The Efficiency of Three-level Active NPC Converter for Different PWM Strategies

The efficiency of power conversion is an important factor to design static converters. The paper is focused on the calculus of total losses of 3L-NPC and 3L-Active-NPC converters for different PWM strategies. The calculus was made in the most critical operating points when certain switches have the biggest total losses. Different modulation functions have been elaborated to calculate conduction losses. These are characteristic for each device depending on the structure's type and on the control strategy. Using these functions medium and effective values of conduction currents have been calculated and also validated with PSIM simulations. Some experimental results are also shown in order to validate the doubling of the apparent switching frequency using the 3L-ANPC topology.