Electric vehicles are accelerating towards 800V, and third-generation semiconductors are imperative!

Over the past two years, the global automotive market has witnessed a rapid surge in demand for electric vehicles. Although the COVID-19 pandemic has severely impacted the automotive market, electric vehicle sales achieved record growth in 2020 and 2021. For example, in 2021, global electric vehicle sales (BEV and PHEV) totaled approximately 5.8 million units, a year-on-year increase of approximately 79.3%. The market is expected to maintain double-digit growth over the next five years.

This growth will be driven by significant fiscal incentives such as purchase incentives and vehicle registration tax rebates implemented by all regional governments. Additionally, rapid decarbonization strategies by governments around the world will contribute to the growth of electric vehicle sales. More than 20 countries around the world have announced that they will phase out traditional internal combustion engine vehicles in the next 10-30 years, and more than 100 countries around the world aim to achieve net-zero emissions in the next few decades.

Additionally, several leading OEMs have announced far-sighted plans to reconfigure their product lines in response to the anticipated EV boom. Listed below are some recent OEM announcements.

Volvo aims to achieve 100% electric vehicle sales from 2030; Ford will achieve 100% electric vehicle sales in Europe from 2030; General Motors will only sell electric light vehicles (LDV) from 2035; Volkswagen It was announced that by 2030, 70% of electric vehicle sales in Europe and 50% in China and the United States will be achieved; Stellantis announced that by the end of this decade, 70% of electric vehicle sales in Europe and 35% of electric vehicle sales in the United States will be achieved.

In 2021, electric vehicles accounted for more than 9% of global car sales, nearly four times the amount in 2019. Due to the above factors, electric vehicle penetration is expected to continue on a high growth trajectory in the coming years.

However, to become a viable alternative to the currently dominant internal combustion engine vehicles, the next generation of electric vehicles will need longer range, faster charging capabilities and higher power output. To solve this problem, EV battery architecture requires higher voltage; therefore, the transition from 400V to 800V is inevitable.

Benefits of converting from 400V to 800V:

• Due to the higher charging power output of up to 350-360kW, charging time is reduced by 50% compared to 400V battery systems. These vehicles have the potential to charge from 5% to 80% (200 mile range) in less than 23 minutes! With ultra-fast charging, there’s no need for a battery with a range of 1,000 kilometers

• Doubling the battery voltage from 400V to 800V reduces the current required for charging, thereby reducing overheating and improving power retention. This helps extend mileage and improve performance levels.
  

As of mid-2022, most electric vehicles on the market use 400V battery systems. However, EV manufacturers are aware of the techno-commercial advantages that moving to an 800 V architecture can bring. Therefore, a rapid transition to 800V systems is expected in the next few years, and by 2027-2030, more than 90% of electric vehicles may be equipped with 800V battery systems.

Currently, 800V EVs are in the early stages of commercialization. Automakers such as Audi, Porsche, Hyundai and Kia are already selling 800V EV systems, while LUCID motors has a 900V battery system built into its model Lucid Air. The Porsche Taycan, launched in 2019, is the first 800V electric car on the market with a charging power of 270kW, while the Lucid Air is the fastest charging electric car on the market with a charging power output of 350kW. Hyundai Motor has promised to launch 23 EV models equipped with 800V systems by 2025.

Silicon-based MOSFETs and IGBTs are the dominant power semiconductor device technologies in the electric vehicle industry. However, silicon-based power semiconductors have reached the theoretical performance limit of 400V EV. Therefore, as the mobile industry transitions to 800V battery architectures, newer materials such as wide band gap (WBG) semiconductors that provide better electrical and thermal properties than silicon-based semiconductors are needed. Silicon carbide (SiC) and gallium nitride (GaN) are two WBG semiconductor materials gaining maximum traction in electric vehicles for applications such as traction inverters, on-board chargers and DC-DC converters. Specifically, SiC continues to attract increased interest from all major electric vehicle manufacturers and is considered a natural choice for 800V battery systems in electric vehicles. All major automotive OEMs are committed to developing 800V EV systems in current and future products.

1. SiC in traction inverters supports key applications of 800V EV

The traction inverter is one of the most critical electric vehicle systems, responsible for the overall performance of the vehicle. The key roles of traction inverters in electric vehicles are:

a. Convert the DC power of the battery into the AC power of the traction motor

b. Convert AC power back to DC power for regenerative braking

c. Control the EV motor speed according to the accelerator input by the driver.

The focus is turning to developing 800V traction inverters with SiC modules. Several automotive Tier 1 suppliers have been demonstrating their 800V inverter capabilities. Delphi Technologies (now acquired by BorgWarner) was the first company in the industry to mass-produce 800V SiC inverters using Wolfspeed's SiC MOSFETs. McLaren Applied will demonstrate its 800V SiC-based traction inverter (Inverter Platform Gen 5) in early 2022. Vitesco signed a deal with a major North American automaker (Ford or Stellantis) worth nearly $1.08 billion from 2025. Similarly, Marelli launched an 800V-SiC traction inverter platform in mid-2022. Likewise, BorgWarner is developing SiC-based inverters for a German EV OEM.

2. SiC leads the semiconductor race for electric vehicle traction inverters

Using SiC MOSFETs in 800V capable traction inverters enables faster, more efficient and lighter EV powertrains. Compared to Si, SiC generates less heat, is less sensitive to temperature, and enables more efficient power switching. Less heat release results in a lighter cooling system, resulting in an inverter that weighs less and has a smaller footprint. The higher bandgap in SiC results in lower leakage current at high temperatures, while the high critical field voltage significantly reduces on-resistance, allowing for smaller/thinner devices. This reduces switching losses, increases current carrying capabilities, and enables faster switching. Thermal conductivity is another key aspect where SiC stands out. SiC modules can handle junction temperatures up to 200°C compared to Si, which can withstand temperatures up to 80°C. Another well-known WBG semiconductor, GaN, is in a very niche development and application stage in 800V EV applications.

Figure 1 shows a comparison of Si, SiC and GaN material properties.

The band gap, critical electric field and saturation speed of GaN are almost equivalent to, or even better than, SiC. However, its low thermal conductivity poses challenges for high power and temperature applications such as EV traction inverters. For GaN, 650V modules are the best choice to find applications in 400V EV systems, which are almost dominated by mature silicon-based chips. However, when the voltage increases to 800V, GaN loses efficiency due to its lower thermal conductivity. The industry is working on developing vertical/3D GaN structures to support high-power EV applications.

As mentioned previously, GaN technology for 800V systems in EVs is still in the early stages of commercialization. One of the main differences between current GaN devices and other power devices (based on Si and SiC) is that the former mainly use lateral device structures to conduct electricity (GaN on Si, GaN on SiC or GaN on sapphire), while the latter (Si and SiC) devices conduct vertically. Therefore, to achieve higher voltages with lateral GaN, the chip size needs to become larger, which is not feasible from a scaling perspective.

Several industry innovators are working to improve the efficiency of GaN devices through advancements such as vertical GaN structures and advanced packaging technologies in lateral structures to make GaN FETs usable for 800V EV applications. For example, Odyssey Semiconductor recently demonstrated its 1200V vertical (GaN on GaN) device, and engineering samples are expected to be tested by several automotive OEMs in 2023. Vertical GaN structures bring GaN's high switching efficiency advantages in the smallest possible size Chip sizes are associated with voltage and power levels currently addressed only by Si and SiC. Likewise, NexGen Power Systems recently tested its commercially viable 1,200V vertical GaN Fin-JFET using VisIC’s D3GaN (direct drive d-mode) technology. In early 2022, Transphorm demonstrated its 1200V lateral GaN power transistor, with samples expected to be available in 2023. Such technology developments and buzz highlight GaN’s potential as a market disruptor for electric vehicle applications.

The move to 800V EV is inevitable for obvious reasons, but it is also important to note that 400V systems will not be phased out. 400V EVs are expected to be used in cost-sensitive markets. Additionally, even EVs with 400V battery systems may follow Tesla's lead (the SiC modules in its 400V Tesla Model 3) in transitioning to SiC in the short term as countries around the world set new efficiency targets. For example, China released car sales targets from 2021 to 2023 in 2020, which lowered the maximum acceptable energy consumption of some electric vehicles from about 23kW/100kms to about 18kW/100kms. SiC offers nearly 5-10% greater mileage per kWh due to its heat resistance, low on-resistance and faster switching speed than Si. Therefore, companies such as ROHM Semiconductor and STMicroelectronics also provide SiC solutions for 400V EVs.

As SiC becomes an important trend in electric vehicles, chip manufacturers urgently need to conduct better planning to ensure optimal production capacity and a robust supply chain to cope with the upcoming surge in SiC for electric vehicles. The shift from planar to trench structures, the move from 6-inch to 8-inch wafers, and capacity expansion initiatives will bring cost and performance advantages. In addition, in order to improve the SiC wafer defect problem and achieve self-sufficiency in the SiC supply chain, the industry is witnessing a vertical integration trend of semiconductor companies acquiring supply-side companies. Additionally, automotive OEMs are venturing into designing and manufacturing their own traction inverters, thereby establishing direct relationships with chip manufacturers, which is not common in traditional industries.

As the electric vehicle industry moves from 400V to 800V battery systems, the move to WBG semiconductors seems inevitable. Due to its technical specifications, SiC is currently a perfect choice for car manufacturers. GaN is a relatively new niche technology that currently has limited use in EV power applications due to its low thermal conductivity and lateral structure. However, technological advancements such as vertical GaN structures and advanced packaging are expected to provide significant market opportunities for GaN in 800V EV traction inverters.

In the short term, high-end 400V EVs may also adopt WBG-based traction inverters due to stringent emission and efficiency standards set by countries around the world. In the long term, entry-level and mid-level 400V EVs, mainly in cost-sensitive markets, will eventually transition to SiC and GaN technologies.

The industry is witnessing a radical change in traditional supply relationships. Automotive OEMs and Tier 1 suppliers are looking to secure their component and chip supplies through strategic collaborations and direct relationships with chip manufacturers.

Additionally, automakers are moving towards designing traction inverters in-house instead of relying on Tier 1 suppliers. In addition, chipmakers are vertically integrated by acquiring supply-side companies to better control supply quality and product development. The expected speed of the transition of electric vehicles from 400V to 800V battery systems is unprecedented in the industry, and the semiconductor field plays a vital role in realizing this process.

With silicon no longer able to meet the performance demands of electric vehicles, the competition for WBG semiconductors is full steam ahead. Device technologies, whether Si, SiC or GaN, will find ways to sustain the market transition and will coexist, with no technology completely replacing another. What remains to be seen is who eats how much of each other’s pie!

Note: The opinions and findings in this article are the result of extensive research conducted by Frost & Sullivan's internal semiconductor practice on Global Electric Vehicle Semiconductor Growth Opportunities (Research Code: K725) and its other semiconductor-based research. Author Navdeep Saboo, industry analyst at Frost & Sullivan.