The electrification of heavy-duty transport presents unique engineering challenges. Trucks operating in demanding duty cycles require powertrain systems capable of delivering high efficiency, reliability and durability under extreme operating conditions. Within this context, the RHODaS project has developed and validated an advanced Integrated Motor Drive (IMD) system designed specifically for next-generation electric trucks.
The project’s latest research results present a comprehensive testing and standardisation framework for the RHODaS high-power inverter and IMD system, forming part of an innovative e-axle powertrain.
An Integrated e-Axle Architecture for Electric Trucks
At the centre of the RHODaS powertrain concept is a highly integrated e-axle designed for heavy-duty electric vehicles in the 12–16 tonne category. The system combines several key technologies into a compact and efficient architecture.
The e-axle integrates a hybrid high-power T-type multilevel inverter, an electric motor, and a two-speed gearbox. These components are supported by an IoT-based monitoring platform that enables real-time data acquisition and system supervision. This integration not only reduces system complexity but also contributes to improved energy efficiency, performance and reliability.
A defining feature of the RHODaS inverter is its use of wide bandgap semiconductor technologies. By combining Gallium Nitride (GaN) and Silicon Carbide (SiC) devices in a modular architecture, the inverter achieves high switching performance while maintaining excellent thermal behaviour and compact system design. These characteristics are particularly important in heavy-duty applications, where power density and thermal management are critical design constraints.
Digital Monitoring and Predictive Capabilities
Beyond hardware innovation, RHODaS incorporates digital technologies to enhance system performance and operational reliability. The integrated IoT platform enables continuous monitoring of key parameters across the e-axle system, providing real-time operational data and diagnostic insights.
This capability supports predictive maintenance strategies by allowing early detection of potential faults or performance deviations. In practice, such digital tools can improve fleet management, reduce downtime and optimise vehicle operation over the lifetime of the system.
The integration of monitoring and data analytics also contributes to improved safety and operational transparency, supporting the broader digitalisation trends shaping the automotive and transport sectors.
Comprehensive Laboratory Testing
To validate the performance of the RHODaS powertrain system, extensive experimental testing was carried out at the mechanical testing laboratory of BOSMAL Automotive Research and Development Institute. The testing campaign was designed to evaluate the behaviour of the inverter and IMD under realistic operating conditions representative of heavy-duty vehicle use.
The test programme included detailed efficiency mapping, enabling the project team to characterise the performance of the inverter across a wide range of loads and operating points. Additional tests analysed temperature rise during high-power operation, confirming the effectiveness of the system’s thermal management and cooling design.
Regenerative braking capability was also evaluated, demonstrating the system’s ability to recover and reuse energy during vehicle deceleration. This function plays an important role in improving overall vehicle energy efficiency, particularly in urban and mixed driving environments.
Further tests examined electrical harmonics and power quality to ensure stable and reliable inverter operation. Finally, simulated driving cycles were implemented to replicate real-world vehicle conditions, allowing researchers to observe system behaviour during representative heavy-duty transport scenarios.
High Efficiency and Robust Thermal Performance
The testing results confirm the strong performance of the RHODaS inverter architecture. Under certain operating conditions, the system achieved efficiency levels of up to 99.31%, demonstrating the advantages of combining advanced power electronics with optimised system integration.
Thermal imaging analysis provided additional confirmation of the inverter’s robustness. Even during high-power operation, temperature distributions remained within safe operational limits, validating the design of the cooling system and overall thermal management strategy.
These results are particularly significant for heavy-duty electric vehicles, where sustained high loads and demanding duty cycles place considerable stress on power electronics and drivetrain components.
Towards Standardised Testing for Heavy-Duty Inverters
In addition to validating the RHODaS technology, the research highlights the need for harmonised testing methodologies for high-power automotive inverters used in heavy-duty vehicles. Currently, testing procedures and performance benchmarks can vary across laboratories and manufacturers.
The RHODaS report therefore proposes a structured approach to testing and evaluation that could contribute to the development of standardised protocols for heavy-duty electric powertrain components. Such standards are essential to ensure consistent performance verification, safety and reliability as electrification expands across the commercial vehicle sector.
Establishing common testing frameworks will also facilitate technology comparison, certification processes and faster industrial adoption of next-generation power electronics.
Driving the Future of Heavy-Duty Electric Transport
The testing and validation work carried out within RHODaS represents an important step forward in the development of high-performance electric powertrains for heavy-duty vehicles. By combining advanced semiconductor technologies, integrated system architecture, digital monitoring and rigorous experimental testing, the project demonstrates the feasibility of highly efficient and reliable e-axle solutions.
As the transport sector accelerates its transition toward zero-emission mobility, innovations such as the RHODaS Integrated Motor Drive will play a critical role in enabling clean, efficient and competitive electric freight transport.
Through its research results and contributions to future standardisation efforts, RHODaS is helping to establish new benchmarks for performance, efficiency and reliability in the electrification of heavy-duty mobility.