Lithium Battery Pack BMS Product’s the Third Architecture

Currently lithium battery BMS products are mainly two kinds of architecture, centralized management system and distributed management system. Centralized have lower cost, but the wiring harness is more complex, and the need for a single cell to corresponding, if the wrong battery will be short-circuit the risk of fire.

Distributed wiring harness is relatively simple, but the monomer management unit (CSC) still need to maintain a one-to-one correspondence with the battery cell (by setting a soft address or hard address on the CSC to solve), it let the production and maintenance of an additional workload. Another point to note is that if the active balancing function is to be implemented, the BMSs of the two architectures will require additional wiring to complete the energy transfer. Moreover, another problem to be solved is the switch matrix, which is how the energy flows into the cell from the entire cell.

There are currently used in the program is through the relay, to achieve a simple, but also brought the issue of life and reliability. Because the relay is a mechanical electronic components, there are life-time restrictions and the risk of adhesion during switching. Another solution is the use of electronic switches, MOSFET, but will bring the cost and complexity of the circuit rise.

From the functional realization point of view, BMS all functions are not insurmountable technical threshold, but from the practical point of view, BMS product is difficult to complex wiring harness, one-to-one relationship and high current active low balance cost realization. Centralized management systems and distributed management systems are not a good solution to these problems.

There is a company has proposed a third architecture, modular architecture, clean and agile to solve the BMS problem.

The system consists of UM (single module), controller and bus (2-wire system) three parts. The battery pack is divided into one or more groups according to the number of cells. Each cell is equipped with a UM module, which is a standard module, without any hard and soft address setting. The module is 4 ports, 2 inputs 2 outputs, the input is connected with positive and negative pole of the battery cell, the output is connected with each bus line; The bus line is 2-wire system, can transmit data and energy, active equilibrium current can reach 10A; Controller connection, thus forming a system. Like building blocks, multiple systems can be connected via CAN bus to build a larger (100 series level) of the battery energy management system, building modular architecture hence the name. The modules and buses that make up the system are standard components, and only the controller is set up according to the size of the system.

At first glance, this architecture is similar to a distributed architecture in that its UM and distributed 

CSC functions are similar; however, their UM is simpler and more flexible than the CSC without any

 address setting, that is, any 2 UM can replace each other, production and maintenance efficiency will be much higher, the operator requirements are not so high. Bus only two lines, yet the data transmission and energy transfer unify, solve the wiring harness and matrix switch problems. This third BMS architecture has the potential to become the ultimate BMS product architecture.