Strategy of Synchronized SVPWM for Dual Three-Phase Machines in Full Modulation Range
Linghao Wu, Jian Li, Yang Lu, Kun He
Abstract
In high-power drives, the switching frequency of the inverter is always strictly limited to avoid high switching losses. Synchronized space vector pulsewidth modulation (synchronized SVPWM) is usually adopted in this case to reduce harmonic distortion. In this article, an effective synchronous modulation strategy based on 24-sector SVPWM is proposed for dual three-phase machines in the full modulation range. A more accurate criterion is proposed to select the implementation under different pulse patterns through the inductance characteristics analysis of the dual three-phase machines. A new overmodulation strategy considering harmonics performance is proposed to guarantee a smooth transition to square wave mode under each pulse pattern. Besides, more pulse patterns are created in this article that satisfy voltage symmetry conditions, and it can reduce the sudden drop in switching frequency to improve control performance during the pulse pattern change. The proposed synchronized SVPWM strategy and its implementation method are validly verified by simulation and experimental results in the field-oriented-control system.