State of Charge Monitoring System of Electric Vehicle Using Fuzzy Logic

The purpose of this research was to design a state of charge (SoC) monitoring device and to understand the effect of temperature on SoC during trials of an electric golf cart. A fuzzy logic system was used to design the prototype SoC monitoring system. The source of the SoC fuzzy logic system was repeated real-time current (I), voltage (V), and temperature (T) measurement during battery charge and discharge. For the charging data, the battery was charged with a constant current (~15A) and the variable data (V and T) were measured using a monitoring device until the battery was fully charged. Then, the variable discharge data (I, V, and T) were captured as the electric car was being used to move around the campus area. It was found that temperature affects the beginning and end of charging time for 10 to 20% of the SoC value. However, during battery discharge, the temperature randomly affects voltage due to the random power consumption by the electric motor.