A Hybrid Overload Current Limiting and Short Circuit Protection Scheme: A Case Study on UPS Inverter

In this paper, a combined current limiting algorithm is proposed for voltage controlled inverters. The proposed method combines the analog and digital current limiting algorithms. It provides fast response and better voltage waveform quality even during the transient stages. The proposed system is implemented and tested with a three-phase 10kVA UPS inverter. In addition, both digital and analog current limiting techniques are also implemented and tested for the same conditions and the obtained results are compared with the proposed combined current limiting algorithm. It is seen that proposed hybrid algorithm provides successful current limiting performance with its fast response in short circuit and overcurrent conditions, and significantly improves the reliability and fault tolerance of the inverter.