Power electronic systems such as inverters play a vital role in today's life serving various applications. It has a great impact on renewable power integration and energy savings techniques. Condition monitoring of these devices is challenging due to several factors like accessibility of physical components. There are various faults which affects the inverter performance and cause shutdown if not diagnosed and rectified early enough. Fault diagnosis is a critical reliability tool to minimize the inverter's operation downtime. There are several approaches of inverter fault diagnosis. However, this paper presents a new fault diagnosis technique for multi-switch open circuit faults using the load current average and rms, the method centred around using fuzzy logic based identifications technique to identify the faulty switch. The results show the capability of the developed technique in accurately identifying the faults in a single switch as well as multiple switches in different phases.