Improving the Performance of a Two-Level Voltage Source Inverter in the Overmodulation Region Using Adaptive Optimal Third Harmonic Injection Pulsewidth Modulation Schemes

Abstract

Voltage source inverters (VSIs) are widely utilized in motor drives and renewable energy integration. Pulsewidth modulation (PWM)-VSIs are employed to generate a controlled alternating current (ac) waveform from a finite direct current (dc) link voltage. When the amplitude of the reference signal exceeds its linearity limit, which is V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> /2 for sinusoidal PWM (SPWM), a PWM-VSI operates in the overmodulation region which causes a significant reduction in the quality of the output ac voltage and the dc bus utilization (DBU). In this article, first, two adaptive optimal third harmonic injection (AOTHI)-PWM schemes are proposed to minimize voltage total harmonic distortion (THD) (AOTHI-THD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</sub> ) and maximize DBU (AOTHI-DBU). To validate the effectiveness of the proposed schemes, the resulting THD and DBU values are compared with existing continuous/discontinuous PWM scheme results. Then, to meet the practical implementation inmicrocontrollers, one generalized AOTHI-PWM is formulated to adaptively generate an optimal injection level using two proposed mathematical models. Aside from the simulation evaluations, the performances of the proposed schemes are also validated through experimental comparisons, which show a superiority over the other PWM schemes.