Battery charge and discharge control for energy management in EDV and utility integration
Electric drive vehicles (EDVs) have many benefits as compared to normal petrol or gas cars. Moreover, the electrification of transportation systems would enable increased electricity generation from carbon-free and renewable energy sources, such as wind, solar, and hydro. However, due to highly distributed and mobile nature as well as high charge and discharge power demand of EDVs, it is important to investigate how to manage EDV charge and discharge to enhance the usage of renewable enough resources in the future smart grid framework. For this purpose, this thesis first investigates typical battery electrochemical properties which are important concerns for the design of EDV charge and discharge. In this section, mathematical and circuit-oriented battery models are investigated to reflect typical battery electrochemical properties. Meanwhile, the relation between mathematical and circuit-oriented battery models is analyzed. Then, this thesis presents an energy control study in a charging station, a typical integrated EDV and utility system. The charging station consists of an AC/DC converter for grid interface and multiple dc/dc converters for EDV battery management. For the grid-side converter, a direct-current control mechanism is employed for reactive power, ac system bus voltage, and DC-link voltage control. For the EDV-side converters, constant-current and constant-voltage control mechanisms are investigated for charging and discharging control. The thesis considers energy management need for charge and discharge of multiple EDVs simultaneously as well as energy transferring from vehicle to grid and grid to vehicle requirements. A real-time simulation model is investigated and the performance of the integrated EDV and utility system is investigated.