A Fault-Tolerant PMSG Drive for Wind Turbine Applications With Minimal Increase of the Hardware Requirements

Fault-tolerant permanent magnet synchronous generator (PMSG) drives for wind turbine applications play a major role in improving reliability and availability levels, since power converters are very prone to fail. In this paper, a fault-tolerant converter with the ability to handle power switch open-circuit faults is addressed. The main concern of the proposed converter topology is the minimization of the hardware requirements, leading to a low increase of the system cost. First, the employed fault diagnostic technique does not require additional measurements, nor high computational effort. Secondly, the circuit topology reconfiguration implies a minimum number of extra components as well as minimal oversizing of the standard ones. Accordingly, a four-switch three-phase converter with the dc bus midpoint connected to the transformer neutral point and a three-switch three-phase rectifier are adopted for post-fault operation of the grid- and PMSG-side converters, respectively. Vector control strategies are proposed for both converters under analysis, focusing the issues of capacitor voltages balancing and torque ripple minimization. The performance of the proposed fault-tolerant PMSG drive is analyzed by means of experimental results.