Analytical modeling and experimental evaluation of MOSFET switching characteristics

In this thesis, analytical modeling of a MOSFET as well as investigation of its gate drive\nwas studied. Firstly the performance of the gate drive during switching transients under\ndifferent test conditions were studied. In order to do so, the elements in the drive were\nchecked separately and their effect on the gate voltage and current were observed. Then\ntwo simple case set-ups consisting RC circuit were switched by the gate drive. For the\nfirst case a large capacitor and resistor was selected (C = 68nF;R = 209Ω). The results\nmatch well with the simulations. The rise time of the voltage was 39 s. For the second\ncase very small values were selected to check the gate drive performance in higher\ncurrents(C = 13nF;R = 22Ω). The results in this case also were in agreement with the\nresults from the simulation test set-up, the voltage rise time was 898ns in this case.\nThe next step was modeling a MOSFET analytically, using its turn-on and turn-off\nequations in MATLAB. Two cases were considered for this part. First large capacitors\nwere attached between the gate-source and gate-drain of the device in order to overrule\nits inherent capacitors and slow down the switching transient(Cgs = 68nF;Cgd = 5nF).\nThe results from the simulation were in agreement with the experimental results. Afterwards\nthe capacitors were detached and only the inherent capacitors of the MOSFET were\ncharged and discharged during switching transients. For both cases gate voltage/current\nand drain-source voltage/current from the simulation were compared with the experimental\nresults. Finally switching losses were calculated and compared for both experimental\nand simulation, which at switching frequency of 2kHz losses for simulation and measurement\nwere 21mW and 28mW during turn-on and 28mW and 30mW during turn-off\nrespectively.