Evaluation of Power Losses in a Boost PFC Unit by Temperature Measurements

High power conversion efficiency is an important requirement of the front-end power-factor-corrected (PFC) boost rectifier that is used in shaping the ac input current in a typical modern switch-mode power supply. A reasonably accurate estimate of the power losses in individual components is essential in order to improve the efficiency of the PFC rectifier. In this paper, difficulties in the measurement of individual component power losses with particular reference to an ac-dc converter are brought out. A method of loss evaluation by measurement of temperatures of individual components and surrounding ambient is presented. Experimental results that are carried out on the front-end boost PFC rectifier of a commercial ac-dc converter are presented to validate the loss estimation method.