Fault-Tolerant Structure and Modulation Strategies With Fault Detection Method for Matrix Converters

This paper proposes a fault-tolerant matrix converter with reconfigurable structure and modified switch control schemes, along with a fault diagnosis technique for open-circuited switch failures. The proposed fault recognition method can detect and locate a failed bidirectional switch with voltage error signals dedicated to each switch, based on a direct comparison of the input and the output voltages. Following the fault detection, the designed converter architecture isolates the faulty parts and bypasses the remaining load phase, resulting in a 3 x 2 matrix configuration with six bidirectional switches. Based on the reconfigured hardware topology, novel fault-tolerant modulation strategies are developed to produce three-phase balanced sinusoidal output voltages/currents with only six bidirectional switches, but at a reduced output voltage magnitude as compared with the normal matrix converter. Thus, the developed switching function matrices for the reconfigurable converter structure, containing an appropriate positive- and negative-sequence set of matrices with input voltage vector, can preserve continuous operation even after switch failures and improve reliability of the drives.