A powerful heart surging with strength

Siemens provided the ELFA powertrain system for Chongqing Hengtong's latest pollution-free, zero-emission, fast-charging pure electric bus, essentially giving the vehicle a powerful heart and providing a continuous source of power for long-distance travel and overcoming rugged road conditions. The bus has already completed trial runs in the Jiuzhaigou scenic area, overcoming challenging road conditions such as sharp bends and steep inclines, and completing a 12-hour, 463-kilometer run. It has become the first pure electric large bus in China to operate continuously for an extended period and distance, traversing mountains at an altitude of over 3,600 meters to reach a high-altitude tourist area.
With the increasing consumption of fossil fuels and the severity of exhaust emissions, green and environmentally friendly pure electric vehicles have become a major trend in the automotive industry. Major international automakers are vigorously promoting the development of electric vehicles, aiming to reduce the current automotive energy structure's reliance on fossil fuels and, as a green and clean energy source, significantly reduce environmental pollution. Chongqing Hengtong Bus Co., Ltd. (hereinafter referred to as Hengtong) is one of China's largest professional urban bus manufacturers and a pioneer and promoter of urban bus manufacturing in New China. To practice its commitment to environmental protection and energy conservation, the company has decided to implement pure electric tourist buses in the Jiuzhaigou Scenic Area and has selected Siemens as its powertrain system supplier.
This pure electric bus has completed its trial operation in the Jiuzhaigou scenic area. Compared with diesel-powered buses, it not only performs comparably in acceleration but also boasts unparalleled advantages. First, it is energy-saving and environmentally friendly, with zero emissions and no pollution. Second, it has strong endurance and fast charging speed. This bus traveled from Chengdu to Jiuzhaigou, stopping briefly four times for charging, and drove continuously for almost 12 hours, becoming the first pure electric large bus in China to traverse a plateau at an altitude of over 3,600 meters. It also set records for the longest continuous driving distance and duration for this type of bus in a single day. Finally, it exhibits superior performance, overcoming the challenging road conditions of the Jiuzhaigou scenic area, including sharp bends and steep slopes such as the "Six Turns" and "Nine Bends."
This powerful functionality is supported by a robust heart – a powertrain system provided by Siemens. To ensure the bus can stably operate while continuously climbing the steep slopes of the Jiuzhaigou scenic area, Siemens provided Hengtong's pure electric bus with an ELFA (Electrical Low Floor Axile) powertrain system. This system includes: one DICO strategy controller, two ELFA ‖ frequency converters, two 85kW traction motors, and one constant-ratio gearbox. Combined with a third-party vehicle controller and battery management system, the equipment delivers exceptional vehicle performance, providing ample power to handle the challenging road conditions on the Chengdu-Jiuzhaigou tourist route.
As a dedicated pure electric large bus for the Jiuzhaigou scenic area, the biggest challenge is that the bus must adapt to the complex mountainous terrain of the scenic area, which involves traversing 3,600 km of high mountains with rugged and undulating road conditions. This is a considerable challenge for both electric and fuel vehicles: on the one hand, there is the need for higher output torque and power, and on the other hand, there is the need to ensure the continuous and reliable operation of the electric bus.
Firstly, the ability to provide high torque and high power output is the result of the coordinated and seamless operation of all components of the ELFA powertrain system. This requires high-precision data control from the DICO drive controller, high-quality power inversion from the ELFA frequency converter, high-performance power output from the traction motor, and high-efficiency energy conversion from the gearbox. The ELFA II frequency converter in the powertrain system is a traction-level frequency converter with strong short-term overload capacity. It can continuously traction for 30 minutes with a 200KVA load and for 1 minute with a 320KVA load. In challenging steep inclines, it can generate powerful thrust, enabling the bus to climb continuously. Experiments have shown that using the Siemens ELFA powertrain system, the bus achieves a gradeability of 24%. Furthermore, the frequency converter provided by Siemens has an IP6K9K protection rating, providing extremely high dust and water resistance, eliminating concerns about wading operations.
In addition to meeting the requirements for buses operating in the high-altitude mountainous environment, they must also have continuous and reliable operating capabilities, be able to carry large numbers of people in scenic areas, and provide passengers with the most comfortable travel experience. This requires the ELFA powertrain system's unique dual-motor redundancy structure. On the one hand, it provides the bus with stronger driving force, ensuring that the bus can easily cope with harsh road conditions and provide strong climbing ability; on the other hand, the redundancy structure ensures that in the event of a failure of one motor, the entire vehicle can still be driven by the other motor alone, maintaining normal and reliable operation.
In addition, the ELFA powertrain system boasts high power density and an extremely compact installation space, providing passengers with a more convenient and comfortable travel experience. However, achieving this is no easy feat, as it requires maximizing output power while simultaneously minimizing the size of all related components to save space for passengers. The ELFA system, a space-saving powertrain solution from Siemens for electric vehicles and a sister solution to Siemens' high-speed rail system, features all products imported directly from Germany. Its superior traction motor manufacturing process results in higher power density, meaning that the effective power generated within the same volume is twice the average level of products in the domestic market. This maximizes space utilization without compromising overall vehicle power performance, ensuring a low chassis design and allowing for comfortable and convenient passenger travel.
Thanks to the excellent design of the ELFA powertrain system, this electric bus achieved an average power consumption of only 0.7 kWh per kilometer under urban bus conditions, maintaining low power consumption while ensuring a strong power supply. Furthermore, the zero emissions of the electric bus perfectly complement the green scenery of Jiuzhaigou Scenic Area with green transportation, allowing tourists to spread the concept of "energy conservation and environmental protection" around the world.
Powered by the Siemens ELFA powertrain system, this newly developed pollution-free, zero-emission, fast-charging pure electric bus successfully completed its trial run in the Jiuzhaigou scenic area. Starting from Chengdu city, it traveled 463 kilometers in 12 consecutive hours, overcoming challenging road conditions including sharp bends and steep inclines, before arriving at Jiuzhaigou. This makes it the first pure electric large bus in China to undertake a continuous, ultra-long-distance, and uninterrupted journey, traversing mountains at an altitude of over 3,600 meters to reach a high-altitude tourist area, marking a significant milestone in the promotion of new energy buses in China.
What's truly impressive is ELFA's efficient power and torque output, continuous and reliable operation, and compact space design. ELFA is also a flexible solution, offering single-motor or dual-motor drive options to suit different operating conditions. It can also be equipped with hybrid or pure electric solutions. The hybrid system can achieve up to 50% fuel savings on board, without being constrained by charging stations or charging time. This project opted for a dual-motor pure electric system. It is thanks to ELFA's powerful core that it unleashes a continuous surge of power, turning mountains into plains and rugged roads into smooth paths! We believe Siemens will pierce through the fog of future energy uncertainties, paving a green road ahead.