Power Device Losses in Two-Level Converters with Direct Current Controllers for Grid Connected Applications

Direct current controllers have been widely used in grid-tied applications and electric drives. Direct controllers select the switching states of the converter without the intervention of a modulation stage. In comparison with PWM based controllers, direct controllers have a faster dynamic response to reference-tracking and disturbance rejection. The different control strategies can affect the total converter losses and device loss distribution; hence it is important to evaluate them when novel control methodologies are presented and compare them to the conventional PWM current controllers. To this end, fully electrothermal simulations can be paramount. Using a grid connected two-level converter, this paper evaluates the power device losses and the resulting junction temperatures excursions of the power semiconductors chips when a direct current controller is used and compares the results to those obtained with PWM controllers working at the same operating points.