Improved equations of switching loss and conduction loss in SPWM multilevel inverters

Loss is a very important parameter in the analysis of the power electronic systems, and accurate calculation of this parameter directly effects on the economic and technical evaluation. Junction temperature, heat-sink sizing and cooling system, failure rate and MTTF 1 are some examples of the basic parameters in designing a multilevel inverter, which all depends on the loss. Through previous methods, the loss and power equations were general and the results were limited to the simulations, where this paper proposed estimated equations for the switching loss and conduction loss. Previously, calculating the loss of an IGBT, estimating the conduction and the switching times in an on/off cycle, were a major obstacle. This paper utilizes a simpler method which provides more accurate results to calculate the conduction and switching times. Simulations are performed for a 5-level NPC 2 inverter. All of the results confirm high accuracy of proposed equations. Also, these equations can be extended to the n-level SPWM 3 inverters.