State of charge

About: State of charge is a research topic. Over the lifetime, 12013 publications have been published within this topic receiving 201419 citations. The topic is also known as: SoC & SOC.

Static Output Feedback Frequency Stabilization of Time-Delay Power Systems With Coordinated Electric Vehicles State of Charge Control

Abstract: In this paper, for the first time, electric vehicles are used for both the primary and secondary frequency controls to support power plants to rapidly suppress fluctuations in the system frequency due to load disturbances. Via networked control and wide-area communication infrastructures, multiple interval time-varying delays exist in the communication channels between the control center, power plant, and an aggregation of electric vehicles. By coordinating batteries’ state of charge control, the behaviors of the vehicle owners and the uncertainties imposed by the changes of the batteries’ state of charge are taken into consideration. A power system model incorporating multiple time-varying delays and uncertainties is first proposed. Then, a robust static output feedback frequency controller is designed to guarantee the resulting closed-loop system stable with an $H_\infty$ attenuation level. By utilizing a novel integral inequality, namely refined-Jensen inequality, and an improved reciprocally convex combination, the design conditions are formulated in terms of tractable linear matrix inequalities which can be efficiently solved by various computational tools. The effectiveness of the proposed control scheme is verified by extensive simulations.

Battery capacity estimating method and apparatus

Abstract: A method for accurately estimating battery capacity based on a weighting function is provided. The disclosed system monitors battery current and uses the monitored battery current to calculate the state of charge (SOCbyAh) of the battery. The system also measures the open circuit voltage (OCV) of the battery when the system is at rest, rest being determined by achieving a current of less than a preset current value for a period of time greater than a preset time period. The state of charge of the battery is calculated from the OCV (SOCbyOCV). The weighting function is based on ΔSOCbyAh and ΔSOCbyOCV, where ΔSOCbyAh is equal to SOCbyAh First time minus SOCbyAh Second time , and where ΔSOCbyOCV is equal to SOCbyOCV First time minus SOCbyOCV Second time . The weighting function also takes into account the errors associated with determining SOCbyAh and SOCbyOCV.

Vehicle, method of estimating state of charge of secondary battery, and method of controlling vehicle

Abstract: A vehicle comprising a chargeable/dischargeable battery, a current sensor for detecting the current from the battery, and a control unit for estimating the charged state of the battery and controlling the charging/discharging of the battery according to the charged state. In a first operation mode in which charging and discharging cycles are repeated, the control unit estimates the open-circuit voltage of the battery, and determines the charged state on the basis of the value which is obtained by correcting the open-circuit voltage according to the polarization. In a second operation mode in which either one of charging and discharging is continued, the control unit determines the charged state on the basis of the result of integration of the current detected by the current sensor. Hence, the charged and discharged amperehours are large, thereby providing a vehicle which can effectively utilize the secondary battery.