Hybrid Modulation of Dual Inverter for Open-End Permanent Magnet Synchronous Motor

This paper analyzes the dual inverter driven open-end permanent magnet synchronous motor (PMSM) system and proposes control method which can generate maximum output power in overall speed range for integrated starter/alternator. Dual inverter driven open-end machine system consists of two inverters which are connected to the both ends of the machine winding. By disconnecting one inverter from the power source, the dc-link voltage of flying capacitor can be boosted through the machine. Because one inverter is connected to the only power source, output power of the machine is regulated by the source connected inverter. In this paper, modulation method for maximizing output power of inverter and motor with reduced harmonic and loss is proposed. It is a hybrid modulation combining six-step and pulse width modulations. With proposed method, efficiency and operation area are improved and cost of entire driving system is also decreased due to the removing of dc-dc converter. Analyses, strategies, control method, and simulation results are descripted. The experiments with PMSM are accomplished to verify the feasibility of proposed method.