Impact of Linear-PWM and MPC controllers on the power device losses in a grid-tied two-level inverter

This paper presents a comparative analysis of the estimated power losses and device junction temperatures in a two-level grid-tied converter commanded by a linear current controller with a pulse-with-modulator (PWM) or a finite-control-set (FCS) model predictive controller (MPC). This analysis is performed for two points of operation: (a) converter delivering only active power to the grid, (b) exchanging capacitive-reactive power with the grid (STATCOM). Using an electrothermal model based on the firing signals and measured converter currents, the simulation results show the important role of the operating point and control methodology of the converter losses and device junction temperature excursions. The results show that using the MPC controller improves the converter performance when the converter delivers only active power to the grid. In the case of STATCOM operation the total losses are similar, but there is a relative increase of the losses on the diodes. The use of SiC Schottky diodes has been evaluated, with an improvement of the converter performance for both controllers.