PROJECT TITLE :

Fault Diagnosis and Tolerant Control of Single IGBT Open-Circuit Failure in Modular Multilevel Converters

ABSTRACT:

The modular multilevel converter (MMC) is distinguished by its modularity that's the employment of standardized submodules (SMs). To enhance reliability and avoid unscheduled maintenance, it's desired that an MMC will remain operational while not having to pack up despite a number of its SMs are failed. Notably, in this paper, complete fault diagnosis and tolerant control answer, as well as the fault detection, fault tolerance, fault localization, and fault reconfiguration, are proposed to ride through the insulated gate bipolar transistor open-circuit failures. The fault detection method detects the fault by means of state observers and also the knowledge of fault behaviors of MMC, without using any further sensors. Then, the MMC is controlled during a newly proposed tolerant mode until the precise faulty SM is found by the fault localization method; therefore, no overcurrent issues can happen throughout now interval. After that, the located faulty SM can be bypassed while the remaining SMs are reconfigured to provide continuous operation. Throughout the fault periods, it permits the MMC to operate smoothly while not obvious waveform distortion and power interruption. Finally, experimental results employing a single-phase scaled-down MMC prototype with six SMs per arm show the validity and feasibility of the proposed methods.