A Cost Effective Fault Diagnosis Technique for Cascaded H-Bridge Multilevel Inverter

Multilevel Inverters are universally accepted due to their wide range of applications and numerous advantages. In spite of this the reliability of the multilevel inverters are still questionable due to the repeatedly failures of power semiconductor switches. The industries need a cost effective and reliable solution of switch failures, which can be implemented without making major changes in the existing system. If the fault cannot be located within few seconds then fault may cause for multiple switch faults or malfunction of entire system. In this contrast, a cost effective solution to detect open circuit fault of a power semiconductor switch in five level cascaded H-Bridge multilevel inverter has been presented in this paper. The detection method is based on output pole voltage analysis of inverter. The principle of this technique can be implemented on existing system with little modifications. It requires only one voltage sensor per phase, which is already available with the main control system. The output of the multilevel inverter and fault detection results are validate through simulation results.