3 - Modeling of power electronic devices

Abstract

Power electronic devices are the key components of power electronic converters. To implement accurate simulation of converters the behaviors of the power electronic devices should be modeled with sufficient accuracy. Different switch models can be used to represent power electronic devices in the simulation. The choices are usually made based on the required accuracy, the acceptable complexity level, and the required computational workload. Due to the computing time constraints of the real-time simulation the power electronic device models should be carefully selected to offer the good balance between accuracy and computational efficiency. In this chapter, two types of electric switch models typically used in real-time applications are presented, that is, the static model and the transient model. The static model includes the average model, switching function model, ideal model, binary resistor model, and associate discrete circuit model. The static models describe steady-state turn-on and turn-off states discretely in the simulations and neglect the switching transient. In contrast the transient model includes the switching transient behavior of the power electronic devices in the simulation, bringing the possibility to observe higher-order effects like semiconductor losses and improving the real-time simulation accuracy to the device level. The transient models including the nonlinear equivalent circuit model, piecewise linear transient model, curve-fitting model, and two-level quasi-transient model are described in detail. Considering that the electrical and thermal behaviors of power semiconductors are usually coupled, to improve the modeling accuracy of power electronics, in this chapter, the equivalent thermal network models and the electrothermal models of the power electronic devices are also introduced.