Modulation Strategy for 3HI2MC With Improved Input Currents for Multiple Drive Applications

A highly cost-effective multiple-drive system is desirable in high-power applications that need multiple drives, especially in the field of ship propulsion and electric locomotives. In this article, a discontinuous pulsewidth modulation (DPWM) strategy with improved input currents for an active third-harmonic injection indirect matrix converter (3HI2MC) is presented. The proposed DPWM modulation strategy not only preserves the inherent advantages of the 3HI2MC, maintaining independent modulation and control of the rectifier and multiple inverters, but more importantly, the narrow pulsewidth problem existing in the conventional indirect matrix converter (IMC) is avoided and the input current ripple is reduced dramatically. The above features make the 3HI2MC with the proposed DPWM strategy competitive for the applications that require multiple drives and high-quality input currents. Besides, to obtain the third-harmonic injection current reference, an input current reconstruction method utilizing the output parameters of the inverters without extra current sensors is developed. After describing the topology structure, operating principles, modulation strategy, and control algorithm in details, the experimental results are presented to demonstrate the validity and effectiveness of the proposed modulation strategy.