E-Mobility Engineering 016 l Aurora Powertrains eSled dossier l In Conversation: Thomas de Lange l Automated manufacturing focus l Torque sensing insight l Battery Show Europe 2022 report l Sodium batteries insight l User interfaces focus

ShowReport | Battery Show Europe 2022 The complete system includes power electronics, control electronics hardware with embedded firmware, and software. Most of the control at pack level is done by the main control board, with subordinate power and control boards at cell/ cell group level. The main controller sends data via a web gateway to the cloud where, for example, a fleet operator or owner can access it. “A lot of the data analysis is done at the cell level by the boards themselves, while some of it is done at the cloud level and could be done retrospectively for analysis,” Grondel noted. Brill power has commercialised the technology for stationary energy storage batteries, and is at the prototyping stage in the development of an EV application. The company is working with vehicle OEMs to develop the technology into a product that can go into a vehicle, an effort that has so far involved lab- scale tests with Aston Martin and Delta Motorsport, and with which the Advanced Propulsion Centre UK and Innovate UK have been “hugely supportive”. The system could be deployed on a vehicle at a meaningful scale within 2 years, according to Grondel. The example system was designed for cells with both the positive and negative terminals on the top, and included two return busbars that also form the module’s positive and negative terminals. “We also include a signal path to collect voltages and temperatures from battery modules and send the data to the BMS,” Tan explained. This example was also designed for a vehicle with four large battery modules under its chassis. “The customer takes our product, puts it on top of their modules and sends it into an automatic machine that completes the welding within 2 minutes. To complete an EV battery with four modules you need about 10 minutes,” Tan said. Tan pointed out that as EV battery modules are getting larger, so demand for Interplex’s ability to stamp thin aluminium components in large formats of up to 2 x 0.5 m is increasing. The company’s development roadmap includes allowing individual cells to be replaced if customers ask for that capability, as well as accommodating cell-to-pack and cell-to-chassis battery architectures. Brill Power has patented a novel approach to battery management that incorporates power electronics at the level of connections between cells and groups of cells within the pack, said Stuart Grondel. “It allows the power electronics to actively manage the load between the series connections, ensuring that every battery cell is used to its full potential during the pack’s life,” he explained. “By varying the load between cells in proportion to their health, we enable the cell degradation curves to converge instead of diverge. That way you end up with a battery pack that lasts far longer.” Basic functions of a BMS include protection from overcharging and over-discharging, and passive balancing of the cells. Cell balancing in a passive system relies on the dissipation of excess energy in certain cell groups at the top or bottom of charge, which is inherently inefficient because the energy is dissipated as heat using resistors, Grondel said. A little more advanced is active balancing, he added. This involves shifting a small amount of current (usually less than 1 A) between cell groups in the pack, effectively shifting the charge around rather than dissipating it as heat. Brill Power calls its approach ‘active loading. “Basically, we can divide up the full battery current and send it in different proportions to different cell groups, and we do that in proportion to that particular cell group’s health,” Grondel said. This is where the power electronics come in, as the key switching technology the system relies on are transistors, specifically MOSFETs. “They can switch cell groups in and out at a very high frequency, ultimately creating a form of pseudo duty cycle or load profile for a given cell group,” Grondel explained. 54 Winter 2022 | E-Mobility Engineering The Cell PLX interconnect system for a large module holding cylindrical cells