The growing development of battery technologies for the transposition of use of fuel in electric vehicles leads to the competent Battery Management System (BMS) design implementation. The chapter focuses on how the voltage difference perturbs the battery pack's performance by using an optimized control strategy. It helps in battery operated vehicles to charge and work efficiently. The control strategy involves the proper switching of the resistors connected to the charging circuit. The thermal balance of the resistors is balanced using the thermal power dissipation modelling in simulation. The models are tested under variable cell voltage conditions in MATLAB Simulink. The technique for voltage error balancing is termed passive cell balancing in BMS for the arrangement of a multiplicity of cells in stacks. The major issue of the passive cell balancing arises due to the State of Charge (SoC) imbalance in the batteries. The charging conditions of the battery are taken into the parameter estimation for the control technique of the balancing technique.
Top1. Introduction
Recently, Li-Ion batteries have risen to the top of the most popular battery categories. Li-Ion batteries with fast charge capabilities are crucial components of grid-connected and automotive systems because of their light weight, high capacity, and high energy density. A BMS is an electrical component that acts as the brain of a battery pack, manages output, and guards the battery against extreme harm (Hemavathi, 2020). Data collection is needed to study the battery's parameters, predict or prevent failures, and monitor temperature, voltage, and current via an interprocess connection.
The ratio of the energy now stored in the battery to its nominal capacity is known as the battery's state of charge (SOC). The cell balancing approach is one of the crucial elements of BMS (Vezzini, 2014; Yusof et al., 2016). The voltages of the individual cells will fluctuate over time without a suitable normalisation device, drastically lowering battery capacity. These problems will reduce the lifespan of the battery and the electric car range. A Li-Ion battery requires the use of a balancing device due to the imbalanced characteristics of the cells in the same series string that make overcharging possible. Passive and active balancing systems are frequently separated into these two types. However, because it is easier to operate and less expensive than an active balancing system, the latter is more widely used (Aizpuru et al., 2013; Cao et al., 2008; Daowd et al., 2011; Moore & Schneider, 2001; Quan, et al., 2018; Wei et al., 2017; Zheng et al., 2014).
Passive equalizing processes remove an excess charge from fully energized cells and bring about a condition in which all cells have a charge that is identical to the lowest cell charge by using resistor components (Loniza et al., 2016). Because it uses fewer components and is more reliable, this technique cuts the cost of the complete system. This method causes energy losses because of heat dissipation, which reduces the effectiveness of the system. As a result, this strategy is appropriate for low-power applications.
(Vulligaddala et al., 2020) presented an all-encompassing HEV and EV battery monitoring system. The seven Li-ion batteries in the design, which were implemented as an IC, may be tracked and balanced. The cell voltages of a stack of series-connected cells can be measured using a daisy chain of integrated circuits. Both the temperature and the cell voltages were measured using a 12-bit SAR ADC. In order to determine the reference voltage, this data can be transmitted to an external host utilizing a bidirectional synchronous voltage mode communication link.
For electric vehicles, Chen Duan (2018) proposes a solar energy harvesting and storage system-based battery balancing method (EVs). To prevent the energy loss that occurs in traditional active and passive battery balancing systems, the battery module with the lowest SOC/voltage during discharge can be charged using solar energy or energy from a storage cell. According to the simulation results, the suggested approach can save 2.1%–3.3% of the 50Ah battery pack's overall capacity per 13.2 miles. The battery modules can be balanced when the solar current is between 6-7A. Even when the solar current is restricted to 2-3 A or when using cell-storage mode with the same current restriction, the balance is still remarkably successful. The passive cell balancing technique will aid in preserving the same SOC and voltage across cells for low-powered electric vehicles. in order to prevent uneven voltage across cells and excessive cell heating.
For the energy balance of battery cell strings, Claudio (2016) offers an offline approach based on convex optimization that addresses a number of control issues. Using the provided method, seven balancing circuit topologies are compared. The outcomes revealed that applying the suggested technique can result in a variety of benefits. All topologies, except for the CB topology, show loss reduction compared to a no-control technique. But the most obvious benefits for all topologies in terms of energy losses are the variances in power loss between cells.