Frequency-Domain Modeling and Simulation of DC Power Electronic Systems Using Harmonic State Space Method

For the efficiency and simplicity of electric systems, the dc power electronic systems are widely used in a variety of applications such as electric vehicles, ships, and aircraft and in homes. In these systems, there could be a number of dynamic interactions and frequency coupling between network and loads and other converters. Hence, time-domain simulations are usually required to consider such a complex system behavior. However, simulations in the time domain may increase the calculation time and the utilization of computer memory. Furthermore, frequency coupling driven by multiple converters with different switching frequencies or harmonics from ac-dc converters makes that harmonics and frequency coupling are both problems of ac system and challenges of dc system. This paper presents the modeling and simulation methods of a large dc system by using the harmonic state space (HSS) modeling. Through this method, the required computation time and CPU memory can be reduced, where this faster simulation can be an advantage of a large network simulation. Besides, the achieved results show the same results as that of the nonlinear time-domain simulation. Furthermore, the HSS modeling can describe how the frequency components are coupled with each other through the different switching frequency of each converter.