MEGATRON - Large Capacity Lithium Battery Management System
BATKON prepared "MEGATRON" BESS systems , with the R&D and P&D studies carried out by BATKON on the Lithium Battery Energy Storage System (Li BESS), which is the most frequently used type of technologies designed to store large amounts of electrical energy.
Our basic approach to BESS was to make the system "Modular" and to reach the desired DC voltage and desired Wh capacities by adding and removing these modules. In this context, we have equipped our “BMSLion” lithium battery management hardware with special communication and management algorithms, and we have prepared an infrastructure that enables the production of storage systems that can reach from 16 cells to 300 cells and in practice reach 1000 VDC voltages.
Typical MEGATRON Array Structure
The smallest unit of the system is formed as a box in the LBM (Lithium Battery Module), where up to 16 cells with the desired Ah capacity are monitored with BMSLion hardware and embedded software. The cell chemistry (LFP, NMC, NCA, LCA, LTO etc.) to be used can vary completely according to the application because BMSLion can be adapted to any Lithium chemistry as hardware and software.
We also designed a Master BMS to coordinate the BMSLions controlling the LBM modules and manage the high voltage storage system, and created the protocol for this hardware to communicate with the Slave BMSs in the LBMs via CANBus. In this way, the Master BMS can take the measured data from all other slave BMS's over CANBus and use it to make decisions about the system.
Master BMS; OVP (Over voltage protection), UVP (Under voltage protection), OTP (Over temperature protection), OCP (Over current protection during Charge/Discharge) expected from a Lithium BMS as it instantly learns the voltages and temperature values of all cells on the array ) can operate all protection algorithms. Master BMS can also control the contactors connected in series to the cell array (String) it controls, and can cut the current flow in the direction of charge and discharge when necessary. At the same time, by sensitively reading the string current with the “hall effect” current sensor; In addition to the overcurrent protection function, it can also calculate the current capacity of the array in Ah.
Multiple cell lines can be used in a MEGATRON system. This is a necessary feature for the LBM modules to be ergonomically lifted off the ground and placed in racks. Because when you try to put 15-16 cells larger than 150 Ah and put them in a single metal box, the weight of the box can exceed the limits of ergonomics. For this reason, it becomes necessary to run more than one array in parallel to reach Megawatt-hour capacities. Considering this at MEGATRON, we planned each series as a maximum of 150 Ah. We have added high voltage power electronics systems called “Power Conversion System – PCS” in the literature, which functions as a “bidirectional rectifier/inverter” with a capacity of 100 kW in front of each array. In this way, for example, for a BESS requiring 1 MW of power, we have created a structure that will connect 10 strings in parallel on the AC side.
While our BMS communicate with each other via CANBus, they also manage features such as passive cell balancing and passive module balancing within LBM boxes. In this way, we help to optimize the energy storage capacity of BESS by reducing the voltage and hence the SoC differences between hundreds of series-connected Lithium cells.