Maximizing linear modulation range in single three-leg inverter-based dual-machine drive systems for single-phase and three-phase machines
摘要
In a dual-machine configuration driven by a single three-leg inverter, where a single-phase machine is tied to the neutral node of a three-phase machine, a trade-off inherently arises between the voltage amplitude of the single-phase machine and the linear modulation range of the three-leg inverter. To address this limitation, a third-harmonic voltage injection technique is introduced. The third-harmonic voltage is used as the voltage reference for the single-phase machine drive. This lowers the peak value of the pole voltage, which extends the linear modulation range for the three-phase machine drive. Furthermore, when the voltage amplitude of the single-phase machine is set to one-sixth of that of the three-phase machine, the system achieves the same dc-link voltage utilization as a conventional three-phase machine drive system using a three-leg inverter. Experimental validation confirms the effectiveness of the proposed method and demonstrates improved dc-link voltage utilization.