An Improved Transient Model of High Voltage IGBT Based on Vector Fitting

In the voltage source converter based high voltage direct current (VSC-HVDC) converter station, the transient switching process of insulated gate bipolar transistor (IGBT) in the converter valve is one of the main sources of electromagnetic interference. At present, the behavioral model is widely used in the transient switching process modeling of IGBT. Although this model has significant advantages in terms of simulation speed and universality, it has some disadvantages such as low simulation accuracy. Given the shortcomings of the existing models, this paper proposes an improved behavioral model based on the vector fitting method. Firstly, this paper builds the traditional behavioral model and compares the simulated waveforms with the actual waveforms to identify the stages with low simulation accuracy of the traditional behavioral model. Then the vector fitting method is used to fit the waveforms of low simulation accuracy, and the fitted equation is transformed into the form of equivalent circuit in time domain. After that, the equivalent circuit model is combined with the traditional behavioral model to complete the improvement for the traditional model. Finally, this paper builds the improved model in Matlab/Simulink, and the comparison and error analysis between the simulated waveforms and experimental waveforms are carried out. The results show that the simulation accuracy of the proposed model is greatly improved compared with the traditional model.