Quasi-Z-Source Four-Switch Three-Phase Inverter With Split Capacitor DC-Link Voltage Input

This paper proposes a new quasi-Z-source (QZS) four-switch three-phase inverter (FSTPI) where one load phase is connected to the split DC-link capacitor of the input voltage. Compared to the conventional QZS-FSTP topology, the proposed topology eliminates the LC component's instability in the QZS network thus making it suitable for a fault-tolerant control system. Furthermore, the proposed topology does not require any additional active switches. The switching modulation technique is designed to control the proposed topology where a DC-link voltage compensation is introduced in the modulation algorithm. This technique minimizes the output voltage imbalance by sensing the split DC-link voltage error and adjusting the switching algorithm accordingly. The dynamic performance of the proposed topology is evaluated in MATLAB/Simulink environment. It is shown that by using the proposed topology; there is an improvement on the line-to-line output voltage, and reduction in the total harmonic distortion of the line-to-line voltage compared to the previous topology. The proposed topology also produces a similar boost factor as the conventional QZS based on the six-switch three-phase inverter (SSTPI). The theoretical analysis based on the proposed topology are also in line with the simulation results.