EV Engineering & Infrastructure

Designing EV powertrains for high voltage and ultra-fast charging

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Electric vehicle (EV) powertrains comprise the components that convert stored electrical energy into mechanical motion. These systems span the inverter, electric motor, single-speed gear reduction, and control electronics. Powertrains also integrate dc-dc converters to step down high-voltage dc for low-voltage systems, along with batteries, onboard chargers, and vehicle control units (VCUs).

This article explores how higher-voltage EVs are transforming powertrain architectures, bridging voltage gaps, and efficiently managing increased thermal load. It also discusses the role of silicon carbide (SiC) in driving efficiency in high-voltage powertrains and highlights how gallium nitride (GaN) boosts power density and conversion performance in 400-V systems. Lastly, it covers the engineering and safety challenges of scaling to 1,000 V EV platforms and beyond.

Transforming powertrain architectures

Higher-voltage EV architectures are transforming powertrain design, delivering significant efficiency gains and enabling faster charging. While many EVs still operate at 400 V, some manufacturers are transitioning to 800-V platforms.

The Porsche Taycan (Figure 1) and Hyundai Ioniq 5 feature 800-V systems, while the Lucid Air runs at 900 V, and the Tesla Semi adopts the 1,000V+ Megawatt Charging System (MCS) standard.

Figure 1. The 800-V Taycan Turbo GT. (Image: Porsche)

Increasing voltage reduces current for a given power level, minimizing resistive losses, lowering thermal load, and enabling the use of thinner cables and more compact motors. Doubling voltage from 400 to 800 V can halve charging time without increasing current. Smaller cable cross-sections also reduce vehicle weight, improving range and handling. Supporting these high-voltage powertrains requires upgraded components, including inverters, dc-dc converters, and advanced thermal management systems.

Bridging voltage gaps and managing thermal load

Ultra-fast charging is now a key design consideration for many EV manufacturers. Chargers rated at 350 kW and above can deliver 80% of battery capacity in under 20 minutes. BYD’s 1,000V Super E-Platform targets 1,000-kW charging, enabling up to 400 km of range in just five minutes.

As shown in Figure 2, BYD’s all-liquid-cooled Megawatt Flash Charging terminal system supports a maximum output of 1,360 kW.

Figure 2. BYD’s all-liquid-cooled Megawatt Flash Charging terminal system, with a maximum output capacity of up to 1360kW. (Image: BYD)

To support 800-V fast charging, EV powertrains must safely interoperate with high-voltage charging stations while managing internal energy conversion. Since most public infrastructure still operates at 400 V, onboard dc-dc converters are required to bridge the voltage gap.

The powertrain must also coordinate closely with battery and thermal management systems to handle rapid energy transfer without degradation.

Higher-voltage platforms also support bidirectional charging through integrated bidirectional dc-dc converters. In vehicle-to-grid (V2G) applications, the powertrain’s inverter and control systems regulate energy flow back to the grid, supporting load balancing and energy reuse.

Modular powertrain designs allow manufacturers to scale voltage levels based on vehicle class and cost targets. For example, Hyundai’s 800-V E-GMP platform integrates bidirectional functionality directly into the inverter.

How SiC drives efficiency in high-voltage powertrains

Many automakers (such as Tesla, Hyundai, and Porsche) now rely on silicon carbide (SiC) semiconductors to support higher-voltage architectures and faster charging. As shown in Figure 3, SiC enables higher switching frequencies and greater power density while significantly reducing power conversion losses.

Figure 3. Infineon CoolSiC MOSFETs enable efficient and compact power conversion in high-voltage EV systems. (Image: Infineon)

These characteristics allow SiC to replace conventional silicon in key powertrain components, such as inverters, dc-dc converters, and onboard chargers.

In traction inverters, SiC devices can reduce power conversion losses by over 40% compared to silicon insulated-gate bipolar transistors (IGBTs), contributing to a seven to ten percent increase in driving range. They also support fast charging by handling higher current throughput without overheating.

SiC’s material advantages include higher thermal conductivity, lower on-resistance, and the ability to tolerate junction temperatures above 175° C, with some devices rated up to 200° C. These properties reduce dependence on bulky cooling systems and help improve overall efficiency.

Higher switching frequencies also allow EV manufacturers to shrink magnetic components in converters by 30 to 60%, supporting more compact and lightweight designs.

Efficiency gains are especially important in 800-V powertrain systems, where even minor improvements in conversion performance can result in significant benefits. SiC-based inverters exceed 95% efficiency, and onboard chargers can surpass 96%, minimizing energy waste during both operation and charging.

Boosting power density and efficiency with GaN devices

While SiC is widely used in high-voltage applications such as 800-V traction inverters and onboard chargers, GaN is emerging as a key enabler of high-efficiency power conversion in 400-V EV powertrains. Far exceeding silicon’s 20 kHz, GaN devices switch at frequencies above 500 kHz, minimizing switching losses and enabling more compact, lightweight designs.

GaN also demonstrates lower conduction losses, reducing thermal load and improving overall powertrain efficiency. In traction inverters, GaN’s fast switching speeds (up to 150 V/ns) support near-lossless dc-ac conversion, optimizing motor efficiency and reducing energy loss.

In dc-dc converters and onboard chargers, GaN can reduce power losses by up to 80% compared to silicon, reaching efficiencies as high as 96.5%. As shown in Figure 4, hybrid designs such as ICeGaN optimize efficiency by combining GaN’s low-loss switching at light loads with the high-current handling capabilities of IGBTs.

Figure 4. The ICeGaN Combo, a hybrid design combining a GaN HEMT IC with an IGBT for optimized efficiency in EV applications. (Image: Cambridge GaN Devices)

GaN also supports high power density, up to 3.8 kW/L in onboard chargers, allowing manufacturers to reduce component size and system weight. Lower heat output reduces cooling demands, limiting the energy diverted from the battery for thermal management.

High-voltage, high-complexity: challenges of 1,000V EV Systems
Key components, such as inverters, dc-dc converters, and onboard chargers, must be rated for higher voltages, increasing cost and limiting availability. Dual-voltage compatibility may also be necessary to interface with existing 400-V charging infrastructure, adding onboard complexity.

Efficient operation at these voltages typically relies on SiC MOSFETs, which outperform traditional silicon devices at a higher cost.

Additional design challenges include:

  • Post-crash discharge safety: Stored energy in 1,000-V systems is significantly higher than in lower-voltage designs. Meeting safety thresholds, such as reducing voltage to below 60 V within five seconds after a crash, requires multiple discharge units or self-discharging components.
  • Electromagnetic interference (EMI): The faster switching speeds of SiC inverters increase EMI risk, necessitating advanced shielding and filtering to protect vehicle electronics and motor insulation.
  • Component miniaturization limits: Higher voltages demand greater physical clearances to prevent arcing, complicating efforts to reduce component size while maintaining compliance with isolation and safety standards.
  • Battery management complexity: Increased cell counts in high-voltage battery packs require more advanced battery management systems (BMS), raising system cost.
  • Thermal management: Fast-charging 1,000-V batteries generate substantial heat and need robust cooling systems that compete with cabin climate control for limited thermal capacity.

Summary

High-voltage EVs operating in the 800 to 1,000-V range are rapidly reshaping powertrain architectures. To minimize conversion losses, manage voltage compatibility, and handle increased thermal loads, many EV manufacturers are replacing traditional silicon-based semiconductors with SiC components in high-voltage powertrains.

In 400-V systems, some are turning to GaN in place of silicon to boost power density and optimize energy conversion efficiency.

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