Comparative study on different five level inverter topologies

The diode-clamped multilevel topology has the problem of voltage unbalance of dc link capacitors. This can be solved by using separate DC sources, or adding auxiliary circuits or adopting space vector modulation control in three-level inverter applications. For higher level applications, the use of separate DC sources is not viable and the control techniques for other two methods will be more complicated to implement. Hence the Hybrid Multilevel Inverter Based on Switched-Capacitor and Diode-Clamped units can be used for higher levels. This topology can balance the capacitor voltage and also step up the output voltage. The boosting of output voltage contributes to lessen the transformation ratio of the input transformer or even eliminate it, thereby reducing the cost, which will benefit the design of converters in medium-high voltage applications. The topology is simulated using MAT lab simulink software and compared with other voltage balancing techniques.