Use of IGCTs in Modular Multilevel Converters for HVDC Link: Influence of the Modulation Method on the Efficiency

The efficiency of high-power converters, especially for high-voltage direct current (HVDC) power transmission, represents a crucial issue. For modular multilevel converters (MMCs), a simple way to improve the efficiency is to drop the switching frequency. Nevertheless, to insure a proper control of the converter, the choice of the modulation method is essential. From this observation, the study throws light on two multilevel modulation methods to estimate their impact on converter efficiency. An average difference of 0.13 % on the total efficiency of the converter is obtained between the two methods, with the possibility of using IGCTs optimized for low frequency operation.