NXP Powers Battery Management System For VWs’ EVs

Article By : Junko Yoshida

NXP unveiled a major design win for its battery management systems: Volkswagen. The German auto maker will use the system for its EV car platform...

NXP Semiconductors unveiled a major design win for its battery management systems at its developers conference, “NXP Connect.” The customer is Volkswagen, which will use the NXP system in its EV car platform called MEB (Modularer E-Antriebs-Baukasten)

VW’s MEB is hailed as an innovative and scalable platform, due to an architecture that offers modular building blocks. While the platform is aimed at consolidating electronic controls and reducing the number of microprocessors, it also allows a flexible battery layout that serves various battery needs from smaller city cars to long-haul vehicles.

According to the German carmaker, MEB will be used in brands ranging from Audi and SEAT to Škoda and Volkswagen.


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According to NXP, its battery management solutions can respond to the needs of a compact car, Volkswagen’s ID.3, a plug-in hybrid, or a luxury electric vehicle like the ID.4, Audi e-TRON or Porsche Taycan.

The MEB platform can support a variable number of battery packs fitted onto a vehicle’s floor. For example, Volkswagen’s ID.3, the first VW to use the MEB platform, offers three battery choices. ID.3’s medium 58 kWh battery pack fills up whole floor with cells, but the base 45 kWh setup doesn’t. For its 77 kWh long-range model, the platform allows another rear-mounted cell.

(Source: Volkswagen)

Lars Reger, NXP’s CTO, noted during an interview with EE Times that NXP is helping Volkswagen make “the world’s best chocolate bar” (one of the more interesting metaphors we’ve heard for a battery pack) capable of pumping in more electrons, using them effectively, safely managing charge and discharge, and extending battery life.

The beauty of a unified platform like MEB, married with NXP’s scalable battery management systems, is that “there is no need to redesign, redevelop or requalify EV battery systems” every time a brand designs a new electric car model, Reger explained.

In any given EV, batteries are the costliest component. Batteries are also the linchpin of EV range. By bringing precision battery management into the MEB platform, “We can optimize range,” claimed Leger. The goal is to do this while ensuring the EV’s robustness and safety.

Volkswagen factor
Egil Juliussen, an independent automotive industry analyst who currently writes the “Egil’s Eye” column for EE Times, called the Volkswagen design win significant for NXP.

Why?

First, volume matters. Juliussen pointed out that Volkswagen, in 2019, remained the world’s largest automaker — ahead of Toyota — with record annual sales of 10.97 million vehicles.

Second, Volkswagen is investing heavily in its EV platform, partly to compensate for the “Dieselgate” crisis. That massive emissions cheating scandal 5 years ago did grave damage to Volkswagen’s credibility. Pointing out Volkswagen’s commitment to deliver “up to 75 full-electric vehicle models to market by 2029” pledged by Holger Manz, VW’s EV czar, Juliussen said, “Volkswagen is trying to change the perception of the world.”

(Source: NXP)

Juliussen also found NXP’s battery management system (BMS) solutions remarkable. NXP’s BMS cover all types of electric vehicles from mircorhybrid (start/stop) to mild hybrid and EV/plug-in hybrids. He said, “I’ve never seen anything like that. It’s a good strategy.”

In sum, the NXP/VW announcement illustrates, “So many high-tech elements — processors, MCUs and software — are coming into a vehicle, and they are literally changing everything,” including how far EVs can travel, observed Juliussen.

Look inside battery modules
Reger walked through what it takes to manage batteries efficiently and safely.

Click the image above to enlarge. (Source: NXP)

Today’s battery modules are complete packs installed with many separate cells. The highest charge level of a module depends on the fullest cell in that stack. As Reger explained, “You cannot charge higher than the fullest cell that reaches the maximum level.” Inversely, “you cannot discharge until the lowest cell is empty.”

Optimization requires a balance in which all cells are at the same charge level. This makes it possible to charge the entire stack to the cell maximum and also discharge the entire stack to minimum. Hence, the vehicle’s engine uses the optimum number of electrons.

This optimization theory is well known. But Reger asked: “What if you are measuring these charging levels more precisely?”

Answering his own question, he said, “The use of precision analog electronics can let you measure these charging levels more precisely, which results in the further optimization of the entire stack.” He told us, as a rule of thumb, one millivolt of higher accuracy can extend range by “a marathon of running distance.”

But in Reger’s mind, extending range is half the story. Safety is a key issue when dealing with sensitive, “bitchy” chemistry in battery cell packs, he noted. “Never ever mistreat battery cells.”

According to NXP, battery management systems must come with ASIL-D, the highest level of functional safety. Given the complex management electronics used in these stacks with hundreds of battery cells, “You need to have electronics that never, never, ever creates mistakes. Or if mistakes are detected, the electronics must heal itself, and carefully manage individual cells.”

System-level approach
NXP claims its system-level approach to EVs proves advantageous in partnering with car OEMs.

The company’s broad product portfolio includes cell management, battery controllers and connectivity from batteries to wiring harnesses.

Among battery management systems, a new wireless system recently launched by Analog Devices, Inc. (ADI), is getting a lot of media attention. ADI claims that its wireless solution will save up to 90% of the wiring and 15% of battery pack volume in EVs. At the time of the announcement, ADI discussed a design win by General Motors’ production vehicles powered by Ultium batteries.


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Reger acknowledged, “There’s a religious war going on” among car OEMs looking for different battery management architectures. Options range from centralized high-voltage battery management system (BMS) to daisy-chained, distributed BMS and wireless distributed high-voltage BMS.

OEMs will make the ultimate decision. NXP claims to be ready for the different possible choices. NXP said that 16 of the leading Top 20 carmakers, currently, have designed in NXP battery management solutions.

$100/kWh in 2024?
NXP is predicting that various types of EV and internal combustion engine vehicles will reach cost parity in 2024.

Vehicles currently running at $130 to $150 per kilowatt per hour (kWh), as an industry average, will drop to $100/kWh in 2024, the company projected.

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