Challenges facing automotive power supplies

Electric and hybrid vehicles are gaining a foothold in the automotive market and are becoming a key area of ​​interest for electronic system suppliers. Technological advancements such as autonomous driving and electric vehicles are likely to increase the application areas of electronic components.

According to Transparency Market Research, the global automotive electronics market will grow at a compound annual growth rate of 19.0% from 2017 to 2025, reaching a value of more than $22 million by 2025.

In this interview, Carlos Castro from Littelfuse takes us through the different aspects that connect power management to the automotive industry. Carlos Castro joined Littelfuse in 2015 and is currently the Global Marketing Director for Automotive Power. Prior to joining Littelfuse, he worked as an Application Engineer at Infineon Technologies for 12 years and led various technical and product marketing teams in the automotive division.

Describe the latest updates for Littelfuse power semiconductors. What markets are you driving heavily towards?

We completed the largest acquisition in our company’s history in 2018 when we acquired IXYS Corporation, a global pioneer in the power semiconductor and integrated circuit markets. IXYS specializes in medium and high voltage power control semiconductors for the industrial, communications, consumer and medical markets. This acquisition provides us with several valuable strategic advantages, including a broader technology platform and the ability to further expand into the industrial and electronics markets. It also supports the long-term penetration of our power control portfolio into the automotive market and expands the percentage of power semiconductor content per vehicle that we can provide to our customers around the world.

Essentially, IXYS is the cornerstone of our power semiconductor business. It makes us one of the strongest players in the power semiconductor industry, able to leverage our collective resources and product portfolio to support our customers. Now that we have integrated IXYS into our operations, it expands our engineering expertise and intellectual property related to high voltage and semiconductor technologies and increases our reach across the semiconductor industry, adding scale and volume. It enables us to redraw our power semiconductor roadmap.

Some of our latest technology releases include the X-Class family of 850V – 1000V superjunction power MOSFETs and the X4-Class family of 100V – 150V N-channel superjunction power MOSFETs, both with HiPerFET™ options. Our competitors do not offer superjunction MOSFETs with such low drain-source voltages (Figure 2).

In addition to the IXYS acquisition, we are also growing our power semiconductor business through our investment and acquisition of Monolith Semiconductor. We began working with Monolith in 2015 and completed the acquisition late last year. Monolith is focused on developing silicon carbide power device technology using a unique process architecture that combines standard, non-differentiated process blocks used in silicon wafer fabs with proprietary process steps to provide performance advantages to finished devices.

Last year, Monolith SiC Schottky diodes and MOSFETs have transitioned from prototypes to production. Our expanded power semiconductor portfolio opens up the markets we can serve, such as true high-power and high-voltage products, such as our IGBT stacks, for markets such as rail transportation, power grid, infrastructure, DC motor drives, etc. On the other hand, our low-voltage products in smaller packages enable us to serve different markets, such as solar energy, electric vehicle charging and industrial robotics.

Electric vehicles can be considered the new green technology in every sense of the word. How involved is Littelfuse in this application? What are you doing to improve the technology, for example, the efficiency of battery power management?

We are definitely involved in developing electric vehicle technology, not only from a power semiconductor perspective, but also from a circuit protection and sensing perspective. One of the best examples is the onboard charger, where we are working hard to be a one-stop shop for almost all the components that our customers need in their systems. We have a lot of power semiconductor content there, and there are other examples of applications in EVs or HEVs, such as main switches or auxiliary systems. We are also working with electric vehicle manufacturers on high-voltage air conditioning components. For electric vehicles, more and more applications are moving from 12 volts to high-voltage grids. We are definitely involved in this new green technology and the steps we are taking to improve the efficiency of the entire electric drivetrain. For example, we are working hard to optimize available and mature silicon technologies, such as IGBTs, for very specific applications to reduce power losses. What our customers ask us to do is to fine-tune and optimize those standard available technologies for very specific hybrid and electric vehicle applications (Figure 3).

What does the future hold for new semiconductor materials like GaN or similar materials? How will they impact the design of power solutions?

As I mentioned, we are focused on silicon carbide. This has many applications in the hybrid and electric vehicle market, such as on-board chargers, main inverters, DC-DC converters between low-voltage and high-voltage batteries.

The benefits of silicon carbide depend a lot on the requirements of the application. For example, for an on-board charger for a hybrid car, there are usually a lot of constraints in terms of space and weight because a hybrid car also has an internal combustion engine, so there is not a lot of space for additional systems such as an on-board charger. Therefore, the on-board charger must be as small and light as possible. This is why silicon carbide absolutely provides a huge benefit because silicon carbide provides very high efficiency, it reduces losses, and you can reduce the size of the components and increase the switching frequency. We see a lot of designers evaluating and using silicon carbide for on-board chargers.

What challenges do you see impacting the automotive industry in the future, and how do you plan to evolve your product suite to address them?

I prefer to see them as opportunities rather than challenges. I see major opportunities in two different areas: one is autonomous driving, and the other is what I call "e-mobility," which includes hybrid, electric, and other technologies. Autonomous driving and electric vehicles are definitely changing the traditional concept of mobility and passenger transportation. This is not an evolution that we have seen in the last century; this is a revolution. So far, what we have seen are new applications, new systems are slowly being introduced into high-volume vehicles. What we are seeing now with autonomous driving and electric vehicles is a completely different way of transporting passengers.

Both opportunities introduce a lot of new applications. The requirements of these new applications are very different from the current applications. For example, if we talk about autonomous driving, we see much higher requirements in terms of safety and reliability. If the car drives itself, you don't want it to have any problems, and, in terms of electric vehicles, the introduction of 400-500 volts in cars now, the problems you have are very different from the problems you had for the last 100 years with only 12 volt batteries in cars.

We're also seeing more and more non-traditional automotive customers trying to participate in the business with these new applications and those brand new technologies. We've talked before about silicon carbide and other wide bandgap materials that are now being introduced into automotive, and other materials like LiDAR, which is the basic sensor technology for autonomous driving. This is definitely a challenge for the entire automotive community.

We are currently developing an expanded semiconductor roadmap, and power semiconductors will play an important role in these challenges. We are interested in products such as automotive silicon carbide, automotive high-voltage MOSFET and IGBT, and automotive gate drivers. We are committed to being a player in the power semiconductor industry and the power semiconductor automotive industry. We will also continue to expand our product portfolio and capabilities, not only for power semiconductors, but also for circuit protection and sensing. We still want to operate in as many areas as possible and be a one-stop service point for these automotive applications. When we talk to customers, we want to discuss with them not just a part of the circuit, but the largest part of the circuit.