Improved Synchronous Space Vector Pulse Width Modulation Strategy for Three-Level With Common-Mode Voltage Suppression

Abstract

In addressing the issue of high common-mode voltage amplitude and output waveform distortion caused by low switching frequency in medium and high-voltage high-power variable frequency speed control systems, the neutral-point clamped three-level inverter is taken as the research object, from the perspective of switching sequence design, a detailed analysis of the switching sequence design method to mitigate the common-mode voltage amplitude, minimize the switching times and enhance output waveform quality. An improved synchronous space vector pulse width modulation strategy is proposed. Secondly, the improved strategy is applied to the closed-loop control of permanent magnet synchronous motor. Aiming at the defects of single modulation mode, the multi-mode modulation strategy based on the improved strategy is proposed, and the smooth switching of modulation mode is realized by limiting the switching phase. The compensation schemes for angular deviation under synchronous modulation and angular delay under digital control are studied to improve the system’s stability. Finally, a simulation and experimental platform is built to verify the correctness and effectiveness of the improved and multi-mode modulation strategies.

Keywords

• Common-mode voltage
• closed-loop control
• multi-mode modulation
• permanent magnet synchronous motor
• space vector pulse width modulation
• three-level inverter