The epidemic has actually had a big impact on GM's business in China, but the good news is that SAIC-GM's Cadillac LYRIQ's first pre-production vehicle was officially rolled off the production line at the Cadillac plant.
From 2021 to 2022, GM is under a lot of pressure on the volume of electric vehicles, and even has been thrown out of the North American market by Ford. Therefore, GM's "queen" Maribara said that GM's stock portion of executive compensation is linked to the company's electric vehicle goals (north American electric vehicle sales, launch time and product quality), "2 million units sold by 2025" and "whether it can launch a $30,000 vehicle in 2027" these two really related to GM's lifeline.
What's particularly interesting here is that the low-end entry-level FWD front-drive model (trolley), the RWD rear-drive model (mid-size) and the long-wheelbase model (luxury car) around this cell, follow-up module and Pack design are covered respectively; then the pickup and SUVs designed by CTC are considered, as well as the low-top pure electric sports car design. There are more content, let's first expand the two important (running volume) content that can be seen in China.
Figure 1 GM's ev platform product line
My understanding is that GM was developed around the soft package design at the beginning, and then adopted the mod design method to be compatible with the needs of Chinese square shell batteries. Under the three needs of cars, medium and large SUVs and sports cars (Low Roof), to package battery production, which is in line with the current US economic & industrial policy to do a long-term huge investment model to transform.
Figure 2 Design pattern of single cell
Part 1: Battery level and module planning
Because it is a single-cell mode, it is equipped with a battery system of the same width, different length and different thickness, and the following amount of power is calculated from the planned 1/3C power, and there is a difference between the Chinese version of the 1C charge-discharge square shell battery.
Figure 3 Configuration of the Ultium battery of a General Motors vehicle
Note: If we use the 4680 single-cell mode, the following configurations will be easier and more optimized in terms of balancing capacity and voltage.
Low battery mode (shortest length L1, thickness H1)
1. 6 modules (50kWh) and 8 modules (66kWh), these two are the minimum configuration of 50kWh batteries, using 2P12S modules (voltage is 48V), 6 modules configured as 2P72S 300V battery packs; 8 modules configured as 400V battery packs. Both battery packs are used around low-cost batteries.
· Medium power mode (normal length L2, thickness H1)
10 modules (84kWh), using 3P8S 32V battery module to configure, made into a 330V battery as a battery configuration for medium-sized SUVs.
· Standard power mode (normal length L3, thickness H1)
12 modules (100kWh, China is 95.7kWh), using 3P8S 32V battery module to configure, the whole package voltage of 400V 3P96S, is a relatively efficient configuration, used in luxury cars.
Remarks: The 10 module and 12 module batteries correspond to the front-drive and rear-drive (including four-wheel drive) models respectively, so the difference between the two wheelbases must also be considered, which brings the problem that the energy of the front-drive is difficult to further increase.
Figure 4 Considerations for the two models of the FWD and RWD
· 16, 20, 24 modules (integrated length L4, thickness H2)
All three are in CTC mode, used on medium and large SUVs and pickups, and are also divided into 400V platforms and 800V platforms, and there are a lot of interesting designs here.
· other
The 110mm battery pack with length L5 and thickness H3 is for sports cars, and we will introduce it later.
As shown above, there are many kinds of battery configurations in a battery platform, and I think it is indeed a bit complicated.
It is precisely because there are so many changes that the cell from the volume energy density of 400-750Wh/L to the stacked matrix is reduced by 1-20%, the module group is reduced by 15%-25%, the module and battery pack height are lost by 10-20%, the overall XY layout is lost by 10%, and the final energy density is only 200-275Wh/L. In contrast, compared with China's long knives, short knives, and Kirin batteries, there is no obvious advantage at least from the perspective of layout efficiency and cost structure.
Figure 5 Energy density of a battery cell to an encapsulation energy density
An interesting place here is that the wireless wBMS objectively allows GM to change the module in this way, remove the communication line, and the group effect brought by the CMU is still relatively good.
Figure 6 Battery BMS management configuration, considerations between different modules
Part 2: Comparison of universal soft pack and square shell batteries
GM uses both soft bags and square shells, mainly because the particularity of the Chinese market makes square shells necessary. In the United States, four battery soft pack factories have been fully invested, which is still very firm.
Figure 7 Two different configurations
As you can see in the figure below, what is more valuable here is the overall package layout, cooling, and wireless connection compatibility in all aspects.
Fig. 8 The soft package is designed with a water-cooled plate
Since the goal of design and development has been shortened from the original 50 months to 26 months, it is still worth paying attention to whether the models can be exploded in the back, and the reduction here is the model and engineering development time, and these two links have been completely shortened.
Figure 9 Changes in the development cycle of the GM
Because GM sets a very low price expectation for the battery, the battery cell is required to be within 100 US dollars per Wh, and it is not known whether it can be kept under today's battery material system.
Figure 10 Battery cell price expectations
Since the investment and upstream of the battery have been supported by the US official, the transformation and investment in North America is still very smooth.
Figure 11 Battery plant input
Brief summary:
I sincerely hope that GM can make some weather, just in terms of the data such as the group efficiency that has been released so far, it can only be said that the original goal has been achieved, and compared with the Chinese roll kings who are now pursuing the ultimate, they are still not cruel enough to themselves. It should be directly on the soft pack of CTP.
Figure | network and related screenshots
About author:Zhu Yulong, senior electric vehicle three-electric system and automotive electronics engineer, author of "Automotive Electronics Hardware Design".
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