ISSUE 012 Winter 2021 Sigma Powertrain EMAX transmission dossier l In conversation: David Hudson l 48 V systems focus l 2021 Battery Show North America and Cenex-LCV reports l Everrati Porsche 911 digest l Switching insight l Motor laminations focus

“By eliminating so many components that could suffer from surface tracking or isolation breakdown and short- circuits, the intrinsically isolated BMS is safer as well as simpler, and has a smaller bill of materials,” Brown said. Further claimed benefits include improved measurement accuracy and better performance from the on- IC processing algorithms, enabled by avoiding comms latency and downsampling. This kind of architecture is also inherently more flexible and scalable, as it allows pack designers to add cells one at a time. A full understanding of how batteries behave in conditions such as a crash has yet to be achieved. To predict the likelihood and timing of a fire and explosion, engineers need to know what has caused any shorts, where they will be and how quickly their effects will progress. Prediction requires strong simulation capabilities in multiple physics domains, according to Ansys, which explained how the company’s LS-DYNA crash simulation software approaches this multifaceted problem. “The computational challenge involves combining the mechanical, electromagnetic, electrochemical and thermal domains while also dealing with length scales from around 1 m for the battery to between 0.01 and 0.1 mm for individual layers in a cell, in order to model internal shorts at cell level,” the team behind the software said. A wide range of timescales must also be taken into account, ranging from the milliseconds of a crash to the minutes, hours or days over which a thermal runaway can develop and a fire or explosion ensue. LS-DYNA is based on a multi-physics solver that, for example, simulates electrochemistry using distributed Randles Circuit models. Such models treat electrochemical cells as if they were electric circuits, to make it simple to model internal and external shorts. The solver also uses mechanical simulations to predict the deformations that will cause the shorts, and electrical and thermal simulations to model the joule heating caused by current flowing through the shorts, plus exothermal models for thermal runaway. To cope with differences in the timescales over which various processes take place, LS-DYNA operates in the regimes of milliseconds and seconds. In the first, it carries out mechanical, electromagnetic and thermal calculations in very small crash time steps for a total of 20 ms to obtain results for mechanical deformations owing to impacts and electrical shorts. Then, in the seconds regime, it freezes mechanical deformation and performs electromagnetic and thermal calculations over larger time steps totalling 20 seconds, calculating battery discharge and temperature rise. Developed in collaboration with Ford, the battery module for LS-DYNA is now commercially available, said the company, describing it as unique in its multi-physics simulation capability, particularly in its coupling of mechanics with the other domains. Further development on the electrochemical side is aimed at moving beyond Randles Circuit models. CSM showed two new variants in its line-up of breakout modules that are used for real-time, inline measurement and analysis of high-voltage electricity to evaluate the efficiency of EVs, both in test bench set-ups and driveable test vehicles. The breakout modules are part of the Vector CSM E-Mobility Measurement system, a set of hardware and software tools for developing hybrid and electric vehicles. Inverter efficiency is one important factor for maximising the range of an EV for a given battery capacity. Winter 2021 | E-Mobility Engineering 43 ShowReport | Battery Show North America 2021 4ustanN 4acO E in front oɈset iTpact test (nsys Ke]elopeK tOe Iattery ToKule for 3: +@5( in cooperation ^itO -orK C:4»s /= )reaRout 4oKule