This paper is about an electro-thermal model to estimate the semiconductors junction temperature of bidirectional quasi Z-source inverter. Firstly, three types of averaged loss models are presented and compared. In the presented model the impact of the output current waveforms on the loss calculation is considered. Then, based on the instantaneous power loss and developed thermal model, junction temperatures of power devices are estimated. Finally, this paper discusses the factor that influences the junction temperatures: output frequency. It was found that extended model C can be directly presented the temperature peak value and fluctuation amplitude in faster simulation speed. Good agreement between model B and model C. Simulation results are shown to verify the operation and theoretical analysis.