| In the current transportation industry electric vehicles (EVs) and hybrid electric vehicles (HEVs) are becoming more common. Majority of current EVs run on a battery. Accurate determination of State of Charge SOC in the battery is one of the major problems in current EVs. The major focus this thesis is in addressing this problem. Hardware implementation of the system in an Embedded-controller is also another focus of this thesis. This is to facilitate easy integration of the above SOC-determining-system into the existing EVs without altering any of its design.;Fuzzy logic is proven to be an accurate and feasible method to estimate state of charge of the battery. To implement the fuzzy logic, a voltage pulse was generated by a widely accepted and used Handyboard-Embedded-controller. The generated pulse was fed to a chopper-circuit. The pulse-response, which is a function of the battery-impedance, was captured into the Handyboard-controller. The voltage values are used as inputs to the FLES which is embedded into the Handyboard. In this thesis, the FLES is being modeled using Interactive-C program. Interactive-C is the programming language for the Handyboard. The FLES-estimated value of SOC is displayed on LCD-display of the embedded-controller.;There are many inaccurate methods; direct measurement, specific gravity measurement, coulomb counting method, kalman filter, and neural network in estimating state of charge of a battery. Several factors can affect the estimated-SOC in a battery such as charge-discharge rates, hysteresis, temperature, and cell aging. Each of these factors has different degree of influence. The primary focus of the thesis is to develop SOC-determining-method which is immune for variations of the above factors. This is accomplished by pulse-interrogation of the impedance of the battery. Impedance of the battery is reflective of all the above factors. In this thesis, therefore, we have measured the pulse-response of the battery. This response is then analyzed through a fuzzy logic expert system FLES to determine the battery-SOC. |
