Project description
Electricity is very critical in our lives, and with environmental and economic considerations, renewable and regenerative systems have been increasingly used in recent years. Furthermore, with technological advances, capturing and storing the energy in a secondary battery has grabbed attention, especially in high-power and high-voltage battery applications such as renewable power systems and Electrical Vehicles (EV). In these high-power applications, the total voltage of a battery relies on the cells in series. In addition, the current capability depends on the parallel-cell connections to increase the current and power. A typical current Battery Management System (BMS) shown in Figure 1 controls the batteries in 3 levels. In the lowest level, a Cell Controller (CC) charges/discharges the batteries connected in parallel (for high currents). The next level, called Cell Management Unit (CMU), controls a group of parallel batteries connected in series to increase the voltage. Finally, the top level, referred to as BMS, has the function of controlling multiple CMUs and monitoring the total battery condition, such as full capacity, remaining charge, state of charge (SOC), state of health (SOH), state of power (SOP), total and maximum voltage, total current and maximum temperature. Moreover, BMS can control the operation of the cooling system and the input power. The aim is to achieve the same condition on battery cells for safe, efficient and affordable usage. The existing BMS systems can only control the batteries connected in parallel as a single unit and cannot control them individually. Hence, if one cell is faulty or short-circuit, the entire parallel cells will be out of action. This in turn makes the whole system unusable because the series connection will not have the correct voltage, rendering the entire battery package unusable despite the remaining power capacity. The aim of this project is to introduce another lower level to control each individual battery cell in the parallel connection. An additional level, commonly referred to as Central Processing Unit (CPU), is required to integrate the status of individual cells to pass to the upper levels, as shown in Figure 2. In this way, the system can charge and discharge an individual cell depending on the requirements or status of that cell, detect a faulty cell, and isolate it from the healthy ones. Hence, if one or more cells in a parallel connection fail, the healthy cells can still work with a reduced capacity. As a result, the system can keep working without interruption unless all of the cells in one of the parallel groups fail entirely. The proposal is to build a prototype to demonstrate that such a system is feasible and can work effectively. The findings can be applied to design and construct larger BMS systems.
Industry involvement
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