Input Current Source-Based Modular Multilevel Converter for Wound Field Synchronous Machine Drive With Improved Low-Speed Operation

This article proposes a new configuration of modular multilevel converter (MMC)-based wound field synchronous machine drive for high power applications. In this configuration, the MMC incorporates the field winding and delivers power to the three-phase stator windings of the synchronous machine. There is no need for a separate dc power supply for the field winding of the synchronous machine. The proposed control strategy of this drive ensures that the peak–peak ripple voltage of the submodule capacitor does not depend on the operating frequency of the drive. Thus, the problem of high peak–peak ripple voltage of the submodule capacitor at a low frequency of the drive is solved without overloading the machine and the MMC. The article analyses the operation of the drive and proposes a suitable control strategy for this drive. The operation of this drive has been verified using simulation in MATLAB/Simulink platform and a scaled-down proto-model developed in the laboratory.