Fault-Tolerant Three-Phase VSI Based on a Modified Impedance Source Boost Inverter

This article proposes a fault-tolerant solution for the three-phase dc-ac converter using a modified impedance source boost inverter. Besides the additional modified impedance source, the solution is based on the reconfiguration of the topology to maintain the desired operation in case of an open-circuit failure mode of a power device. The proposed topology presents important features such as a boost capability to operate under fault condition and avoid extra active power devices in normal operation (without failures). Besides that, the circuit does not require dead times between the switches of each leg, which increases the reliability of the topology. Regarding the control solution for this converter, it is adopted a closed-loop current controller combined with a vectorial voltage modulator. Since this modulator is also function of the shoot-through, it will be possible to recover the amplitude voltage space vectors due to failures in power devices. The combination of these elements allows to obtain three-phase balanced ac currents with reduced total harmonic distortion even in fault-tolerant operation mode. The fault-tolerant performance of this solution is confirmed through several simulations and experimental results.