Decoupled Modulation Scheme for Harmonic Current Suppression in Five-Phase PMSM

Abstract

Harmonic currents always exist in a five-phase permanent magnet synchronous machine due to some disturbances. This letter proposes a unique modulation scheme to synthesize the control voltage in the harmonic subspace, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -space, to suppress harmonic currents actively. The advantage of the proposed modulation scheme is that it is decoupled from the modulation process in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> -space, thereby not affecting the torque output or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis currents. First, according to the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> -space control voltage reference, the action time ranges of two large and two middle voltage vectors adjacent to the control voltage reference are determined. Second, the ranges are divided into several segments equally. Then, the best action time is selected from these segments to generate a proper control voltage in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -space. Finally, the switching pattern of the inverter is designed with the selected action time. Experiments have been implemented to verify the effectiveness of the proposed modulation scheme.