A Quasi-Three-level Asymmetric NPC Converter with less Switches for Switched Reluctance Motor Drives Cost Reduction

In this paper, a quasi-three-level asymmetric neutral point diode clamped (NPC) converter is presented with decrease in the number of switches. The conventional asymmetric three-level NPC converter for a three-phase motor has four switches per phase and totally includes twelve switches. The proposed converter reduces the number of switches by half. Three switches are commonly used for all phases and one switch is added per each phase. So, this converter can be called n+3 switches converter that n is the number of motor phases. The nominal values of the switches in the proposed converter are equal to the conventional type. So, the total cost of switches will be reduced by half. Also, the proposed converter losses are compared with conventional converter. Because of less switches, the switching losses reduced in the proposed converter. Finally, a multi-level hysteresis control method has been proposed for controlling this converter and it is compared with the conventional prediction control method. Using the hysteresis method reduces the response time and cost of implementation.