The computer simulation was used in order to analyze and compare circuit configurations of pulse-width converters and pulse-frequency converters. The principle of operation and main differences were described. The circuits of pulse-width converter and pulse-frequency converter were modelled in the Matlab software using blocks from the following library: Simulink / SimPowerSystem / Simscape. The block, which performs calculation of static and dynamic power losses of insulated gate bipolar transistor (IGBT), was created. The performance curves of the IGBT were approximated in order to calculate losses. The obtained curves quite accurately describe those of the IGBT in use (CM800HC-66H by MITSUBISHI). It was shown that dynamic losses can be reduced and conversion efficiency can be increased when using the pulse-frequency converters in comparison with pulse-width converters. It was noted that for values of duty cycle in the range from 0.1 to 0.5 the efficiency of pulse-frequency converter is significantly higher than that of pulse-width converter.