INVESTIGATION AND ANALYSIS OF LOSSES IN MOSFET OPERATIONS

Abstract

This thesis presents a detailed and systematic simulation-based investigation into the power losses occurring in N-channel enhancement mode IRF540N MOSFETs when op erating under high-frequency switching conditions. The analysis focuses on three criti cal loss components—conduction losses, switching losses, and gate drive losses—each of which significantly impacts the thermal performance and efficiency of power electronic circuits. Using MATLAB as the primary simulation platform, loss models are developed from established semiconductor equations that incorporate parameters such as drain cur rent, duty cycle, switching frequency, gate charge, and gate resistance. The simulation framework performs extensive parametric sweeps across a range of switching frequencies (10 kHz to 250 kHz), load currents (1 A to 33 A), and duty cycles (0.2 to 1.0), thereby offering a comprehensive understanding of how each variable influences total power dissi pation. The measurements locate the conduction losses to be controlled mainly by duty cycle and drain current, being dependent quadratically on current and linearly on duty cycle. The switching losses are linearly dependent on frequency and current and have been found to predominate more heavily in high-speed circuits. While gate drive losses are of lower value, they become significant in high-frequency applications and are directly dependent on switching frequency and gate charge. Additionally, the thesis investigates the effect of diverse gate resistance on switching behavior, reporting the compromise be tween switching speed and electromagnetic interference (EMI). Increased gate resistance produces slower switching transitions, and corresponding reduced dV/dt and EMI, but with the penalty of additional switching losses. Graphical visualization, such as surface plots and heatmaps, is used to depict the higher-order interactions between variables. These graphical aids are useful for the identification of major thermal zones and assist in best parameter selection for thermally stable and energy-effective designs. Finally, the thesis is a guide of practical use to engineers and researchers seeking to optimize power electronic systems by optimal loss management in silicon-based MOSFETs. The conclu sions emphasize the need for end-to-end design methods taking into account electrical, thermal, and EMI factors to deliver robust and reliable system performance.