AMT E-Powertrain vs Direct-Drive System for Battery Electric Buses

The shift to battery electric buses (BEBs) has become a central priority for both bus manufacturers and cities focused on reducing emissions and enhancing the sustainability of public transportation. In recent years, some bus manufacturers have transitioned from traditional direct-drive systems to more advanced e-powertrain configurations that incorporate Automated Manual Transmission (AMT) technology. But what does this mean for the performance of electric buses, and how does it impact the overall driving experience?

Direct-Drive System

• Configuration features: Power is directly transmitted from the motor to the rear axle, offering a simple and reliable structure.

• Performance: Good acceleration performance, but limited hill-climbing ability;
• Efficiency: Narrow range of optimal operating speed;
• Cost: Lower cost at low torque; higher cost at high torque
• Comfort: Seamless power delivery with no interruptions
• Reliability: As the complexity of the e-powertrain assembly increases, reliability decreases;
• Weight: Larger overall weight for the same torque output

AMT E-Powertrain System

• Configuration features: Motor torque is transmitted through the gearbox to the rear axle, optimizing both performance and efficiency by adjusting the gear ratios.

• Performance: Acceleration performance is average, but hill-climbing performance is good;
• Efficiency: The range of optimal operating speeds is relatively wide;
• Cost:?The cost is high at low torque, but moderate at high torque;
• Comfort: There is a power interruption during gear shifting;
• Reliability: As the complexity of the e-powertrain assembly increases, reliability decreases;
• Weight: Lower overall weight for the same torque output

Comparison

Not all battery electric buses require an AMT system. When compared to the conventional direct-drive system, electric buses equipped with an AMT powertrain offer both benefits and drawbacks. To illustrate this, let's use a 12-meter bus as an example to compare the power performance of the AMT e-powertrain system versus the direct-drive system:

• Applicable model: 12-meter battery electric bus
• Gross vehicle weight: 18000 kg
• Final drive ratio: 5.375
• Rolling radius: 512 mm
• Frontal area: 6.08 ㎡

1. Appearance

2. Motor Parameters

3. Dynamic Performance

4. Energy Efficiency (Constant Speed)

5. Energy Efficiency (Urban Driving Conditions)

Our AMT E-Powertrain for Commercial Vehicles

We offer e-powertrain systems based on AMT technology, utilizing PMSM for drive. The AMT is co-axially connected to the motor, taking advantage of the gearbox’s speed control and torque-boosting features. This enables a smaller motor to achieve the same performance as a larger direct-drive motor, while also enhancing the vehicle’s adaptability and efficiency.

Our e-powertrain system with AMT ranges from 60 kW to 550 kW, making it suitable for applications in buses, trucks, heavy commercial vehicles, municipal vehicles, and loaders. Currently, our powertrain systems have been supplied in bulk to various bus chassis manufacturers, such as Zhongtong, Golden Dragon, Foton, etc.?

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