Modeling of the electrical DC-link in fuel cell vehicles for DC-DC converter control design

Abstract

High-Power DC-DC converters are used in hybrid fuel cell vehicles to control the power flow between battery and fuel cell and therefore have an important impact on the design and the dynamics of the electrical drive train [1]. Controller design for such converters might become more and more important in the future as it not only assures the desired power flow in the system but also affects the amount of low-frequency disturbances seen by fuel cell and battery. Furthermore converter control significantly impacts the voltage dynamics of the drive train which have to respect strict bounds to prevent severe damage to components such as semiconductors. Converter control is therefore related to voltage stresses, filter design as well as lifetime considerations. The complexity of the electrical drive train interfacing with the converter as well as the range of operating conditions require a detailed analysis of the complete system and its various dynamics to allow for more sophisticated control approaches as well as assessment of the controller’s impact on the drive train. In this paper, an analytical model of a possible drive train configuration will be derived step by step. After setting forth an adequate model for each component, the complete model will be validated using a detailed simulation model. A similar model and its application to Model Predictive Control have also been presented in [2].