Simulation of the Thermal State of Self-Excited Voltage Source Inverters

Abstract

A brief survey of self-excited voltage source inverters suitable for use as a parts of traction frequency converters is carried out. The power loss for two-level and two types of three-level voltage source inverters (an inverter with clamping diodes and a cascaded inverter) and capacitors with a direct current link are determined. The parameters of power keys correspond to the parameters of the keys of FF300R12ME4 and F3L300R07PE4 modules. It is shown that, despite a greater quantity of semiconductor elements and capacitors in the three-level inverter with clamping diodes, it can be recommended for use in modern traction electric drives, as it is more energy efficient than the two-level inverter. Equivalent thermal circuits for semiconductor keys with one- and two-directed current conductivity are presented. On their basis, equivalent thermal circuits for two- and three-level inverters with clamping diodes are synthesized and the corresponding heat-balance equations are derived. The simulation results are presented in the MATLAB/Simulink environment, and the distribution of temperatures between different transistors and diodes of power modules is shown. The boundary switching frequency is established at which the maximum temperatures of two- and three-level inverters coincide.