1. Background

The automotive industry is a major source of global greenhouse gas emissions. As the number of vehicles in China continues to increase, reducing emissions in this sector is a critical part of reaching carbon neutrality and peak carbon targets. China’s achievements in new energy development are widely recognized, laying a solid foundation and providing essential support for these goals. Given the carbon neutrality and peak carbon context, developing the new energy vehicle (NEV) industry is necessary. As an important segment of NEVs, new energy commercial vehicles are encountering both opportunities and challenges.

Since commercial vehicles are often used for long-distance travel, they require extended driving ranges and efficient, convenient charging methods. Charging technology is one of the key factors influencing the practicality of new energy commercial vehicles. This article focuses on the current state and analysis of fast charging while parked and charging while driving.

2. Status of New Energy Commercial Vehicles

Like passenger vehicles, commercial vehicles can be classified into several types, including Hybrid Electric Vehicles (HEV), Plug-in Hybrid Electric Vehicles (PHEV), Battery Electric Vehicles (EV/BEV, including solar-powered vehicles), Fuel Cell Electric Vehicles (FCEV), and other forms of new energy vehicles (such as vehicles using high-efficiency storage devices like supercapacitors and flywheels).

1. HEVs

· HEVs reduce fuel costs, but vehicle prices are generally higher, so fuel savings are limited.

2. BEVs and PHEVs

· Long-range requirements for commercial vehicles remain unmet.

· Necessary charging time impacts the vehicle’s overall usability, failing to match the convenience of fuel vehicles.

· Battery installations reduce commercial vehicles' maximum payload capacity (in terms of weight and volume).

· Battery performance is significantly affected by environmental temperature due to battery charge/discharge characteristics.

· Commercial vehicle batteries have large storage capacities, resulting in longer charging times.

3. FCEVs

· The high cost of hydrogen fuel vehicles is a barrier. Although FCEVs offer longer ranges than BEVs, hydrogen is expensive, partly due to production costs.

· Infrastructure, like hydrogen refueling stations, is also limited. Only 59 hydrogen refueling stations are operational in China, with 53 under construction and 20 in planning, highlighting slow progress.

· Hydrogen production often involves high emissions. Though FCEVs are emission-free during operation, producing hydrogen typically relies on burning fossil fuels (a process known as steam reforming), which limits environmental benefits.

3. Current Development Trends in New Energy Commercial Vehicles

Solutions to the above issues for BEVs and PHEVs include increasing battery energy density, improving braking energy recovery efficiency, and reducing the cost of peripheral vehicle equipment. Another approach is to reduce onboard battery capacity by improving external power supply methods, i.e., fast charging while stationary and charging while in motion. The following sections introduce these two technology development directions.

3.1 Fast Charging While Stationary

Apart from manual fast charging, fast charging while stationary includes horizontal plug-in, pantograph, stationary wireless power transfer (SWPT), and battery swapping systems. Key characteristics of each method are summarized below.

Horizontal Plug-in: This method provides high charging output and efficiency but requires compatibility with charging stations, limiting charging site flexibility and preventing compatibility with passenger vehicles. Integrating the plug-in structure into the vehicle’s mass-produced body increases material costs.

Pantograph: Early electric commercial vehicles, such as trams, used a pantograph system to collect power from overhead lines. Like the horizontal plug-in, it has spatial limitations and lacks compatibility with passenger vehicles.

Stationary Wireless Power Transfer (SWPT): Capable of outputting up to 200kW, SWPT offers lower transmission efficiency than contact-based systems. Foreign manufacturers like BMW and McLaren have begun small-scale applications, while companies like Volkswagen, FCA, Audi, and McLaren are in the pre-research and mass-production stages. Safety concerns related to metal debris between coils require specific protection measures. The technology is gaining attention in China, especially in combination with automated parking.

Battery Swapping: In a battery-swapping system, pre-charged and inspected batteries are installed into vehicles, reducing downtime to under three minutes. Although this system provides a convenient alternative, infrastructure investments for automatic battery swap stations are high, and battery storage poses fire risks. Commercial and passenger vehicle swap stations cannot be shared.

3.2 Charging While Driving

Electric Road Systems (ERS) have developed rapidly over the last decade and provide dynamic power transmission between roads and vehicles. ERS encompasses inductive (wireless), conductive overhead, and conductive rail options, each offering similar functions but with distinct characteristics. The following sections summarize each type:

Overhead: Siemens developed an overhead charging system that outputs 600kW with over 97% efficiency. A pantograph on top of the vehicle extends to connect with overhead lines, transferring power for direct motor drive or battery charging. Infrastructure costs are high, but compatibility with passenger vehicles is possible.

Side Roller: Developed by Honda, this system provides 450kW output with around 95% efficiency. It uses side-mounted rollers on vehicles that connect with roadside infrastructure, offering lower infrastructure costs than wireless systems.

Ground Rail: This system places conductive rails on the road surface, delivering 240kW output at up to 97% efficiency. Safety measures are necessary to prevent accidental contact. Infrastructure costs range from 2.8 to 9.5 million RMB per kilometer, with compatibility for both commercial and passenger vehicles.

Dynamic Wireless Power Transfer (DWPT): DWPT systems use embedded electromagnetic coils for wireless charging, achieving over 92% efficiency. However, long-term exposure to electromagnetic fields requires further study. Infrastructure costs range from 5.1 to 29 million RMB per kilometer.

Summary

In terms of practicality, short-distance vehicles, like light delivery trucks and city buses, are better suited for BEVs with random or battery-swapping charging. For long-distance transport, hybrid options (HEV, BEV, PHEV) are more suitable. Battery swapping is ideal for light vehicles with fixed routes, where charging downtime is impractical. Wireless charging, though still limited by infrastructure, offers high convenience, and dynamic wireless charging has matured significantly, poised to boost market adoption as infrastructure develops.