In the promotion of NEVs, challenges such as short driving range, difficulty in charging, and slow charging times are prevalent. To address these, increasing the system voltage has become the mainstream approach to improving charging efficiency, as larger currents can cause excessive heat loss in components. Since the electric drive system is a core part of NEVs, enhancing its performance is crucial. Major automotive brands such as Volkswagen, BMW, Mercedes-Benz, BYD, Geely, and Great Wall Motors are all developing high-voltage platforms, with the 800V electric drive system becoming a key area of focus for industry research.

1. Development Trends in 800V High-Voltage Electric Drive Technology

On September 4, 2019, Porsche introduced its first fully electric sports car, the Taycan. The first models, Taycan Turbo S and Taycan Turbo, feature Porsche E-Performance, marking the highest performance within the Taycan series. While most electric vehicles operate at 400V, the Taycan became the first production vehicle with an 800V system. It uses dual motors with all-wheel drive and integrates technology from the Le Mans-winning 919 Hybrid race car. This 800V system offers low energy consumption, an internal boost converter, enhanced continuous output power, higher charging capacity, and reduced system weight. Additionally, the Taycan's dual permanent magnet synchronous motors utilize HairPin winding technology with a slot fill factor of up to 70%. Porsche claims the Taycan can support over 10 launch starts without power derating, thanks to its excellent thermal management.

On December 2, 2020, Hyundai Motor Group unveiled the Electric-Global Modular Platform (E-GMP), which also adopts an 800V electrical architecture. It supports bi-directional charging with a charging power of up to 350kW, allowing an 80% charge in just 18 minutes or 100 km of range in 5 minutes. Hyundai also developed a patented Integrated Charge Control Unit (ICCU) that enables 800V charging through a 400V fast charger. Following Hyundai’s lead, companies like ZF, BYD, Geely, and others have also started developing 800V high-voltage platforms, with mass production expected in 2022.

2. What Are the Advantages of 800V Systems Compared to 400V Systems?

Higher Charging Power & Faster Charging: The 800V system can achieve charging powers up to 400kW, much higher than the approximate 200kW limit of 400V systems. For example, charging a long-range battery (100kWh from 20% to 80%) could take as little as 9 minutes, matching the refueling time of traditional gasoline vehicles.

Lower Fast-Charging Costs: Although there are fast chargers based on 400V systems, 800V systems offer lower costs for high-power charging applications. In the long term, for charging above 150kW, the 800V system demonstrates clear cost advantages.

Lower Charging Losses: With the 800V system, the charging current is lower than in 400V systems, resulting in reduced energy losses in the battery, wiring, and charging stations.

Increased Energy Efficiency During Driving: Vehicles with 800V systems can achieve longer driving ranges with the same battery capacity or reduce battery size for the same range, thus lowering the overall cost. Additionally, the introduction of third-generation silicon carbide (SiC) technology can further reduce energy losses in high-voltage components like the electric drive.

3. What Components Need Upgrading from 400V to 800V?

The shift to an 800V platform requires upgrades to core electric drive components and power devices to handle higher voltage, heat, and power losses.

1. Motor Components

· Shaft Voltage Generation: The motor controller, being a variable frequency power supply, introduces harmonics that cause common-mode voltage, creating shaft voltage at both ends of the motor. This can lead to shaft current, damaging bearings. With the 800V system's SiC inverters, the frequency increases, requiring better insulation and EMC protection in motors to prevent corrosion in bearings.

2. Power Electronics

· Current Si-based IGBT technology, rated for 650V, would need to be upgraded to 1200V for 800V systems. However, this significantly increases switching and conduction losses, making SiC a more efficient alternative. SiC power devices can also be applied in onboard chargers and charging stations, enhancing overall efficiency.

3. Battery

· The limitation in fast charging lies primarily with the battery's negative electrode. Current graphite materials have long ion transmission paths, leading to high polarization and the risk of lithium plating during fast charging. Thus, improvements in battery technology are essential for better fast-charging performance.

4. Connectors & Cables

· The transition to 800V necessitates new connectors and possibly more of them for high-power fast charging interfaces. With increased voltage and reduced current, cables can be made smaller while still ensuring high durability and insulation.

5. Filter Systems

· Filters, such as capacitors and magnetic rings, need to be redesigned to accommodate the different EMC characteristics of an 800V system.

6. Relays

· Relays used in 800V systems require improved voltage endurance, though some current models are already compatible with higher voltages.

In conclusion, 800V high-voltage systems represent a major technological advancement in the NEV industry, providing faster charging, reduced energy losses, and improved driving range. As the industry transitions from 400V to 800V, significant upgrades will be needed across motors, power electronics, batteries, and related components to ensure compatibility and efficiency.