Electrification, EVs and battery management: an interview with NXP - Embedded.com

Electrification, EVs and battery management: an interview with NXP

Vehicle electrification is on the rise, and with governments around the world attempting to achieve sustainability targets, it’s likely to continue growth. This article presents excerpts of a conversation with Jens Hinrichsen, executive vice president and general manager of the advanced analog business line at NXP Semiconductors, on the various aspects of vehicle electrification – from the technology aspects, including battery management, to the challenges for growth, including addressing factors like range anxiety, a common consumer hesitation.

To set the scene, electric vehicles seems to be gaining market share. A scan of the reports from CleanTechnica paints a positive picture all around for electric vehicles (EVs) or plug-in vehicles, driven by full electric (also known as battery electric vehicles or BEVs). For example, in October 2020, the Germany, France, Sweden and the UK, all had record months for plug-in vehicles. In Germany, the plug-in vehicle share of the market was 18% at 48,000 units registered, driven by 365% growth over the previous month in BEVs. Similarly, France saw plug-ins record 11.8% market share in October, Sweden saw 36.2% market share, and the UK stood at 12.1% market share.

Looking to the future, based on third party research, NXP said it anticipates the market for various forms of EVs (xEVs) will make up nearly 25% of the total autos produced by 2023, and it believes the xEV (which stands for all types of EVs, including plug-in and BEVs) should account for just under 50% of the total autos produced in 2030.

So on to our conversation with Jens Hinrichsen. To listen to the full interview, play the podcast link above.

Presented below are some excerpts of the interview.

Market adoption drivers and challenges
First, we asked about what’s driving EV adoption, and what are the challenges?

Hinrichsen: There is indeed a trend towards electrified vehicles. Even in challenging years like 2020 where the overall car production was down, the electrified vehicles was still increasing in such a year. From my perspective, there are multiple elements driving the increasing demand and adoption rate. Overall, it really starts with the increasing desire to do something good for environment, to find a more sustainable and environmentally friendly way of mobility.

But then, it comes really quickly down to a compromise of cost and convenience. You can imagine if the EV does not perform in a similar way you to what you are accustomed to based on cars with a combustion engine, then you wonder whether it really makes sense to go for such a car. So, range and the speed of charging is really critical from my perspective. Convenience is a key element as well.

Cost and affordability is also another critical item. While the car makers constantly have to increase the performance, in the same way they also need to drive down the cost and make these cars very affordable. From that perspective, I really, truly think that a little bit of a catalyst is still needed to drive this process: this includes government regulations and mandates, and then from a consumer perspective is subsidies and tax incentives.

The technology perspective
Next, we moved on to the technology and the challenges, including how you address fast charging, safety, and ‘range anxiety’.

Hinrichsen: If you want to extend the range and also make fast charging possible, so you probably have to put way more energy and power into the battery, and also establish very, very quick speeds of charging. That makes the battery and also the charging process a fairly hazardous element of your car. So, you have more and more power in this battery and leverage and unleash the maximum power and efficiency out of this battery.

This means it needs a super high level of functional safety. You need to ensure that that battery is constantly operating fine and that this battery is not getting into any kind of trouble. And if that is the case, that there are mechanisms around that it’s basically shut down or stopped or controlled. Functional safety is becoming a critical element for this very, very important system in the car.

From a technology perspective, what’s needed to deliver an electric vehicle? What are the different elements, the pieces?

Hinrichsen: The most important part is the power train: this differentiates it from a regular car with a combustion engine. In the power train of a hybrid vehicle, probably even a little bit more complex than for a pure electric vehicle, you need a couple of elements. You still have the combustion engine and that needs a bit of a motor control for the combustion engine. On top of this, you have an e-motor, and the e-motor needs an inverter platform, and that inverter platform is just there to make the e-motor move.

Then you usually have a low voltage battery and you have a high voltage battery. The low voltage battery is simply there to support regular features, your entertainment system, your seat control, everything. The high voltage battery is the energy source for the e-motor, and that’s a real critical element.

When you have a low voltage and a high voltage net in your car, you need a DC-DC converter to connect these systems. And usually, if you have a plug-in hybrid, you need an AC-DC converter for onboard charging that you can take your normal power supply and plug it in and then the car is doing the conversion. In addition to the high voltage battery, which is the energy source for the electric motor, you need a smart and a pretty sophisticated battery management system, which is really critical in such a set-up. That’s pretty much all you need.

What’s NXP’s role in enabling all of those technology pieces?

Hinrichsen: NXP provides the semiconductors which control the power and control and monitor the systems. We are not providing power to the motor – these are usually the power semiconductors such as MOSFETs and IGBT, so silicon carbide solutions. We are not focusing on the power semiconductors.

We do all the control systems – all the processors which do the intelligent processing, and all the networking components. We have the power management components to support the intelligent processors. We have the entire connectivity to interlink all these systems. And we also do have all the analog front-end solutions. This includes the battery cell controllers, which basically sense all the data in this system from the outside. We process and control the system. We don’t provide the power to the system.

Battery management

battery management NXP
(Image: NXP)

OK, so what’s the importance of battery management and how does it work?

Hinrichsen: The battery management system is constantly monitoring and controlling the battery, and constantly checking in nearly real-time the state of health, the state of charge and the state of function, for each cell of this huge battery pack.

It checks temperature and measures a other critical items and the accuracy of the high precision analog. Then, it can decide, “Can I consume the power out of this cell at the moment or is the cell maybe too hot and I should leave it alone for a while? Is the cell now empty and do I need to charge this particular cell? And is there anything I need to do to leverage each particular cell of the system in an optimized way to unleash the full energy density, the full energy power of that particular system without damaging it and without overstressing it so that we are not getting into a status of malfunction?”

The more precisely you can do this, the more you can truly unleash the full power out of a battery and therefore achieve a very long range with the battery so you can get the maximum out of your power while at the same time not damaging the battery. And that results into long lifetime. In the short-term, of course, you need to ensure it is not getting out of control and so need to constantly ensure the functional operations and the functional safety of this particular system. That’s what the battery management system does.

How many battery cells are there typically that you need to manage? This is quite complex, isn’t it?

Hinrichsen: Right, it’s really complex. Let’s take a simple example. A typical system is 400V, for a high performance car, it can be 800V or 900V. That’s the voltage you need to manage. Each particular cell can handle, based on your setup, between 3-4V roughly. So if you take the 400V example and let’s say 4V per cell, that means you have 100 cells which you need in the battery. You need to control 100 cells, and they need to be controlled constantly in real-time.

Listen to the full interview, which goes on talk more about the semiconductor components in vehicle electrification, what will drive further adoption of electric vehicles, plus how manufacturers can get costs down. Produced as part of the NXP Smarter World podcast, click here: “Electrification and the Future of EVs.

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