Different battery architectures have inherent advantages and disadvantages.
Vehicle OEMs, need to analyze and decide which architecture is a better fit
for their production models while keeping the system at a competitive price.
One innovative solution for this challenge is to use two independent 400 V
The two 400 V batteries can be connected in series when charging (800 V in
total), reducing the charging time and connected in parallel when driving (400
V). This enables the use of standard high-volume 400 V drivetrain components
like the inverter and on-board-charger, where the capacity and range remain
This approach can gives designers the best of both worlds by allowing fast
charging and the reuse of existing 400 V solutions. Costs are controlled, but
they there is the enormous competitive advantage of much faster charging,
making their car more appealing to consumers.
Key Systems in xEV Powertrain
This diagram above shows the key systems in an EV powertrain. You can see the
main high voltage (HV) battery, with its management system. The low voltage
(LV) battery is lead-acid or also lithium-ion based and delivers typically
12-14 V. This delivers the lower voltages required for systems such as
interior lighting, door locks, navigation and driver assistance. The 12 V
battery also provides a backup source of power to take over safety-critical
functions such as steering, if the main HV battery cannot provide power.
For any solution, there are criteria that are non-negotiable, regardless of
cost. The car must have inherent functional safety, and must meet all relevant
safety and environmental regulations wherever it is going to be sold. In order
to be a success, the vehicle also needs to offer features and benefits that
consumers want, which means the car must have sufficient range, performance
and comfort, as well as a style.
With all these parameters specified, how can a designer keep costs down?
Firstly, they should look at the components on their bill of materials (BOM).
Has this list been simplified where possible? Can any components be replaced
with lower-cost, more integrated alternatives? Or will changing one component
provide benefits elsewhere – such as a processor or system on chip (SoC) that
reduces the number of external parts needed?
For example, the analog front end (AFE) is an essential part of the battery
management system (BMS)—acquiring data from the battery cells and digitizing
and conditioning the resultant data. By using a highly integrated AFE, such as
MC33775A, a 14-channel battery cell controller, the BOM cost can be reduced and
overall system costs cut by decreasing the amount of cabling required.
Then, the designer can think about the production and manufacturing process.
Can they select components that will enable automated assembly, bringing down
Also, can cost savings be achieved with a modular design that’s reusable and
scalable across multiple car models? This approach is common nowadays, with a
single vehicle platform underpinning different body styles. This means that
the car manufacturer can offer consumers multiple options without their
development costs ballooning and can benefit from economies of scale in
component costs. For example, Volkswagen has adopted NXP’s BMS into its MEB
platform, making it much easier to scale this system across many car models –
which is a big advantage, considering that VW is planning to bring up to 75
full EV models to the market by 20291.
Looking more specifically at the
this will acquire data from the battery cells, and analyse it to determine the
battery’s SoC and state of health (SoH). The BMS can use this data to manage
the battery for optimal performance, range and lifetime, and can also diagnose
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Volkswagen Adopts NXP Battery Management Solutions for its MEB Electrical