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Photovoltaic Systems and Applications
Published in Radian Belu, Fundamentals and Source Characteristics of Renewable Energy Systems, 2019
Charge controllers manage the electricity flow among the PV array, storage units, loads and eventual grid connection. The appropriate charge control algorithms and charging currents are required for the batteries, storage units, loads and grid connection specifications. High quality charge controllers allow for adjustable regulation voltages, multiple stage charge control, temperature compensation, and equalization charges at specified intervals for flooded batteries, loads and grid connection. The main purpose of a charge controller is to protect system components from damage due to excessive overcharging, discharging or over-currents. Most controllers function by sensing battery voltage and then take action based on voltage levels. Other controllers have temperature compensation circuits to account for the effect of temperature on battery voltage and state-of-charge. Controllers pose more problems than any other component in a stand-alone PV system, because they are complex devices, depending on the battery state-of-charge. The battery’s state of charge depends on many factors and is difficult to measure. The controller in a PV system must be sized to handle the maximum current produced. It is recommended to multiply the array short-circuit current by a factor of 1.25 or greater to allow for short-term insolation enhancement by clouds. The maximum current value and system voltage is the minimum needed to specify a controller. The battery charge controller, an electronic device that prevents overcharging and excessive discharging, both of which can dramatically shorten the battery’s life is essential for the long life of the battery. In large PV systems, equilibration of the battery charging (so that all battery cells charge equally) should also be incorporated. In hybrid PV systems, which combine photovoltaics and a diesel or wind generator, the control unit must connect and disconnect the different generators according to a plan. Also, loads can be categorized, so that in case of low battery charge and low PV output, some loads can be disconnected while some essential ones are maintained active. Among the most important requirements of charge controllers are: low internal consumption, high efficiency value (96%–98%), load disconnection if deep discharge occurs (current-dependent, discharge cut-off voltage, if possible), regular charging at a higher voltage to promote gassing, temperature compensation of the charging cut-off voltage, breakdown voltage of the semiconductor components at least twice the open circuit voltage of the solar generator, integrated overvoltage protection and good ambient temperature range.
Implementation of constant current and constant voltage charging control of a wireless charging converter
Published in International Journal of Electronics, 2022
In the battery charging applications, the use of wireless power transfer (WPT) is very popular because it is very comfortable, provides safe charging and has also weather proof feature. The battery charging with WPT is used in a very different applications such as low-power biomedical implants, high-power vehicle charge applications (Li & Mi, 2015; Xiao et al., 2018). In the battery charge applications, Lithium-ion batteries are usually preferred due to their high power density and long life cycle (Chen & Rincon-Mora, 2006; Dearborn, 2005). The constant current (CC) and the constant voltage (CV) charge control modes are usually applied to the batteries to provide safe charging process (Andrea, 2010; Cetin & Yenil, 2021).
An Integrated Energy Control System to Provide Optimum Demand Side Management of a Grid-Interactive Microgrid
Published in Electric Power Components and Systems, 2023
Izviye Fatimanur Tepe, Erdal Irmak
In addition to energy management, maximum power flow and power efficiency should be ensured in microgrid systems. Therefore, various additional controls are necessary to ensure power quality. In PV/battery systems, due to nonlinear P-V characteristics of the PV module under different temperatures and shading conditions, a charge/discharge management system and the state of charge (SoC) control are required so that the battery maintains its safe operating range [4]. Both controls for the battery system and MPPT control for the PV system should be coordinated to get the maximum efficiency from the system. Abu Eldahab et al. have presented a detailed literature review on this subject and proposed a new controller based on MPPT technique optimized using genetic neural algorithm [12]. In their approach, the charging time has been shortened by a charge control algorithm designed with a multi-stage and constant current and constant voltage approach, combined with a faster MPPT performance than conventional controllers. Similarly, Reddy et al. have proposed a safe battery charging system optimized for commercial systems that controls the PV system and battery connection in coordination with the switching operations of the MOSFETs and the state of charge of the battery [13]. Thanks to this control system, to use solar energy efficiently and to extend the battery’s charge life have been provided. Jana et al. have discussed a battery controller with five-stage charge management and a PV system powered by MPPT control. While a variable step size Perturb and Observe (P&O) algorithm has been recommended for MPPT, soft charge-discharge control of the battery has been provided with the help of switching operation of a synchronous converter [14].