching angles in sinusoidal pulse width modulation (SPWM) is presented. Based on the obtained switching angles and single Fourier series, a more concise calculation method is proposed to perform quantitative analysis for the impact of dead-time on harmonics. The harmonic model is able to reveal the mechanism of harmonics generation from dead-time. Finally, the inner relationship and essential difference between double- and single-Fourier series are summarized. The simulation and experimental results show that both of the proposed quantitative analysis methods can accurately evaluate the effect of dead-time on harmonics.

Keywords

• Harmonics
• dead-time
• double Fourier series
• single Fourier series
• SPWM