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One of the most foremost announcements of the last few weeks, was GM\u2019s communication around their new improved battery pack called Ultium<\/a>. Described as a flexible and multifaceted platform, the Ultium pack has been developed to underpin all future GM\u2019s electric vehicle architectures.<\/p>\n\n\n\n But what intrigues me is GM\u2019s choice to invest in large-format, pouch-style cells, enabling them to stack cells vertically and horizontally. Such a choice done early in the definition of what will be the strategy of GM for the next decades has certainly been preceded by a smart combination of virtual investigation and a minimum of battery pack prototypes. <\/p>\n\n\n\n The second move that differentiates the Ultium battery pack from most EV batteries in production today is the addition of aluminum within the well know NCM (nickel, cobalt, magnesium) chemistry mix, reducing the cobalt content by 70%. A great move towards a safer production, for both cobalt miners and the environment. <\/p>\n\n\n\n When an outsider like Tesla tumbles into your industry and starts the E-race at a high pace, one possible effect is for you to panic or yet to go blind and stick to your plan. Experienced runners take their time, visualize the finish line and smoothly deploy a counter-attack. General Motors is one example. <\/p>\n\n\n\n Of course, even\nif they took some time before moving any pawns, GM engineers and their partner\nLG Chem did not build and test all possible combinations for such chemistry mix\nand cell geometrical design. I can assure you they deployed a simulation-based\napproach to virtually assess cell performance. Which means they required a virtual\nplatform proposing at least the following features: <\/p>\n\n\n\n Having access to software capable of cell performance simulation with the detailed geometrical specification of the cell is indeed a key to understanding the impact of your design choices. Will I run after a commonly used cylindrical cell, already available on the market, and optimize its design to fit my requirements? Or will I work with a partner to develop a pouch cell with new chemistry? Using a physical simulation approach leads to an improved consideration of your design decisions and their impact on your system performances. <\/p>\n\n\n\n At this level of detail, you can virtually\nselect individual cell part geometry, like electrodes, tabs, current collectors\u2019\ndesigns, etc. Each part should be more precisely defined with characteristics. As\nan example, you will analyze which material and which thickness is the most\npromising for the current collectors and the list goes on to fully build the\ncell.<\/p>\n\n\n\n From the point of view of a simulation engineer, the expectation is to work on realistic models embedded in a cell manufacturer-oriented interface. But also, on the openness of the tool to import test data and to efficiently calibrate an Empirical Circuit Model (ECM); or yet the model export capability of the software to flow and thermal simulation tools in order to support battery pack design and its integration within the vehicle. <\/p>\n\n\n\n I invite you to (re)-watch how Saft company designs graphite-silicon anode cell<\/a> which gives an understanding about what might have been the workflow used by LG Chem to confirm their strategy to implement Aluminum within an NCM mix; or yet how Battery Design company efficiently calibrate ECMs<\/a> using Simcenter Battery Design Studio. <\/p>\n\n\n\n Back to GM\u2019s Ultium battery pack. This modular architecture will be capable of 19 different battery and drive unit configurations; 400 and 800-volt packs with storage ranging from 50 to 200kWh, and front, rear, all-wheel-drive transmission. <\/p>\n\n\n\n Same acceleration\ntowards electrification as the Volkswagen group, which plans to reach a total\nof 15 electric vehicles as part of its I.D. fleet, vehicles which capacities will\ngo from the I.D. Crozz (83kWh pack) to the I.D. Buzz Cargo (47kWh) or yet the\nI.D. Buggy (62kWh). <\/p>\n\n\n\n I can assure you that these two stakeholders did deploy a simulation-based approach to pre-size, define the layout, and validate the control strategy of these battery pack configurations and their thermal management system. The main objective for them has been to reduce the number of physical prototypes and to frontload possible integration challenges. Neither General Motors nor Volkswagen can afford 100 iterations on 19 configurations using physical testing, in terms of cost, capabilities and time. <\/p>\n\n\n\n This is the reason why a system simulation approach for system requirement definition, component pre-sizing, and integrated system performance validation, combined with a multi-physics simulation, including flow & thermal aspects for a detailed analysis of the battery pack performance is paramount.<\/p>\n\n\n\n From the point of view of a simulation engineer working on the battery pack, expectations are slightly different. At each stage of the development cycle, the objective is to have access to multi-physics models (electric, thermal, fluid, mechanical) embedded in a domain-oriented interface. Some examples: <\/p>\n\n\n\n Note: to go deeper into the control virtual test bench topic, I invite you to read the following <\/em>Everlasting project report<\/em><\/a> which stands for \u201cElectric Vehicle Enhanced Range, Lifetime And Safety Through INGenious battery management\u201d. <\/em><\/p>\n\n\n\n This is\nwhat makes the Siemens Simcenter portfolio relevant for any stakeholders\nengaged in the electrification race. A portfolio of simulation software and\ntest solutions structured like its customers, including inter-connected domain-oriented\nsoftware as Simcenter STAR-CCM+ and solution-oriented software as\nSimcenter Battery Design Studio. \n<\/p>\n\n\n\n Or again on another example covering the electric traction motor component<\/a>: Simcenter SPEED and Simcenter Motorsolve for electric machine design, strongly coupled with Simcenter STAR-CCM+ and Simcenter MAGNET respectively dedicated to electromagnetics domain-oriented simulation. <\/p>\n\n\n\n It is finally worth mentioning that seamless connectivity to a Design Space Exploration tool like HEEDS, for example, will not only increase engineer efficiency to find an optimized configuration but also bring innovative designs, faster to the market. <\/p>\n\n\n\n What about\nthe predicted charging performance of the Ultium battery pack? From the different\narticles published, GM\u2019s new EV architecture enables Level 2 and DC fast\ncharging, with up to 100miles of range available in the first 10min. This\ncharging performance matches with Tesla V3 supercharger with an average of 620\nmiles per hour. <\/p>\n\n\n\n When you charge a battery pack at this high rate, you can expect the electrochemistry reaction to deliver heat, which needs to be rejected to guarantee cell safety and lifetime. We don\u2019t know yet which strategy will be used by GM but Tesla did develop a smart thermal management system with several fluid loops including the Air Conditioning system<\/a>. Even heat pump technology is now being used on some of the new configurations such as the Jaguar I-PACE<\/a>. <\/p>\n\n\n\n Can a simulation approach help with selecting the technology to manage the thermal behavior of your battery during such a fast charging scenario? Can the cell geometry be optimized to support the high electro-thermal transient excitation? From the above, you should already have the answer. <\/p>\n\n\n\nTo the right manufacturer the right tools <\/strong><\/h2>\n\n\n\n
Electro-chemical simulation in a cell-manufacturer oriented interface<\/strong> <\/h2>\n\n\n\n
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The Digital Twin deployed from the start to the end of the E-race <\/strong><\/h2>\n\n\n\n
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\u201cNo time for a coffee, let\u2019s charge the car and hit the road.\u201d <\/strong><\/h2>\n\n\n\n
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