Analysis and Compensation of Dead Time Harmonics Based on Time Compensation Strategy in the Single-Phase Full-Bridge Inverters

Abstract

A short period, called dead time, is implemented to prevent power switching devices from shoot-through in voltage-source inverters (VSI). While adding dead time is required in the switching signals, it also causes negative effects on inverter operation such as distortion at output voltage due to significant number of harmonic components, and reduction in voltage magnitude of fundamental components. Eventually, the negative effects caused by dead time have to be compensated with compensation schemes. Different modulation schemes, which are called unipolar and bipolar switching, can be implemented in VSI, which in return might change the dead time effect. Although analysis of bipolar switching on the dead time effect has been implemented, analysis of unipolar switching is not addressed by most. In this paper, the effect of dead time on unipolar sinusoidal pulse width modulation (SPWM) is analyzed, the principle of the proposed compensation strategy is described in detail and the time compensation method with unipolar SPWM scheme is implemented using microprocessor-STM32F407G. The technique is intensively simulated and the evaluated through experimental results on resistive and resistive-inductive loads by comparing uncompensated and compensated states. Simulation and experimental results are presented to demonstrate and confirm the validity of the proposed dead-time compensation method.