Global emission limits and a larger demand for sustainability have led to a significant focus by OEMs to electrify off-highway vehicles to achieve zero-emission standards. However, electrification poses significant challenges in regard to thermal management. Efficiently dissipating heat generated by electric machines is vital to ensure optimal performance and longevity of off-highway vehicles.

The Importance of Thermal Management in OHVs

Electric machines within off-highway vehicles operate under strenuous conditions, subjected to variable loads and harsh environments. These factors contribute to significant heat generation within components such as motors, inverters, and battery packs. The excessive heat can lead to decreased efficiency, accelerated wear, and even catastrophic failures if not properly managed. 

Advanced Cooling Techniques

Traditional air cooling methods can be ineffective for modern electric off-highway vehicles due to their limited heat dissipation capacity. As a result, more advanced cooling techniques are being explored and implemented:

• Liquid Cooling: Utilising coolant fluids to transfer heat away from critical components, liquid cooling offers superior thermal conductivity compared to air. This method is particularly effective for high-power-density machines.
• Direct Oil Cooling: By circulating oil directly over heat-generating parts, this technique enhances heat extraction and also serves as a lubricant, reducing mechanical losses.
• Heat Pipes and Vapor Chambers: These passive cooling devices use phase-change principles to efficiently spread heat from hotspots to cooler areas, maintaining temperature uniformity.

Design Considerations for Thermal Management

Planning for thermal management strategies is important from the beginning of the design process of an electric vehicle. Things to consider include:

• Material Selection: Employing materials with high thermal conductivity, such as copper and aluminium, facilitates efficient heat transfer.
• Geometric Optimization: Designing components with optimised shapes enhances the  surface area for heat dissipation and allows for better airflow or coolant distribution.
• Integration of Cooling Channels: Incorporating internal cooling channels within motor housings or stators enables direct heat removal from sources, improving overall thermal performance.

Challenges and Future Directions

While advanced cooling techniques offer improved thermal management, they also introduce complexities:

• System Complexity: Integrating sophisticated cooling systems can increase the mechanical complexity of off-highway vehicles, potentially leading to higher maintenance requirements.
• Energy Consumption: Active cooling systems consume additional energy, which may offset some efficiency gains achieved through electrification.

Advanced cooling techniques are being further researched with the aim of developing innovative solutions that balance effective thermal management with system simplicity and energy efficiency. New innovations such as advanced thermal interface materials and smart cooling systems that adapt to operational conditions are helping to develop better and more efficient thermal management techniques. 

In conclusion, as the electrification of off-highway vehicles progresses, addressing thermal management challenges remains critical. Through the adoption of advanced cooling techniques and thoughtful design considerations, the industry can ensure the reliability and efficiency of next-generation electric OHVs.

To discover the latest in innovations and technology for zero-emissions machinery, network with peers and solution providers and attend talks from industry leaders, book your place to attend the 6th Design and Development of Zero-Emissions Off-Highway Machinery Summit will be taking place May 21-22, 2025 in Berlin, Germany.

For more information, click here or email us at info@innovatrix.eu for the event agenda. 

Source:

The Institution of Engineering and Technology