Solving EV System Design Challenges in Today’s Evolving Market
In a dynamic and rapidly evolving EV market, system designers need to keep up with industry-wide trends.
Today, the automotive industry is undergoing a revolution unlike any in its history. Marked by the large-scale and rapid transition towards electric vehicles (EVs), today’s automotive sector is rife with innovation and change.
As EVs become the new norm, the demands from consumers are building as well. As more consumers enter the market, the next generation of EVs is expected to offer significantly greater performance, longer ranges, and lower costs than what’s currently available. To support these ever-increasing demands, EV designers face a myriad of technological challenges.
What are the challenges facing EV designers and how is the industry planning on meeting consumer demands?
EV Technology Trends
To meet the needs of the EV market, the industry is embracing a number of key technological trends. One market-level trend is the shift from hybrid electric vehicles (xHEVs) to full-blown battery electric vehicles (xBEVs). In 2021, xHEVs captured a larger market share than the xBEVs according to the US Bureau of Transportation (Figure 1). Now, as consumers and governments alike strive to meet tighter CO2 reduction targets, xBEVs are gaining a larger share of the marketplace.
Figure 1. Full-blow battery electric vehicles have seized the momentum in the market. Image used courtesy of Bureau of Transportation Statistics
Inside the vehicle, a noteworthy trend can be found in xBEV transaction systems. Driven by a need to make more compact and modular systems, traction system designers are adopting new technologies such as the E-axle and in-wheel motors.
While traction systems historically consist of an engine, transmission, inverter, and motor as disparate units, E-axles, and in-wheel motors integrate these functions into one unit. The result is systems that are more space and cost-efficient.
Figure 2. The industry is trending towards more highly integrated X-in-1 systems. Image used courtesy of Renesas
In these electrical systems, designers have also started consolidating ECUs into the axle system. Instead of traditional systems that consist of multiple MCUs and subsequent power systems, newer systems are integrating ECU functionality into one single MCU. This central MCU is then placed in the axle in what is known as an X-in-1 E-axle solution (Figure 2 above). This reduces system complexity and eliminates networking concerns between ECUs.
With respect to battery management systems (BMS), the industry is adopting a shift in mindset as well. BMS have historically been small, centralized systems that monitor individual battery cells one by one. As battery packs become larger, a more distributed BMS architecture is used, and the industry is adopting a more distributed BMS architecture that leverages wireless communications to monitor many cells simultaneously.
Thermal and Integration Challenges
Each one of the trends we’ve mentioned so far presents unique technological challenges. With respect to more highly integrated solutions, a major challenge exists in creating power-efficient solutions. Specifically, concerns over thermal density start to threaten device reliability as high-performance components become more tightly integrated with one another. Keeping thermals under control requires power-efficient semiconductors that convert minimal power to heat. Therefore, the industry is adopting a SiC MOSFET instead of IGBT. Power-efficient semiconductors enable xBEV batteries to last longer without recharging, extending the car’s driving range. Because travel range is such an important feature, this in turn enhances the value of EVs in the marketplace.
As ECU functions become consolidated into a single MCU, the need for more performant MCUs grows as well. To support the ECU integration trend, the industry needs access to highly functional MCUs that can individually control multiple ECU functions at once. Creating these high-performance devices while keeping the MCUs affordable requires exceptional expertise and design experience.
Figure 3. Wireless BMS systems for automotive eliminate bulky wire harnesses. Image used courtesy of Renesas
For new distributed BMS solutions, designers are challenged to deliver reliable and low-power wireless connectivity (Figure 3). Achieving reliable wireless connectivity at a low power budget is extremely difficult in automotive environments, which are notoriously rife with EMI, vibrations, and other noise. The industry needs turnkey solutions to make the design of these systems more attainable.
Finally, the greatest challenge of all lies in integrating all of this advanced functionality into a single, high-performance system, and releasing it in a timely manner and short period of time.
xEV Reference Solution Address Key Challenges
To address all these unique challenges, Renesas offers a portfolio of solutions for xEVs, including individualized solutions for inverter systems, onboard chargers, DC-DC conversion, and BMS/wBMS systems. Leveraging all those resources, Renesas has created its xEV Reference Solution to be a solution built to tackle the design challenges we’ve discussed.
The xEV Inverter Reference Solution (Figure 4) is a hardware- and software-level solution that provides a reference for EV designers building the next generation of EVs. From the hardware side, the xEV Reference Solution includes full inverter hardware design schematics and Gerber data, which includes MCU, IGBT, gate driver, PMIC, cooling solution, and so on.
From the software side, models & software are included. Renesas has a Dyno Bench for Inverter (Figure 5). The design data has been verified on the Dyno bench. Renesas provides highly confident design data and system-level support for customers, including hardware and software.
Figure 4. A system-level block diagram of the xEV Inverter Reference Solution. Image used courtesy of Renesas
Figure 5. The Renesas Dyno Bench for Inverter. Image used courtesy of Renesas
Using the Renesas xEV Reference Solution and its associated product portfolio, EV system designers can optimize MCU, PMIC, and discrete and peripheral components to meet the needs of their specific systems, making development faster and easier. Ultimately, the reference design seeks to be a turnkey solution that helps designers build highly integrated X-in-1 systems that deliver compactness and cost optimization. The X-in-1 system integration solution is scheduled for release in 2024.
Smoother Designs Lead to Better End Products
Nowadays, the design engineers need full-fledged reference designs that embrace the industry’s most notable trends and make EV design accessible. When more designers can more readily solve challenges, the industry can move closer to its goal of providing more performant and affordable vehicles to the masses.
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